Your opinion, please?

hr

The final stone surface needs to be in direct contact with the concrete. The waterproof membrane R will work against you a little bit, and should be calculated.

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Don \"Grumpy\" Walsh

Elevated deck

I have an elevated deck built with 12" steel beams and projects out from the building 20' and is 15' above grade.
The deck is constructed from the bottom up as follows:
3/4" teak,
6" dow board within a 2x10 lattice,
2 1/4" air space,
3" of concrete,
2 ply torch down SBS membrane,
1" pedestal carrier spacing,
2" x 18" x 18" stone slabs as top surface.
Owner wants this snow/ice melted so there is NEVER any impingement on his use of the deck.

So the question is.... where would you install the pex? In the concrete or in the air space created by the 1" pedestal risers? Or both?

Richard_6

How are you...

Placing the pex tubing? This product may help you in this situation. www.crete-heat.com

Don \"Grumpy\" Walsh

No room.

> Placing the pex tubing? This product may help you

> in this situation. www.crete-heat.com

Don \"Grumpy\" Walsh

No room.

Thanks for the reply, but there would be no room in the construction layers for that product. It has to be either in the concrete, or in the 1" air space.

hr

I think in the concrete

to get the best transfer from the tubing to the load. Any air or air gaps around the tube will lessen the conduction transfer, which you may need all you can get

Speaking of load, did you run some numbers on what it might take to warm that. Is it a snow melt application?

A suspended deck will see wind loads above and below and all the edges for loss. Sounds like a very high load potential.

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Richard_6

We have...

> Thanks for the reply, but there would be no room

> in the construction layers for that product. It

> has to be either in the concrete, or in the 1"

> air space.

Richard_6

We have...

a product that is 1" thick that would slow your heat loss out the bottom and hold your tube in place. Just a thought, I'm only trying to help. Have you concidered using Level Rock from USG to help save space & yet get you a faster reacting slab. I would need to check if this product can be used outdoors. It has a much higher PSI rating than typical gyp crete.

hr

What is the 1\" pedastal carrier space?

> a product that is 1" thick that would slow your

> heat loss out the bottom and hold your tube in

> place. Just a thought, I'm only trying to help.

> Have you concidered using Level Rock from USG to

> help save space & yet get you a faster reacting

> slab. I would need to check if this product can

> be used outdoors. It has a much higher PSI rating

> than typical gyp crete.





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hr

What is the 1\" pedastal carrier space?

> a product that is 1" thick that would slow your

> heat loss out the bottom and hold your tube in

> place. Just a thought, I'm only trying to help.

> Have you concidered using Level Rock from USG to

> help save space & yet get you a faster reacting

> slab. I would need to check if this product can

> be used outdoors. It has a much higher PSI rating

> than typical gyp crete.





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Don \"Grumpy\" Walsh

1\" pedestal

Te pedestals are the mini-risers that will hold the pavers above the SBS membrane is to allow for water drainage. I have been trying to get the architect to eliminate the risers and to allow the pavers to sit flush on the membrane with 1/4" gaping to facilitate water run-off. So far, to no avail! The deck surface area is 320 sq. ft., this one is posing a real challenge!

hr

You're making me nervous

There seem s to be a lot of forces working against you Be sure they are clear with their expectations.

Remember that flowing melt water will also wick away some of your horsepower.

Air gaps, suspended slab, flowing water, ouch.

They might be better with overhead radiant units or portable mushroom radiants, like restaurants use?

I did an elevated deck once for a wealthy customer that wanted to be able to walk out, barefooted, mid winter and pee off his deck!

Unfortantly, or luckily they got divorced and sold the place shortly after moving in. And before "peeing"season.

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Peter Invision

Don \"Grumpy\" Walsh

Agreed!

This project is one of those "once-in-a-lifetime" challenges (for the 5th time). This total project has 22,000+ sq.ft. of radiant living space, 30,000 sq ft of driveway and parking area snow/ice melt, and 2000 sq ft of suspended decks to snow/ice melt. The decks were just added to the equation this past week, so a good bit of brain storming is being done to come up with a workable solution. I am leaning towards installing pex in the concrete slab portion, AND then install a second layer of pex in the 1" air space using railfix and extruded aluminum plates immediately under the pavers. I think it might work?? What do you say?

Paul Fredricks_3

I don't have a clue, but make sure an engineer does the calcs for the increased weight, assuming they get a 2' snowfall and no one is there to turn on the snow melt.

hr

Oh, sure it will work

but will it work up to the owners expectation.

Start by looking up the ASHRAE classifications for snowmelts. Determine with the owners and engineers which class they are considering.

The unknown is the suspended aspect as well as the R-value above the tube,and the tube in an air space.

If the melt waters run across all the tube, in the air space, to exit the deck that to becomes a challange.
If they are willing to spend the cash to try it , why not. But I wouldn't make any promises. And do that in writing

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