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basrijn
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# Posted: 15 Oct 2013 03:10pm
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Hello,
We just spent our first (long) weekend in our new cabin and it was awesome! One thing we noticed was that it's rather poorly insulated. Since we will be spending quite a bit of time there during the winter, it's something I would like to improve.
Lot of large windows will probably be expensive to fix/replace so that will have to wait (unless there is some cheap ways to increase the R value)
The floor is plywood with nothing on it, or under it. To me the easiest would seem to be to mount rigid foam to the underside of the plywood (on the outside of the cabin). It's open to animals, so I think any of the glasswool stuff would make very nice nests. Don't want to cover it all up with another layer of plywood.
Rigid insulation is much more expensive that that, but if I put in say 2" thickness I would go from an R-value of 0.96 (3/4 plywood) to 8-10. I would guess that will make a noticeable difference.
I would glue it to the bottom of the plywood using the polyurethane save construction glue.
I've read some warnings about trapping moisture on top of it that would cause rot. I also read that the joists (that would be uncovered) help to wick the water away and prevent rot.
Tips / suggestion on the best approach are welcome!
Bas
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bldginsp
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# Posted: 15 Oct 2013 06:45pm
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Sounds like a good plan. Only thing I think I can add is that I have heard of people placing a vapor barrier on top of the subfloor before putting down flooring. This would reduce the amount of vapor that can get below the floor to condense in contact with colder surfaces. Never heard of joists wicking water away. You want to either keep the moisture away to begin with or ventilate in a way that gets rid of it.
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MtnDon
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# Posted: 15 Oct 2013 06:54pm - Edited by: MtnDon
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A T&G subfloor makes a decent vapor barrier for a floor. Using Advantech OSB may be the best possible subfloor, IMO. Just a FYI.
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basrijn
Member
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# Posted: 15 Oct 2013 07:53pm
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Hi,
@bldginsp: There is no flooring on the subfloor at the moment, and that will probably stay like that for a while. I'll keep the vapor barrier suggestion in mind if we do put something down. I'll bring a hygrometer next time, so I can keep an eye on moisture levels in the cabin. It's very well ventilated at the moment (contributing to the heat loss).
@MtnDon: I'll double check if it's T&G, I never saw light shine thru. Would it make sense to put tuck tape over any plywood seams as an extra measure. Or would that do nothing since moisture would still condensate, now only in the first mm op the plywood, instead of on the boundary between insulation and plywood.
But good to know there is no big "wrongs" in the approach. I'll go ahead and measure everything and prepare myself for the sticker shock!
TX!!
Bas
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Truecabin
Member
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# Posted: 15 Oct 2013 08:09pm
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Quoting: basrijn Lot of large windows will probably be expensive to fix/replace so that will have to wait (unless there is some cheap ways to increase the R value)
single pane glass is about r1 double pane is about r2
triple pane is about r3 and you have to spend a lot more money to get r5
an insulated wall next to the window is about r15 or more maybe r21 so changing the window cant make a lot of difference unless you are getting rid of air leaks too you might just look into sealing your windows better
nobody would spend a lot to get there wall from r1 to r3 but a window salesman can make a lot of people change windows from r1 to r3
to make a real heating difference you have to remove the whole window and replace it with insulation
maybe you need new windows then it works but dont do it just because window salesman needs a sale
if you sit next to a cold window you can feel cold air falling on you this makes it seem worse than it really is but if you like to sit by the window then buy one new window
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basrijn
Member
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# Posted: 15 Oct 2013 08:39pm
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@truecabin: Didn't realize the difference was that small. A quick google on it pointed to shades with side tracks as an effective way to increase R-value (eg http://www.comfortex.com/cellular/Comfortracks_carb.php). That might be a much more cost effective way to improve on it.
Thanks for the info!
Bas
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ShabinNo5
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# Posted: 15 Oct 2013 09:46pm
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Bas,
Not sure how tight the space will be to install the ridgid foam, but another method of holding the insulation is place is to use small brackets. You can press the bracket into the foam board and then screw or nail the bracket to the joist. No glue required. I spaced brackets every 24 inches to hold the foam tight to the subfloor.
