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Nobadays
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# Posted: 19 Aug 2019 11:45
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I know this has been hashed over before.... and fiberglass insulation is out because of rodents. So I'm looking at ISO rigid foam. I priced out having spray foam done and that won't fit into our budget! With rigid foam I can layer it up doing what we can afford at a time... using 2" R10 then sealing the edges with spray foam. I figure I could do one layer a year or maybe one in the spring and one in the fall.
The cabin is just east of the continental divide at 9500'. We do get monsoon weather patterns in the summer but overall it is a pretty dry climate.
The cabin sits on piers and it is always dusty dry under there... even in the early spring with snow melt.... dry as a bond under the cabin.
My dilemma is do I insulate the metal skirting, only 340sqft, or do I insulate under the floor, 575sqft. The savings by doing 2 layers on the skirting would buy a third layer. I'm looking at $451/layer on the skirting opposed to $738/layer under the floors.
I have read that sealing up the perimeter could lead to moisture problems.... but have also read the "new thinking" is to limit venting of the crawlspace. Again.... I'm not sure where the moisture would come from unless the temp difference because of the warm floor would cause condensation.
Most of the newer cabins around me used 4" foam for the forms for a perimeter concrete fondation then left the foam on. The water tanks are under the cabins and don't freeze it the winter.... another point for doing the perimeter.
Help guys! What would be the best practice?
BTW... going fishing so will check back in a a couple of days!
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Princelake
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# Posted: 19 Aug 2019 12:15
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Lots of debate over the proper way of insulating a crawl space. I was taught if your living there year round treat it like it is a basement. Put the heavy duty plastic down on the ground so moisture doesnt come up. Insulate the skirting and then add some form of heat to keep the crawl space heated and the heat rises so it will help with heating the rest of the place and you'll have warm floors.
If its seasonal and your only there on say weekends and such insulate the floor and seal it off from critters and moisture and let air flow under the cabin.
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Brettny
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# Posted: 20 Aug 2019 08:45
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If your going to insulate the perimeter you should really lay concrete underlayment down ( heavy heavy plastic) and possibly put gravel ontop of that. By doing the perimeter you could be making a breeding ground for animals or a space that will forever be almost unuseable, dusty or if very low useless except for water.
My vote is for doing at least one layer under the floor.
We use to stay at a cabin with only crappy metal skirting and no floor insulation. From cold cabin to warm floors was only a day. This was in northern ny.
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Aklogcabin
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# Posted: 20 Aug 2019 11:39
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If you are not going to put your water under your cabin. My suggestion would be to heat the smallest area you could. That being the floor. With a well ventilated crawl space.
If you need your crawl space heated. I continue to hear about new concepts of not having crawl space vented. There are reasons that crawl space is vented, it works best.
At our house the crawl space walls are insulated with the required ventilation needed for make up air because i have a forced air fuel oil central furnace. I also put a 4†fresh air from outside directly into my intake plenum. This allows fresh air to enter into my ducting which flows throughout the house. I leave it open year around . I do not heat with this furnace , it is used as a backup. I heat with wood pellets on the bottom floor. And have a toyo on upper level. Yep in Ak I have 3 different heat sources. Even separate fuel tanks. Anyhow my point being. That with the crawl space walls and rim joists insulated, 8†of spray urethane. My crawl space stays 70 degrees. And with a 6 mil vapor barrier. Very dry.
If you’re water storage was there it would not freeze. But you are introducing a lot of water by storing your tank there. You may have evaporation from sweating but there are insulated blankets that some folks use to reduce this.
This is just my experience and it gets kind of cold here so I hope that helps.
Hopefully soon you’re sitting back enjoying your cabin. Good luck.
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Nobadays
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# Posted: 21 Aug 2019 14:07
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Thanks all! Fishing stunk... well the catching of fish stunk, did a lot of fishing.
Good points for both the perimeter and under the floor. A concrete truck can't get up to our cabin so anything concrete is out unless mixed by hand/mixer. I ain't doing that!
We just can't decide if we want to put a tank under the house or not. We do come up here in the winter and it can get into the -20's F. We melted snow last year for toilet flushing and dish washing and hauled water from the spring (a mile away) for drinking water. A 350 gallon tank under the house would be great if we stayed here all winter but not sure if it's cost effective to do for a couple weeks three or four times a winter. The whole system would have to be drained each time. I'm kinda trying to talk my wife into just putting a small tank in the loft right above the kitchen... where I'm thinking would have close access to plumbing pipes if I wanted to 0lumb it to the system or we could just put a "winter plumbing system " from the loft right down over the kitchen sink and gravity water out.
