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Shawn Honeychurch
03-28-2008, 12:22 PM
Morning all;

Well, it's almost time to work on my workshop. Old building 20' by 12', siding is the pits, needs to be resided and some re-framing. I already redid the roofing.

What I am thinking of is replacing the framing as needed, then sheeting the interior with 7/16" OSB, priming and painting. That should be fine.

It's for the outside I need advice. My thought is to sheet it in 7/16" OSB, prime and paint, then vapor barrier then 1/2" shiplap fir, stain or paint.

Any thoughts?

Shawn

Art Mulder
03-28-2008, 12:40 PM
Isn't this a bit of a "personal preference" area?

For instance, plain old siding doesn't do much for me. Boring. I really like the look of Board-n-batten.

Shawn Honeychurch
03-28-2008, 1:13 PM
Not sure about personal preference, mostly just wanting to know if I am overlooking anything, and if this makes sense.

Jim Becker
03-28-2008, 1:35 PM
OSB isn't really designed for continued exposure, even with paint. Consider T1-11 if you want a wood-based product. It will soak up the paint, but is a common material for shed and outbuilding siding...and even on some homes. There is also a siding product that looks similar, but is more of a hard-board material and sold specifically for this purpose. It comes pre-primed which saves work and looks very nice when installed. A shed kit I bought for my previous residence came with it and it painted up wonderfully.

Joe Chritz
03-28-2008, 1:43 PM
It appears you want to add shiplapped fir over the exterior osb? If that is the case that works fine.

Siding is a very personal decision and it should match or complement the other buildings as much as possible.

I like board and batten but most of my place has plain vinyl. The porch has sawn cedar shake and those are very nice but not for the cost and work involved for an entire house.

You don't need to prime the OSB before the vapor barrier but it wouldn't hurt anything but a few extra gallons of paint.

Joe

Shawn Honeychurch
03-28-2008, 2:20 PM
Thanks Joe;

That confirms it for me, Shiplap fir over the OSB, I will still prime the OSB, a little protection never hurt.

What are peoples thoughts on using vapor barrier? I have had a few people tell me that it's not really a good idea as it traps the moisture against the wood, instead of letting the walls breathe.

Thom Sturgill
03-28-2008, 2:37 PM
House wrap is not a vapor barrier. It helps water shed down the wall without penetrating into the sheathing, but still allows the wall to breath. Vapor barrier goes on the INSIDE closest to the warm space to prevent condensation (and mold) inside the wall. It only works well if all penetrations are sealed.
Be sure to prime the back side of the fir too.

Shawn Honeychurch
03-28-2008, 3:00 PM
Ah Ha;

That clears a few things up, thanks Thom.

So the material order would be as follows, inside to outside:

7/16" OSB / Vapor Barrier / Insulation and Framing / 7/16" OSB / House Wrap (Same thing as tar paper?) / 1/2" Fir.

Right?

Thom Sturgill
03-28-2008, 3:07 PM
Tar paper would probably work, its what was used many years ago. I think it did act as too much of a vapor barrier. Tyvek is one brand of house wrap that can be bought at the BORGs.

Jim O'Dell
03-28-2008, 3:16 PM
I had a rehab job for my shop that sounds similar to what you are doing. I peeled off 1/4" plywood, changed from 24" on center to 16" on center, sheathed it with 7/16" OSB with the radiant barrier on it, wrapped with Tyvek, then finished with Hardiboard planks. The Hardi took the sealer and paint very well. Has been on for 3 years now, and, except for the dirt from the splatters of rain from the roof and the dogs feet, it still looks the same. Just a thought. Jim.

Chris Padilla
03-28-2008, 3:19 PM
Stucco, Baby, stucco! Lasts FOREVER! :D

Bart Leetch
03-28-2008, 3:50 PM
So if your putting a vapor barrier on the outside of the OSB why paint it?

Another thing if you use something like craft faced fiberglass or rock-wool insulation & install it with the craft facing inward you will already have a Vapor barrier remember this structure has to be able to breath. Don't go into overkill.

I don't know much about building but I did start following Dad around at a young age & all the way up through 2 years of college, as he built houses, apartment buildings, schools & restaurants. I have also seen what trying to seal a building up to tight can do. I wouldn't paint the OSB exterior sheathing either.

I guess what I am saying don't complicate the job, sometimes more isn't better

Shawn Honeychurch
03-28-2008, 4:45 PM
Thanks Bart;

Complicating things is one of my crosses to bear in this life :).

