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this is the final plan worked out between the rfh guy and myself, what do you lot think?
ground floor – we put in the foundation walls under and fill in with hardcore rubble compacted; then 4″ of subfloor concrete; then 2″ of rigid polyurethane foil faced foam as the thermal break; then steel reinforcing mesh with the piping attached, which will be raised to the middle of a 4″ finished concrete floor. this will have floor coverings of a floating wood floor 5/8″ thick plus underlay, carpet and underlay material, and standard tile.
second floor – joist’s; 3/4″ t+g ply, sleepers infilled with 1.5″ sand cement screed. the thermal break underneath the screed will be that foil bubble roll.
is this enough? are there any holes in the theory?
please, at this stage i need guidance.
good stuff
Replies
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Why two slabs on the first floor? Why not just eliminate the lower slab? I could see doing two slabs if the upper one, above the foamboard, was like 2" thick for quicker response times. But unless you work on Peterbuilts in your kitchen, why pour two slabs? The tiled areas will give much more heat per sq foot (like 2 or 3 times) than the carpeted and wood areas. So more tile is good both for maximum output on the coldest days and also for responsiveness.
Upper floor looks fine. The metalized bubblewrap could be used under the concrete (note that you will NOT get the R-value the package claims, they take credit for sheathing and drywall and two air gaps that you won't have). Or you could have insulation in the bays below. Either way is okay.
The trickier questions that deserve more thought are about zoning and controls. Your ground floor is fairly high-mass and somewhat insulated by carpet and wood. That calls for smarter controls than the lower mass system upstairs. Each zone adds some $ but also adds flexibility and comfort. Only combine rooms that are similar in the heat-demand patterns and in their use.
With warm feet on a -3F day, -David
*thanks for the post David.the reason we put two slabs in here in ireland is because it is a building regulation. something to do with trapping in the radon barrier and getting the strenght needed. it is also a product of the field, easier to put in half and half than to cope with all that concrete in one go. tradition moves into reg.'sas for the higher mass ground floor. i'm going with a geo heat pump, and want to take advantage of the cheaper night rate electricity, storing the heat in the slab and riding the comfort for a few more hours during the day.thanks again David, anymore suggestion people.good stuff
*i that foil bubble rollI'm also about to do my upper floor by adding sleepers with sand infill over existing plywood on wood joists... but my supplier is saying that I don't need any thermal break/reflective barrier underneath? Just a layer of 6 mil plastic to keep the sand in and the moisture out.What flooring are you putting on the second floor? I'm putting plywood over the sleepers then carpet, so I can use dry sand without the cement. still dreaming of warm feet
*Jim: The downside of not isolating the two floors is that the ceiling can heat the downstairs. If the upstairs needs heat, the ceiling will be hot. But if, at the same time, the downstairs is reaching its setpoint (and maybe overshooting due to all that hot mass), the hot ceiling is only going to make things worse.Is it fatal? No. Is it a big deal? Not compared to people who live on 1000 calories a day in a mud shack. Peeling one layer of clothing will maintain your comfort. But is it as good as it can be? No. Better control can be acheived if each heat source heats only one zone. So a zone doesn't get extra heat when it doesn't need it. And insulation is CHEAP when installed during new construction. Eddie: see if your RFH or geo-heat pump vendors have a smart controller to handle the heat storage aspect of it. Something that looks at outside temperature trends and can told when the power is the cheapest. -David
*eddie:"something to do with trapping in the radon barrier"Out of curiosity, what is the radon level at which your local authorities recommend remediation?
*bob, in ireland, you always put a radon barrier down.always!!!
*Dry sand? Really? Haven't heard of that being used. I did staple-up on the first floor with foil-faced Celotex under, and I put tubing in the slab when I dug out the basement, and have been looking at ways to do the 2nd floor (attic conversion). Was thinking of Gyp-crete, but sand is something I could do myself. (I've built the rest of the system myself). What kind of sand? Those bags of play sand?
*You can get bags of sand where you get ready-mix (sacrete) bags. Or have an excavation contractor dump a load (of sand, that is) in your driveway.
*Thanks David (and hi Mike :-)It would seem like putting the insulation between the joists below would be more effective then the foil under the sand? And seeing as everything is open now this would indeed be the easy time to do it. On the sand, I checked prices today... something like $114/ton if I buy it by the bag, versus $9 - $12/ton if I get it in bulk at the sand & gravel plant. Since 2-3 tons would require a bunch of trips in my little truck I'll probably go with the $9+/ton and $90 delivery fee.Of course the sand is like 'crete in that it adds to the dead load... about 4.5 psf extra for the 3/4" I'm using (9 psf with 1.5" sleepers). I suppose I should check, but I don't think it will be a problem.