Steve
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toyota_mdt_tech
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# Posted: 15 Oct 2013 10:11pm
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Can you install fiberglass wool type, then go over the joist with 1/4" wire mesh tacked to the joist? Fold it over in areas to keep all critters out. All available from Home Depot etc.
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rockies
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# Posted: 15 Oct 2013 10:12pm - Edited by: rockies
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Hi. If I'm reading things right you can access the cabin from underneath and that there isn't a layer of plywood on the bottom of the joists (you can look up and see every joist with the subfloor on top of them)? If that is the case I would recommend a product like "Tiger Foam" http://www.tigerfoam.ca/ (US or Canada). The foam is in two parts and the chemical is environmentally safe. It mixes at the nozzle and you can spray it yourself onto the underside of your subfloor (from below). It expands in seconds and acts as both a vapour barrier and insulation. You would have to attach plywood to the underside of the joists afterwards as a fire barrier (it can release fumes if burned). When the cannisters are empty you return them to the company. The spray seals all gaps, cracks, and bonds to the wood without shrinking. Saves a lot of time cutting rigid foam, gluing it with special glues, then sealing the edges to the joists with those little cans of expanding foam. All you need is a 2-3 inch layer for really good R values.
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basrijn
Member
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# Posted: 15 Oct 2013 11:05pm
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@ShabinNo5: that is an interesting approach. Would allow for easy removal if ever needed. Are these shelving brackets?
@Toyota_mdt_tech: I could, but worried that a single miss will allow critters to get it. Does the fiberglass need to be against the subfloor, or it sits flush with the bottom of the joist? I'll price the rigid and fiberglass both and see where I end up with.
@rockies: I had seen that stuff before in a Youtube movie, looked the price up and thought it was rather expensive. But having a better feel for other prices now, makes this a more attractive option. I have plenty space to work.
I'll price all three options and post back here with that and a photo of the underside. I have plenty room to use the spray, so if that ends up being not to expensive, I guess is the superior solution. Great R value and not space for critters etc. The extra plywood to go in is a bit of a pain, but alas
So many options 
Tx all!
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bldginsp
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# Posted: 16 Oct 2013 12:26am
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There are two types of spray foam insulation, closed cell and open cell. I'm assuming the type Rockies mentioned is closed cell, which has the reputation of providing the best moisture seal of any vapor barrier. Generally the open cell is used in walls, the closed in ceilings. If moisture is a serious concern for you this may give you more peace of mind. Requires good operating room to apply. Tends to be pretty flammable which is scary.
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ShabinNo5
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# Posted: 16 Oct 2013 06:50am
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Bas,
The ones that I used are referred to as "small corner brackets". I found a supplier, on the web, a few years ago that offered them in bulk. Unfortunately I do not recall the specific web site. You can also buy them at any hardware store or places like home depot or lowes. However they are typically in packages of 4, which is much more expensive.
I used this approach because I was filling a 6" area with three layers of 2" foam board. The thin nature of the brackets did not interfere with the installation of the second and third layer.
Since you are only installing a single layer, another approach would be to buy 1" x 2" furing strips and cutting them into 1.5" blocks. Then pre-drill a hole to avoid splitting and screw or nail these blocks to hold the foam board in place.
Steve
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creeky
Member
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# Posted: 16 Oct 2013 08:27am
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find used XPS rigid insulation if you want to save money.
cut the foam board a little narrower between the joists and spray foam between the joist and the board. that will hold pretty well. also PL300 is an approved rigid insulation adhesive.
depending on your climate insulating between joists can lead to quite a few moisture problems (see buildingscience.com in high r-value foundations and energy efficient retrofits).
i found used 4" XPS insulation, type 4, laid it out over my floor and put a new subfloor over that. less cutting. and it eliminates moisture problems. i did have raised ceilings in the building I used this technique on. so losing 5" of ceiling height was not a problem.
(getting the door out and putting it back in ... that's another story)
if you use rigid board insulation don't put in a vapour barrier as the board will act as one and you don't want to trap moisture between two vapour barriers... good luck.
