Planning for optional radiant sub floor, existing and adjacent addition
4000sf remodel over existing plywood subfloor, want to provide a radiant option to the customer. Looking for the lowest cost quality install, ruled out Warmboard approach because of cost.
Finish floors are a mix of 3cm stone, tile, and wood.
New addition has a poured slab planned, have to level to adjacent subfloor and account for different methods and heights for finish materials.
So, my thought is to pour the slab 1″ low and use gypcrete to level later, with the option of embedding pex. The gypcrete thickness can be a late decision once the floor schedule is finalized.
On the adjacent wood subfloor, use Troba to receive pex tubes and where wood goes over it fill it and glue.
Existing wood/plates are not PT, would a 6mm vapor barrier be adequate separation …?
Opinions/advice?
Replies
troba?
The Troba comment has me confused regarding RFH, but it's not a material I've looked at in several years. The only Troba I know about is an exterior drainage mat for balcony installations, etc. Is it now used in RFH applications?
Hi QJ,
Will there be access under the exisiting wood subfloor? If so, then you could install the tubing anytime from underneath in aluminum channels. I have used this alot in remodel scenarios. It worked extremely well, even under hardwood (which is not my favorite situation to begin with). The key to making the tubing below the subfloor work is proper/enough insulation. At my own house (new build), we installed the tubing in the aluminum channel to the underside of the subfloor with zip screws, then "panned" the joist bays with foil faced bubble wrap leaving an inch or 2 air space. Then the bays were insulated with open cell foam. I wouldn't do a large project this way, but I had only 3 rooms with tile so this was still cost effective. It has worked very well.
As for the addition floor slab, you will most likely be installing subslab foam insulation and reinforcing wire mesh? Just tie loops of pex off to the wire and make sure the ends make it back to the boiler to be connected later. No need for gypcrete of TBD thickness if you are not adding to the top of the existing wood subfloor. I think this would be simplest and most cost effective, assuming you can get under the existing wood subfloor. Good luck. Curious to hear more about your particular situation. This seems like an issue that we work through often in remodel scenarios where planning for the future really makes sense.