Anyway... this was about insulation!! So much to consider.
I guess, even though more costly insulating under the floor would be effective and not possibly introduce other moisture issues in the crawlspace.
Thank you!
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Nobadays
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# Posted: 4 Nov 2020 08:57
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As an update, we had under the floors spray foamed a few weeks ago. They laid on between 3-4", some places it looks closer to 6". Closedvcell foam. The outcome has been warmer floors! They are wood so still cool on the feet but not freezing like they used to be. I did lay down a heavy plastic tarp - old billboard tarp, way heavier than a run of the mill plastic tarp, and cheaper. We are very dry under the cabin so not so much for a vapor barrier than just to get us out of the dirt and rocks when crawling under there. As a side note, I have hung a thermometer sending unit under there and so far, even with outside temps in the low teens, it has been well above freezing under the cabin. Some of that I'm sure is ground temperature and some is radiated heat from the floor joist. They insulated between the joist but not the whole joist so roughly +6" and the bottom of the joist are exposed wood. I think this is likely transfering a small amount of heat into the crawlspace.
We will continue to monitor the temps under there but once again leaning toward a tank under the cabin for winter. If we decide to go that way we will have the perimeter spray foamed as well.
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paulz
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# Posted: 4 Nov 2020 09:14
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Ha, I have been wondering about this. Did you get that killer price you got quoted?
One of my winter projects is to redo my floors with some hardwood flooring I have been storing. What's the deal with above floor insulation? I know they make it, cork or something. With only two doors and no sheetrock on the walls yet I could handle some extra height.
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Nobadays
Member
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# Posted: 4 Nov 2020 09:26
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Paul... yep, $1,100 for the spray foam, that's covering 572sqft - 22' x 26' footprint. Very pleased.
I have read of folks laying down furring strips and putting foam insulation between them then flooring over it. No experience with that... do a search on here, I remember it being discussed in some thread.
Hey, check out my "winter prep" thread... I put up a couple of pictures of our Geo Tracker up on tracks... pretty cool! We are slated for anywhere between 10" and 2' of snow between Friday night and Monday night so you can bet we will be out tearing it up!
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paulz
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# Posted: 4 Nov 2020 10:16
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What a deal! Hey, ask that foam guy if he wants to take a vacation down to the Pacific coast, in his work truck.. 80 degrees today..
Here's some of that above floor insulation. R value 1.5? Is that compared to like R13 for walls? If so, doesn't sound like it helps much.
https://www.homedepot.com/p/ThermoSoft-Cerazorb-2-ft-x-48-in-x-3-16-in-Synthetic-Cork -Subfloor-Insulation-Sheets-4-sheets-CR5MM-2448HD/203993104?source=shoppingads&locale =en-US&mtc=Shopping-B-F_D23-G-D23-23_14_FLOORING_TOOLS_And_MATERIA-NA-NA-NA-Feed-NA-N A&cm_mmc=Shopping-B-F_D23-G-D23-23_14_FLOORING_TOOLS_And_MATERIA-NA-NA-NA-Feed-NA-NA- 71700000070971523-58700006247030605-92700056377813216&gclid=CjwKCAiAv4n9BRA9EiwA30WND y5GCxPkn0vsa2LoGO3O3Qn9hGjvQv42vSk3XFX5GN6_ymBNsZ12MhoCXCAQAvD_BwE&gclsrc=aw.ds
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gcrank1
Member
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# Posted: 4 Nov 2020 20:33
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Not long ago I stumbled upon a vid of a guy who has built and lived in several cabins. He had 'tried it all' for floor insulation with less than satisfaction. The latest try is a some kind of a plastic membrane (for lack of a better term) that has little bubbles in it. I think it is tacked to the top pf floor joists in a build with the subfloor going over it, or on a floor lay it down and put the flooring over it.
He wasnt pushing or selling it, just giving a heads-up 'cause it is the best so far for him.
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Nobadays
Member
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# Posted: 4 Nov 2020 21:56
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Gcrank1.... likely Boss of the Swamp, he swears by reflextix mylar/plastic bubble wrap. Similar to the stuff you put in your windshield in the summer. I thought about it but opted for closed cell foam.
