Friday, January 27, 2012
Fact, Fiction or Opinion (cont.)
By Craig DeWitt
One aspect of an inspection is the background information. This information is usually collected by talking to other parties such as the homeowner, installer or builder. Is this information fact, fiction or opinion? How much of it can be used in reaching a conclusion and cause? If you ever end up in court, you will hear that much of that kind of information is hearsay, and not information you can present. It’s also not something on which you should base a conclusion.
For instance, the builder tells you that he put a vapor barrier under the slab. Now the slab is wet. Can you use the builder's statement to rule out below-grade moisture? You shouldn't, because at this point it may not be fact. Worse even is that the homeowner told you that the builder told her that he put a vapor barrier under the slab. The only way to determine if, in fact, there is a vapor barrier under the slab is to find it out for yourself. Construction photos might work, but cutting a hole and eyeballing the vapor barrier is better.
So basically, everything in the background information is opinion unless you have proof that it is fact or not. In many cases, people don't tell the truth, so some of your background information is fiction. A homeowner once told me that the floors were never wet-mopped. The floor looked like it had been wet-mopped. So I started looking for other possible causes, until the cleaning lady came in and started wet-mopping the floor in front of me.
Sometimes background information can be used, if there is documentation to back it up. Delivery tickets and invoices can support acclimation and installation times. If the homeowner said the floors were left in the house to acclimate for five days, and the manufacturer's instructions call for 10 days of acclimation, can we say the floors were not properly acclimated? Based on her statement, we had better not say, "The floors were not properly acclimated." But we could say, "Based on Mrs. Homeowner's comments, the floors were not acclimated to manufacturer's instructions."
Speaking of which, is acclimation even an issue with the floor you’re inspecting? Or, is it irrelevant (in which case we shouldn't even mention it)? If acclimation is an issue with the floor, does the background information tell us anything? No, the floor tells us whether it was properly acclimated or not.
I rarely use background information in forming a conclusion and cause. When I do use it, I do everything I can to verify that information first. People don't always tell the truth, but floors don't lie. Let the floor tell you what is happening.
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Tuesday, January 10, 2012
Inspector Reports: Fact, Fiction or Opinion?
By Craig DeWitt
Fact, fiction or opinion: In writing and evaluating reports, I am often faced with determining whether something is fact or fiction, or just an opinion. Some "facts," like my "grits come from grit palm" statement from last week's blog, are easy to verify or disprove with a simple web search. On the other hand, we've all faced an unusual name for a product or material, and "grit palm" could be someone's proprietary name for their material.
"The floor is cupped because of subfloor moisture." Is that fact, fiction, or opinion? In my opinion, it could be any of those. In fact, it could be any of those. One of our jobs as an inspector is to collect, analyze, interpret and present data such that we separate fact from fiction. Done correctly, our opinion doesn't really enter into things. Because if you have an opinion, I might have a different opinion.
How about "Using a XXXX moisture meter, the floor was 8% MC, the subflooring was 14% MC and the slab was 80% RH. This exceeds industry standards. The cupping is therefore the result of excessive subfloor moisture." Which of this is fact, fiction and opinion? First, the meter could have read 8% and 14%, but are they actually the MC of the materials? The numbers could easily be false because of the way meters work and how we use them.
Then I dare say that industry standards are opinions. In the opinion of the industry, if you do/don't do this, you will have problems. Some of us have talked about this many times in the past: Just because you violate industry standards doesn't mean your floor will fail. But it can be a fact that you followed industry standards or not.
Then the last statement, "Cupping is the result of…" could be fact, fiction or opinion. If it’s based solely on an industry standard, it is based on opinion (and we inspectors certainly have our opinions). Actually, if it is based on the 8% and 14% numbers, that could be opinion also. A board cups as a result of a top-to-bottom difference in moisture, or possibly, as Howard recently clarified, because of differential movement in a board as it changes moisture content. How about if the MC of the floor and subflooring were still 8% and 14% two months after the floor was disassembled and leaned against the wall? How does that change our facts and opinions?
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Thursday, January 05, 2012
A Closer Look at Bamboo & Palm
By Craig DeWitt
My house has been below 30% RH for over a week now. A couple gaps have opened in my hickory floor, but nothing in the oak floors.
My last post about a floor installed over a slab and this one will set the stage for some upcoming bits about inspections.
A year or so ago, I mentioned seeing palm floors in Fiji. My buddy, Genia, mentioned a palm floor that she looked at more recently in a forum post. Palm is one of those kinds of groups like oak or pine where there are lots of different species in the group. In palms, we have coconut palms (where coconuts come from), and date palms (where dates come from). The SC tree is the palmetto palm. The floor I looked at recently was a grit palm (where grits come from.) If you're not from the South, you may not be familiar with grits. But shrimp and grits are tasty, as are grits with butter or syrup.
Palm wood looks a lot like bamboo, but is big enough that it doesn't need to be glued together to be big enough to use as flooring. Here are photos of the end grain of a piece of bamboo…
… and palm. The pictures are about 10x magnification. Both don't really have growth rings or grain that you would find in typical woods.
The next thing we see will probably be banana wood flooring.
