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Radiant Floor Heat on Wood Subfloor

atvjoel

Registered User
Joined
Aug 1, 2021
Messages
124
Location
Alaska
My plans call to forced air heat, but I am wanting to change up to radiant floor heat.

I went with ICFs/crawl space (actually ended up being a 5'4" crawl space).

I am in cold climate and will be installing electronic fans for venting that can be shut off in the winter. Rather then go with forced air I want to go with radiant floor heat. For me its better because I can do the work myself because I do not have HVAC experience, but also cold feet suck.

I have 2x10 floor joists 16 o/c with 3/4" T&G OSB. Single story duplex w/ engineered trusses. I know my inspector wont care as long as I am complying with international building code but does anyone see a problem with switching to radiant floor heat and pouring 1 1/2" of gypcrete on the floor? I am adding quite a bit of dead load but with 16 o/s I really dont see a problem with it. I had built my door rough ins 1 1/2" high just in case I decided to do this a few months back and think its better way to go for me.

Anyone that has experience with this feel free to chime in.
 
This brand says 1.5" thickness would add 13.8 lbs. per square foot. Depends on the joists span and if it is for bedrooms or other room floors..
ttp://www.maxxon.com/gyp-crete/data
 
Joel,

There are other options to gypcrete, and I know you have material issues getting stuff, but look up Warmboard. You are late, but the reno options they have might work.

Also if you don't mind the extra work you can lay down reflective insulation and install sleeper boards ripped from 3/4" ply or thicker and then drop your floor over that. Insulate good underneath the sub-floor.

The weight of gypcrete is huge and takes the floor system a long time to recover if it get cool, so secondary heat is critical, I am guessing you have a fireplace or wood stove for backup.

But nothing like radiant and saves life on boilers also with the lower temps settings needed.

Good luck.
 
Joel,

There are other options to gypcrete, and I know you have material issues getting stuff, but look up Warmboard. You are late, but the reno options they have might work.

Also if you don't mind the extra work you can lay down reflective insulation and install sleeper boards ripped from 3/4" ply or thicker and then drop your floor over that. Insulate good underneath the sub-floor.

The weight of gypcrete is huge and takes the floor system a long time to recover if it get cool, so secondary heat is critical, I am guessing you have a fireplace or wood stove for backup.

But nothing like radiant and saves life on boilers also with the lower temps settings needed.

Good luck.
I plan on spraying rigid spray foam for the floor. That is a really damn good idea, just rip some 3/4" with router and create the grooves and just go over existing subfloor. I am in Alaska so there is no chance on getting Warmboard.

Never seen that warmboard before. Pretty cool and the weight isnt a factor.

That is my primary concerns. My floor is very beefy but it wasnt designed to support that much gypcrete. Second issue is i dont want to wait until April/May to pour gypcrete because right now it too cold.
 
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