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justins7
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# Posted: 27 Jul 2017 02:38pm
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I have been trying to find someone to do insulation, but I guess this is the busy time, and it's been hard to get anyone to call back.
Can anyone tell me a ROUGH estimate — ballpark, even — to insulate a small board-and-batten cabin ceiling? Just the ceiling: wood beams. It's in the Northeast, so it gets cold (upstate NY). The ceiling currently has open rafters and just needs some to be insulated and then finished with pine slats at about 7-8' high. That space is 12' x 18'.
I recently found that the previous owner had started to insulate some of the nooks up in the ceiling wall with fiberglas at some point — and it was turned into a mouse haven for what looks like decades. I had to clean out the horrible mess of rodent carcasses (which was fun!). So I need to maybe find the most rodent-proof insulation, if there is any (spray?).
Advice and experiences are appreciated.
Thanks!
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rockies
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# Posted: 27 Jul 2017 06:38pm
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I take it it's a cathedral ceiling? If it is they are an extremely difficult ceiling in which to install an adequate amount of insulation. This is because the rafters are usually 2 x 10 (if you're lucky) and if you are using batts you have to leave a 2-3 inch air space above the batts for ventilation, plus cut vents into the eaves and preferably along the entire ridge (capped off with a ridge vent). Therefore you might get 7 inches of insulation at best which is not much to keep out the cold.
I would recommend using a spray kit like Tiger Foam.
http://tigerfoam.com/sprayfoaminsulation/
Look through their products and pick the best one for the size of your job. Look through the FAQ section too. This type of spray product is applied to the underside of the roof sheathing and creates an complete insulation blanket and doesn't require any venting of the roof. You will have to enclose the underside of the rafters though with plywood, wood paneling or drywall as a fire protection measure.
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toyota_mdt_tech
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# Posted: 27 Jul 2017 08:21pm
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Quoting: rockies Therefore you might get 7 inches of insulation at best which is not much to keep out the cold.
And I'd bet he is required to get R-38 or better too.
I think the spray foam is the best route here too.
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Just
Member
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# Posted: 27 Jul 2017 10:25pm
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Roxul is resistant to mice but you should be vigilant and take many preventavent measures . About $1.35 per sq. ft.US with vapor barrier R 23. 6 in thick .
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razmichael
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# Posted: 28 Jul 2017 08:01am
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Gambrel roof on mine. Although I used Roxul for the main floor (love the stuff - so much easier than fiberglass and pest "resistant"), I contracted out spray foam for the ceiling. Looked at the kits but you will find a lot of horror stories (and some good as well). It is not easy to do it right, the conditions need to be correct, protective equipment, scaffold etc etc. Lots of stories where it all goes wrong and, not always a lot cheaper anymore.
I cannot remember the cost I paid (and likely not worth trying to compare to your location) but I used closed cell foam and over R38 in depth. They also did the loft end walls for just a few hundred extra. As Rockies explained, no venting and no worries about leaks. It also provides and added level of structural strength (not that you should need it)
If you do want to do it yourself with batt - consider roxul. It is no longer a lot more expensive than pink and often is on sale. One of the few products that historically has been cheaper in Canada than the US! So easy to cut. holds it shape and expands into a tight fit. Again, as Rockies explained, other things to consider with batts.
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Borrego
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# Posted: 28 Jul 2017 10:39pm
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As a General Contractor, I've found that it is always cheaper to sub this trade out than do-it-yourself......They can provide/install the material for less than I can buy it for, even with my discount. So unless you have such a remote cabin that they won't go there, wait and find someone to do this for you....
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justins7
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# Posted: 29 Jul 2017 02:11pm
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Thanks for all the information! (I love this forum.)
It's not that remote... I left a message with a local spray-insulation company, so we'll see.
Although the ceiling is cathedral, there does appear to be sufficient space for different types of insulation, as well as venting of the soffits.
