Optimum sleeper witdhs?

Gasper

I've read different opinions on the best way to install sleepers for a thin slab under a hardwood floor job.  Any opinions on 2" x 2"s vs 2"x 3"s?   I'm leaning towards a 3/8" cherry quartersawn x 4" finish floor, over a 3/8" sub-floor, over the gypcrete.  Any thoughts?  Also is a expansion edge (expansion joint?) required?  Thanks for any feedback, or tips.  I do lot's of steam and hot water heat, but very little radiant.  This is my own residence, so I want to do it "top of the line", and use it to help sell radiant.   Thanks

Mark Eatherton

WIder targets are BETTER targets...

And keep your tubing an inch or so away from the edge of the sleeper so that errant nails don't hit it.



Put it down at 8" (roughly) on center for a good low, even temperature of operation.



Make DARNED sure that the wood is COMPLETELY stabilized as it pertains to moisture.



Avoid cutting sleepers. Run your tubing home runs below the floor and into the area of fill. Use a 3/4" high speed steel drill, chucked in a Hole Hog, go in vertically, then with the bit spinning fast, slowly angle the bit to give you an easy transition from the bottom of the floor to the top of the floor. Tape the excess hole to avoid gypcrete loss.



Expansion joints are not usually needed for gypcrete because the applicator is supposed to spray an adhesive prior to pouring.



Have you considered Warm Board? www.warmboard.com



Good luck and enjoy your end product.



ME

Gasper

1/2" tube spacing?

I already have the 1/2" tubing.  It was recommended that I run 9" centers (by the manufacture).  However I keep hearing 8".  I am a bit undecided which to use at this point.  Any suggestions or opinions on this subject?  I'm building an addition, two stories, over a crawl space.  Staple down with sleepers, then pouring light-weight gypcrete, then I was going to put down 3/8" ply, then 3/8' hardwood (cherry 5" wide) on top.  Insulate under both floors also.   Another question using 2" x 3" sleepers..... you loose a bit of gypcrete surface......will I notice.

Gasper

1/2" tube spacing?

I already have the 1/2" tubing.  It was recommended that I run 9" centers (by the manufacture).  However I keep hearing 8".  I am a bit undecided which to use at this point.  Any suggestions or opinions on this subject?  I'm building an addition, two stories, over a crawl space.  Staple down with sleepers, then pouring light-weight gypcrete, then I was going to put down 3/8" ply, then 3/8' hardwood (cherry 5" wide) on top.  Insulate under both floors also.   Another question using 2" x 3" sleepers..... you loose a bit of gypcrete surface......will I notice.

Mark Eatherton

I prefer Uponor (formerly Wirsbo)

I think they are pioneers in Radiant (pick your surface) design,and they have the best "system" for good distribution.

9" centers is THEIR minimum. Tighter centers yield even lower water temperatures, which are always a good thing. And I've not given it a whole lot of geometric thought, but if your floor joists are 16" OC, and your sleepers are echoing that load bearing imprint, then running tubing at 9" OC is eventually going to cause problems with tube placement. Meaning you will eventually end up with one run in one bay and 2 or 3 runs in another bay, hence the reason for going with (roughly) 8" centers. Generally speaking, you want 2 passes per sleeper bay.



One distinct advantage of WarmBoard is that their tubing can (must) be installed at a 12" center, which is possible due to the lateral heat transfer characteristics of the aluminum substrate. I am waiting anxiously for someone (Larry, you reading this?) to come out with a product that utilizes the new carbon fiber composite product like what Watts Radiant is using, but incorporate it into a structural element like WarmBoard.



I also am anxiously awaiting for someone (hopefully Warm Board) to come out with a less expensive method for doing radiant walls and ceilings in a 4 X 8 configuration, using either aluminum or carbon composite fiber materials.



Lastly, can you imagine how many FREE btu's a south facing roof could harvest if it were covered with say a dark colored metallic standing seam roof with one of these heat transfer agents incorporated into the plywood substrate for the roof decking?



Granted, not as thermally efficient as a glazed flat plate collector, but then again, it could be used at night to provide FREE night sky re-radiation cooling.



Plus, if used properly, the roof could reduce the AC load of the home beneath it by sending the falling radiation into a GSHP loop field, or large seasonal solar energy storage tank.



Thinking outside the box again....



ME

Gasper

tube spacing

Thanks!  However I guess I misspoke, my job is on top of the sub-floor, with sleepers, in a 1-1/2" gypcrete pour, then 1/4" plywood, and  3/8" cherry on top.  I was planning on supplying the outside walls first with 6" on center for a couple of loops.  If I were to go less then 9" centers with wirsbo-uponor, 1/2" hePEX plus.......what would be the optimum spacing distance?     Thanks again for your expertise, and time.

Mark Eatherton

I haven't done 6" OC in 12 years...

There really isn't any advantage to doing 6" centers on an outside wall. A guy I use to work for did, but my next business partner didn't and we never had any complaints from any customers.



Most people don't spend a lot of time relaxing near an outside wall. They tend to congregate more near the inner core of the home.

.

The tubing manufacturer really makes no difference as far as output is concerned. Plastic tubing is plastic tubing, unless I am misreading your question.



The only reason for doing 8's as opposed to 9's is because you're dealing with sleepers that are on 16's, and 9's don't work with 16's, but 8's do.



We're here to share, you're here to learn, and that's a good proposition.



Glad I could help.



ME

jp_2

I don't like the idea

my experience is limited, but over time I have seen gyp shrink 3/16".   could have very well been due to installation mix, but too, this shrinkage has seemed to take  6 yrs.



so if this were to happen, your 3/8 plywood is unsupported and will flex along with the 3/8 T&G making for a funky springy floor.  plus you loose important contact between the heated subsurface and your flooring material.  you also talk of 1/4 ply, I don't see this as useful?



if you cover your sleepers with plywood its harder to know exactly where the sleepers are and great chance of tubing punctures.



are you gluing the flooring to the ply?



jp

Gasper

Shrinkage?

I was going to cut the 4' x 8' plywood in half.  I was told to leave a 1/4" gap at all edges, and between all 4' x 4' sheets.  While time consuming I was going to mark on the top of the wood exactly where the sleepers are under the plywood.  Then screw and probably glue down.  The finish 3/8" floor (quartersawn cherry) would nail down to the plywood with 1" brads, on a 45 degree angle.  Sound OK?

As far as the shrinkage.....you are scaring me.  I will definitely do more investigating on this.  I believe it is a Maxon product.  I don't know why it would take 6 years to shrink?  I would think if it's going to shrink, that would happen withen a year?  Any one else have any experience with gypcret shrinking in a radiant pour?