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ontariogirl
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# Posted: 1 Jan 2021 04:17pm
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Building a 12×16 cabin w/loft. Metal roof.
Going to start insulating it this week and I am struggling to decide whether I want to use spray foam, fiberglass or something else. Any advice would be appreciated
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Irrigation Guy
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# Posted: 1 Jan 2021 04:41pm
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Spray foam will be best but affordable is a subjective term.
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Nate R
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# Posted: 1 Jan 2021 04:54pm
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If you want affordable, put in fiberglass batts and make sure your airsealing details are carefully done.
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gcrank1
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# Posted: 1 Jan 2021 05:35pm
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I like to use something I can do myself with simple tools and skills. And if you build the structure well and airtight it will heat decently as is, just wont hold it long (but longer than a tent!).
Fwiw, I did my '83-'84 12x24 c/w 12x12 loft, Swiss chalet style with 1" blue DOW styro under the floor (between the joists) and the walls. I had intended to do the cath ceiling 'someday' and never got aroundtuit.
Once we got the deep chill (the cold sink) out of the interior and everything inside became the heat sink it really did stay warm with the little wood stove. We often wore 'light clothes' inside and opened the door a bit to vent.
Yeah, spray foam would have made it built like a Yeti cooler, I guess....but sometimes I gotta ask myself,"how much is enough?".
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Brettny
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# Posted: 1 Jan 2021 06:26pm
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12x16 even if you use r13 fiberglass every where and air seal decently good even a normal size buddy heater should keep you warm. But two 250sqft diy spray foam kits should easily do the walls, ceiling and floor.
Have you priced out getting spray foam done? I did last month and just simply asked for the square foot price. I got quoted $0.90 per inch per square foot. Generally its r6-7 per inch.
If you plan on keeping this place for a while I suggest at least spray foaming the roof then everything else with fiberglass. If you dont plan on keeping it foam batts in the ceiling and dont do a thing else.
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ontariogirl
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# Posted: 1 Jan 2021 07:22pm
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Thanks. I think I will do fiberglass on the walls for now. Maybe spray foam the roof later on.
I have zero experience so I prefer the simpliest methods as well. It will be hard to screw up the fiberglass I hope
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rpe
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# Posted: 2 Jan 2021 08:45am
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There are pros and cons to each. Here's my thoughts:
Spray foam is great from an insulation and sealing point of view, but it is highly flammable and when burning creates suffocating fumes.
Fiberglass batt insulation is usually the cheapest, but has the lowest R-value per inch. It's flimsy to work with, critters love it, and if it gets squashed, doesn't spring back nicely, ruining the R-value.
Rockwool (Roxul) is a bit better insulator, a bit more expensive, and much nicer to work with IMO. It holds it's shape well, cuts easily with a bread knife, and if fit properly, holds nicely in place between the studs/joists while awaiting vapour barrier. It also doesn't bother my skin nearly as much as fiberglass.
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razmichael
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# Posted: 2 Jan 2021 09:52am
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Quoting: rpe Rockwool (Roxul) is a bit better insulator,
Second this. Cost difference for a small space is not much but ease of use and effectiveness is much better. Cut with a bread knife, expands into space, less itchy - well worth the slight cost difference (although way back it was much more expensive in the US than Canada - not sure now).
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gcrank1
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# Posted: 2 Jan 2021 10:34am - Edited by: gcrank1
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Affordable....hmmm, that is going to be tough. A quick check online just now (USA) shows rock wool batts about 70% more than comparable fiberglass, and the fg aint inexpensive either.
For a small structure Id consider it. But once again I just realized there is no way I could afford to build a whole house at the price of building materials nowadays!
