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Tips for Top-Nailed 5/16-Inch Floors

By Avi Hadad
April/May 2011
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In my region, here in California’s Bay Area, older homes typically have a floor not commonly found in many other areas: solid 5/16-inch-thick, top-nailed oak floors. Some are 2 inches wide with a square edge, some are random widths with a full bevel and walnut pegs, and some are parquet floors. That is why most flooring contractors around here must know how to renovate, install, sand and finish these floors (there are also pockets of this flooring in other regions of the country, such as Philadelphia and New York). If you mainly do tongue-and-groove floors, then you will be surprised and challenged by working with these top-nail floors (and vice versa). I have learned the following while working on these floors over the last decade.

Job-Site Conditions

As always, it is important to follow the NWFA Guidelines regarding job-site conditions and acclimation. Treat these floors like plank flooring; when acclimating the wood, stay within two points of difference in moisture between the subfloor and the wood floor. These floors do not tolerate a lot of movement well—there is no tongue and groove, so finish nails are all that is holding the boards down.

In the Bay Area most installations are on-grade or above-grade over a wood subfloor; in older homes they are 1-by-8 solid board subfloors. Some have shifted in parts and are no longer straight, and some have sagged. When homeowners add onto their homes they ask us to install new floors over these subfloors where they previously had carpeting or other floor coverings. A minimum of 3⁄8-inch CDX plywood needs to be installed over the old subfloor (glued and mechanically fastened) before installing a new top-nail floor.

Installing 5⁄16 Flooring

The thickness, or lack thereof, of this 5/16-inch floor creates challenges for installers. Here are some tips:

Get the subfloor dead-on flat. If your subfloor has variations in it, you will most likely split the floor as you nail it. The other problem you will have is trying to sand the floor flat—you don’t want to be sanding down more than 1/32 inch on your new floor, because you will run into nails very fast and be out of wood to hold them in place.

Use an approved vapor retarder. Avoid using roofing felt, as the asphalt may heat up while sanding and bleed into the floor.

Mix bundles. The floors come in nested bundles in different lengths. Make sure you mix your short and long bundles when racking for joint location, color and grain uniformity.

You can set your first row anywhere. I usually place the first row along the longest line I have and mark my nail schedule with a pencil 1½ inch from the ends and every 7 inches along the face. After you nail the first row, you can rack as many rows as you want and rough-nail a few rows at a time. I usually drive a screwdriver into the subfloor and pull the floor together, and then I randomly place enough nails to hold the floor tight. When you are done, you simply transfer your marks from the first row and use a straightedge to finish nailing the floor.

Check the settings on your compressor. If your psi is too high, you will drive the nails too deep and the floor will split very easily. If your psi is too low, you will be setting a lot of nails by hand.

Sanding Top-Nailed Floors

Again, follow NWFA Guidelines for sanding and finishing, but keep in mind the following procedures that make these floors a little different:

Set nails as you go. I can’t emphasize this enough. Doublecheck when done installing, again when you vacuum, and again before you start sanding. These nail heads are nasty and will get your drum and your edger. Did I mention they are hard to see?

Use the right filler. Some fillers are good at filling grain but not at filling nail holes—they will show a slight depression over each nail hole and, when the floor is stained, they take the stain darker than the floor. I have found that making your own filler works the best. Usually when you do this you are using products that smell horrible and are extremely flammable, so keep the job site well-ventilated. But I find that for the best color match and a true-flat nail hole, it is the way to go.

Sand with good lighting. When fine-sanding the filler off the floor, work carefully in a well-lit environment. It is easy to miss a spot, and the buffer won’t take care of it.

Work with a nail set. If you hit a nail head with your drum on an old floor you will put a scratch in your floor. It’s likely that you will not see this until your finish coat is dry, so change your belts more frequently.

Successfully installed and finished, a solid top-nail floor can last more than 100 years. It is our job as contractors to keep up with the demand for all different products; and here, this top-nail product is a must if you want to stay in business.

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See photos of 5/16 wood flooring:

An old solid board subfloor, commonly found under 5/16-inch wood flooring.

A new top-nailed 5/16-inch wood floor before sanding.

A random-width plank top-nailed wood floor with plugs.

An existing top-nailed plank floor with plugs in the Bay Area.

A new stained red oak top-nailed 5/16-inch wood floor in the Bay Area.

