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Royalwapiti
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# Posted: 10 Apr 2023 02:35pm
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I am in northern Iowa and will be ripping off the hardwood floors in a cabin. That's the only current floor, no subfloor.
When I google insulating cabin floors I see two styles. They add cleats to the floor joists and insert tight fitting foam or they add plywood under the joists and then stuff with fiberglass or foamboard.
Has anyone seen the Youtube's with the reflective foil bubble wrap. See below
https://www.youtube.com/watch?v=xPTJD9nuWvQ&t=8s
The guy is a genius if this really works.
I am too afraid to try it and since the whole floor is being replaced I might as well go all in.
I think I am going to cleat the joists (to hold the foamboard up), add foamboard, seal edges of foamboard with spray foam from a can, maybe add some fiberglass if enough space then leave the air gap required for the reflective foil wrap then subfloor. Then add my pex and gypcrete for radiant floor heat then luxury vinyl plank.
Any thoughts on this.
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curious
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# Posted: 10 Apr 2023 04:15pm
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https://www.greenbuildingadvisor.com/article/stay-away-from-foil-faced-bubble-wrap
https://neo.ne.gov/info/neq/neq-archive/2014-08-aug/aug2014.02.htm
https://www.energyvanguard.com/blog/the-foil-faced-bubble-wrap-sham-understanding-rad iant-barriers/
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travellerw
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# Posted: 10 Apr 2023 05:37pm
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Garbage.. Its essentially an R value of 1 or 2.
Another option is to have 2 subfloors with foam sandwiched between. Costs more, more work, but the best solution. That way you have no cavity for critters to make homes. Unfortunately it won't work for everyone as doors require modding.
Foam on cleats would be my next choice!
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gcrank1
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# Posted: 10 Apr 2023 07:21pm
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+ Foam On Cleats +
I did 1" blue DOW on my 1st build in '81-'82 and would do it again only with 2".
Most of my hand cuts were a press fit into the 16" oc joists so with the 1x2 cleats below there was no gap to spray foam fill. Foam was flush beneath the floor deck.
I guess now I would tape the foam butt ends.
Doing a ground up now (rather than 're-do) Id probably do 1/4" luan over the floor joists, 2" styro, then top with the floor decking.
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spencerin
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# Posted: 10 Apr 2023 09:47pm
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Skip the reflective foil bubble wrap. It's a good product, but not when used as you've proposed. A single layer is good only to reflect radiant heat and act as a vapor barrier. Note - Reflectix's website DOES show you how you can install it to create a much higher R value - 2 layers with an air gap in between them. But, that's not the best for your situation anyway.
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Royalwapiti
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# Posted: 10 Apr 2023 10:42pm
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I was thinking the reflection would send the heat from my pex hot water radiant heat upward. No?
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aazard
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# Posted: 11 Apr 2023 01:19am - Edited by: aazard
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Your best bet, imho: PIR (NOT PUR)
Non off gassing, non flammable, NON-COSTLY, R14.2/1"
It can be used as "Underlayment" in your application (its stronger per mm thickness than OSB sheeting)
PIR (polyisocyanurate), typically cut into boards, can be used in insulated metal panels, wall cavities and as insulated plasterboard (your application). PIR has such a high R-value per inch (2x that of Rigid PUR), it requires only half the thickness of other mineral-based insulation products.
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Royalwapiti
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# Posted: 11 Apr 2023 08:38am - Edited by: Royalwapiti
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The PIR is what I have used, but I have never seen any with the r values you speak of. R -value is 6 per inch. What is the brand and availability of the R14 stuff?
I used it in an addition at the cabin. Lined the crawl space walls with it. JohnMannsville polyiso is what I used. I put the foil side facing in, then put mineral wool batts up against it.
I was going to use the same or the Pink foamular 150 for the old cabin part’s floor joists.
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aazard
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# Posted: 11 Apr 2023 10:53am - Edited by: aazard
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Quoting: Royalwapiti R -value is 6 per inch
No thats good quality "PUR" (R6/1"), good quality PIR is R13+ (they sell under R15, moniker)
Kingspan is the USA manufacturer, the PIR product is quadcore
https://www.kingspan.com/us/en/products/rigid-insulation/
Look for the "ugly stuff" ("K" & "KS" panel), not the sheathing/wall core unit
//
why: (chemical bonding process)
PUR foams are essentially made by reacting a “polyol†component and an “iso†component in which the OH groups of the polyol component chemically balance the NCO groups of the iso component and form urethane linkages.
In PIR foams, the iso components react with each other in trimerization reactions to form isocyanurates. Excess iso reacts with polyol to form urethane linkages as well.
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Brettny
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# Posted: 11 Apr 2023 10:54am
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Quoting: travellerw Garbage.. Its essentially an R value of 1 or 2
I'm with you there. In that video he shows how the ground under the cabin isnt frozen. Well dry dirt with no moisture in it dosnt freeze like ice.
If you have no acess under the floor I would not use anything but foam board. I would also pit your cleats high enough so mice and rodents cant get ontop of it. Theres no point in making a rodent highway you can never fix.
If you still want to use thin insulation the fan fold 3/8-1/4in foam is prety cheap and easy to work with.
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aazard
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# Posted: 11 Apr 2023 03:59pm - Edited by: aazard
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A "very cheap" alt:
"Pink Panther" PUR Rigid R7.5 glued/adhesived 2 layers would be R15 (plus the R1 of the sheathing layers).
Most hardware shops sell 4x8ft sheets in 5 packs (160sq ft) for under $20
but it would be 1-5/8" (+/-) thick
Do you have an image of the target floor/gap?
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travellerw
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# Posted: 11 Apr 2023 10:39pm
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So as to the reflective properties. Absolutely, it works and has an effect.. BUT, BIG BUT, its when new. Even the smallest amount of dust/dirt reduces that affect to a negligible level.
I may have been a little harsh. It has its uses, but this is not one of them.
You will be served much better by traditional foam insulation.
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Royalwapiti
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# Posted: 24 Jun 2023 09:20am
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I did the subfloor. It is only 6†off grade in some spots and 42†on the lake side. I used a cleat to hold foam, sprayed the edges to hold it and left a 1-2†gap between the subfloor which was 3/4†Osb sturdi-floor.
We’ll see how it does in the next 20 years. With the close proximity to grade I couldn’t get any sheets of plywood under it to make it totally pest proof.
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Nobadays
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# Posted: 24 Jun 2023 09:28am
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Quoting: Royalwapiti With the close proximity to grade I couldn’t get any sheets of plywood under it to make it totally pest proof.
Some folks have decent results covering the insulation with 1/4" hardware cloth. A cheap small 1/4 crown stapler from HF and you can tack it up.
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Atlincabin
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# Posted: 25 Jun 2023 12:46am
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Hardware cloth (1/4" because mice can get through the 1/2" stuff) works well. But be careful not to leave any places the mice can get into the area above the hardware cloth. If there is a hole, they have all the time in the world to find it and make a mess....
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Brettny
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# Posted: 25 Jun 2023 07:28am
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Quoting: Royalwapiti I did the subfloor. It is only 6†off grade in some spots and 42†on the lake side. I used a cleat to hold foam, sprayed the edges to hold it and left a 1-2†gap between the subfloor which was 3/4†Osb sturdi-floor.
You can also put foam board ontop of your sub floor.
I have seen mice climb up rough cut wood walls so I would assume that they can also climb T1-11 siding.
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