Tech Talk: Perimeter Expansion Space

“How do you handle projects where the required perimeter expansion space is unachievable?”

Cesar Cardona – Cardona Flooring

In situations where full expansion space cannot be achieved, the key is to find a balance between protecting the floor system and respecting the site’s restrictions. The first step is to determine why the space doesn’t allow expansion space, whether it is due to structural walls, stone, or cabinetry, etc. Once identified, I explain to the client that wood flooring is always moving with seasonal changes and eliminating expansion space increases the risk of buckling.

If the expansion space truly cannot be created there are some strategies we can use; for example:

• Undercutting trim casing, drywall, or stone to gain expansion space.
• Transition moldings at thresholds to add expansion space.
• Make some change into the layout, like using internal expansion joints or borders that relieve pressure in large areas or choosing a more dimensionally stable product like engineered flooring.

Moisture control and monitoring to ensure the subfloor, flooring, and environment are maintained within NWFA or the manufacturer’s recommended moisture conditions before installation gives the best chance for success.

Document everything and explain it to the client in writing. This way they understand the risk and accept the responsibility if anything happens. As professionals, our role is to mitigate movement wherever possible, but we also have to educate the client when design conditions don’t allow for textbook installation. Finally, the most important thing is to follow manufacturers’ recommendations.

Jason Carter – Carter Quality Hardwood Flooring

We’ve all been told by the architect, the designer, the general contractor, or the homeowner that you can’t have an expansion gap. Especially when we are butting up to tile and other permanent fixtures. Number one, we have to make sure everybody involved knows that this is against the rules, and if this is what they’re demanding, then we need to rely on educating them as to why wood moves. The whole reason we need an expansion gap is because of changes in humidity. As long as the homeowner is informed of where to keep the humidity levels at, and they’re able to keep the humidity in-check, the floor is not going to move.

Any time we are forced to do alleviate expansion space against tile, we back bevel any of those boards. Then, if we do have a failure because the wood expanded, at least now only that one board should be affected instead of the whole floor  buckling. We would rather see that last turn board or that picture frame up against the fireplace react because that’s a somewhat easy fix versus the catastrophe of not leaving enough expansion and the floor buckled in the middle of the living room.

Ben Totta –Totta Hardwoods

We worked on a real modern, new house and the sheetrock went all the way down and there was not a traditional baseboard. The letter of the law in our NWFA guidelines is to match the thickness of the wood for expansion space, so with solid ¾” thick flooring, you would have a ¾” gap between wood and wall at the base. This wasn’t achievable in this scenario. In the spirit of the law, I sometimes try to achieve as much expansion space as I can that could still work.

A piece of solid wood really only moves in its width, and not hardly at all in its length. When it comes to walls where the wood is butting into the ends of the boards, those are easy because wood doesn’t really move that way even when it gets wet. You can go a lot tighter on your expansion gap and it’s not much of a concern; it’s the sidewalls we are more concerned about.

The sheetrock is normally a ½” maybe 9/16” coming off the stud walls. , This is nowhere close to the required ¾” gap we need at the base. It had to be closer to ¼” to 3/8” to not see it. Sometimes on the edge of the board, instead of just cutting it a square edge, you can actually cut it at an angle so at the top of the board it’s reaching out further than the bottom. You’re not going to have as much of an issue with that because the lower you go on that piece of wood, the more of a gap you have there for expansion and only the top of the board that is reaching up.

Another scenario is where windows go all the way down to the subfloor in a home and just have a metal window frame. You don’t do trim in front of those. We run the flooring up to it and leave a consistent gap of about ¼” and fill it with the black silicone or caulk. It leaves a flexible joint for that piece to move when it needs to move, but still looks like it is cut tight to fit.