While the expansion and contraction of a particular kind of flooring is not usually one of the top 10 factors in the decision about which kind to buy, it is a feature of almost all floors. Changes in humidity and temperature have an effect on most building materials. It’s minimal – we wouldn’t be able to build buildings if steel had a 25% change in size when the weather shifted – but it is still something we have to prepare for. The changes are minimal, but they matter, and if your room is subject to greater changes it may actually be a big issue for you. Regardless, with most flooring we have to leave ‘expansion gaps’ between the floor and the walls to allow these changes to happen without harming the floor.
Here’s a look at the main types of hard flooring – I’m leaving out carpeting in this piece. My rankings are not based on good chemistry, a Dimensional Change Coefficient for instance. I can only find those for wood, so I’m using recommended expansion gaps. That’s the most across-the-board factor I can find, how much space we are to leave between the edge of the flooring and the walls or other vertical surfaces, though there are ranges within each.
So which are the best, ‘best’ in our case meaning they change the least? We’ll go best to worst. I’ll list the ranges of expansion gaps I could find, but keep in mind that whatever floor you buy, your instructions will give you your exact number.
Expansion Gap: 0mm
(Hover your cursor over the ‘mm’ for inches. With such small numbers, mm show the differences best)
These are designed to not react at all to standard indoor environmental changes. In fact, the installation relies on that. These are placed snug against each other, and snug against the walls. That’s what keeps them in place.
This is a new-ish product (just a couple of years old at the time of writing) in part because its complete dimensional stability has been so unattainable. Even other vinyl planks, the click-together kinds, which rank very high here, aren’t 100%.
Expansion Gap ranges: 1.3mm to 6mm
This is good, solid, often vulcanized, stone-like Earth-stuff. It’s natural, so it does react a bit, but it’s also just so dense that the grout between the tiles can serve as part of the expansion handling. Imagine leaving just over 1 millimeter around an entire room? It shows how stable these can be, but the fact that we still do it shows how much it still matters.
Expansion Gap ranges: 3.175 mm to 7.9375 mm
The brother of loose lay is also the next best plank style floor, and has been around longer. It was really designed to give us the wood plank looks while being 100% waterproof – both of them are that. These top three floors can go pretty much anywhere in the house or business as far as environmental concerns go. You still have to consider design, traffic, durability and many other factors, but the heat and humidity aren’t big ones here.
Expansion Gap ranges: 6.35mm to 12.7mm
Usually categorized with hardwood, bamboo is different enough to make a difference in this area. It is the top non-engineered, wood-ish floor product for dimensional stability.
Engineered Flooring which is attached to the subfloor
Expansion Gap ranges: 6.35mm to 13mm
When glued, nailed or stapled down, an engineered floor comes pretty close to bamboo, though it can occasionally require a larger gap than bamboo should. Engineered hardwood is made of layers of wood which are criss-crossed with regard to their grain direction, then a top layer gives you your species or color. That criss-crossing is what helps engineered wood maintain its lovely shape. This is exactly the reason engineered flooring was invented, to handle this issue. Wood is so responsive to the environment that solid planks cannot even be installed below ground level. Engineered floors can when they float, but even when attached they still have the advantage.
Engineered Hardwood installed as a floating floor
Expansion Gap ranges: 6.35mm to 19.05m
These are not different products, but the same ones installed differently. On one hand floating is ‘worse’ than attached engineered is here because, not being stuck to a subfloor, it might actually be able expand a little more (up to 3/4” instead of just 1/2”), and yet of the two it can be put into a basement. That’s because a basement is going to give it the greatest likelihood of having the most expansion, and it may move too much to withstand being attached. Odd, almost contradictory distinctions, but it’s all true.
Expansion Gap ranges: 7.9375mm to 16mm
This is a slight step down from the engineered woods because the start of the range goes larger. While laminate flooring does improve on the dimensional stability of solid hardwood, the leap had already been made with engineered woods, so laminate was primarily invented to allow us to get the look of hardwood while saving a lot of money. It can also go into a basement because it’s installed floating, not attached.
The Most Responsive Floor
Expansion Gap ranges: 9.525 to 19.05
It’s the thickest, unengineered mass of the most responsive material out of which we make floors, solid hardwood flooring. It needs the largest expansion gaps both on the low and high end of the range. This is a fine floor in so many other areas, but when you have unusually high fluctuations in temperature or humidity, sometimes you will have to look at another floor.
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David is a Writer at Floors To Your Home (.com), as well as the PPC Manager, a Marketing Strategy Team member, a Researcher, Videographer, Social Strategist, Photographer and all around Resource Jitō. In my spare time I shoot and edit video, explore film history, mix music (as in ‘play with Beatles multi-tracks’) and write non-fiction for my friends. Connect with me on W. David Lichty’s Google+
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