Shop insulation and wall covering

[Boondox]

Thanks! I'll look it up!

The past couple of days I've been removing the fiberboard and insulation from the walls and ceiling. I'm finding large sections that were never insulated at all, and much of the ceiling insulation had been "rearranged" by nesting squirrels over the years. There was also a gable vent that had been covered over years ago when the outside was refaced. Small wonder ice dams were such a consistent problem!

Pete

[Stoneheartfarm]

</font><blockquote><font class="small">In reply to:</font><hr />
I'm finding large sections that were never insulated at all, and much of the ceiling insulation had been "rearranged" by nesting squirrels over the years.

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That's where your heat has been going. [img]/forums/images/icons/grin.gif[/img]

Steve

[Pat]

Now wait a minute, man. There is an opportunity here. Squirrels are not only heat sources but have a a pretty good R-value as well. Although not a topic of discussion in "Fine Homebuilding" there is likely a way to make use of these squirrels besides .22 targets, dinner, and decorative tails to put on your handlebars.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[retired_young]

<font color="green"> Insulate your 2X4 walls as normal then put up 2" styrofoam sheets over the whole thing. Mark ahead of time for stud locations. On top of the styro, put plywood with long screws going through the styro and into the studs.
</font color>

We did that around the walkout in our basement. About 32 ft of stick built wall. It does an awesome job acting as a moisture and air barrier. It still pays to seal the space behind it and make sure the insulation is nice and snug (not compressed). Any air leakage will still find its way to the nearest opening...such as electrical outlets.

r_y

[Stoneheartfarm]

When I bought the cabin years ago, I re-wired and insulated it. While wiring, I found a spot in the attic where the wire's jacket and underlying insulation had been stripped away. Spot was maybe 4 inches long. One wire was bare for a couple inches and the other was bare for the space of exactly 2 rodent teeth. There was also a small skeleton laying next to the spot. I've heard of it happening, but that's the only time I've ever seen it.

Steve

[Pat]

Stoneheartfarm, My previous house was built in 1928 and had solid not flexible steel conduit throughout except in a small remodel in the late 50's and my handiwork a few years ago. Rodentia would have a tough time in the old part.

[img]/forums/images/icons/smile.gif[/img] Pat

[Leef]

. Ceiling insulation is probably a better bet than insulating the underside of the roof (if they aren't the same thing.) Foaming the underside of a roof can promote rot. Some shingle manufacturer's waranty is void if the roof deck isn't ventilated.

Pat, What is wrong with spraying expanding foam insulation ( one brand name I've heard of is ICYNENE ) right onto the rafters and bottom of the decking? This would then allow the attic space to be insulated from the cold/heat and ventilating above the attic space but below the roof decking would not be necessary.

I don't know if this form of insulation is available nation wide, but I've seen it on the HOME TIME PBS program and have read that it's very air tight b/c it expands into every possible nook and cranny. If an insulated attic space above the shop is desirable, then I think this could be an option if it were available and cost was reasonable.

Leef

[Pat]

Leef, I'm familiar with that and some other spray in place eurathanes and other foams. I'm not debating the physics or practicality or performance of insulation materials, I'm reminding you that the manufacturer's warranty for shingles may be void if you do not ventilate the roof deck. Check with your manufacturer for your specific shingles or whatever you roof with.

I just had this same problem. I ended up with insulated ventilated nail deck. It is a layer of OSB and a layer of rigid foam separated by spacers to create a ventilation chanel adjacent to the bottom side of the OSB decking. You put tarred felt on top and then shingles as in conventional shingle roof jobs. The chanel between the deck and the insulation connects the ventilated soffit to the roof ridge vent and sets up quite a chimney effect when the roof heats up.

Reducing the delta T across the rigid foam to 1/2 of what it would be without air flow is the same as doubling the R-value of the foam and it is free. Once you have this nail deck in place, you can add additional insulation beneath it if you choose as it does not interfere with ventilation of the botom of the deck (handled by chanel). The insulated ventilated nail deck that I used had an aluminum IR reflective layer on the top side of the foam that should reflect 97% of the IR coming off the bottom of the deck. Lots of things working together to make a good cool ceiling in the garage/shop.

There are both cardboard (some aluminized) and thin styrofoam "wind chutes" that you can staple between your rafters. This maintains an air chanel for soffit to ridge air flow without restriction from batting. It keeps the batting from closing off the whole space and leaves a ventilation chanel. If you used a product such as those, you could then spray foam in between the rafters and not violate shingle warranties since there would still be a ventilation chanel. These accessories are real cheap, essentially free compared to cost of the foam-in-place insulation.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[Leef]

Pat,

I have followed your construction post and remember the decision process you went through. I think combining both ventilated roof decking and spray on insulation underneath is a great combination [img]/forums/images/icons/smile.gif[/img] .

I've saved many pieces of advice from this forum, but I don't see a cost estimate for that decking. Do you recall how much it was per 4x8'?

Thanks again

Leef

[Pat]

Leef, I hope I didn't convey the impression that I used spray-on insulation, just that it could be put on such that a vent chanel was left. If I recalled the price of the decking, I'd be happy to tell you (sad it cost that much). I bought during a time of rapidly escolating prices on the heels of the huricanes in the east and the aftermath of war in Iraq. I don't know what happened as I quit following prices after I bought but they went up DRAMATICALLY. So the price I paid, around $50/sheet, is not an indication of current cost. It could be up or down form there.

I'm paying a premium for certain materials, much of which is a fallout of the war in Iraq which I support so I just go on.

While spray-on foam under the insulated ventilated deck would perform very well, it would, in my opinon, be a poor choice when considering performance for cost. If you are going to spray the expensive foam, just use the "wind chutes" under conventional decking, OSB, ply, boards, or... and spray under those. The same performance for many many dollars less in cost. The applicator will have to use a bit of caution to ensure the expanding foam doesnt smash the chutes flat against the deck but a thin coat followed up by the rest should do the job. If the foam firms up quickly enough it won't really require doing the job twice with moving of scaffold and ladders. Just spray a quick first pass everywhere the applicator can reach and then a second pass as soon as the first has expanded close enough to its final value to not get shoved into the chutes too hard by the expanding second layer. This should prevent pressure of the expanding foam from squeezing the chutes closed. The second layer is free to expand into open sp[ace so shouldn't be too hard to control. I'm not an experienced applicator, maybe there isn't a problem with collapsing the chutes and it would not require special technique.

The chutes are real cheap and added to the cost of regular decking you are still way below the ventilated deck cost.

The peak of my roof where the vented deck was used is 30 feet up in the air which would have elliminated a lot of applicators.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]