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Wednesday, December 28, 2011
Board Cuts, Moisture Changes & Cupping
By Howard Brickman
This blog will explore simple moisture content changes of individual S4S RO boards and how that would be related to changes in shape and how that could be related to cupping. But first…
A quick review of the initial article: Cupping = boards that are concave on the face. I have initially proposed six experiments where variables are limited to see which actions cause which reactions. The list of experiments is summarized below, but you can see the more complete explanations in my Dec. 11 blog link.
Experiment 1: 10 S4S RO boards ¾” x 4” x 72” edge-to-edge into a panel ¾” x 40” x 72”. Place and tighten pipe clamps at 3” intervals across the 40” dimension. What happens?
Experiment 2: 10 pieces RO flooring ¾” x 4” x 72” edge-to-edge into a panel ¾” x 40” x 72”. Place and tighten pipe clamps at 3” intervals across the 40” dimension. What happens?
Experiment 3: 10 pieces RO flooring ¾” x 4” x 72”, MC 6%-8%, nailed to ¾” plywood with a MC of 6%-8%. Put a wet towel on the face of the boards with 6-mil ploy over towel. What happens?
Experiment 4: 10 pieces RO flooring ¾” x 4” x 72”, MC 6%-8%, nailed to ¾” plywood with a MC of 14%-16%. 6-mil poly on underside of plywood. What happens?
Experiment 5: 10 pieces RO flooring ¾” x 4” x 72”, MC 14%-16%, nailed to ¾” plywood with a MC of 6%-8%. 6-mil poly on underside of plywood. What happens?
Experiment 6: 10 pieces RO flooring ¾” x 4” x 72”, MC 14%-16%, nailed to ¾” plywood with a MC of 14%-16%. 6-mil poly on underside of plywood. What happens?
We are going to discuss the effect of a simple change in MC of individual RO boards. Since I did not include this in my original list of experiments, we will call this Experiment 1A. There is a cool graphic in the Wood Handbook that shows shape changes in boards with varying grain orientations:
(Note that you can download the chapters of the Wood Handbook for free here; you can download Chapter 4: Moisture Relations and Physical Properties of Wood by clicking the illustration above.)
We are going to keep this simple and use a very slow and gradual change in MC with very small differences in MC within the board, which eliminates the effect of having large differences in MC on opposite sides of the board. Again, we are controlling conditions, so that we will only see what happens when a single factor causes the individual boards to change shape. These boards are unrestrained so that we don’t have any additional factors related to installation to worry about.
The intent of this experiment is to see what effect a simple gradual change in MC would have on the shape of individual boards without any other compounding factors such as:
- configuration of the tongue and groove edges
- mechanical fasteners along the edges or into the face
- gluing of the boards to a substrate
- configuration of the relief cuts on the bottom surface
We can see that changes in shape after individual solid boards are manufactured are to be expected and would vary depending on the amount of MC change and in conjunction with differences in growth ring orientation between the opposite faces of the boards. Quartersawn (radial) boards shrink and swell less than plainsawn (tangential) boards, so if opposite faces have different shrink/swell factors, voila. If just the occasional board is cupping, then it might be caused by a grain-orientation-related effect. If every board is cupping, it is extremely improbable that it is a grain-orientation issue.
Bonus information: Now remember that we are talking about boards that are completely unrestrained (that means not installed). So if you were to allow wide-plank flooring to “acclimate” under high RH conditions, the individual boards would definitely change size (swelling), and there could also be significant changes in shapes. Would the boards be cupped? Yes and no, because flooring is fed into the molder/matcher with the best-looking face as the exposed face, the orientation of grain would be random. Some boards would be cupped (concave) and some would be convex. Unless there was a really big change in MC, these shape changes would probably not be that noticeable other than some complaints from the installers about varying width and difficulty banging the tongue and groove together.
On a separate note, on Saturday, January 21, I am putting on a one-day seminar on Dyeing Dark Floors at the Bona Regional Training Center in Bridgewater, Mass. Topics will include mixing and applying aniline dyes and which finishes can be applied over dye. E-mail me for information. I need to limit the class to 15. Lunch will be served.
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Monday, December 19, 2011
What Causes Cupping? Experiment 1 Explained
By Howard Brickman
We are going to start deconstructing some of the variables related to cupping and what many people believe are the causes of cupping.
A quick review of the initial post about this. Cupping = boards that are concave on the face. I have initially proposed six experiments where variables are limited so we can see which actions cause which reactions. The list of experiments is summarized below, but you can see the more complete explanations in my Dec. 11 blog post.
Experiment 1: 10 S4S RO boards ¾” x 4” x 72” edge-to-edge into a panel ¾” x 40” x 72”. Place and tighten pipe clamps at 3” intervals across the 40” dimension. What happens?
Experiment 2: 10 pieces RO flooring ¾” x 4” x 72” edge-to-edge into a panel ¾” x 40” x 72”. Place and tighten pipe clamps at 3” intervals across the 40” dimension. What happens?
Experiment 3: 10 pieces RO flooring ¾” x 4” x 72”, MC 6%-8%, nailed to ¾” plywood with a MC of 6%-8%. Put a wet towel on the face of the boards with 6-mil ploy over towel. What happens?
Experiment 4: 10 pieces RO flooring ¾” x 4” x 72”, MC 6%-8%, nailed to ¾” plywood with a MC of 14%-16%. 6-mil poly on underside of plywood. What happens?
