I was just reading about radiant heat in FHB and It talked about “lightweigh gypsum”. I’ve never heard of gysum instead of concrete. Anyone have experience in this area? Any web sites I can go to?
Cheers
M. Stehelin
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Try this link:
http://www.thermafloor.com/product_detail.asp?ID=4
Product has worked well for me.
So you have used this system?
Looks easier than concrete. Is it cheaper? Do you need a special machine? Did you have to level it? What did you put over the gypsum?
I have a friend who used concrete. They have not put flooring in but the carpenter that is putting it in is going to put a layer of builder's paper down first. Is this necessary?
Cheers
M. Stehelin
I probably am not going to be all that much help to you, but I'll tell you what I know.
The only time I used this product was about 6 years ago in a custom home that was designed with a lightweight floor to house the radiant tubing.
I had to locate a proprietary (sp?) installer in my area, and I'm sorry, I don't remember the cost. I think it would be better to contact a Maxxon rep and receive a current quote. Anyway, an installer showed up with all the right stuff and did the pour.
The 3/4" tubing had been stapled to the floor. We had placed an extra bottom plate on the walls. He started by floating the first pass to the top of the tubing, then went over the area again with another 3/4", which he placed with a large squeegee, the product is very fluid and self-leveling.
I have no experience with lightweight concrete, but I assume that the procedure would be similar. Concrete of any kind is very expensive in my area.
Ceramic tile was the flooring that was installed in most areas. Prior to setting the tile, we placed a 'crack isolation membrane' directly to the gypsum surface. These membranes are trowel-on products available from tile suppliers, and their function is to allow for slight differences in movement betwen the gypsum and the tile.
Another area in the home was floored with a Pergo-like flooring product placed over a thin foam pad without any other preparation of the gypsum.
In the 6 years since completion I can make this report:The house system functions beautifully. I had to repair 3 cracked tile within 1 year, near an opening where the tile changed to the pergo...I attribute the cracking to movement of a girder located there that had subsided some, due to the drying of the crawl space soil (high clay). Since then, there have been no other problems.
Hope this helps.What the HECK was I thinking?
Looks easier than concrete. Gypcrete is much easier to place than concrete. It's esentially self-leveling, flows much easier, etc, etc.
Is it cheaper? Two different animals. Concrete basement slabs are obvious. Elevated slabs require a bit of engineering. Gypcrete is designed to go over a framed subfloor. Apples-to-oranges. Can;t give a cost comparison without factoring in how the slab integrates into the whole structure. Over a framed subfloor, gypcrete runs $2.50-$3.00 a square foot...though your mileage may vary.
Do you need a special machine? Did you have to level it? See the previous post. The gypcrete sub will have all the equipment needed. I'm not aware of DIY set-ups for rent.
What did you put over the gypsum? What type of flooring is going over the gypcrete? If strip harwood, often times wood sleepers will be fastened to the subrloor 16" oc and the gypcrete poured level with the top of the sleepers. The strip flooring gets nailed off on the sleepers. Tile usually requires a membrane between it and the gypcrete. Glue-down engineered wood can be, as far as I know, glued directly to the gypcrete.
I have a friend who used concrete. They have not put flooring in but the carpenter that is putting it in is going to put a layer of builder's paper down first. Is this necessary? Define "builder's paper". I hope not tar paper. Tar paper can give off an odor if used as a slip sheet over radiant floor heat. Maybe he's using red rosin paper?
You might want to email Cloud Hidden. You'll see him on the forum. I'm fairly certain he used gypcrete and concrete slabs throughout most of his house, which has radiant floor heat. I also believe he did a bamboo gluedown directly over the gypcrete. He can give you pravtical advice regarding installation and living with the gypcrete.
Realize that (to me) there are three types of rfh. High-mass (concrete slab), low-mass (staple-up or warmboard-type) ad medium-mass (gypcrete).
Depending on where you live and what type of house you have...which dictates your heating requirements...one or more of these types of systems may be better than another. I think gypcrete a great product...but in southern New England it just doesn't fit into my requirements for RFH.
The main advantages of gypsum concrete over regular concrete are the pumpable self-leveling installation, and net weight.
The disadvantages include the cost and special equipment needed. Gypsum concrete also has somewhat lower conduction (for less heat transfer) than regular concrete, though not enough to make any major difference in the design and layout.
Then of course, thin slab competes with radiant subfloor panels like Veiga and Warmboard, as well as under-sub-floor designs.