A new 5/16-inch strip top-nailed oak wood floor in the Bay Area.

Avi Hadad is owner at San Pablo, Calif.-base Avi’s Hardwood Floors and is NWFACP-certified in Inspection, Installation and Sand & Finish.

Wood floor filler            Installing wood flooring    Sanding wood floors                   


Here in Portland Oregon, many of the grand NW and SW Portland homes have "Siberian Oak" as the top nail material. It came to America in the 1900's as dunnage on freighters and became flooring thru Yankee ingenuity. Problem can be that domestic red or white oak neither blends nor complements the antique that is there and when attempting add on or repairs many a floor man has had to visit the local reclaimer or deconstuctor to accomplish their goal.
Eric C. Jensen  Senior Territory Manager  4/12/2011 12:19:45 PM

I've delt with top nailing for over i have to say.its not recomended to use a compressor nail shoots the nail in to quik an doesnt pull the board down tight to the floor.theres a tool called a Cavinough (not sure about the spelling).you hand feed nails into top tray,they work their way down a the head.hit the head with a raw hide a steel pin drives nail into wood. when you hit a nail with the doesnt scratch puts a bald streak on paper.which leaves a slightly raised strip of flooring.due to lack of grit on your paper.alittle extra screening levels it out.
MB Flooring  owner/operator  4/19/2011 12:28:20 AM

The cavanaugh nailer is the only way to go, To shoot one of these floors down with an air gun is an exercise in futility as the nailer drives the nails in but does not drive the flooring down tight to the sub floor. This causes the flooring to move after it has been sanded and finished. The bad news came when they discontinued manufacturing this type of nailer. The worst news is that the nails for this nailer are now longer available. Thank goodness we had the forsight to purchase several thousand pounds of the nails,
D Durr  Owner VIctorian Hardwood Floors.  4/19/2011 8:43:51 AM

Aahh yes I remember the Cavanaugh Still own it, haven't used it in years. They have been replaced with an air actuated nailer. Same general principle. You feed nails, in this case strips of 1" barbed fastners same as you put in your finish gun. In fact we use 'em for the stay tacking and near the walls. Anyway you then smack the nailer on the top, we use our Bostich dead blows, drives your nails exactly like the Cavanaugh. Set the nails 1/8" They don't leave perfectly round holes like the floor brads of old but sorta rectangular. You orient the nailer properly so the rectangles are with the grain and the holes virtually disappear. You do have to watch your pressure settings and adjust for different sub-floors. You also have to be careful you don't run out of pins! The nailer does NOT make a different sound when it is empty than when you are driving nails. (Like your 3/4 nailer does) We have marked ours and keep an eye on the magazine. It works quite well. Made by Hi-Pro
Scott Leslie Owner Leslie Flooring    4/19/2011 6:44:39 PM

Thank you for the comments on my article. About the nailer: 1. A nailer should be used to drive a fastener in place - that is it. It should not be used to pull the floor down to the sub floor. Using a power nailer (on t&g floors as well) to close gaps and drive the flooring tight causes the fasteners to bend. 2. On my floors I use a wood block to hold the floor boards down as I nail them. This guarantees the floor sits tight on the sub floor. 3. If your sub floor is flat and you hold the floor boards down as you nail them, there should not be any problem with wood movement after the fact. There are many ways to install any floor. As long as you and your client are happy it does not matter which nailing method you exercise or how you get the floor to last 100 years. Hope to see you all in San Diego.
Avi Hadad  Avi's Hardwood Floors  4/19/2011 11:57:40 PM

Just to add something. I still have my great grandfather's (Doc Bast)Cavanaugh nailer. I was also lucky enough to get his nailing hatchet. I believe they used a hatchet to cut the boards to length or maybe this was just a Kentucky thing, not sure. When I was much younger I actually used this nailer on several jobs. Never got a chance to work with my great grandfather but it was cool to his his tools. I have been blessed enough to also recieve some of my grandfathers's (John Bast Sr) old tools as well. Just thought you may like to know.
John Bast III  Family of Four Generations  4/20/2011 3:04:16 PM

nothing new on this article. it is so simple and common that every wood flooring specialist knows. i have been working as flooring person in bay area for 20 years. much more needs to be addressed.
Dan Tr.  RMO  5/6/2011 1:16:12 AM