Experiment 5: 10 pieces RO flooring ¾” x 4” x 72”, MC 14%-16%, nailed to ¾” plywood with a MC of 6%-8%. 6-mil poly on underside of plywood. What happens?
Experiment 6: 10 pieces RO flooring ¾” x 4” x 72”, MC 14%-16%, nailed to ¾” plywood with a MC of 14%-16%. 6-mil poly on underside of plywood. What happens?
We are going to discuss Experiment 1 in greater detail this week. Here is the expanded description from Dec 11.
Experiment 1: We place 10 S4S red oak boards ¾” x 4” x 72” edge-to-edge, which approximates a panel ¾” x 40” x 72”. Then place pipe clamps at 3” intervals across the 40” dimension and tighten the clamps until a pressure of 200 pounds per square inch is reached. What do you think is going to happen to the shape of the individual boards?
The intent of this experiment is to see what effect pressure would have on the shape of individual boards without any other compounding factors such as:
- changes in moisture content
- configuration of the tongue-and-groove edges
- mechanical fasteners along the edges or into the face
- gluing of the boards to a substrate
- configuration of the relief cuts on the bottom surface
If you were to place adhesive on the edges of the boards before clamping them, you would end up with a pretty good rough panel for fabricating a table top. This is the procedure for making any edge-glued panel out of solid wood (for example, stair treads, shelves, top-bottom-side panels, etc.). A bazillion of these solid wood panels are made this way every week. If the individual boards don’t change shape because of this pressure across the width of the boards, this goes a long way toward refuting the argument that pressure by itself causes cupping. It may be that pressure in conjunction with some other factor(s) may cause cupping. However, based on Experiment 1, which has eliminated all other factors, pressure is not the cause of cupping.
After having proved that cupping is not caused by pressure, we need to start adding some new variables one at a time to see what effect the individual variables have. So, next week we will add the tongue-and-groove to the edges. After all, if you can’t make something happen on purpose, how do you really know what caused it?
Bonus information:
In the Wood Handbook Table 5–3a. Strength Properties of Some Commercially Important Woods Grown in the United States (metric) lists the “Compression Perpendicular to Grain of Red Oak” at 12% MC in the range from 6,000 to 8,600 kPa, which converts to 870 to 1247 psi (Pounds per Square Inch) using the conversion factor of 1 kPa (Kilopascal) = 0.145037738 psi. If the force applied to the pipe clamps is limited to 200 Psi, there should be no crushing where the jaws contact the edge of the panel.
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What's Going on with this Cupped Floor?
By Craig DeWitt
Here's a question related to my fellow blogger Howard Brickman's last post about what causes cupping:
Situation: The wood flooring is cupped with spots that have raised off the slab. The construction from the bottom up is slab, 6-mil poly, two layers of 1/2" plywood stapled together and floating on slab, 15# red rosin paper, 5 & 6" solid red oak stapled to the floating plywood. The slab was 85% RH, the plywood was 14% MC, and the oak was 8% MC. The poly was full of holes from protruding staples.
So, what is happening?
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Sunday, December 11, 2011
What Causes Cupping in Wood Floors?
By Howard Brickman
The official topic of this blog will be an excruciating discussion of the term “cupping” for your consideration. But first…
My apologies for taking so long to get another submission ready, but for me writing is very hard work and extremely time consuming, and I marvel at those gifted individuals who can churn out wonderful written content on a regular schedule. I must admit that I’m not certain that I would be able to increase my output even if I were offered bushel baskets of legal tender to do it on a full-time basis. Time is finite and moves at an increasingly rapid pace. I remember watching the classroom clock as a youngster on Friday afternoons thinking that 4 o’clock would never arrive, and now Friday afternoons pass by faster than the pickets on a fence. But I digress…
If I were going to give an official definition for cupping it would be, “boards that are concave on the face.” There is a common misconception in the wood flooring bidness that all cupping is moisture-related and that pressure that develops due to swelling is the primary cause. Let’s explore some thought experiments.
Experiment 1: We place 10 S4S red oak boards ¾” x 4” x 72” edge-to-edge, which approximates a panel ¾” x 40” x 72”. Then we place pipe clamps at 3” intervals across the 40” dimension and tighten the clamps until a pressure of 200 pounds per square inch is reached. What do you think is going to happen to the shape of the individual boards?
Experiment 2: We place 10 pieces of red oak flooring ¾” x 4” x 72” edge-to-edge, which approximates a panel ¾” x 40” x 72”. Then we place pipe clamps at 3” intervals across the 40” dimension and tighten the clamps until a pressure of 200 pounds per square inch is reached. What do you think is going to happen to the shape of the individual boards?
Experiment 3: We nail 10 pieces of red oak flooring ¾” x 4” x 72” at a MC of 6-8% to a ¾”-thick plywood panel 48” x 72” at a MC of 6-8%. Then we place 1½” deck screws at 3” intervals into the first and the last boards so that they will be prevented from moving. We predrill the oak so that there will be no splitting. Then we place a bath towel on the face of the boards and saturate it with enough water to completely wet the towel but not have water puddling onto the surface of the flooring. Then we put a piece of 6-mil polyethylene over the towel to keep the water from evaporating. What do you think is going to happen to the shape of the individual boards?
