With staple-up PEX tubing for radiant heat, against the floor sheathing’s bottom surface, tell me how you would insulate the floor from the cold garage below.
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Like this, I think.
(Bear in mind I haven't had my full measure of coffee yet this morning)
Edit: Yes, the plastic vapor barrier is theoretically redundant. Belt and suspenders kinda deal against vapor migration if this room is Aced during the summer.
Knowledge is power, but only if applied in a timely fashion.
Edited 12/27/2003 10:18:52 AM ET by GOLDHILLER
gold.... when i click on your xxx.doc..
it open's a blank screen in wordpad...
the most reliable way of displaying something here is with xxx.jpg format
Mike Smith Rhode Island : Design / Build / Repair / Restore
I opened his drawing just fine.
Dave
Hmmmmmmmmm.
Here we go again, but maybe it's best if you can't view it. <G>
Probably gonna shoot the notion full o' holes. ;-)
Knowledge is power, but only if applied in a timely fashion.
mmmm . thanks..
it opens at the office but not at home.. ?????
anyways.. looks like a good detail.. with 2 small observations..
the vapor barrier is redundant with the foam underneath it.. the foam is a great vaporbarrier all by itself..
and 2: most vapor transmission is from hot to cold... and/ or moist to dry.. odds are pretty good the direction of vapor will be from the heated side to the cold garage...
and .. putting a vapor barrier at the cold side may create a condensing surface... i think i'd eliminate it and be satisfied with the foam ...
another thought: the foam can be placed and then furring installed below it ... this will facilitate hanging the gypsum.. and blowing in your " insulation of choice "
here's a pic. of a garage ceiling with all of the plumbing in the floor including water lines.. notice the 4" holes drilled in the band joist so we could blow cells in on top of the 1"EPS & furring
the 2d pic is blowing the cells in from the outside
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 12/27/2003 1:50:08 PM ET by Mike Smith
Edited 12/27/2003 1:51:29 PM ET by Mike Smith
here's the pic. of the garage ceiling.. i had nightmares of frozen pipes.. between the pex and the insulation i sleep well now...Mike Smith Rhode Island : Design / Build / Repair / Restore
Yup. Definitely forgot to put the furring in the illustration for the drywall mount.
Nice pics.
Did you put an access panel in to get at that trap?
Knowledge is power, but only if applied in a timely fashion.
no.. no access panels.. just the pictures and a sawzall if we can't snake it form the topMike Smith Rhode Island : Design / Build / Repair / Restore
On that note, I gotta ask another question.
Being of the persuasion that just because you can do something, doesn't mean you should……….I sometimes find myself at odds in situations like Mr. Micro's with this floor or any similar flooring situation where said floor contains plumbing runs. If one should install those pieces of foam board (particularly the bottom one) to up the R value, it seems any chance of an "early warning system" has been thwarted or at the very least, obstructed.
My fears/nightmares concerning this would revolve around the potential for a tiny to smallish leak that can't evidence itself because of well-sealed foam board. In my mind one could theoretically suffer substantial structural damage before there was surface indications. These sorts of scenarios give me the heebies-geebies once in a while.
Same thing applies for me when it comes to vinyl siding. All manner of "stuff" can be going on back there without any readily visible signs like peeling paint.
Even when I was a young man racing 85mph down these backcountry gravel roads in the dead of night, I always shut off my headlights as I approached an intersection to look for headlights from other vehicles. Now that's a prime example of exercising prudent caution, huh?
And so……..on to the question. Do you or your clients ever choose to omit some r-value in lieu of that "early warning system" or do ya just always put your pedal to metal and go for broke?
Knowledge is power, but only if applied in a timely fashion.
well... on that note... i don't believe we seal the foam board sufficently to hold water like a boat hull....
and since we're using dens-pak cellulose as our bulk insulation.. it is going to air seal anyways.. bottom line.. i gave up on vapor barriers when i gave up on fiberglass insulation..
i will admit to buying a couple rolls of unfaced batts for every job.. but the only thing we use it for is for blocking on some perimeter areas..
but no.. if any of those pipes in the previous example sprung a leak... it wouldn't take long to show on the ceiling below... and... it would be fairly localised too.. the pipe would piss.. saturate the cellulose around it.. gravity would drop it straight down.. then it would find a nail hole or blowing access ahole in the foam.. and on to the blueboard.... it would run along the blueboard to the nearest seam and start dripping...
Mike Smith Rhode Island : Design / Build / Repair / Restore
Here is what I thought I might do. My foam guy charges $1.20/sf for 2" thickness as shown here. I sketched an I joist and a sawn 2x12 to show how we fix the foam board either way. A light press-fit with the foilfaced rigid, a few tacks with a gun, and the urethane binds and seals everything.
