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-   -   Need advice on a rural cabin insulation project - new construction. (http://www.diychatroom.com/f103/need-advice-rural-cabin-insulation-project-new-construction-160111/)

imautoparts 10-14-2012 11:06 PM

Need advice on a rural cabin insulation project - new construction.
 
My Son is making me proud and building his own 30' x 30' home using mostly salvaged wood.

The foundation will be similar to a pole barn - large square posts at a 48" depth with concrete poured around them. He chose the number of posts with the help of an Amish builder friend - I don't know how many but it sure looks like plenty.

He has sufficient metal saved to plan exterior walls of pole-barn steel, hung on 2x4 framing with crosspieces to secure the metal well (we live in a windy area). The studs will be 16" on center apart. He does not have sufficient means to buy exterior wall sheathing for under the metal. Interior walls will be drywall over studs.

Now for my questions:

1. How do you recommend we plastic wrap this type of exterior wall? Where should it be placed? Directly under the metal? Under the lath cross pieces? Somewhere else?

2. Since the floor will be floating off the ground on posts, how much clearance do you recommend for the crawlspace? How would you seal the skirt of the building to reduce heat loss?

3. What type of insulation material do you recommend that might be widely available as surplus or teardown scrap? Are the R-value gains possible with spray-in foam worth the cost and hassle? Any tips on how to keep the interior walls warm with exterior steel?

Sorry for such general questions - but the kid has a great start and I want to help him every way I can.

John, Indiana, USA

md2lgyk 10-15-2012 07:31 AM

It would certainly help to know where this "rural cabin" is located.

imautoparts 10-15-2012 09:03 AM

Paulding County, Ohio (NW Ohio).

Our temperatures aren't as mild as Indianapolis, but not as severe as Chicago.

jklingel 10-16-2012 01:40 AM

Quote:

Originally Posted by imautoparts (Post 1030965)

Now for my questions:

1. How do you recommend we plastic wrap this type of exterior wall? I would not put up any poly in NE Ohio, but I'd put on a layer of Tyvek on the outside, under furring strips, which are under the steel. That will give you a rain screen should the steel leak. Use the airtight drywall approach (Google it) on the drywall, and use air tight elect receptacles, seal any gaps, cracks, etc.

2. Since the floor will be floating off the ground on posts, how much clearance do you recommend for the crawlspace? How would you seal the skirt of the building to reduce heat loss? Often crawl spaces are conditioned. Read on buildingscience.com for options insulating floor joists. FG batts are a poor choice here, unless you apply rigid foam to the bottoms of the joists and goo/tape the seams. I hate fg batts, and suggest Roxul to anyone; no itching and glass in your face/lungs. Do put poly on the ground, sealing it to whatever skirting you have.

3. Are the R-value gains possible with spray-in foam worth the cost and hassle? One big advantage w/ closed cell is that it air seals. Make sure the joists are covered completely; if you leave the outer edges naked, they may condense and rot. You'll have to run the numbers on economics; no idea what your prices are.

Any tips on how to keep the interior walls warm with exterior steel? See above, and get some Roxul instead of fiberglass batts. OR, and better, dense pack w/ cellulose, either through the sheet rock or InsulWeb mesh.

John, Indiana, USA

See after the bullets, above. BTW: nice name. john

imautoparts 10-16-2012 07:35 AM

Moving this Post over from Construction - Need advice on New Home based on Pole Barn
 
http://i48.photobucket.com/albums/f2...seproject1.jpg

imautoparts 10-16-2012 08:06 AM

OK - Just found 70 bags of cellulose that was leftover from a job and paid $2 a bag for it. :thumbup:

So - blown in cellulose thru-drywall for the walls,

Tyvek for house wrap, over studs, under lath,

Spray poly foam for corners, cracks and window/door edges

Still need advice as far as the crawlspace - recommendations on inexpensive method to either insulate the floor or ideas on how to skirt the house effectively even though the foundation is on posts OR

Perhaps we shouldn't do a crawlspace.... thoughts? We could always plumb the house from the attic.... but I hate the thought of a leak up there in 20 years.

House will be on a woodburner for the first few years, so I don't know how we would warm the crawlspace without big losses. thoughts?

Anyone know how much per sq ft Roxul should cost? Any ideas on where to find leftover or scrap or salvage Roxul type material in the Midwest?