Experiment 4: We nail 10 pieces of red oak flooring ¾” x 4” x 72” at a MC of 6-8% to a ¾”-thick plywood panel 48” x 72” at a MC of 14%-16%. Then we place 1½” deck screws at 3” intervals into the first and the last boards so that they will be prevented from moving. We predrill the oak so that there will be no splitting. Then we put a piece of 6-mil polyethylene covering the underside of the plywood to keep the water from evaporating. What do you think is going to happen to the shape of the individual boards?
Experiment 5: We nail 10 pieces of red oak flooring ¾” x 4” x 72” at a MC of 14-16% to a ¾”-thick plywood panel 48” x 72” at a MC of 6-8%. Then we place 1½” deck screws at 3” intervals into the first and the last boards so that they will be prevented from moving. We predrill the oak so that there will be no splitting. Then we put a piece of 6-mil polyethylene covering the underside of the plywood to keep the water from evaporating. What do you think is going to happen to the shape of the individual boards?
Experiment 6: We nail 10 pieces of red oak flooring ¾” x 4” x 72” at a MC of 14-16% to a ¾”-thick plywood panel 48” x 72” at a MC of 14%-16%. Then we place 1½” deck screws at 3” intervals into the first and the last boards so that they will be prevented from moving. We predrill the oak so that there will be no splitting. Then we put a piece of 6-mil polyethylene covering the underside of the plywood to keep the water from evaporating. What do you think is going to happen to the shape of the individual boards?
The great thing about these thought experiments is that we could actually do them. If you had a university or commercial testing company do these for you, it would cost many thousands of dollars. If someone wants to send me $12,479.00, I will do the experiments and send you a report on the results with cool pictures. In my next episode we will start to discuss the individual experiments. I want to thank Don Sgroi for the very thought provoking e-mail, which is the inspiration for what will I think be a very interesting series of blogs.
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Friday, December 02, 2011
When Is Your House Outside the Right Range?
By Craig DeWitt
Friday, December 2, 2011, 9 a.m. in Clemson, S.C.: Conditions in my house were 65 degrees F and 34% RH. It’s Dec. 2 (not even winter yet), South Carolina (classified as a warm, humid climate) and my hardwood floors are exposed to conditions outside what many wood floor warranties and installation and use guidelines allow.
If an inspector showed up then to look at problems with my floors, the report would likely have pinned the floor issues to the house's dry conditions, and therefore owner responsibility. I guess it’s a good thing I have site-finished NOFMA flooring in my house.
So my question today is: When does the RH in your house drop below the 35% RH minimum stated in many wood floor warranties and industry guidelines? Watch your house and let me know.
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Wednesday, November 30, 2011
The Fungus Among Us
By Craig DeWitt
Anyone roller skate these days? I looked at a nice old roller rink recently that would make your teeth chatter. The flooring was cupped pretty badly. The owner made an interesting comment: The floor moved. Or, more precisely, the floor rotated. People skate counter-clockwise. And the force exerted when they made the turns at the ends caused the floor to rotate clockwise. So think about that when you are racking out flooring and doing tongue reversals, and trying to keep the forces pushing the fasteners tighter rather than pushing them loose.
In this situation, much of the problem was related to a wet subfloor. Water from the underside was causing the cupping. And the water was also making the subflooring softer, so fasteners moved more easily. This floor system was very wet. Here's a picture of some fungus I observed under the floor. You can also see a very rusty nail in the upper left corner. We may even have rusted-out flooring fasteners.
Roller skating can be strenuous, which means you warm up nicely… which means you need to keep the place cool for people to be comfortable. And cool isn't a good situation in the warm, humid Southeast U.S. in the summer. Combine that with a big vented crawl space, and we ended up with subfloor moisture issues. The solution is easy, but I don't think the overall repair cost will be very cheap.
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Monday, October 31, 2011
Can We Fix These Dents?
By Craig DeWitt
Some inspections just break my heart. This was a nice old historic home that was being restored. Old furniture was moved out to allow for plaster repair and re-painting, but the piano was simply rolled out of the way. The result was some nice deep tracks across this floor.
I have been on many inspections over the years looking at dents in floors. Some seem to be related to carelessness, like these piano grooves, or accidents, like where something gets dropped. Worn shoes and chair legs cause a lot of dents, as do sand and grit. Dog toenails leave dents and digs.
Many of my dent inspections are related to consumer expectations and sales claims. We as an industry know that wood flooring dents. And some woods dent easier than others. And we know that things consumers do in buildings can and will dent wood floors. So my first question today is: Why do we keep over-selling the hardness properties? Sure, hickory is harder than walnut, and some exotics are even harder. But they will all more than likely dent at some time during their useful life span.
My second question is: Can we fix these piano dents? In many other woodworking areas, wetting a dent can swell the wood and make the dent disappear. Has anyone had success in this kind of situation?
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Monday, October 24, 2011
Calculating Shrink/Swell & Why It Matters
By Howard Brickman
Wood shrinks and swells when it loses and gains moisture content (MC). For example, if a piece of 2¼" wide plainsawn red oak flooring were to decrease in MC from 8% to 5%, the net change in MC would be 3%. Using standard values from the Wood Handbook Table 4-3 Shrinkage Values of Domestic Woods, the net change in dimension would be .021" (2.25" x .086 x .03 / .28 = .021"). Expressed as a fraction, .021" would be between 1/64" (.015625") and 1/32" (.03125").