*I've got three 1-ton dumps, so getting a load is no problem, but it would be wet, or at least damp. I think the bagged stuff would be the way to go. Sleepers on 16" centers and then another layer of 3/4" T&G ply? How much is Gyp-crete? Can you mix and spread it yourself, or not really? Two bedrooms and a short hall (carpet), and a bath with tile floor is the plan.
*JimI am not up on all of the details as I can't use any of this right now.But I don't think that mass (sand) and insulation is an either/or.You have two different problems here. The insulation is used to direct most of the heat into the desired area and the area that is being controlled.The mass is to help provide a more uniform heat but spacialy and over time.
*but guy's, do you think that the foil bubble layer recommended to me, which is 5/32" thick, would be anough of a thermal break to send the heat into the 1.2" screed, and through the carpet flooring?
*Eddie...for wall to wall carpeted rooms, I use baseboard along the walls. And upstairs rooms need much less heat than downstairs especially in open floor designs.near the stream,ajAs to radiant under carpet...it works...but less heat. OK for upstairs...but I would never do it...often anyways.
*aj,appreciate the post.the only options for heating over here is RFH or radiators. no baseboard or anything else for that matter. regardless of the preffered fuel.and the radiators we use over here need approx. 185 F temp., pretty hot eh! and they are no good at what they are used for.the RFH revolution is only beginning here.i'm applying RFH with a geo heat pump, and bumping the domestic hot water using what we call an 'emersion', a heating element inside a copper cylinder.so what do you think on this?and again, what about the bubble foil, will it do the job, or, would 1" polyurethane (foil-faced), be much better?appreciate the help!
*and aj,how do you lot make sure you don't puncture an RFH pipe in the slab when your nailing down the interior walls?appreciate the help.good luck
*>how do you lot make sure you don't puncture an RFH pipe in the slab when your nailing down the interior walls?The layout for the PEX should avoid crossing through walls whenever possible--I kept 6" from walls. When not possible, we sleeved the PEX in conduit so that there was additional protection (not perfect protection, mind you). Also, good photographs of the PEX before the concrete can help you remember where you ran it.
*Cool - I think I'm getting it now. Much obliged.Like eddie, I just need to chose what insulation to put underneath. Pictures of the sleeper/sand method (sans insulation) are at:http://www.radiantcompany.com/details/suspended.shtml
*I am holding a piece of Reflectrix's metalized bubblewrap with the label attached. Two layers of bubblewrap, tin foil on the outside, all stuck together. They claim a R-value of 9.8 in a horizontal application. The small print notes that they include the effects of 3/4" interior, 3/4" exterior plywood and all air spaces in the wall system. They don't note but I will that they certainly also assume that the outer metal layers will never collect dust (which minimizes its radiant-barrier effects). Would I rather sleep on the snow on this stuff or an inch of poly-iso rigid foam? The poly-iso is an honest R-value of 5 and I'd prefer that except in weird applications (insulating a airplane where surfaces are curved and removal is important for inspections, etc.There are many reasons not to use FG batting. But it is cheap, easy to install, fits in the floor bays and can't sag in a horizontal application like it does in vertical bays. FAR cheaper than bubblewrapcrap and with higher, more honest R-values. -David
*thanks david, but over here the bubble wrap stuff is far far cheaper that FG.is the stuff you have the same thickness that i mentioned?goof luck
*Eddie...You sound like you are set on the bubbles. Fine. It will do something. I would say an inch of foam would be 10 times higher insulation value at most and 2 times better at least.near the stream,ajTime to decide eddie. What will it be?
*Eddie: The metalized bubble stuff I was citing is about 1/4" maybe 7/32". Definitely more than 5/32". Maybe your stuff is a single layer of bubbles with foil on both sides. My sample has two layers of bubble plus foil. Best guess on my stuff would be an honest R-2 to R-3. Sounds like a bit R value with yours.Maybe your installer has a system that works okay in retrofits and likes to use the same system in new construction. I'll check bubblewrap versus FG when I get home. I'm working on a bathroom in California just now. 45F - shorts weather. -David
*thanks aj, thanks david.i think i'll go for the 1" polyurethane(foil-faced).i had this in mind originally, but when he suggested it, i had to check it out with you guy's.thanks againgood luck