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rpe
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# Posted: 2 Jan 2021 01:12pm - Edited by: rpe
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gcrank1, you are right on the price difference. The per-bundle price is similar, but the coverage is much greater for the fiberglass, as it can be compressed greatly for packaging and shipping. My local HomeDepot pricing (Ontario) shows:
Pink Fiberglass - $53.50 R12, 97.9 ft^2, 54.6 cents/ft^2
Rockwool - $55.39 R14, 59.7 ft^2, 92.8 cents/ft^2
Having installed both (as an amateur mind you...), I greatly prefer the Rockwool. I bet the amateur-installed R-value difference is greater than the R12/R14 indicates also, as getting a good fit with proper cavity fill is much easier with the more rigid batts. No, I don't work for the company. 
Following paulz's lead, I keep an eye out for partial or excess bundles of Rockwool on local FB Marketplace and Kijiji. I got 24 bundles for less than half retail price from a guy that was renovating an old historic building near me. In the end, the construction was so varied that the batts weren't going to work well for him. He went the spray foam route, and the installer got overspray over Rockwool bundles, and other bundles got ripped in handling, and he couldn't return them.
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gcrank1
Member
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# Posted: 2 Jan 2021 01:47pm
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Well done!
Wish I had a small pole building to put 'savaged' and sale materials in, AND in order and accessible, before a build.
Iffn I were you, OG, Id think about not insulating right away and using it 'for a year' while scaring up some rock wool or fg like rpe did. That would also give a chance for running elec wiring and/or gas piping, etc. before closing up the walls. Seems there is always something I should have done......
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Brettny
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# Posted: 2 Jan 2021 02:14pm
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I have a 10x14 shed with only 2in of foam board in the ceiling. I have those foam puzzle tiles on the floor. 20f* at night and we survived. Wood stove for primary heat and buddy heater for secondary. Usualy about 4am il wake up and light the buddy heater. Above 30f at night and the stove will last all night. I plan on building a real cabin in the future so dont want to spend any more money than what's needed on this shabin.
I see a roll of R13 is about $20 a roll now yet 8yrs ago when I re insulated my house it was closer to $12.
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gcrank1
Member
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# Posted: 2 Jan 2021 02:17pm
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Fiberglass batts were way higher than that this morning.
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Houska
Member
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# Posted: 2 Jan 2021 04:47pm
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I also echo looking at Rockwool. Much better product than fiberglass for most purposes.
I understand it has historically been more expensive (+20-30%) in the USA per batt / sq ft of wall (though it is also higher R-value), but that the price difference is a lot less in Canada.
Last time I checked at my local Rona it was about 10% more expensive.
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LittleDummerBoy
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# Posted: 2 Jan 2021 06:58pm
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I recommend you avoid installing mouse habitat.
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ontariogirl
Member
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# Posted: 2 Jan 2021 08:23pm
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Haha thanks. My dad and I just finished the electrical yesterday so I think i'm ready to insulate. Sounds like Rockwood is the way to go.
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rpe
Member
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# Posted: 2 Jan 2021 09:50pm
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LDB, that's another benefit of the Rockwool - critters don't like it.
Houska, the price per bundle is very similar, but coverage area per bundle is much more for fiberglass as it is compressed significantly when packaged. See my numbers above. Cost for Rockwool is significantly more, but worth it IMO.
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Brettny
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# Posted: 3 Jan 2021 06:52am
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Quoting: gcrank1 Fiberglass batts were way higher than that this morning.
$19 was for a roll not batts. I believe 38-40ft long for 16in OC.
Someone on here used Rockwol in Hope's it wouldnt be as attractive to mice. It didn't work. Best thing you can do is build things square, level and seal everything up. Spray foam alone is not a seal to a mouse.
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Houska
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# Posted: 3 Jan 2021 06:58am
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Quoting: rpe Houska, the price per bundle is very similar, but coverage area per bundle is much more for fiberglass as it is compressed significantly when packaged. See my numbers above.
Interesting. I think your numbers are HD, 3.5" insulation. I've just looked at my local independent lumber yard's price list (a month old, so may be out of date) and for 5.5" insulation it's C$1.27/sq ft for the Rockwool vs C$1.02/sq ft for the fiberglass. So more than the 10% difference I remembered (I may be misremembering or may have miscalculated the bundle coverage adjustment in my head when I saw it). But also quite a bit less than the ~70% premium you're seeing.