The only drains coming through the floor above the garage will be from a laundry, and a kitchen sink, so there will be no traps. I'll try to consolidate them quickly in one joist bay and run the drain in a cavity under the 1" rigid foam. Water feeds will all be through the floor and up into the walls before reaching the space over the garage.
I had a bad experience living in a very poorly built house once, where the stupid GC that built it had put all kinds of plumbing, supply and drains, into the floors over a 3-car cold garage. Insulated and sealed poorly. Suffered some major leaks after a deep cold snap.
i like doc's better .. you have too much thermal bridging thru the framing... and ..
you like to do system cost analysis... ( analyize this ! )....
run the numbers on your two inches of foam sprayed in place.. vs.
2" of EPS tacked to the joist bottoms and firred with 1x3.... then the joist bay blown with dens-pak cells..
now run your annual heating costs with both systems...Mike Smith Rhode Island : Design / Build / Repair / Restore
I would start figuring, if there was anyone within a 90-minute driving radius of me that did blown-in dense-pac.
Going under the staple-up PEX lines, don't you feel you miss something using EPS without a foil face? The only foil-faced stuff I can get is extruded polyisocyanurate.
As regards the thermal bridging, how much of it is retarded by the 3/4" of dense-pac you get under the joists between furring members?
The only insulation available to us up here in these beautiful boonies is do-it-yourself glass, blown cellulose, and urethane foam.
micro... our EPS is continuous under the joists.. 2" = R10
and the staple -up would depend on what the mfr. wants.. if he wants foilfaced, he gets it.. but your example didn't show foil faced.. just 2" of foam
doc's had foil face.. insulation of choice.. then foam sheets under the joists
as far as dens-pak.. just a fancy name for blown-in cellulose.. same machine.. just a small change in technique... so, if you have insulators who blow cellulose... they blow dens-pakMike Smith Rhode Island : Design / Build / Repair / Restore
So let me see if I have it right from you. An inch of foam board, foilfaced up if so specified, is up there in place to provide an insulated cavity 1-1/2" deep, housing the PEX runs. Nice 'n toasty in there. 2" EPS is up against the joist bottoms, tacked in place just well enough to be there when the strapping goes on next, which really binds the EPS to the joists. Gypboard or blueboard on the strapping, when the insulation job is complete.
Your paperfluff guy damp-blows into the cavity between the foamboard above and the EPS below. With 2x10 joists that dense-pac is 6-3/4" thick. End of insulation job.
Right?
The papers I had to file with my last permit app, to be in accord with New York State's new energy code, called out an R-19 value for any floors not heated below. Since we are probably in the R-12 to R-13 range with just the foamboard and EPS, maybe we don't need so much dense in our pac. What do you think?
How far can Mr. Dense-Pac snake that hose and get good fill in the cavities? How often do you need to leave a void for the paperfluff hose? Could he blow it in there to just half-fill the cavity?
micro.... (it's gene , right ? ) anyways... typical garage is 24' - 26' deep.. insualting it from both band joists means you have to go 12' - 13'
there is no damp blow.. this is regular dry cellulose.. with 2" x 8' tube extension on the hose.. the guy pokes it in each bay and listens..
it's easier if you put a block of foam in the middle so the cells can pack.. the stream will flow the 4' to the block and build up pressure to a density of 3 - 4 lb/cf (hence "dens-pak")... as the sound of the blower changes and the flow thru the hose slows... the insulator can tell he's getting good packing...
he slowly withdraws the tube and continues packing to the band joist as he withdraws
there is nothing to be gained by half-filling the bay.. and there is no way of knowing if it's half full or a quarter full.. the only thing you can tell is that it's FULL and PACKED..
now... from the PEX down.. 1" foil faced ( R7).. 6 " cells (R22) 2" EPS (R10) = nominal R39... the section thru the joists a nominal R18.. call the average about R35 or so... in your heating Degree Day climate ( what 7000 DD ? ours is 6000 DD)
why wouldn't you want your floor section to be everything you can get ....?
anyways.. that's the way i would do it if i had RFH over a garage...
View Image
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 12/28/2003 9:52:22 PM ET by Mike Smith
Edited 1/1/2004 3:33:25 PM ET by Mike Smith
Edited 1/1/2004 3:33:51 PM ET by Mike Smith
Mike,
Twice you have referred to 2" of EPS (expanded vs XPS which is extruded) yielding R10. Is this a typo or did you really mean EPS? Hopefully I'm not splitting hairs, but I always see 1" EPS=R4 and 1" XPS=R5. I have heard that they were reformulating the blowing agent for the EPS to yield R5/inch. Is that what you're using in RI?