I really want to avoid the rodent-haven problem in the future. I can deal with a few mice, and some nests, which is not that big of a deal. But the recent discovery of the mouse "cemetary" where there was unfinished insulation (just squares of fiberlass) was pretty digusting and it's unhealthy too, no doubt. There must have been hundreds of little skulls and spinal cords among the piles dried feces and loose fibers. A nightmare to clean out. (I was even thinking of cutting into the soffits and just letting it all dump out onto the grass outside instead of cleaning from inside. But my girlfriend and I did it!)
(I just bought the cabin last October. Note to self: next time take a ladder up to the rafters when inspecting! I would have had the seller remove that mess first if I discovered it earlier.)
Thanks again!
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rockies
Member
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# Posted: 29 Jul 2017 07:34pm
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You will always have a rodent problem with batt insulation. Always. It is a natural rodent hotel. The other big problem with batt insulation is that it is porous so the wind can move right through it quite easily (and if air is moving through it you know that moisture is also moving through it). So if you use batts you'll have to staple up a vapor barrier, tape all the seams and seal the edges of the barrier to the top of your wall plates or you'll have warm moist interior air moving through the insulation and condensing on the cold interior surface of your roof sheathing. You'll still have to install a finished ceiling over batt insulation too (plus don't forget about installing eave and ridge vents, insulation baffles, etc).
Spraying closed cell foam allows you to apply the insulation and vapor barrier all in one product. Have it sprayed and then put up some nice tongue and groove pine ceiling boards and you're done. As long as you have no vent openings in the roof you shouldn't ever have to worry about rodents again.
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Jabberwocky
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# Posted: 1 Aug 2017 11:02am
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I can't answer the original poster's question, but I have been surprised at the total budget overrun for insulation and air sealing on my own project. I'm at $3000 and counting... that's purchasing used poly-iso boards and doing all the labor myself. Spray-foam cans, tape & caulk have nickel and dimed us to death. And I still have fiberglass batts to buy for the interior walls... 
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KelVarnsen
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# Posted: 1 Aug 2017 11:07am
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I'm in the middle of retrofitting my cabin with insulation using mainly Roxul. I'm installing vapour barrier, etc. I cut and cobbled rigid foam insulation under the floor. I'm kind of regretting going this route. For the amount of work and expense I should have got everything professionally spray foamed. I'm too far in to go back now. Oh well...hindsight.
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justins7
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# Posted: 1 Aug 2017 02:49pm
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Thanks for all the useful info.!
I'm finding it frustrating that it's hard to get a call-back from professionals this time of year. Everything is so seasonal in the northeast, yet I wasn't ready in the winter when I should have been making calls. Oh well.
I would do it myself but spray foam seems daunting (and possibly toxic if not done correctly).
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rockies
Member
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# Posted: 1 Aug 2017 07:53pm - Edited by: rockies
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I find one of the main problem with most renovations (or new construction) is that people unconsciously "nickel and dime" themselves to death without even realizing it (not a comment on anyone in particular).
The "disconnect" usually happens when the best or "correct" method (from a construction point of view) is thought to be "too expensive" so the owner starts looking for something cheaper. He then finds a site or a person who says "Oh, I could do that for less than half the price of that guy". Next thing you know you're looking at dozens of different products needing a similar number of tools and before you know it the project has wound up costing as much if not more than the "professional solution".
Closed cell spray foam is the best solution in this situation. Can other things be done? Sure, but you'd better know how all the products go together before you start combining them.
To KelVarnsen: What are you using for "vapor barrier"? Most DIYers rely on info from the 1960's to the 2000's stating that "6 ml poly is the material to use". However, modern building science has shown that poly creates far more problems with trapped moisture, rot, and mold than it solves.
The better product should be a vapor permeable barrier like "CertainTeed Membrain". It lets your wall cavities breathe so if any moisture gets in it can also get out. Most people don't know that these types of products exist though.
A great resource for building is the "Green Building Advisor" website. Lots of free articles by professional building scientists who actually build mock-ups of walls, roofs, foundations and test every conceivable method of construction. They find out what works and what doesn't.
