It all depends on the manufacturer of the hardwood. We use Anderson Engineered Hardwood a lot when we install radiant heat under floors. Maple and sometimes hickory wood species can be used over radiant heat. I would be a little more cautious with hickory though because when exposed to extreme heat it can have a tendency to split. The reason I am advising engineered is because it is a more stable floor and can handle the heat better. Engineered hardwood is still all real wood and you can not tell the difference once it is down. If you are unsure of the difference between solid hardwood and engineered hardwood please let me know and I would be happy to explain the difference.

When it comes to heating hardwood, the narrower the plank, the better.

• Quartersawn floors: They tend to expand in height, as opposed to plainsawn boards, which expand mainly in width.

• Narrower widths: They shrink and swell less than wider boards.

• Engineered floors: They are inherently more stable, and the more plies, the more stable the product.

• Reclaimed woods: They have a tighter pattern of growth rings, making them more stable.

• Parquet: As a whole, parquet floors have less expansion and contraction.

• Dark floors: Their color makes gaps between boards less obvious.

• Floors with obvious grain patterns: They also downplay the appearance of gaps between boards.

• Distressed floors: They help minimize the appearance of gaps, as well.

• Beveled edges: They also make gaps less obvious.

Hope this helps!

Engineered American Black Walnut would look really nice and be stable with your RH system. You can even finish the floor on site so it will look identical to a solid site finished floor.

The type of radiant heating system is going to come into play. Hydronic (water/oil/gel) is one of the few systems that has a wide variety of flooring that is "allowed" to be used over top. If it is electric, you may have issues finding a flooring manufacturer who "allows" their floor over top. The biggest consideration = temperature at the concrete/floor interface. Most systems are allowed so long as the INTERFACE temperature (where the concrete meets the bottom of the floor) is less than 84 F (28 C).

Electric heating systems...even when sunk in cement, have issues with over heating and thus they tend to scorch wood flooring. Working with a flooring company like Oak & Broad, Select Hardwood, etc will be the best solution for you.

As mentioned by others, your type of system will come into play. We have been heating hardwood for decades without any issue, but we recommend always following manufacture guidelines.

One key thing is to make sure the wood is properly acclimated before install (this should happen with or without the radiant heat).

Cancork... what about ULTIMATE ??? I have successfully installed finished on site over radiant so many times I can't even count. The wider the plank the more the problem is a myth. Hire somebody that knows and u can avoid costly mistakes.
I did a 8" wide plank in Fort Mac and it turned out well. Most ppl crank that heat. It only needs to be between 4C-10C. If the homeowner does not listen to their flooring contractor that's on them. I always collaborate with the plumber if I have the opportunity to make sure the end result is desirable.

Hickory is scary yes. White oak and walnut seem to behave the most. If you go quatersawn that also helps. It also depends on the environment in the home.Dry cupping seems to be the major issue if there's not enough RH in the home.Oak likes that 30% mark and walnut likes the high 30's to low 40's. You need to consider all these factors BEFORE you buy your floors!!

These floors were installed 4 years ago over glycol heated concrete. I was there last week and there's no gaps and it's the middle of the dry season. Yup that's a solid maple floor!! The barnboard is maple 5" plank.

We had gypcrete radiant heat and ended up using quarter sawn white oak. We also installed a whole house humidifier and a dehumidifier in the basement to try to maintain fairly consistent humidity. We went through our first winter and floors still look amazing. Must admit we were nervous!