Any ideas of any kind are VERY welcome. Thanks!

joecaption 10-16-2012 09:03 AM

What size are those post sticking out of the ground?
Is that what he plans on using to hold up the floor?
Was there any permits pulled to build this like that?
Where's the center supports?

imautoparts 10-16-2012 09:35 AM

Quote:

Originally Posted by joecaption (Post 1031901)
What size are those post sticking out of the ground?
Is that what he plans on using to hold up the floor?
Was there any permits pulled to build this like that?
Where's the center supports?


The home is Paulding County, Ohio; and this is a common construction method for rural homes. I'm not sure of the exact number of posts, but looking at his first two rows I'm assuming there will be 16 of them. The house is 30' X 30'.

They are 48" deep, the holes are approx 20" in diameter and concrete is poured in to about an 18" depth, then the remainder is filled with tamped earth. I believe they are 8x8 or 10x10 treated timbers, which have been slathered with tar on the part that is below ground. This is a common method of construction here. - the nice thing about using treated lumber piers is the ability to adjust the floor joists later if settlement occurs. Since this land is inNW Ohio, it was all once part of the "Great Black Swamp".

The home is on farm land, and local code allows this construction technique. My brother in law has a nice modern home in the same zip code of about 1700 sq ft; it is a two story, and yes, it is on the same type of foundation.

Here is an example: http://i48.photobucket.com/albums/f2...ileAndPier.jpg

What type of "center support" do you mean?

If you want to learn more about wood foundations, here is a great link: http://www.apawood.org/level_b.cfm?c...p_rfl_cs_about

beenthere 10-16-2012 10:30 AM

Thread moved to Insulation forum.

imautoparts 10-16-2012 12:08 PM

Update: Just came home from buying 70+ 25LB bags of cellulose insulation from an old farmer a few miles away. Price was $120. I'm calculating the SF now but it is a HUGE pile of bags.... :) They are old and a bit tore up, so we'll take some barrels with us when we make the pickup. Turns out a local hardware store will loan the blower equipment for free if we buy a few more bags from them.

Next we need to learn about the best and most cost effective technique for insulating and sealing the floor.

Anybody have a good idea or two?

beenthere 10-16-2012 05:48 PM

Spray foam would be the best for the walls. As it will provide your vapor barrier.

jklingel 10-16-2012 10:46 PM

$2/bag? You outta bea arrested for stealing like that. Ship me any leftovers. Thanks.

imautoparts 10-17-2012 07:28 AM

Quote:

Originally Posted by beenthere (Post 1032211)
Spray foam would be the best for the walls. As it will provide your vapor barrier.


Can't afford it - cost is $3000 just for materials (including ceiling). We'll be using it at corners and around openings of course, but old-style cellulose will have to do; since now we've got two pallets of the stuff!

Can we carefully use heavy poly instead of genuine Tyvek for the wall vapor barrier if we carefully seal the seams? One of my sons-in-law works at a tape factory, so we can get tape at a huge discount. I suppose I should visit the Tyvek website to learn the differences.

Still looking for advice on insulating the crawlspace/floor.

jklingel 10-17-2012 01:23 PM

Tyvek is vapor open, w/ a perm rating of about 40. Poly (visqueen) is vapor closed, with a perm rating of about 0.6. People are shying away from poly in all but the coldest climates because it will not let vapor through. That is problematic in cases where you have solar vapor drive (from the outside) and it hits the cool poly; condensation. An outfit in southern Ohio went belly up because of that several years ago. http://www.greenbuildingadvisor.com/...moisture-walls For the floor, if you install rigid foam across the bottoms of the joists, taped and goo'd edges and seams, and can then dense pack cellulose from the top somehow, you'd probably be fine, imo. Otherwise, get Roxul batts in there, then the foam. The floor joist edges need to be covered. I'd also suggest searching on buildingscience.com and/or greenbuildingadvisor.com.

imautoparts 10-17-2012 03:00 PM

I found a tyvek equivalent called tydol at our local home store (Menard's) for $107 for a 9'X100' roll. At those prices we can afford it for the walls.

For the floor, a very knowledgeable guy working in the insulation department said he built his own home using lumber uprights for the foundation, just like ours. He has a crawlspace - sounds like a very similar build.

He recommended a 12" thick 24X48 batts of fiberglass insulation with the paper side down between each joist, edge-stapled and held in place with lath strips every couple of feet. Thoughts? Cost would be about $350


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