Hardwood Floor Gaps & Cracks - Yikes!

Gaps? Why Do We Have Gaps?

During winter months complaints usually start trickling in. Often it's a floor owner concerned with new hardwood floors separating or gapping. "They weren't there in the summer." Solid 3/4" hardwoods will Hardwood floor gap expand and contract with seasonal changes in moisture. This is especially noticeable with site finished floors whose final appearance after the work has been done is near flawless.

Gapping occurs when hardwood floors lose their moisture content. Several factors can lead to it's cause. By examining it from a layman's view; even though the hardwood is no longer living and growing, it contains cells that still take on and lose moisture with changes in relative humidity.

What Time Of The Year It Was Installed - Conditions

Often gapping is a result of hardwood flooring that was installed during periods of higher humidity. Months may pass, even years, depending on the conditions until gapping becomes evident. A few unusually warm winters without the extensive use of heating in the home may not show the potential. Conversely, extreme cold winter months will require more heating. Dry air is forced into the environment. Moisture is now removed from not only the environment but the cells or pores of the hardwood. Contraction occurs.

How much gapping is dependent on several factors. Wider width boards will show more while narrow strip floors can show less. Methods to reduce gapping include the use of furnace humidifiers. These products work principally by evaporation of water that is introduced into the environment through the heating system. With more moisture in the air, cells in hardwood begin to expand.

Best Time To Install Floors?

Often a myriad of opinions can be found on this subject, but professionals agree finding what the average humidity level in the home year round will reduce contraction and minimizing gapping. It's also vital the actual installation and acclimation period be close to this level to achieve the best results. Products that test humidity, called hygrometers are best used to monitor jobsite conditions.

What Filler Will Fix My Gapped Floors?

Unfortunately no filler will work effectively unless the humidity level is kept constant. During the expansion process when warmer days allow for houses to be open to outside air, gapping will close up as the hardwood takes on moisture and the filler eventually gets squeezed out.

For very wide more permanent gapping, gluing rope with a urethane adhesive between boards has been successful. Caution should be exercised here as glues can stain and become rather noticeable once the floor is finished. Wiping clean with a rag and mineral spirits is suggested prior to the application of any finish.

Maple Hardwood. Gaps, Cracks

The most common hardwood we hear complaints about with gapping and cracks is Maple. Below are summaries of questions we've fielded over the years.

Winter in Chicago

Question: We had a beautiful Maple hardwood floor installed in July of this year. Now that he weather has turned colder here in Chicagoland, the floor looks awful! There are gaps everywhere and some boards are beginning to split. What the devil happened and how can we get someone to fix it?

Reply: I'm guessing the colder weather has made you turn on and keep the furnace cranking. What happens with most hardwood when it was installed in warmer more humid summer months, the installers did not acclimate the hardwood. Essentially what happened is it was installed with a high moisture content level then shrunk with heating. A good way to correct this is adapting the heating system with a humidifier. That will close up the gaps but the splitting will be permanent.

White Pine Floors Gap And Grow At The Edges

Question: Our 20 year old white pine floors always show gaps in the winter and White Pine Gaps they are also uncomfortable to slide your feet across. It's almost like they're growing upwards on the edges. Any ideas how to fix?

Reply: The gapping condition is seasonal as you've probably realized, but the other part about the edges tell me they're also cupping. This is created from moisture affecting the underside of the boards. I would look for a source. The problem seems to be coming from what's under the floor. Is this a crawlspace home?

Wide Plank Maple Cupping

Question: I am thinking of using wider plank (4 1/4") maple flooring. I have heard various opinions as to whether this would be a good idea or not. Some have said that there will be too much cupping. Others say it would be fine. Any comments or experiences?

Reply: Maple isn't the most stable of all North American species. I've seen 3/4" material cup and it puzzled me too. All proper guidelines were followed to a tee. In one case the installation was very near to water but the flooring was on the second floor. If you're thinking of engineered there is no need for concern. If you do choose the solid wide Maple, I've heard some guys seal the backside of each plank before it's installed. This does minimize the cupping effects.

Floating Floor With Gaps

Question: I am buying a new construction loft which is to have floating maple floors. They were just put down, and the problem is I think they look terrible because you can see several gaps between the panels (a few are large enough to insert a credit card with plenty of slack). Is this expected? I've lived on a lot of hardwood floors and they have never looked like this. I need to know if I should be insistent with the builder to make it better. Please help.

Reply: The way I see it the only way of making it better is to have it replaced. It sounds like a poor installation to me unless there are flaws with the material itself. Once a floating floor is installed it expands and contracts as a whole instead of individual planks that are nailed to the subfloor.

• Acclimation
• Moisture Testing - Procedures and awareness
• Hardwood Floor Filler