How is this information useful? Let’s take a real-world scenario and show how a quantitative understanding of dimensional change helps us perform an analysis.
SCENARIO:
We look at a wood floor that we installed last year where the customer has called to complain about gaps between boards. As part of our normal procedure, we look at the surface of the floor to see if individual boards are flat, cupped (concave), or crowned (convex). In this case, the boards are still very flat. Then we determine the size, frequency and distribution of the gaps. We note the minimum and maximum gaps, then we eliminate the smallest and largest gaps to describe the range, which characterizes the majority of the gaps (80-90%). In statistics this is referred as “eliminating the outliers." Now we choose several locations where the gapping is the most severe and begin a series of accurate board-width measurements, along with MC of the individual boards. Our results are:
MC of all of the boards is less than 6%. We estimate the MC at 5% based on interior RH for the last three weeks using Wood Handbook Table 4-2 Moisture Content of Wood in Equilibrium With Stated Temperature and Relative Humidity. The widths of individual boards range from 1/64" to 1/32" less than the manufactured width of 2¼". The gaps are located between every board and range in size from 1/64" to 1/32".
Danger! FORMULA ALERT: IF YOU BECOME SHORT OF BREATH, BREAK OUT IN A COLD SWEAT, AND HAVE DILATED PUPILS WHEN YOU READ FORMULAS, please skip this section of the blog. For you brave souls, let’s proceed.
FIRST FORMULA (Change in Dimension)
Δ D (change in dimension) = Manufactured Width x St (Shrinkage factor from Wood Handbook) x Δ MC / .28
SECOND FORMULA (Change in Moisture Content)
Δ MC = [Δ D x .28] / [ Width x St ]
With these two formulas we can:
1 - Predict the amount that a board will swell or shrink (Δ D) and
2 - Estimate the magnitude of change in MC (Δ MC) based on the current width of the board.
IT’S SAFE TO START READING AGAIN. Danger over.
Now it’s time for some SHRINKAGE RULES:
Rule Numero Uno: If a board is less than its manufactured width, it has lost MC since it was manufactured.
Rule Numero Dos: If a board is exactly its manufactured width, it is at the same MC as at the time of manufacture.
Rule Numero Tres: If a board is greater than its manufactured width, it has gained MC since it was manufactured.
Applying Rule Numero Uno, we know that our boards that are smaller than the manufactured width have lost MC. Using the SECOND FORMULA for Δ MC, we can pretty accurately quantify the change in MC.
For boards that are 1/64" narrower than 2¼", the Δ MC is 2.26%:
Δ MC= [Δ D x .28 ] / [ Width x St ]
Δ MC= [ 1/64" x .28 ] / [ 2.25" x .086 ]
Δ MC= [ .015625" x .28 ] / [ 2.25" x .086 ]
Δ MC= [ .004375 ] / [ .1935 ]
Δ MC= .0226 = 2.26%
For boards that are 1/32" narrower than 2¼", the MC is 4.52%:
Δ MC= [Δ D x .28 ] / [ Width x St ]
Δ MC= [ 1/32" x .28 ] / [ 2.25" x .086 ]
Δ MC= [ .03125" x .28 ] / [ 2.25" x .086 ]
Δ MC= [ .00875 ] / [ .1935 ]
Δ MC= .0452 = 4.52%
If we add the Δ MC to our current 5%, the boards that are 1/64" narrow were originally at 7.26% (5% + 2.26% = 7.26%). The boards that are 1/32" narrow were originally at 9.42% (5% + 4.52% = 9.53%). This allows us to estimate MC at time of manufacture between 7.26% and 9.52%.
I find these quantitative methods to be useful tools when working through the analysis of a wood floor that has evidence of a change (or changes) in MC. In new construction there are frequently several MC changes, starting with the adsorption of excessive moisture from the subfloor, then the eventual drying during the following winter heating season.
Let’s explore how doing all this rigmarole calculating helps with analysis. Let’s change our scenario by a single factor: instead of gaps that range from 1/64" to 1/32", how about gaps that range from 1/32" to 3/64" with individual board shrinkage that ranges from 1/64" to 1/32"? We have already done the calculations on the board shrinkage, but that doesn’t account for the additional size of the gaps. SO… something besides seasonal low interior RH would have to be the cause of the increased size of the gaps. Maybe the flooring was left on the job to “acclimate" and picked up some excessive moisture before it was it was installed? Or… (to be continued)
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Friday, October 21, 2011
What Pest Control Has to Do With Wood Floors
By Craig DeWitt
This week I am in New Orleans at the National Pest Management Association meeting. What, you ask, does pest control have to do with hardwood floors? Well, the pest control industry deals with termites (the topic of my post from last week), as well as many other wood destroying organisms. Those organisms include wood boring beetles of several types, and mold, mildew and wood decay fungi. Those organisms like moisture, and moisture affects hardwood floors.
Pest control industry guidelines cover how to deal with those organisms in, around and under buildings. Those organisms, and their treatment, can affect hardwood floors. So I am here listening, learning, teaching and raising awareness.