In any case, unless money is *extremely* tight, I'd pay the extra, since installing insulation is a real pain, and redoing it later or shivering due to moisture issues is an even bigger pain. Personally, I value the environmental benefits too.
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gcrank1
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# Posted: 3 Jan 2021 01:21pm - Edited by: gcrank1
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Ok, just now, Home Depot, faced 3.5" x 15" x 32' R-13 Knauf roll is $22 USA. Way cheaper than batts.
Id call that affordable, but still a bit itchy.....
If the rock wool came out up to 50% more to cover the same square footage Id go with it. Thats my conclusion as an admitted 'cheap guy'.
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KinAlberta
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# Posted: 3 Jan 2021 04:36pm - Edited by: KinAlberta
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Myself, I sure liked using the Rockwool (Roxul) in our basement reno.
If you live in a northern climate, before you use fiberglass batts try an internet search for fibreglass and cold weather convection. Years ago, I recall tests saying that fibreglass lost 50% of its insulating ability in deep cold - just when you need it the most. Cellulose didn’t. I don't know if that was ever proved out or not.
However I was always surprised at how highly ranked cellulose comes out in most tests and reviews.
Found this:
Cold-Weather Performance of Polyisocyanurate Researchers are beginning to understand the causes of the problem, but solutions remain elusive By Martin Holladay | September 4, 2015 Excerpts: “It's R-6 per inch during the summer, but only R-4.5 per inch on a cold day in winter. The insulating performance of polyisocyanurate insulation is significantly degraded at cold temperatures. “... The ability of insulation products to resist the flow of heat changes with temperature. Most insulation products — including fiberglass batts, extruded polystyrene (XPS), and expanded polystyrene (EPS) — perform better at low temperatures than high temperatures. At lower temperatures, there is less conduction, less convection, and less radiation — so insulation materials usually work better than they do at warmer temperatures. However, one type of rigid foam, polyisocyanurate, doesn’t follow this pattern. At temperatures below...†https://www.greenbuildingadvisor.com/article/cold-weather-performance-of-polyisocyanu rate
Cellulose or Fiberglass Insulation, Which is Better for Your Attic? | News and Events for Dr. Energy Saver, Inc Excerpts: “R-Value R-value measures the resistance of heat flow through a material – the higher the R-value, the better the material is at resisting heat flow. In most situations, we prefer the air and heat flow resistance of cellulose over that of fiberglass. At 3.5 per inch of material, the R-value of blown-in cellulose is 23% better per inch than fiberglass batts! According to research done at the Oak Ridge National Lab, fiberglass loses up to 50% of its R-value in very cold conditions; making cellulose a better choice for homes in northern climates. In the summer, according to research by the Brookhaven National Lab, fiberglass ...†https://www.drenergysaver.com/about-dr-energy-saver/news-and-events/34256-cellulose-o r-fiberglass-insulation-which-is-better-for-your-attic.html
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KinAlberta
Member
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# Posted: 3 Jan 2021 04:41pm
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Interesting:
Is Compressed Fiberglass Insulation Really So Bad? | Energy Vanguard I've been guilty of perpetuating a myth. Last month I wrote an article in which I said installing insulation, "cavities are filled completely with as little compression as possible." But is compression really such a bad thing? When I posted that same article on Green Building Advisor, commenter Dana Dorsett wrote, "Compression of batts is fine (resulting in a higher R/inch due to the higher density) as long as the cavity is completely filled." He's right. Compression isn't the problem. Incompletely filled cavities are a problem. Gaps are ...†https://www.energyvanguard.com/blog/compressed-fiberglass-insulation-really-so-bad
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gcrank1
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# Posted: 3 Jan 2021 04:46pm
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Unless yer trying to insulate a cath. ceiling with fg then a gap at the deck side is a good thing.
There's always something.......
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