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missouriboy
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# Posted: 16 Oct 2013 05:37pm
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I used R-19 installed between the joists and then added 1/2 plywood and caulked all the edges to keep the critters out. It is about 18" from the ground at the lowest part and 3 1/2 ft. at the highest. I did add roofing felt under my tongue and groove floor that I applied on the inside. We'll see how easy it is to heat this winter.
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Diver
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# Posted: 16 Oct 2013 06:11pm - Edited by: Diver
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For my cabin, I used reclaimed 4" XPS insulation (R20) and Steel door cutouts R10 from a local door manufacturer that I got for free. The door cutouts makes it critter proof. I sealed the gaps with sprayfoam. I installed it from the top but could have done so from the bottom if my floor joists were 2x10. Pannels could be held into place by metal clips as suggested by ShabinNo5 or 1x3 strapping if insulating from the bottom. I left an airspace between the insulation and the plywood. I was told by a few local builders that this helps with the floor feeling warmer as the air between the insulation and plywood gets heated. I will know after this winter if this was the right way to do it.
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rockies
Member
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# Posted: 17 Oct 2013 08:35pm
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I did a lot of reading at the www.buildingscience.com website from articles by Joseph Lstiburek who writes about insulating methods and moisture problems in home construction. The biggest problem with wrapping joists with batt insulation and then covering them with wire mesh is that it has practically no defence against air movement. Wind just passes right through batt insulation even when sealed inside a wall cavity. A plastic vapour barrier can act as the wind barrier as well (and the sheathing and drywall also help prevent air and moisture movement through the walls), but for floors this is the same problem - air moving through or into the cavity and bringing moisture with it. The problem can also happen with air carrying moisture from the inside of the cabin towards the outside, so any small gaps between rigid foam panels and the joists, or the top surface of the panels to the underside of the sub-floor will potentially trap moisture and lead to mold or rot problems in the future. I like the spray system because it bonds to the surface leaving no air gaps, works as a vapour barrier (closed cell foam) and will continue to stick to the framing even if the cabin shifts a bit over the years. You will have to sheet the underside of the joists for fire safety, but the time you save from not having to cut, install and then seal foam the edges of all those rigid panels (and put up a wire mesh to keep the animals away from it) makes spraying a worthwhile expense in my opinion.
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Borrego
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# Posted: 17 Oct 2013 10:21pm
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We did similar to Diver, but with R30 insulation in 2x10's, sealed on the bottom with 1/4" ply, all glued, shot and foamed to prevent air loss and more importantly, critter infestration... works very well.
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toyota_mdt_tech
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# Posted: 17 Oct 2013 11:39pm
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Quoting: missouriboy used R-19 installed between the joists and then added 1/2 plywood and caulked all the edges to keep the critters out. It is about 18" from the ground at the lowest part and 3 1/2 ft. at the highest. I did add roofing felt under my tongue and groove floor that I applied on the inside. We'll see how easy it is to heat this winter.
Missouriboy, wrap your pier post with metal flashing. This will make it impossible for the critters to climb up to gnaw a hole into your wood. 
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missouriboy
Member
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# Posted: 18 Oct 2013 02:39pm
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Quoting: toyota_mdt_tech toyota_mdt_tech
Thanks toyota_mdt_tech. Good idea. Have to get some flashing.
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basrijn
Member
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# Posted: 20 Oct 2013 11:12pm
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After looking at prices, it's pretty obvious that batt insulation is absolutely unbeatable for R value/$
I forgot to measure what size the joists are, but it's either 2x8 or 2x10. Since none of the DIY stores in BC seem to sell the 2x10 sizes insulation, I'm guessing that 2x8 is more common.
I'm looking at: http://www.rona.ca/en/insulate-r28-299-sq-ft
And then add some 1/2 plywood to the bottom. Would 1/4" plywood be fine as well? It not really going to carry any weight, so I guess it would be OK?
Tx for all the advice. One other benefit over the foam is that I can do this install any time. The foam needs to be a very specific temperature, this time of the year that would be a problem
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gunslinger22
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# Posted: 28 Oct 2013 01:18am
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I'm doing the same thing right now and painted the plywood I'm putting on the bottom with that green copper wood preservative. On top of keeping rot out i've heard it helps keep critters from gnawing on the plywood. And the idea mentioned above of wrapping piers with metal so critters cant climb up is a great one!
