Radiant ON TOP of slab

Nikojo

Building new house. Want radiant in lower basement level. Efficiency not greatest concern.
Floor will be wood on plywood subfloor on top of 2x4 sleepers.
Does it make sense to place radiant tubing in between the sleeper studs ON TOP of the slab?
I know efficiency may suffer but system will probably be more responsive, ie quick up and down time.
Seems this would be relatively equivalent to radiant in upper level between joists.

hr

why not

put the radiant in the slab and use a thin engineered hardwood directly on the concrete?

The thin @5/16" engineered flooring products work well as a glue down or floating method directly on concrete. Most are prefinished and sealed on all four sides for excellent moisture resistence. Much better than just sealing the top surface at the site, which is generally the case with most 3/4" nail down. Less wood movement also with plyed engineered products.

Shop for a good brand, stay away from the soft core or chip board products with paper thin top veneers, IMO. Find a brand where all the veneers are hardwood.


Probably less R value than sleepers, plywood, and 3/4" nail down hardwood.

hot rod

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Nikojo

Thanks for reply,
Have floor on slab system now and do not like the "feel" of it. Does not feel natural.
Also any water infiltration damages flooring. Last two homes have had this problem regardless guarantees and build quality from contractor.
Definitely putting floor on sleepers. Question is what is ideal for radiant in this application.

Thanks again.

Nikojo

What about putting sand in between sleepers around the radiant tubing??

Jamie_6

You really have to watch the water temperatures if you would place sand between the sleepers. If you exceed 140 degrees the sand will actually crystallize on the pipe and you would loose all your heating capability (it actually becomes an insulate). If you already know that you will be building a platform why not insulate between the sleepers with foam and place Wirsbo’s Quik Trac above floor radiant heating system?

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hr

A couple more thoughts

If you have water infiltration, inside the conditioned space, you will have problems regardless of the installation method of wood floors. Having water or moisture leak in is not a very good option for radiant heating. Or any heating for that matter.

Best to handle any potential water issues outside the foundation, it's done all the time. Foundation waterproofers, french drains, if needed a foundation drainage and sump pump system. Somehow deal with the water, and keep it outside.

Even with the radiant elevated on sleepers that moisture will wick up into the strips and flooring. Not to mention mold issues with damp or moist wood. Termites love warm, wet wood also

I'd also skip the sand. In addition to all the concerns mentioned in Siggys article it is also an excellent breeding ground for insects. And wet sand is certainly not an option for inside your home.

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,116124,00.html

Plenty of options for a sleeper or possibly a WarmBoard system on top of the slab. Crunch the numbers to obtain a heatloss figure for the space and design the installation system around the required BTU/sq. ft. number.

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Nikojo

Excellent link. Thank you

Nikojo

Never knew that! Will not use sand.

hr

in the sleeper systems

that I have done we always used 2X4s. Hard to find good quality straight, long 2X2's these days and it doesn't provids a lot of nailing surface, almost impossible to have two pieces of hardwood come together on a 1-1/2" thick sleeper. Very little nailing "meat" left.

If I were to do a sleeper system I'd really consider the "Timberstrand" studs. These are manufactured studs that are lazer straight, available in very long lengths, excellent nail holding ability, and very structuraly stable.

Second choice would be finger jointed studs, for the same reason.

TS studs are made much like a micro lam or parallel strand engineered product. They fasten down nicely also with out splitting.

I'd highly recommend construction adhesive and anchors or tapcons.

Builders around here use TS studs where they need straight walls, like kitchens, for cabinet and counter top mounting. I like to use them at corners for a nice true, straight sheetrock detail. Yeah they do cost more, but it's only money

This pic shows a timberstrand and a regular stud in my shop. Notice how the regular stud twisted away from the TS as it dried out. Sorry about the turned photo You don't want that to happen under your hardwood, do you now?



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Nikojo

I like the spray foam too

Thanks for the great info. I like the spray foam in the picture as well