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gcrank1
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# Posted: 4 Nov 2020 22:54
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Yeah, thats the guy.
Did you price the stuff and source/avail?
Btw, on my 1983-84 handbuilt 12x24 cabin I used 16" ctr floor joists, tacked in furring strips 1" down from top then cut strips of blue DOW styro to lay in. The 3/4" CDX subfloor went on top in a staggered layout.
The floor was never cold, never felt wimpy underfoot and never got a floor on top; we just used big throw rugs repurposed out of the house over time. Thing was for us that once a cabin is 'livable' we tend to fill it up and start using it, it gets hard to empty it out to 'finish' those kind of things.
Which then begs the question,"Is a cabin ever done?".
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paulz
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# Posted: 5 Nov 2020 01:17 - Edited by: paulz
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Quoting: gcrank1 Thing was for us that once a cabin is 'livable' we tend to fill it up and start using it, it gets hard to empty it out to 'finish' those kind of things. Which then begs the question,"Is a cabin ever done?".
Boy I know how that goes..
Looks like HD sells Reflectix. And the install manual says you staple it to the bottom of the floor joist. That would be simple enough but I wonder how much it would do.
https://images.homedepot-static.com/catalog/pdfImages/22/2200e01c-6b38-4def-a59d-05e9 5e8e7696.pdf
https://www.homedepot.com/p/Reflectix-48-in-x-100-ft-Double-Reflective-Insulation-Rol l-with-Staple-Tab-Edge-ST48100/202851852?source=shoppingads&locale=en-US&mtc=Shopping -VF-F_D22-G-D22-22_4_INSULATION-Generic-NA-Feed-PLA-NA-NA-INSULATION_GeneralInsulatio n&cm_mmc=Shopping-VF-F_D22-G-D22-22_4_INSULATION-Generic-NA-Feed-PLA-NA-NA-INSULATION _GeneralInsulation-71700000033102370-58700003867202295-92700048704098360&gclid=CjwKCA iAv4n9BRA9EiwA30WND--nkTby-YTspftpIxmhxNXd6_cdnLWQ_MVzCKzsrQlJqoEpqORgihoCnSYQAvD_BwE &gclsrc=aw.ds
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Nobadays
Member
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# Posted: 5 Nov 2020 08:46
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I know Boss of the Swamp swears by it, and I think in new construction over the joists before putting down the decking it might be ok. I just can't wrap my head around how bubble foil... other than the reflection of heat.... can be a replacement for standard insulation. I would put 3-4" of closed cell foam up against a layer of reflextix... as far as heat transfer goes, I think the foam will win.
It would have been cheaper but labor intensive, as a one armed guy I could not picture myself on my back trying to hold the reflextix up and staple it.... my wife is a worker but not sure I'd ask her to help on a job like that.
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paulz
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# Posted: 5 Nov 2020 10:02
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I watched his video on it. Tempting, being inexpensive and comparatively easy to install. Maybe...
https://www.youtube.com/watch?v=6tXoey1Qz6E&ab_channel=OFFGRIDHOMESTEADINGWithTheBoss OfTheSwamp
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paulz
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# Posted: 5 Nov 2020 18:34
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I'm wondering about the value of floor insulation is for me. When we arrive at the cabin after a few days, the inside temp is the same as outside. I don't think any insulation is going to change that. I heat the place up with the stove and or propane wall heater. Not tough to do for 300 sf., and not a big deal to keep it warm. Maybe floor insulation would save a log or two, or a bit of gas. Leave after 3-4 days and repeat again the following week.
Am I wrong in my thinking? Be different if staying for weeks or months at a time and wanting constant warmth.
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Nobadays
Member
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# Posted: 5 Nov 2020 18:39
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In your climate zone, and use pattern, yeah might be an expense not that necessary.
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paulz
Member
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# Posted: 5 Nov 2020 19:30 - Edited by: paulz
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Thanks Nobs, I'm going to put it on the back burner. Crawling around under the cabin is not high on my list of fun. I did find 400 sf of 2" rigid board for $100 tempting. R7 rating.
Speaking of climate, I was previewing the surfing movie (Endless Summer) I'm showing this weekend to some surfer dudes. They were saying the temperature in Hawaii changes a whopping 2 degrees from summer to winter. From 70 to 72. Sheesh. No jackets, no insulation. I've been there twice but so many years ago I don't remember.
Just something to think about while you're bucking firewood.
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