Jon Blakemore
nope.. twice i misspoke.. i think your R-values are correct...
that was one of the judgement calls i had to make.. when i started taking another look at EPS it has a slightly lower R-value.. but it's cost per R-value is SOOO much less that polyiso.. or the blue or pink .. and.... EPS is the only one i've found that can be mfr'd with Borates ( PerformGuard ).. so EPS is all we spec nowadays..
and i can get it in 1.0, 1.5, or 2.0 lb/cf density depending on our applicationMike Smith Rhode Island : Design / Build / Repair / Restore
So, Mike, would you use 2.0 pcf EPS for this application? And, out of curiosity, is your supplier stocking the EPS boardstock under a brand name? Us neanderthals up here in nanook land can only get the extruded stuff like Dowfoam at something like $9.75 a sheet for a 2 x 24 x 96 t&g edge piece.
gene.... if i were using 2", i'd use the 1.0 lb/cf, since it's cheaper..
if i were using 1", i'd go with the 2.0 lb/cf, because it's stronger and you get a lot less breakage..
search the web for R-Control.... that's the name they franchise their manufacturers under...
BTW... i never knew my local mfr. was here until someone told me about them here in BT...
http://www.r-control.com/
Mike Smith Rhode Island : Design / Build / Repair / Restore
gene .. i just looked at that site.. i guess the Smithfield , RI plant is actually the closest one to you... but
the cost per R-value is way cheaper.. so if you're thinking of using some quanitiy, it should be worth your while.. especially if you can talk your supplier into stocking or special orderMike Smith Rhode Island : Design / Build / Repair / Restore
Hey Mike: I'm just following along here but I'm lost at(it's easier if you put a block of foam in the middle) In the middle of the bay??
How would you do a 3 bay garage (Do the center bay first,then the two other bays thru the band joist?)
Last question,If I had a second floor shower drain in the garage area ,would it be wise to spray it with a couple of cans of great stuff for an extra precaution
Thanks Greg
i'm confusing you with "bays"
my " bays " are the box formed by the joists...
so when i talked about a block in the middle of the bay i was talking about "joist bays" ie: if you garage is 24' of span ( the joists ) then you can put a block of foam in the middle of the span.... when you push the tube in to blow.. the cells will pack against the block and build up pressure until they dens-pak.... ( greater than 2.0 lb/cf ... usually about 3.5 or greater ).....
if there is no block you will have to wait until the cells block them selves and that can be more hit-or-miss...
as to the shower drain.. if you're in the lower 48.. and you build a floor systtm like i described... i wouldn't think you'd need any addtional insulation to protect a drain..
keep your plumbing in the high part of the bays... also .. the 2" EPS should keep your plumbing above the freeze point in the insulation barrierMike Smith Rhode Island : Design / Build / Repair / Restore
Got it Mike Thanks ,My joist bays are already blocked (2x10)that's what was confusing me.On the center bay of a 3 car garage(26x36) I assume that I would put up your system complete in that bay/blow the dense pack from the left and right .Then catch the two outside bays the way you already described
Thanks Again Greg
Stay safe
i think we're all on the same page now... your blocking is there for stiffness.. so it obstructs the center section... yes .. treat that as a seperate job.. then do the outside sectionsMike Smith Rhode Island : Design / Build / Repair / Restore
Goldhiller,
"Even when I was a young man racing 85mph down these backcountry gravel roads in the dead of night, I always shut off my headlights as I approached an intersection to look for headlights from other vehicles."
That works great until a like-thinking individual is driving down the intersecting road w/o lights...
Jon Blakemore
"That works great until a like-thinking individual is driving down the intersecting road w/o lights..."
Ah yes. And don't think that didn't cross our minds from time to time.
As always............the devil's in the details. <G>
Knowledge is power, but only if applied in a timely fashion.
Golds "doc" opened for me, but I'll describe what I saw if it didn't for you.
He drew a cross section of a typical bay. Starting in the garage area, he has drywall, then vapor barrier, then foam board. In the bay is loose insulation, then just under the PEX, foil faced foam boards, foil up.
Mongo suggests having an R value a min of 3 times greater than the insulation value of the material above the PEX tubes. If thats ply and hardwood, that R value would be about 1.4 - 2, So your min. R value below sould be 6 or more.
Looking at the drawing, I would add up the values thusly:
Drywall:? (nil)
Foam board: 1"= R3,
loose fill: if 10" floor joists, =R30,
Reflective foam, 1"= R3 (? not sure if the R is consistant with the foil).
In any case, the total works out to be about R36.
Jake Gulick
[email protected]
CarriageHouse Design
Black Rock, CT
I dunno if this is part of the plan or not, but a "garage heater" with a T-stat set at 35 or 40 (or with an exterior T-stat that comes on when it gets to 10 or 15 outside) should help with the freezing pipes concern, no? Don't know where you are at, but I like this idea unless you are in a very cold for very long area. (I am in Southern WI and plan on doing this)