I need to insulate my barn(40×24) for weekend woodworking projects. Currently its exposed cypress, overlapped 1 x 8’s, 10 ft high walls. A friend suggested the radiant barrier stuff in a roll. Claims the foil will reflect heat back into the space. I have a bullet propane heater. I was thinking rigid Owens Corning 4×8’s sheets. Whatever I do, I will cover with 1/2″ drywall but not finish. I posted in Breaktime but only got one, but informative, response.
Any ideas are greatly appreciated as its starting to get cold.
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Replies
For the most bang for the buck, fiberglass batting between studs is usually the best way to go. You can stand the stud wall away from the outside sheathing and get 6" or 8" of insulation in the wall even though you are only using 2x4's for the framing. For all the time and effort involved you should at least use 6" of insulation in the walls and more in the ceiling.
If the outside wall isn't air tight, cover it first, on the inside surface, with Tyvek type wrap then stud out, insulate, and probably install a vapor barrier under the dry wall. An added advantage to a stud wall is that it will be easy to add wiring before you close it up.
Much of your heat will be lost through the ceiling or roof so that is the place to start and where the most insulation should be concentrated.
Once you get the space insulated and relatively airtight, you should invest in a good vented heating unit. The propane heater you have now isn't intended for long term use in an enclosed space. It is potentially dangerous and will cause problems with both moisture and fumes accumulating.
John White, Shop Manager, Fine Woodworking Magazine
Edited 10/24/2006 2:59 pm ET by JohnWW
Thanks a lot. I appreciate the advice, especially about the propane heater.
JohnWW
In all due resect to your expertise I think your comments could be taken wrong and the result would be the dramatic shortening of the life of the barn.
What has allowed the barn to survive up 'til now is the free flow of air thoughout it. Exposure to moving air prevents the damage that may result without that air movement..
Trap air and it's also easy to trap moisture. The result is rot and there goes the barn..
Insulate a barn carefully if durability is important. Work carefully to ensure that moisture doesn't become trapped between the insulation and timbers..
Frenchy,
I've restored a lot of barns and timber frame homes in New England, and I'm pretty much an expert on insulation and airflow, so I think I know what I'm talking about here.
I said to use a breathable barrier on the outside wall, the Tyvek, to allow any trapped moisture to escape and a good vapor barrier, probably poly plastic, on the inside wall to prevent moisture from the interior of the building from getting into the insulation and condensing where it would certainly cause trouble. I also recommended a vented heater since his unvented heater will dump gallons of moisture into the interior air every day it is used.
These are the basic procedures followed whenever an old building is converted to a heated space and I have never seen a problem when the work is properly done, which on an old building can be a challenge. There are a lot of smaller details to be attended to, and I couldn't cover them all in a short piece of free advice, whole books have been written on the subject, but I did steer him in the right direction.
In my experience almost all timber frame failures are due to neglecting to maintain the building's roof, once the roof starts to leak the frame will fail within a few years.
John White
John
NO disagreement here with what you said, however your first post didn't contain the explanation as to why one product over another.. As a barn fanactic I worry about such things. Now granted I probably go way overboard with explanations and your more direct appraoch may wind up being correct, but still I worry..
I think we are singing from the same hymnal here. You are right, I didn't go into a lot of detail, but I can't compress 30 years of knowledge into a posting here on Knots. I have seen the sad results of inept renovation work, so your concern is real.
John W.
While we're on this topic I find myself with a similar project, though it's a very old garage in my case. Rather than drywall I'm tempted to go with 1/4" plywood, the thought being that plywood can take a hit much better. Thoughts on this, as far as durability, cost, etc.? I suspect I'm losing a little bit of insulation with ply but aside from that it what am I missing? The garage has a high peaked roof, so I'll be adding an insulated ceiling as well. Thanks.
1/4 inch plywood is hardly much tougher than dry wall and will cost considerably more. Also you can easily patch a hole in drywall, and drywall is a fire barrier.
John W.
Edited 10/27/2006 8:51 am ET by JohnWW
John,
And paint the walls and ceiling white!
A bad day woodworking is better than a good day working -- yes, I'm retired!
I went through this and settled on DW, even though I HATE taping. It's more expensive than it used to be, but it still the cheapest thing out there for walls. And ask any fire fighter which they prefer.
Been building for many years. The best advice I can offer...is to follow Mr. White advice.
You will want to seal every possible hole where air can enter or escape with caulks, spray foam and whatever you else you need to use.
Appreciate it. Thanks.
That radiant foil "insulation" is pushed alot for agricultural installations, I guess because it's real cheap. But you'll notice you can never get a straight answer from the vendors as to its R-value. That's because it's highly variable based on installation (the foil must have an airspace for it to work), and it's probably not very good.
I agree with John that fiberglass bats give you the biggest bang for the buck. Regarding the comments on the 2x4 studs, I wentthrough that thought process a fe months ago: should I go with the lower R-value insulation and the 2x4's, or spend more money on 2x6's so I could use R-21? Then I realized, as John noted, I could go with the cheaper 2x4's, and still use the thicker insulation by not having the studs right up against the siding.
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