I’m using PEX in floor heat for my new home. The floor is rated to accomodate 1 1/2″ of concrete to encase the PEX tubing. I have used 3/4″ tongue and groove plywood for the subfloor. I could call in a contractor to pour gypcrete over the PEX at a cost of about $4000. I have tried to buy gypcrete and similiar products to install myself without success. The cost of using concrete, which I could install myself, is about $800.
Do I need to use a bonding agent before I place the concrete? Should I provide a vapor barrier or treat the plywood first? Any help or references to placing 1 1/2″ concrete over a plywood subfloor would be much appreciated.
Thanks
Replies
I usually fasten metal lathe on the ply first then radiant tubing,make sure you order concrete with max. 1/2 " aggregate .I did this to my own house 7 yrs ago with no cracks yet.
Thanks. Did you have expansion joints at the doorways or was this one big pour?
I carefully cut expansion cuts ,if you can call them that 3/8 " deep in the doorways after the pour then grouted.
Why can the contractors get gypcrete and you cant?
blue
The manufacture is telling me that I have to specially trained to use their product.
you might ck so pics i posted where i did 10,000 sf of concrete over wood... lightweight concrete... over 4mil plastic... i was 20 ft up from ground level so i used a pump mix... i think you are better off with concrete even without the cost factor...and this is just my opinion... gypcrete dries more than cures... vs concrete cure'n... the moisture i believe leaves concrete faster... i've seen alot of mold on gypcrete... if you want the concrete can be a finished floor the gypcrete never can be..
as for the price... it'd be a no brainer for me
p
What was the mix for the lightweight concrete? At what slump did your pour? Did it have a plastizer in it?
And.... where are the pics? That sounds like a project for a rather expierenced concrete man - which I believe you are...
experience is what you get by do'n... I'm just dumb enough not to be scared of do'n anything... usually inspired by less than steller work by "professionals" and by price...
the mix was a pump mix so it had no slump... it was a 4000lb mix if i recall might have been 3500lb...
I was 20 ft up but even if i'd been ground level the $1200 (if i remember right) for the pump was well worth it... the pics are posted in the pic section might do a search use'n "ponytl" if you are interested... yes it's hard work but thats really what it is alot of labor RIGHT NOW then it's chill for a few... then jump'n back on it with labor... you do want someone there that understands place'n and finishing concrete but if you have done your prep work and set your screed boards ur halfway to get'n a good job... what you have is 6hrs labor for 2-3 guys if you get everything ready... and with your infloor heat I think i'd want to pump it in... a small 3" pump should do... might cost you $500 for the pump and operator but he's the one that should order the mix (you should tell him how much)... all depends on your skill & comfort level doing something like this...
p
use the metal lathe fasten it w a roofing gun someone else sed it, gypcrete molds
Bad Idea
I would not recommend putting 1-1/2" concrete on any wood subfloor.
1. The structure may be rated to handle the weight, but it would put a lot of stress on the framing regardless.
2. Any connectors you may need to use in the radiant tubing will deteriorate in concrete.
I am currently busting up 1-1/2" - 4" of concrete from a house that did the same thing. What a disaster it is!
Pex is burried in concrete more often than not for radiant heat - as for connectors, there shouldn't be any in the concrete - that's easy.