Girl next door

Mark Hunt

cracked...................................


And getting ready to crack!

Mark H

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Rock Solid Restoration_4

Girl next door

Hey guys:

I'm helping out my girlfriend/next door neighbor with her radiant installation in her kitchen/dining room.

The flooring material will be tile.

The room is approximately 400 sf.

After exploring different options, I feel the best way to install the tubing is with a concrete grit mix over expanded metal with 1/2" pex on 8" centers.

Here are the questions:

1- Should I put down tar paper or plastic vapor barrier on the plywood subfloor first? I thought I remembered hearing someone complain that the tarpaper smells when it heats up.

Also, I understand the reason for a vapor barrier in an on grade situation but I'm not sure I understand the need for it in a suspended slab situation.

2- The expanded metal seems kind of sharp. Should I be concerned that it could cut through the pex?

3- I'm planning to use 5/4 X 6's as sleepers on top of the expanded metal to screed off of and set the height of the concrete. This will give me about 1-1/4" of concrete. Is that a good thickness?


Thanks in advance for your advice.

Craig

hot_rod

Yes, yes, and maybe

use a 6 mil plastic on top of the plywood. It prevent the moisture from being drawn out of the mix to quickly, and you don't want the concrete to stick to the plywood. Unlike gypcrete!

Skip the asphalt impregnated felt paper!

Don't water the mix as all the waters of convience will have to leave the top of the slab with plastic underneath.

I would worry about the sharp mesh, also. Find a better product. 6X6#10, 10 is most commonly used but holding an 8" OC gets tricky. Go to 6" OC, more even floor temperature gradiant, and it solves your tie down dilema.

Don't over tighten the fasteners to the mesh, be they plastic wire ties or steel bar ties.

Are you leaving the screed boards in? They will swell when the mud contacts them, then shrink when the heat is turned on. Does this bother you?

1-1/4 is a little thin, in my opinion. Definitally use a pea gravel sized aggreate. ACI recommends 3 times the aggreate size over the tube. 3/8" pea gravel= 1-1/8" OVER the tube.

Use fibers in the mix. Poly or nylon are most common. Double the usual mix to 3lbs. per yard for thin pours.

A sealer or fogger will slow the cure and give you a better job, depending on final floor coverings, compatability.

Make sure your joist are up to the task for this additional weight. Nothing worse than a springy tile floor :0

I'll bet it still cracks!

hot rod



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Thanks hot rod.

I have some more questions.

1- Why don't you want the concrete to stick to the plywood?

2- Why do I care if the concrete cracks?

3- Haven't I seen the expanded metal being used in Wirsbo's literature. And isn't that what is used on bathroom mud jobs?

I will go to 6" oc.

I will remove the screed boards.

Thanks for your help!


Craig

Bill NTSG

How about

Stadler climate panel or Wirsbo quick track? 1/2" plywood and the tube snaps into the groove. You could thinset right over it or put down 3/8" durock then tile ?

tombig

Mortar Bed?

> Stadler climate panel or Wirsbo quick track?

> 1/2" plywood and the tube snaps into the groove.

> You could thinset right over it or put down 3/8"

> durock then tile ?

tombig

Mortar Bed?

hr, If you install a mortar or gyp bed that just covers the tube, an isolation membrane, then thinset and tile, what do you expect of the end result? Will cracks continue through the pours or will they be individual 'floating' slabs? Any experience with this?