New Garage...pour next week need advise

[Pennyanguy]

Just found this site and it is great! wish I had found it befor starting my Garage! Well I am into it now...it is all framed and they are prepping to pour the floor next week so I have some quick questions..

Backround: Upstate NY (rochester area) 20 X 24 attached Garage with bedroom above on 16' door on 20' side. Ground here is Heavy clay...poured foundations (almost 30" wide!) Cement block 32" above the grade (footers came about to grade...on a slight hill about 8" along the 24' side.) 3-6" rolled r1/r2 rolled about 3-4 weeks ago.

Am installing Pex in floor and six foot apron for rad heat (different zones)... we just yesterday layed down 6 mil plastic, 2" polystyrene foam boards where we could and 1" shielded bubble wrap from edges of foam to blocks (about 2-5" where could not get foam over footers. Plan is to pour 4-5" (tapered back to front) sitting on footers. 6" mesh has been tied together and planning on tieing the pex to the mesh.

OK...now for the questions...

-how high to pull mesh above foam?
-should pex be tied to top or under the mesh? (under seems impossible???)
-if mesh pulled say halfway through pour...that leaves pex only about 1" below surface??? seems scant?
- will I need expansion joints or fishure cuts? If cuts...how do you keep from cutting the pex? If expansion joints...what kind would be recommended?
-pour will be going to the block, but should be isolated from the block by a layer of the bubble wrp or possibly 1/2" foam...is that sufficient for expansion?
-should we use the 2" foam in the apron as well or would the bubble wrap be sufficient?

As an aside...I am wary of the floor floating on the foam...not sitting directly on the ground, but everything I read says you need to insulate the floor or the heat loss will be crazy...are you then relying on just the strength of the slab itself to not crack? Contractor says once all that cement is on the foam, the foam will be ON the graound...still seems like the foam could promote cracking over time...I dont ever plan on installing any lifts in here (10' cielings) but I would hate to see cracks in a year or two (non of the contractors in the area would guarantee against cracks)

Any advise at all would be helpful...I basically trust the contractor but am the doubting thomas type...like to know all the in/outs if I can.

Thanks

 

[bdymnjm]

Pennyanguy,

I don't know much from experience on this. From reading here on GJ and talking to a contractor I would suggest putting the pex directly onto the foam boards with special staples made for this purpose. The mesh could go directly on top of the pex and stay there or better yet use rebar on chairs instead of the mesh. It may not be necessary to use reinforcement at all. I hope you get some more responses from experts.

Jim

 

[Pennyanguy]

Boy,

This is dissapointing...almost 200 views and only one response to my questions???

 

[Crazy68Dart]

This might help a little:

http://www.garagejournal.com/forum/showthread.php?t=203328

 

[ConCretin]

I'll take a shot at answering your questions but if it's not too late I'd suggest a different approach. I'd staple the radiant to the insulation and support the mesh above it at the midpoint of the slab.

-how high to pull mesh above foam? - I'd probably just let the mesh lie on the insulation to hold the radiant. Pulling it up runs the risk of it floating too close to the surface

-should pex be tied to top or under the mesh? (under seems impossible???) - Tie the radiant to the top of the mesh

-if mesh pulled say halfway through pour...that leaves pex only about 1" below surface??? seems scant? - I agree

- will I need expansion joints or fishure cuts? If cuts...how do you keep from cutting the pex? If expansion joints...what kind would be recommended? - Expansion isn't an issue, contraction is. Saw cut or tooled control joints will prevent random cracks, which look like hell. Saw cutting obviously is risky if your radiant doesn't stay down.

-pour will be going to the block, but should be isolated from the block by a layer of the bubble wrp or possibly 1/2" foam...is that sufficient for expansion? - Bubble wrap would be OK but I'd use at least 1" rigid for the added insulation value

-should we use the 2" foam in the apron as well or would the bubble wrap be sufficient? - I'd use 2" rigid extending out several feet to provide insulation and keep frost out from under the apron.

As an aside...I am wary of the floor floating on the foam... - This is not a problem. It's the proper method

Some of these questions are complicated and subject to debate, which might explain the lack of responses. Figured I'd give you one man's opinion.

 

[Pennyanguy]

Thank you for the responses...I completely understand that everyone has different opinions on how to do things...Thats the great part about these forums...many opinions...then you choose what you want to go with.

Any other opinions welcome...the pour has been delayed (mason hurt his back) so I have more time to study and confuse myself.

So far, I think I will go with the pex on top of the mesh, as repair seems impossible if undernieth (thanks for the opinions though). I am looking into expansion joints now...trying to find something that is ridgid like the Bometals aluminum that I can also use as a screed board...any ideas?

 

[Pennyanguy]

OK, here is the update. The floor was poured last week, looks good..the contractor seemed to be careful enough about the pex and it held pressure fine....but the mix seemed to cure faster then he expected and he had a B^%$tch of a time smoothing it. Next day it looked like the floor had the chicken pox, leapord spots all over pretty uniformly...contractor stopped by and said that was normal...it would go away...now 7 days later its still mostly there...looks to me like the stones are too close to the surface...am I crazy or did something ****** up???