They call me to inspect probably twenty to thirty solid wood floors each year that after several weeks or months have started to have gaps. A quick reminder: solid wood flooring planks are each one piece of wood, while engineered wood planks are several different layers of wood glued together, much like plywood. Every now and then I see an engineered wood with gaps. In any case, it is a serious and costly problem. If you take the time to read the rest of this article, you can be sure this won’t happen to you, I promise.
“Moisture levels” are very important with solid wood floors. All wood has a certain amount of moisture. When you have installed a solid wood floor, especially if it is nailed / stapled, and then you start opening gaps at the joints so that there is space between the adjacent boards, it is because they have shrunk. The only other possibility is that your home has expanded, but I’m pretty sure that has never happened and never will. So why did the tables shrink? Because they lost moisture since they were installed. When wood dries, it shrinks, when it gets wet, it expands. Okay, now we are getting to the most important part.
Most people are familiar with the term “acclimatization”. Most people know that wooden floors, even laminate ones (like Pergo), need to be acclimated before installing. Usually the instructions say you need to acclimatize for 48 hours, or 3 days, or whatever, and then install. THAT IS NOT RIGHT. If you acclimatize the product as directed by the manufacturer for the proper time, then install it and then break it, the manufacturer will not guarantee or replace it. The fine print for flooring installation is as follows: When the installer installs the flooring, they agree that the flooring and subfloor are suitable for the installation. The problem is, sometimes the wooden floor appears in the house to acclimate to a humidity level of 15% and must be installed in a house with the subfloor with a humidity level of 6% to 9%. There is no way the floor can acclimate to those conditions in a few days. It will still be too wet. And once installed, it will shrink and cause gaps. And the worst part is that the floor will have to be lifted and thrown away. It is not a correctable situation.
I need to make a small point here. “A little” of space on solid wood floors is very normal, especially if you live in an area with real seasonal changes like I do in Eastern Washington. Our homes here will invariably be drier in the winter and wetter in the summer, which will cause some minor gaps and is perfectly normal. A sure way to know if the gap is normal is if it practically disappears every year during the wettest season. But the gap I’m talking about is not like that. A lady showed me how some spaghetti that had fallen on the floor had gotten into the holes. Or if you are missing one or more of your favorite pets, that’s a clue too.
THE SOLUTION So before this horrible scenario happens, be sure to do the following before installing your new flooring. Floor moisture should be checked with a wood gauge. There are pin (invasive) and magnetic (non-invasive) gauges, either of which will work. However, these cost between $ 200 and $ 300 or more. Insist that the installer control the humidity, especially as it will be a BIG problem for the installers if you have gaps later on. Because you know what will happen? The manufacturer will send I To look at the floor, I will take many measurements of dimensions and moisture levels, and using the tables of coefficients of dimensional change in the Wood Manual, I will be able to determine what the actual moisture level of the wood was at that time of installation. I will find that it was too high (or VERY too high), and the finding will be that the wood floor was not acclimated to the normal home environment before it was installed. OH! That will cost someone a lot of money and cost at least a lot of hassle with the replacement issue etc. You don’t want that and neither do I.
By the way, engineered wood definitely needs to acclimatize as well, although some of the manufacturers don’t want the cardboard boxes to be opened for acclimatization and some do, so pay attention to that. Also, laminates (which are actual layers of wood similar to the ones designed except for the top layer which is melamine (aluminum oxide or similar) must also acclimate, but I have never seen a claim rejected because the floor was not acclimatized. Generally, laminates and many engineered woods are “floating”, which means that they connect together and become a unit. Any dimensional change does not normally cause gaps, but rather a change in the amount of free space (perimeter expansion space) on the walls These problems I will cover in another article.
IN BRIEF: With any type of hardwood flooring, but especially solid hardwood, make sure the moisture levels of the wood are between 2% and 4% of the subfloor the flooring is on. In my part of the country where the relative humidity of the houses is usually between 25% and 40%, the floor must be between 6% and 9% before being installed. That brings us to one of my favorite phrases, “IMAGINE WITHOUT SPACES!”