I’m wondering if anyone here could offer comments on why the contractors I’ve talked to are concerned with doing metal siding with 1” rigid foam? Are there mechanical fastening issues here? Or is it cost/labor issue? Or something else? Details below.
Thanks!

One contractor mentioned that the metal siding would be too easily dimpled during installation if it was installed on top of 1” of foam. When I mentioned that there would still be horizontal furring strips, just that they would be over the foam, and asked if that would be OK… he suggested a different product that he says will out perform the insulation value of 1” foam, cost less, and is only ¼ thick so no installation problems. From his description I believe he was referring ‘double-bubble insulation’  which is commonly used on metal pole buildings - this contractor does both pole buildings and conventionally framed buildings. But I am left wondering if this is such a great product, why is it not used on residential construction, and super-insulated houses and such. Maybe it is, but I haven’t seen it in the research I’ve done to date. Also, the double-bubble appears to be a vapor barrier so it would prevent the wall assembly from drying to the outside (as it would with 1” xps) … so that is a concern for me too.

Another contractor expressed concern regarding the metal siding and 1” rigid foam, but was not clear on why it was a problem and did not offer any alternate ideas. When the issue keeps coming up … I think the prudent owner has to pause and try to figure out what’s going on.

Reference Info:
- 30x50x14 machine shop, PA, MD border, oriented due south
- insulated foundation and 5” slab, perimeter insulation
- target temp of close to 60 deg F; no AC in summer
- plan to supplement heat with solar air collectors to help with heating

Wall Assembly:
- metal siding with horizontal furring strips
- 1” XPS (taped, foam, etc)
- OSB - 2x6 24 o.c.
- cavity: fiberglass blown-in
- 1” (or 2” if budget allows) foil faced rigid foam (iso), taped
- wall board, taped and painted

Previous post on wall assembly and earth-link for this building.

I wouldn't expect any dimpling problems if you are attaching the siding directly to the furring strips.

Be wary of radiant bubble wrap claims: http://www.healthyheating.com/Page%2055/Page_55_o_bldg_sys.htm

Radiant bubble is reasonably common in pole barns on the general principle of better than nothing. It would lower cooling loads if done right, until the dust settled thickly anyway.

But you aren't building a pole barn. You may need just the right contractor. You want better performance than the average commercial building.

BabyBldr,

I would omit the OSB sheathing and use 1x4 let-in bracing or a "T"  metal diagonal brace 1" foam over 2x6 studs, then fur-out and metal siding.
I have no faith in the bubble wrap.   Was wondering why you wouldn't just build a pole building and stud-out with 2x6?

http://building.dow.com/na/en/produ...rmaxci.htm

Posted By toddm on 26 Apr 2010 02:18 PM
I wouldn't expect any dimpling problems if you are attaching the siding directly to the furring strips.

Be wary of radiant bubble wrap claims: http://www.healthyheating.com/Page%2055/Page_55_o_bldg_sys.htm

Radiant bubble is reasonably common in pole barns on the general principle of better than nothing. It would lower cooling loads if done right, until the dust settled thickly anyway.

But you aren't building a pole barn. You may need just the right contractor. You want better performance than the average commercial building.

Toddm:
From a little research I too was thinking this bubble stuff sounded too good to be true, and we all know what that means. But the link you provided was very good and really confirms it for me. The builder who suggested the bubble instead of 1” XPS does pole buildings and says they also do frame construction. But I think his primary business is pole buildings. I agree that finding the right builder/contractor would be very helpful. It seems I am proposing a building that is intended to be a shop and yet has specs (in terms of wall assembly) that are more typically seen on a house. House builders/contractors aren’t very interested in the project because it is to small (in terms of revenue) – which I can certainly understand. So a little bit betwix-n-between at the moment and trying to sort out best approach.
Thanks for your feedback.

Posted By cmkavala on 27 Apr 2010 07:46 AM
BabyBldr,

I would omit the OSB sheathing and use 1x4 let-in bracing or a "T"  metal diagonal brace 1" foam over 2x6 studs, then fur-out and metal siding.
I have no faith in the bubble wrap.   Was wondering why you wouldn't just build a pole building and stud-out with 2x6?

http://building.dow.com/na/en/produ...rmaxci.htm

Cmkavala:
A bit of background, since you asked a broader question of why not do a pole building. Over the years I’ve spent a lot of time in Ag purpose pole buildings, in all seasons. Most of them had little insulation, no heat, some with slabs, some without. They are very common structures in our area and I’ve got nothing against them, so naturally that is what I thought we would build for our shop. But then I had a chance conversation with an architect and he offered a free opinion (he was not involved at all I the shop project). He said I should consider a conventionally framed structure instead because he felt you just could never get a good air seal in a pole structure and you would forever be fighting drafts. He also mentioned possible issues with frost heave in the slab. After that, I started really looking at the pole buildings I’ve been in and noticing variations in how they’re built and how they perform… and I started to wonder if a conventionally framed building might be doable (budget wise) and lead to a better building (more comfortable, less operating cost) in the long run (amortize over 25 yrs). Now I’m NO expert, that’s for sure!  ;-)  And I can very easily see a reasonable person choosing a pole building and also getting a good result. In the end though, I had to pick a path and move forward. I’ve got price quotes on the pole building version and will certainly compare them with the total costs for the conventionally framed building once I get all the quotes in.
Regarding the OSB vs let-in bracing. This was something that was briefly mentioned by the designer who did our construction drawings. I relied on his judgment and he specified OSB. Also, the architect I mentioned in the previous paragraph mentioned at the time we were discussing it that he would sheath the entire building on OSB. So these were two separate opinions in that direction (OSB vs let-in). I also did a little research wall sheathing and it seemed that OSB (or plywood) was typical & recommended. My research was limited though, and likely had a residential (vs shop) focus. Here is an example of research: http://bct.nrc.umass.edu/index.php/...hed-walls/
Thanks for your help,
BabyBldr

Babybldr,

I am familiar with pole buildings as well and sold them for Green Bros. Lumber Corp. in the late 70's in Western NY, NE PA and eastern Ohio. They were used for many applications including homes. They can be built as tight as conventional framing with the slab poured directly up against skirt board and 2x6 studs in between poles.
The pole buiding will be a little less expensive to build, but definitely  a do-able alternative.
Ask 50 different people for opinions and you will get 50 different opinions, you will need to discern what best suits your needs

Babybldr,
Have to agree with Chris, many different opinions about pole buildings and their uses.
One reason a pole builder will not want to add insulation to the outside of the frame is that of this type buildings require that the metal be attached directly to the frame in order to maintain their wind loading on the building. By adding the insulation board, you eliminate the racking shear strength that is added by the steel panels. The companies with better engineering can compensate for this in their design of the specific building.
The use of a pole building, or rather its more sophisticated cousin, a post-frame building, in conjunction with SIPS creates a very strong, and energy efficient building.

Cmkavala: Agreed --> 50 people, 50 opinions ... or more.

It is interesting to know that they're also used for homes as I've not seen that and have no familiarity with that level of quality in a pole structure. Unfortunately, at this time, we are through the permit process with the building specs I outlined at the top of this post. I'm not looking to back track through that unless there are really compelling reasons to do so - such as my current specs are unbuildable, which I don't think is the case with my current understanding of the project. Thanks for the added background though as I'm learning something new every day and this will all be useful for our next building project, the house. And that's a whole 'nother can of worms!

Wes: Thanks also for your input. I agree with your comments on the potential problems with rigid foam between the metal siding and poles, in a pole type construction. However, I'm not trying to add 1" exterior foam to a pole building because we've already moved down the road on a conventionally framed building, just with metal siding.