When I first got involved with this industry about 20 years ago, guidelines (and some laws) were to increase ventilation if a crawl space had a moisture issue. Eliminating ventilation and adding dehumidifiers were such a foreign ideas that I nearly got run out of the room every time I brought it up. One of the regulatory people I kept pushing disagreed with the sealed/dehumidified approach, but ended up trying it in his own house with rousing success (after the increased ventilation approach failed). Even then, he was hesitant to push for a change in the regulations. Now, 20 years later, there is a whole sub-industry that seals and semi-conditions crawl spaces to control moisture and pests. This approach is becoming more accepted and routine.
Sealing and drying a crawl space can cause changes to a hardwood floor, or help reduce potential future issues. By working with the people who control moisture under floors, hopefully we can keep the unintended hardwood floor issues to a minimum. And the pest control industry is a major player in moisture control.
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Thursday, October 13, 2011
Mystery Bugs in a Rubberwood Floor
By Craig DeWitt
I was asked by a flooring distributor to look at some insect damage to a rubberwood parquet floor. Rubberwood is pretty susceptible to insect attack. Holes were appearing in the surface of the floor, so there was a possibility of an active infestation. The distributor was concerned that the insects were in the whole container of flooring… and that would mean other floors could have the same problem.
The flooring was glued to a slab in a garage that had been converted to living space. A local pest control company had treated the house recently, so termites had been ruled out. I was shown several areas where holes had developed in the floor. The holes were bigger than a powder post beetle hole, and more like a large grub hole. None of the holes obviously continued from one board to the next.
Too big for PPB's, so I could rule them out. Pre-existing insect holes would not connect across multiple boards, so this was still a possibility. Termites wouldn't normally eat all the way to the surface, but I had surface holes. And the house had been treated recently. Some live, foreign bug sounded like a possibility, but I needed to find one.
So, I started taking the floor apart. The first thing I noticed was there were tunnels that extended from board to board. This indicated an active infestation. The next thing I noticed was that the tunnels were through the adhesive. See the V-shaped lines on the floor and back of board:
I followed the tunnels and came to a crack in the slab. A little more poking around, and I uncovered a termite in the slab crack.?
Some of this floor had been covered with a rug, so a termite could have eaten all the way through the surface. Another possibility is that the termite ate all but the surface, and foot pressure then caved in the thin surface layer, opening the hole up. In all, it was a fun investigation, and the distributor was thrilled that the cause was site-specific and not a whole container load. But I didn't find a new, possibly invasive bug like the emerald ash borer.
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Tuesday, October 04, 2011
Do You Need An Alibi?
By Howard Brickman
Only a guilty man needs to have an alibi prepared. Well, you are all guilty of being wood floor guys, so let’s get those alibis ready for prime time. And maybe the process of getting those alibis prepped will also provide a framework for preventing the need for an alibi.
Tool/Equipment List:
- smartphone with camera
- pin-type moisture meter
- black Sharpie Marker
- hammer
- 6d and 8d finish nails
- thermohygrometer
- flashlight
- spiral notebook
- pencils and pens
- string (fluorescent red, blue, green, or yellow)
Stuff To Do (or Not Do):
BEFORE WOOD FLOORING DELIVERY:
- Do not sign a confession, err, I mean contract provided by the general contractor without carefully reviewing the provisions regarding warranties and terms of payment.
- Check moisture content (MC) of the subfloor and inspect the crawl space. Use the Sharpie to write the MC readings directly on the subfloor with the date and your initials. Check MC near windows, plumbing, and doors, and by obvious signs of water staining or moisture intrusions. More readings are better. Record the readings in your notebook.
- Make a label that lists the date, job address, and your name in large block letters for identifying pictures.
- Take pictures of the high-MC readings with your smartphone. It will automatically time, date, and location-stamp the individual photos.
- Take pictures of other non-compliant issues (e.g., missing windows or doors, tile saws on subfloor, unvented torpedo gas/kerosene heaters, etc.)
- Check MC of joists and subfloor in basement and crawl space. Look for water, mold, and mildew, and take pictures.
- Politely request that the GC or building owner correct any problems noted in a brief and concise e-mail (or using another method that documents the content and delivery of the request).
AFTER WOOD FLOORING DELIVERY:
- Check subfloor MC again and verify the any problems observed during previous visits were corrected. If not, document them again.
- Check wood flooring MC on at least 40 boards. Use the Sharpie to write MC and date on the back of boards. Record the readings in your notebook. Reject the flooring if it is outside the range from 6% to 9% MC.
BEFORE INSTALLING THE FLOORING:
- Verify that you document everything that could negatively impact the wood floor. Use the list from the NWFA Installation Guidelines (the PDF is available free online for all NWFA members).
- Communicate one last time to the GC if there are any issues. This is the point at which you need to present your disclaimer or waiver document for the GC to sign or at least acknowledge. This can be a delicate time in the job. You may want to tread lightly, because there is a fine line between being a concerned wood floor professional and being a pain in the neck who aggravates everyone else on the job, especially the GC. You know the deal. There are 10 flooring guys waiting on the sidewalk to come in and do the work without even “noticing” the all of the potential problems.
