Hello all.
Long time reader, second time poster. I am a licensed builder who works as an engineering technician. I am in the process of constructing our new home in the Upper Peninsula of Michigan. We are most likely going to install a thin-slab (gypsum-based) radiant heat system on the first and second floors of the house. I have questions regarding installation methods of hardwood over the gypcrete. I talked to the gypcrete installer and he mentioned the sleeper method, but he likes to leave the gyp about 1/4″ below the top of the sleepers which leaves an air space. Is that standard practice? The flooring salesman says floating or glue-down floors will work just fine (but he’s a salesman). I’m actually not crazy about the sleeper method and was wondering how the floating floors or glue-down floors have faired in this situation. The largest room is 20’x30′. I’d love to hear any advice or recommendations from anyone who has experience with this application. Thanks in advance.
Replies
doobz26,
My floors are hardwoodflooring over two inch thick hardwood subflooring for a total of three inches of wood.. the radiant floor is underneath all that.
Most likely you will only have 3/4 inch subflooring with 3/4 inch hardwood flooring on top.
Here's the deal with radiant heat.. properly installed it will work just fine even thru 3 inches of wood.. wood will warm up to whatever temp it's set at and stay nice and warm underfoot. The whole purpose of radiant heat.
all pouring gypcrete will do is transfer the heat faster.. it won't get warmer or transfer more heat, it will transfer it quicker. period..
Then of course you can buy several boards that are grooved for the tubing so you don't have to go thru the gypcrete stuff with all it's hassles and potential problems..
Whatever you select you'll be glad you choose in floor radiant heat, I had it as a kid and it's heaven!
Last winter I was having our new home finished. RFH in gypcrete with engineered hardwood over half and tile on the other. I bought Mirage flooring in Santos Mahogany. It is 100% glued down. No cupping or other issues to date. It was done 100% by the book on both the wood and gypcrete manufacturers specs.
If I had to put sleepers down or any of the other stories I hear being put out both in stores and elsewhere, I would have tiled the whole thing.
The job looks great and peoples jaws drop when they see it. As for comfort it's great. Don't expect to walk up to your t'stat and get instant results. Temp changes take a long time on the heating side in both up and down adjustments. I installed a tele t'stat that is nothing short of outstanding. I call a day or 2 ahead and slowly increase the 1st flr temp.
I installed 3/4" white oak flooring over gyp. using sleepers @ 16" centers. I chose the sleeper method because I wanted a sanded and finished in place floor, one without the little v-grooves between boards. My system is great, there's a time lag for heat but we can live with that. My flooring buddy who helped do the install and lent his tools advised that the sleepers be closer together. But with joists at 16" I couldn't see how my sleeper could be effectively supported unless they were right on them. So we went with the 16" spacing but used poly adhesive on every other course of boards. The gyp guy left the surface below the sleeper top in most places...... this is good. Where he had it too high, I had to grind and that wasn't any fun. (nor is it clean)
If you do the sleeper thing, be sure to clearly mark the tubes where they cross over. When going full blast with the nailer, it's very easy to forget about the tubes. Chipping gyp and patching a tube slows down the floor install more than a little. (Don't ask me how I know this.)
From what I know, both floating and glue down engineered floors work well over radiant and gypcrete.