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KelVarnsen
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# Posted: 2 Aug 2017 07:46am
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Quoting: rockies What are you using for "vapor barrier"? Most DIYers rely on info from the 1960's to the 2000's stating that "6 ml poly is the material to use". However, modern building science has shown that poly creates far more problems with trapped moisture, rot, and mold than it solves.
I've read a lot of Green Building Advisor articles and modern articles before coming up with my plan. Don't worry about me. I'm doing it right.
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Just
Member
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# Posted: 2 Aug 2017 08:51am
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I wonder if the Green Building Advisor has ever built ,and financed a small cabin himself, I wonder???
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Jabberwocky
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# Posted: 2 Aug 2017 09:10am
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I personally didn't go the spray-foam route because I was frightened by the cost (a LOT of spray foam to get to R-33), but more importantly, the possibility of bad off-gassing if it wasn't done properly. I'm sure it's no different than any other trade - there are good contractors and not so good. In the matter of spray foam however, I had another factor to consider - my wife's hyper-aversion to off-gassing materials.
As to hiring of professionals, I have definitely done that for the framing, plumbing, and electrical. But insulation and air sealing, to reach the quality level I insisted on, would probably not be possible unless I hired a contractor that was used to building net-zero houses or similar standards. That's just not a thing around here, and I wouldn't have been able to afford that level of quality myself, hence the DIY approach.
If I had the opportunity to do things over again, I probably would have gone with a combination of one layer of poly-iso, and another layer of spray foam under or above that, rather than two layers of poly-iso. The second layer of poly was really difficult to install and created other retro-fit problems that the spray foam would've eliminated.
Just
Green Building Advisor is certainly not concerned with budget matters. Their suggestions, though spot-on, are often expensive.
Sometimes in the back of my mind I wonder how much cheaper my own project would've been had I never started reading GBA  .
Of course it probably wouldn't be as well built either, but at some point I find myself wrestling with the thought of "Is this good enough for the intended purpose; am I being too anal?"
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rockies
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# Posted: 2 Aug 2017 07:44pm - Edited by: rockies
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The Green Building Advisor site is made up of a group of building scientists that study all aspects of design, detailing and construction. The nice thing about this is that they are all super anal and spend far too much time studying, reading and evaluating buildings, products and construction methods.
This is great for us because if any one of them writes an article about anything and they get it wrong they know they'll be called on the carpet by all the other building scientists and ridiculed mercilessly.
Of course, when buildings were being built in the good old days (before 1950) nobody cared about building science. You just built a leaky, drafty, poorly insulated house that performed like everyone else's. You didn't worry about insulation levels or double paned windows or installing vapor barriers because you knew that whatever moisture got into the basement, wall cavities or attic could get right back out.
However, when energy costs started to skyrocket in the 1970's people suddenly started sealing up their houses really tight. They stuffed every wall cavity full of insulation, piled it up 2 feet thick in the attic, insulated the basement and then wrapped the entire building envelope in plastic. Major rot and mold soon followed. After several well documented building failures the building scientists finally came along in the 1990's and began ripping things apart to find out why the buildings were failing.
Personally, I feel that there are too many products, systems, sub-systems, building methods and techniques in the marketplace today for the average DIYer to be able to properly build his own home (Unless you just want a summer shack with no electricity, running water or bathroom). Things are just too complicated.
I do think the average guy can put in a pier foundation on his own, frame up the shell, install the windows, doors, siding and roofing himself but when it comes to managing air and moisture issues these things are best left to professionals. Too much can go wrong just from putting one "right" product in the wrong place, the wrong product in the right place or not knowing that there should be a product there at all.
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Bret
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# Posted: 3 Aug 2017 08:20am
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I guess it's up to us to do the research and then do what we deem best to build the best we can within budget restraints.
Time will tell how well our efforts pay off.
A toast to the average guy and the damage we can do with a hammer and some crooked lumber.
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