- If you are called to help out a GC at the “last minute,” take a deep breath and try to figure out why the other floor guy that has been doing his work for the past three years is not available. Is there a money issue? Or what?
- If you are installing a nail-down solid floor, there are some critical steps that help to inoculate you from problems during an inspection: 1) fasteners every 6”; 2) #15 asphalt-saturated felt; 3) Expansion space around the perimeter of the floor.
The typical inspector will check MC, expansion space, nailing, and will want to see your documentation. If you have done due diligence with your prep work, the chances of a job going South are greatly reduced. If it goes South, you should be certain that a really qualified person performs the inspection. The same qualities that make you a competent craftsman apply to the inspection craft: experience in the wood floor craft, experience in performing inspections, referrals from really knowledgeable people in the industry, and the proper temperament to stand up to the pressure from all of the associated parties. In addition to doing everything right, you have to be able to prove that you did everything right. Here’s to hoping that you never need that alibi. Good fortune favors the well prepared.
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Wednesday, September 28, 2011
Where in the World Was Craig?
By Craig DeWitt
Last week's post contained some weather data for Dubai in the United Arab Emirates, home to the world's tallest building, the Burj Khalifa. This building contains about one million square feet (100,000 square meters) of hardwood flooring. That's a lot of potential issues, especially with their outside conditions. The building is complete now, but while it was being built, they did encounter some flooring issues. Some were due to climate control issues. From what I saw on this trip, they have things pretty well under control.
As a comparison of climates, a dew point of 55 F degrees gives you about 50% RH at 75 degrees. So you can vent with that all day, and just add or remove a little heat to maintain 75 degrees. When you get to a dew point of 75 degrees, you have to remove half the water in the air to get to a RH of 50%. We have to do that in the Southeast, and sometimes the Midwest, in the summer. And we often struggle to do it. Places like Tucson have a lower dew point, and may be hotter outside. You would have to add water to get to 50% RH and 75 degrees indoors.
But at a dew point of 86, like they have in Dubai, you have to remove twice as much water as we do in the Southeast U.S. to get to 50% RH at 75 degrees. That's hard to do with standard A/C equipment. And equipment failures can result in wild humidity swings in a hurry. I covered some of this in my Wood Floors and Summer Moisture webinar. I'll cover more in an upcoming Winter Moisture webinar.
Dubai was probably the cleanest city I have been in. The architecture was beautiful. Getting around was easy and inexpensive, but you could spend a lot of money there if you wanted to. The indoor ski slope was pretty neat. And if you think the Mall of America is big, you should see the Mall of the Emirates.
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Tuesday, September 20, 2011
Can You Guess Where This Is?
By Craig DeWitt
Well, Johannes, ya didn't even give people time to think about my last post showing some teak on the deck of a boat with some caulking between the boards. The flooring (or decking) was left unfinished, and in some spots not sanded very well or with torn grain. And on this boat, you spend the whole time barefooted, so some of us got a few splinters. The caulk appears to have been trimmed flush with a razor blade, which would have been a lot of knee time. Has anyone done this system in a residential setting?
Here's a different scenario for you that I observed that same week: Outside dew points vary from 54 degrees F to 84 F within a week's time. (That's nicely dry air to sopping wet air. For comparison, Miami's dew point ranged from 62 F to 78 F this summer.) During this same week, outside temperatures ranged from 84 F to 107 F, and relative humidity levels ranged from 84% to 17%. Now you need to install floors that can survive this ventilation air. (And you must have ventilation air.) To maintain 35-55% RH indoors, you could use an air conditioner, swamp cooler, dehumidifier and/or humidifier, and some good controls to run the appropriate equipment, essentially depending on which way the wind is blowing. Can you guess where this is?
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Monday, September 19, 2011
Carolina(s) On My Mind
By Howard Brickman
I hope that my loyal fans will forgive the temporary lapse in blogging. Hurricane Irene blew through town, taking with her our electricity for almost a week. On the plus side, I got to break out my “Survivorman” skills and lived to tell the tale. Wood has many other uses besides wood flooring. With my handy new Rocket Stove I was able to cut up the fallen branches and heat water for coffee and tea and also cook some one-pot meals.
By the time my power was restored, I was off to Charleston, S.C., to attend a wood floor class organized by Selva Lee Tucker featuring faculty from North Carolina State University. I must say: The class was yet another home run by Lee. With 10 years of instigating wood floor technical training under his belt, Lee has a knack for seamlessly combining hard-core practical and scientific knowledge.
The four-day class was instructed by two North Carolina State wood science professors and a wood floor guy from the Boston area. (Guess who the latter was?) The fee was $495, and those in the know can appreciate what an incredible value that is. It was a sell-out crowd, with over 50 attendees flying in from all over the U.S.
This was the sixth collaboration between Lee and NC State Wood Science faculty, several of which I have attended. Two of NC State’s finest taught fundamentals regarding the effects of moisture on the building envelope. An all-encompassing body of information was presented regarding the effect of temperature on relative humidity, how moisture moves through building components, and how fungi develop when exposed to moisture.
Dr. Phil Mitchell, wood products extension specialist and associate professor, has extensive experience working at major universities (Mississippi State, North Carolina State), and international wood products manufacturers (Weyerhaeuser). Dr. Phil is an acknowledged authority on the wood-moisture relationship with regard to academic as well as practical applications.
