[LittleBoPeak]

I have question for all you construction wizards out there . . .

I have a 12x20, 2 story shed with a gambrel roof that I would like to convert to a "cabin" for living space. The shed is 2x4 construction, 16" oc, with 24" oc 2x4 roof trusses and ridge vented. It has OSB siding.

How do I insulate and install vapor barrier to insure that I don't set myself up for water damage down the road. I'm sure it is not as simple as just putting in some insulation and sticking up wall board.

Any insights will be most appreciated.

[frankthetank]

Wouldn't you wrap it with Tyvek and then insulate between the studs???

OSB for siding!? What? Is it painted? I would've used plywood and then side it with vinyl (cringes), steel, Al, cedar, etc...

[HeckuvaJob]

Honestly? Ask the very same question over at BreakTime. Having endured my own insulating nightmare this fall, I can attest that there are more factors to consider than you can imagine.

If it isn't sided yet, I agree with frank about the Tyvek. However you have to be careful about how you overlap and tape, especially around windows.

Fiberglass has to be installed with the skill of a surgeon or it will lose most of its value. Blowing cellulose into wall cavities will offer you the advantage of stopping air infiltration.

The best of both worlds? Spray foam like Icynene. This will also server as your vapor barrier. And as you probably already guessed, you'll pay for it.

Please let me know how this turns out. Make sure you mention foundation type, heating source and window type when you post over there.

Edit: Dunewalker mentions an important factor - your climate! Wet-blown cellulose is also an option if you wanted to do the drywall at a later date.

[dunewalker]

What Frank said. OSB is not very weather-proof anyway, even painted. Depends on your climate. If you live in the desert, this is all easier. Wrap the walls in tyvek or tarpaper, for wind protection (tyvek is not a vapor barrier as I understand it) then put another layer of siding, like plywood or planks, whatever. Then install fiberglass R-11/13 (fiberglass bats have a vapor barrier built-in)between the wall studs and put some interior boards on, pine t & g is nice. The roof ought to already have a vapor barrier like tarpaper under the shingles, so just install fiberglass bats & sheath the ceiling same as the walls. If it was mine, I'd do a woodstove installation at the same time. This treatment presumes you have access to cash & supplies. Total cost to upgrade, not including the wodstove, probably will run over $!,000, maybe $2,000. If you're short on cash, just put another good coat of paint on the outside, install fiberglass bats between the 2 x 4s and put some inexpensive wallboard inside.

[kpeavey]

With ease of installation and cost, the Tyvek, pink fiberglass, drywall is right in line with the latest trade secrets. While I've not used it the spray foam is NICE.

I would want to cover the OSB exterior with something more durable. Left exposed, the OSB will begin to swell and decay within 5 years, especially near the ground and close to the eaves. RB&B or T-111 are plywood coverings that will hold up longer. Hardiboard will take the elements, bugs, is fire resistant, and it's as easy to install as OSB. I've used it, I recommend it. Again, you get what you pay for.

Looking through the lens of Peak Oil, the extra you spend on quality and durability can make a considerable difference in the future.

[LittleBoPeak]

Thanks for the responses so far, guys. I know there is a lot to consider.

The shed has been up for several months so it already is finished, at least as much as a storage building usually is. The exterior walls are the OSB sheeting that looks like plywood panels (with the vertical lines etched in it). It has a good paint job on it.

I had thought of the tyvek, but the exterior sheathing is already in place and I'd rather not take it off to wrap it. But if the tyvek is worth the trouble, I'll do it. Unfortunately, money is a concern. So with that in mind, would it make sense to go ahead with the insulation and wallboard in order to get liveable space now and then go back and do the tyvek maybe next year?

The building is in the SE US. Not real wet climate, but high humidity. It is up off the ground about 1 foot on concrete block piers. I do plan to put in a wood stove for heat.

It is the classic dilemma. I want to do it right, but I have a limited budget.

Thanks again for your suggestions!

[kpeavey]

If you had to skip the tyvek, your cabin won't fall down because of it. You can always make up some of the difference with extra caulking, extra paint, and attention to maintenance issues as soon as they present. Extending the eaves by a couple of feet would be handy. Keeps the rain out better and offers shade in the summer.

If what you are calling OSB (Oriented strand Board) has grooves, it is probably not OSB but RB&B or T-111, which is a much better product.

I'd also want that crawlspace buttoned up and insulation under the floor.

Have you given any though to a mirror ball? My sister just loves 'em.

[dunewalker]

$this->bbcode_second_pass_quote('kpeavey', 'I')'d also want that crawlspace buttoned up and insulation under the floor.

[HeckuvaJob]

$this->bbcode_second_pass_quote('LittleBoPeak', 'U')nfortunately, money is a concern. So with that in mind, would it make sense to go ahead with the insulation and wallboard in order to get liveable space now and then go back and do the tyvek maybe next year?

[Quagmire]

.
A good way to insulate the windows is to cover them from the inside with bubblewrap.... flat side toward the glass. This also provides privacy without losing light.
.

[StormBringer]

I cant stress enough about the OSB siding its a temp siding at best the home i bought has a 1 car detached and it has osb that is falling apart, 6 yrs old.

[uNkNowN ElEmEnt]

I ahve learned recently that the spray foam insultation is a great home for wood bugs.... no joke, it looks like an ant farm.

[LittleBoPeak]

$this->bbcode_second_pass_quote('HeckuvaJob', '')$this->bbcode_second_pass_quote('LittleBoPeak', 'U')nfortunately, money is a concern. So with that in mind, would it make sense to go ahead with the insulation and wallboard in order to get liveable space now and then go back and do the tyvek maybe next year?

[gnm]

$this->bbcode_second_pass_quote('LittleBoPeak', 'T')he building has been through several torrential rainstorms and I've seen no evidence of water getting in.

Are you saying that the cellulose is used instead of regular insulation? Is it an equivalent R rating to a comparable thickness of regular insulation?

As far as a vapor barrier, how about putting up plastic sheeting over the insulation, but under the wallboard? Would that be effective or would that create additional problems?

[HeckuvaJob]

$this->bbcode_second_pass_quote('LittleBoPeak', 'T')he building has been through several torrential rainstorms and I've seen no evidence of water getting in.

[LittleBoPeak]

There is a lot of info to digest here. So much for my "simple" insulating job! Thanks to all for the info. And thanks, Heck, for the links . . . Interesting reading. The sprayed cellulose sounds like the way to go.

Like I always say, you learn something new everyday, whether you want to or not!

[uNkNowN ElEmEnt]

Actually after all this talk I am thinking more about a kind of polyliner (its like bubble wrap) and reflects heat back in and acts as a vapour barrier. its supposed to give an R value of 9.5 for 2.5" thickness. for thinner walls that might be the way to go.

[LittleBoPeak]

$this->bbcode_second_pass_quote('uNkNowN ElEmEnt', 'A')ctually after all this talk I am thinking more about a kind of polyliner (its like bubble wrap) and reflects heat back in and acts as a vapour barrier. its supposed to give an R value of 9.5 for 2.5" thickness. for thinner walls that might be the way to go.

[JRP3]

Try googling "reflective bubble insulation".