The Cavanaugh nailer draws all the boards down very tight to the subfloor. It is the combination of the nail, the shape of the nail , the nailers die, and mainly the force of the mallets blow that does this. The nail is set to a correct uniform depth. Nails are placed at both edges of a board. Two adjacent nails are to touch or be covered by a circumference of a dime. This was a standard enforced building code at one time. When nailed in this manner there is very little overwood. Surfacing the floor requires minimal sanding. There are very few nails to set during surfacing. I have had many calls to repair 5/16" floors that have been layed with an air nailer. These floors have been over sanded due to excess overwood, decreasing their life. In many cases boards that were not drawn tight to the subfloor have sunk below adjacent boards, or nails have pushed up out of the board. There can be loose "popping" boards , squeaks etc.. Nails are set at varying incorrect depths.
Mark Walorny  Inlaid Floor Co. Owner  5/7/2011 3:03:31 AM

Thanks for those tips. I got a question, what thichness for the plywood is the best and also the best length of the nails. We do have a similar technic here in Belgium, but we glue it to the subfloor. and use a pin nailer. Got some photos, but does not know how to get it here. Best regards Jean-Marc
Jean-Marc  Flooring layer  10/13/2011 1:37:49 AM

Jean-Marc, 3/4" (19mm) plywood over joists span at 16" on center. This is the minimum. Now, if I don't have to match existing top nail floors I install a t&g product. Your system of gluing and pin nailing is great. I know some guys that glue and nail the floors here as well. There are many ways to install these floors successfully. Whatever nails you are using a minimum of 3/4" penetration into a wood sub floor is my preference. See you in Florida next year?
Avi Hadad    10/15/2011 6:25:54 PM

I have 3/4" thick diagonal plank subfloor in pretty good shape. Still, I wanted to put down an undelayment to minimize squeaks and bowing down the road. (joists are 12" OC, one floor is above an unfinished crawlspace and one is 2nd story) My plan was to lay down a paper vapor barrier then 1/2 CDX plywood and the top nail the 5/16 oak. Questions: Is that the right order? Is that the right thickness plywood and grade? Lastly, should my nails stop at the plywood or how deep should they go into the plank subfloor? Thanks for this article and any imput.
Joe Lamberti  Home Owner  3/3/2014 3:18:13 PM

Joe, the plywood grade and thickness is fine. Glue and screw it to the joists. Then, put down a vapor retarder such as asphalt laminated paper and then your wood floors. The nails should be about 1 1/4" long.
Avi Hadad    3/3/2014 4:27:21 PM

I live in the Bay Area. No one seems to carry 5/16 2" oak unfinished. Everyone looks at me like I have holes in my head when I inquire about it. Does anyone know where I can find the material. I don't care if a contractor does the job or me. I need to replace some and it has to match. Thanks in advance.
James ONeill  Home Owner  7/12/2014 1:09:48 PM

I second James ONeill's inquiry; we purchased a 1950s ranch in North Bay and the existing hardwood flooring is 5/16in thick oak, 2 in wide and top nailed. In addition to needing to fill the cutouts left over from the floor heaters used back in the day, we'd like to add flooring in a couple of rooms and have it match. We're having a hard time finding material; closes commercially available stuff we found is the right thickness but 2 1/4in.
Michael K.  HomeOwner  7/15/2014 12:24:06 AM

I just found 5/16 topnail red oak at Tom Duffy in concord... good guys and it's all in stock... 2, 4, 6, 8 and maybe other widths both 90* and beveled edges. They even helped me figure out the best way to lay it out based on a pic of my space. Trying to do the same to match an existing floor from '53 and apparently the new standards for underlayment are much tougher, but my existing floor has held up great for over 60 years with just cheap paper over 2x8 boards with 1/4" gaps over a crawl space (like you can see through the subfloor). They kinda scared me off from doing it myself without underlayment, but I really want a seamless transition from living room into our kitchen now that we tore out the wall between the two, so maybe worth a shot.
Bill    7/15/2014 2:19:35 AM

Just yesterday I mentioned to my helper how tired I was of 5/16 floors lately, and how we have not done a 3/4" floor in a while :-) those floors are readily available at any wood supply store. They are cheap and will last more than 100 years if installed and finished right. If you need help in any way with these floors email me, I am in the East Bay. Thanks Avi
Avi Hadad    7/15/2014 7:53:23 PM

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