Dr. David C. Tilotta, associate professor and housing extension specialist, has a great deal of experience with contamination of buildings from chemicals and water, with extensive research and teaching background at the University of North Dakota and North Carolina State University. Dr. Dave introduced a software program from Oak Ridge National Laboratories that models temperature and moisture movement in exterior wall, floor, and roof systems.
On a personal note, do you remember how intimidated you were by your professors in college? This couldn’t have been further from the case with these two fun-guys who taught about fungi (pun intended). Tilotta and Mitchell are two of the best-natured and engaging college professors, and they took some fairly complex material and made the concepts much easier to digest (another fungi pun). The presentations were excellent, and the ease with which they answered questions worked to support true understanding. I left wishing that they had been my professors when I was an undergraduate (back when dinosaurs roamed the earth).
It has been exciting to see a major university put some effort into supporting the wood floor industry. Those of you out there who need studies, research, or laboratory testing should have the folks at the NC State Wood Products Extension Department on speed-dial. Dr. Phil’s email is phil_mitchell@ncsu.edu.
Last year, I had the opportunity to attend a three-day Wood I.D. class at the NC State Wood Anatomy Lab led by two of the leading wood anatomists in North America. The class was my personal favorite, and I’m hoping that it will become an annual event or at least every other year. I could see myself making a pilgrimage to attend. Even after 33 years in the wood flooring industry, I’m always pleasantly surprised to take away new insights about my specialty.
Stay tuned for my next blog: a step-by-step checklist to minimize installer liability when there are problems on the job.
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Sunday, September 11, 2011
Water & Wood: The Ultimate Test
By Craig DeWitt
Here's a photo I took of a wood floor last week:
Does anyone want to venture a guess as to what the black stuff is between the boards? I'll give you a hint: The floor is on the deck of a boat.
It looks like a nice way of detailing the floor that will handle water well. But from what I can tell, the floor is only about 8 months old. I'd love to see it again in a couple years. And I don't think it would work on a floor where finish would be applied. I don't even know if this floor can be oiled.
Covered areas of the boat’s floor are parquet glued to plywood and finished with a glossy top coat. Here's a cross section view of a hatch cover in the floor:
We've put water all over this floor for days, with no apparent effect. Again, the floor is only 8 months old or so, and it would be interesting to see how it holds up to salt and fresh water over time.
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Wednesday, September 07, 2011
A Lightning Strike & a Sloped Floor
By Craig DeWitt
This inspection didn't involve a hardwood floor, but it could have. It did have what I would call a "pre-existing condition."
The homeowner had been away from her 30-year-old house for a couple weeks. When she came home, she noticed some cracks in the ceiling and walls of her house, and a slope to her living room floor. The neighbors indicated that lightning had hit a tree between their houses, so she was concerned that the lightning created the cracks and sloped floor.
I have seen a lightning strike damage a house before. The lightning followed a root that went under a slab, vaporizing water in and near the root, which lifted the slab and foundation wall in the steam blast.
The slab floor in this current house was elevated on fill dirt. So a serious shake could have cause the slab to settle. And it did have a significant slope to about 12 feet of one end. After moving a bunch of furniture, I noticed that the chair rail was level, but the baseboard followed the slope of the slab. You might be able to make out the difference in the photo:
Now, baseboard following the same plane as the slab indicates that the baseboard was installed against a sloped slab. So, the sloped slab occurred long ago. (The homeowner indicated no remodeling in the 15 years while she has owned the house.) The slope was not related to a lightning strike, and the homeowner can't believe the floor had been sloped the whole time she owned it. But the evidence says it was. And it could have been a hardwood floor instead of carpeting. So watch for those pre-existing conditions.
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Monday, August 29, 2011
Wood Flooring Gaps: The Rest of the Story
By Craig DeWitt
In my last post, I mentioned a house where a wet crawl space dried such that the beams shrank. But the beams were held in place by hurricane straps, so the beam shrinkage created a gap under the beam. In this house, it was structurally interesting, but the gaps under the beams didn't affect the floor. The outside ends of the floor trusses were set on the foundation wall, so there is no beam to shrink on that end. The result is that you can get different settlement between outside edges and interiors. The different settlement can lead to humps and dips in the floor.
There is another twist or two to the situation in this house that did affect the floor. One of the larger gaps in the floor was at a transition between the tiled foyer and the hardwood floor. In looking at this from the underside, I observed a butt joint between two floor trusses that was aligned with a joint in the subfloor panels:
...and all that aligned with the gap in the hardwood floor.
The situation here is that the subflooring (or even hardwood flooring) gets wet after installation, causing it to expand. The expansion pushes the joint apart, since nothing is really holding it together. Then when things dry, a gap forms, as nothing can pull the joint back together. You end up with a permanent large gap at this kind of aligned joint. Building codes actually require an overlap of joists or some kind of overlapping splice. Even so, some floor system manufacturers do not require an overlapping joint or splice.
And there's more. Cracks in the two tiled floors in his house align with joints in the subflooring. I know it’s not a hardwood floor, but the situation is similar: cracks aligned with joints. A wet floor system before, and a dry floor system now. Sometimes we get pieces of the story in places other than just the hardwood floor.
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