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missouriboy
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# Posted: 28 Oct 2013 08:09am
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basrijin, I used R19 (6 1/2") insulation. That is more than the typical wall which is R13 (3 1/2") plus heat rises so I figured it would be good enough for the floor. Had no trouble heating my 12 x 24 cabin with a 1500 watt electric heater this past weekend. Kept it 70 degrees inside with no problems.
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TheWildMan
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# Posted: 28 Oct 2013 08:28am
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a common practice for floor insulation around here is hay bales. unless you untie them they are packed too tight for vermin to burrow into. a lot of people skirt their cabins and trailers with old hay bales (ask farms for bales left from last year, not good feed value anymore). it creates an insulated crawl space.
you can use plastic sheeting for the windows. the window sheet kits come pre sized for different windows. they are like disposable storm windows (storm windows are like turning single pane into double). if you want to do it very cheap get some 10'x25' rolls of clear plastic from a hardware store (paint section) and cut them to the size you need, and staple or tape them up.
heavy curtains or window quilts work. I hang blankets over the windows, pull them aside in the daylight hours and leave them over the window at night. get them at thrift stores if you can.
you can also use storm windows. I got a couple big sheets of heavy acrylic sheet plastic, sawed to size so it was 1" wider than the window. drilled holes in the corners and sides and screwed it into the wall over the window creating a shatter resistant storm window (and use blankets for extra insulation).
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basrijn
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# Posted: 28 Oct 2013 11:07pm
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@missouriboy. After putting the first rows in (I only got enough for two so far). I'm thinking that R28 might be overdoing it I'll step down to a more commonly available size
@TheWildman. Did some more reading into blinds with track. The current blinds are super crappy, so when they go I think we will get some with tracks that provide quite a bit of additional insulation.
tx
Bas
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Jim in NB
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# Posted: 29 Oct 2013 10:10am
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I have no floor insulation in my camp - 32x24. Heated it this past weekend with kerosene heater - steady 25+ degrees. Have looked at the options detail and easiest fix seems to be constructing insulated skirting walls that I can take down in the warm months - cost is much less. Did install rigid insualtion on the sleeping cabin mostly due to the fact that I had already found and got a pile of it of Kijiji. Used nails to hold the insulation up and works fine.
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creeky
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# Posted: 29 Oct 2013 10:16am
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wildman. i used straw bales for a trailer. worked really well. i'm not sure. but most people avoid hay cause it has nutritional value and critters like it. it also breaks down faster than straw. maybe in your area it's what's available? still. if you find straw...
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TheWildMan
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# Posted: 29 Oct 2013 11:59am
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I ask farmers for their old hay, such as what is left over from a year or two ago (lost much of its nutritional value due to age) sometimes they have some that was stored badly and they cant feed it to livestock. its cheaper for me and cleans out the unusable left overs for them. in the spring I dump it into the compost heap and get more next time around. at my cabin its behind a skirted wall and protected from the weather.
I tried getting straw around here but its not as easy to get and when I find it its more expensive than hay (I usually don't have a vehicle so my range is very limited)
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swampshaman
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# Posted: 31 Oct 2013 12:40pm
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I was just reading up about roxul stonewool insulation,keeps the critters out and comes in batts that friction fit between the studs.All the reviews I read were glowing.It is a bit pricier,but something else to look into.I think thats the way Im going.
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TheWildMan
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# Posted: 31 Oct 2013 02:09pm
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swampshaman I have never heard of this stuff, I advise doing good product research and getting first hand accounts from people who used it. if its glowing its probably sounding too good to be true (in which case it probably is).
I recall seeing youtube videos of people over exited about the solar generator they bought. it was advertised as providing instant on demand 1000 watts of electricity like a power plant in the back yard. despite all the hype and promises it was just a solar panel on a hand cart with a battery and inverter.
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basrijn
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# Posted: 1 Nov 2013 06:55pm
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@swampshaman: That actually the stuff I ended up using
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