I was going to prime/paint the OSB just to ensure it does not come apart if it does get damp. I live on Vancouver Island, we have 2 seasons here, dry (3 months of the year) and wet ( 9 months of the year). Seems a small thing to do to ensure long years of happiness in the workshop.

Josh Bowman
03-30-2008, 10:51 PM
I've hung vinyl on mine and find it very, very easy and not to expensive, plus no painting. I've had it on my house for years, I do find it needs washed a couple of years.

Brad Sperr
03-31-2008, 11:55 AM
I'm also in the process of sheathing and siding my garage/shop with hardipaneling. I went with 15# tar paper (roofing felt) for my weather resistant barrier, because it's considerably cheaper than Tyvek. Just be sure to overlap your layers shingle-style by around 6 inches. You may also want to consider putting up a rain screen in between your weather resistant barrier and your siding to promote drainage and drying. I'm using 7/16 inch ply strips for my rain screen, but this may not be necessary with the ship-lapped fir.

Travis Gauger
03-31-2008, 12:34 PM
Alright now. Speaking from many years in the insulation business, Messing with vapor barriers is dongerous. I have fixxed some pretty nasty screw ups from people putting too much vapor barrier on a home. If the interior area is going to be heated or cooled at any time, then you only should have 1 vapor barrier. Period. House wrap (Tyvek) on the outside isn't a vapor barrier. Tyvek breathes very well. Paint doesn't. If you use a faced insulation, you do not use a poly vapor barrier. Your best bet is to get unfaced insulation and then poly over it. Any time you have two vapor barriers they act as multipliers and trap the moisture in.

We had a house that we went to go fix that had been insulated by the home owner during construction. It had passed code. It was only 14 months old. When you would walk into the house you could smell the musty, damp, moldy smell. To make a really long story short, the home owner caulked all the seams in the outside sheathing before insulating. Then he used craft faced insul, then vapor barrier, then sheet rock. From the out side he had his siding, foam board insulation with taped seams, poly vapor barrier, tyvek, poly vapor barrier, outside sheathing. It took 14 months for the moisture to grow enough stuff in those walls for the house to become un inhabitable. (Condemned) It was actually so bad, The stuff growing in the walls, that they put a perimeter around the area before they did their controlled burn on it.

Moral of the story, Make sure you don't end up with a double vapor barrier. It will cause damage in a hurry. I have a list of these stories for you if you'de like. It happens a lot in the north by me. But it sounds like your in a moist area also. My recommendation would be to follow your local residential building code for a house on your shop.

Mark Drayton
03-31-2008, 3:17 PM
Hi,

I live in South Wales, UK. So we have lots of experience of wet as in Vancouver. My shop is heated on the house central heating system (fanned hot water radiator). The structure from inside out is:
12mm OSB (unfinished), thick builders polythene vapor barrier,
2"x4" preservative-treated framing with Rockwool cavity insulation,
12mm WBP ply treated with preservative and with sealed seams but not painted or sealed,
breathable builders paper,
50mm battening,
external 12mm WBP ply preservative treated and sealed seams with a hardwood drip moulding at the bottom to shed surface water away from the lower edge of the plywood,
externally finished with a proprietary textured roll on polymer finish (? aggregate filled acrylic).

This has stood the test of time - 12 years so far. I recently extended and so had to take down a few meter of wall - that was hard work because of the grip of the annular ring-shank nails used to fix the boards. The interior of the wall was in pristine condition apart from a small area where water had got in around a window frame with faulty sealing.

The plywood provides greater structural integrity and a better surface for finishing than OSB although costs a little more. The internal poly barrier prevents ingress of moisture from the moisture loaded heated interior. The insulation would probably be more effective with insulation board but mineral wool was less expensive. The external air cavity between outer skin and sheathing provides a barrier against any inadvertent rain penetration. Similarly the breathable paper prevents water getting into the structural cavity from outside and at the same time prevents any accumulation of moisture/condensation within the structure. The external coating has provided effective protection to the plywood against the elements over a number of years. It is decoratively acceptable in relation to the adjacent cement rendered brick built hose and will be readily recoat-able when necessary.

It's worked for me.

Mark

Ken Harrod
03-31-2008, 6:44 PM
I think they sell foam sheets in 1/2" and 3/4" that is intended to go between the wall sheathing and the siding for extra insulation. If you have a heated/cooled shop, you might want to consider adding this layer of insulation. I have seen it, but never used it. So, off hand I don't know the price or R-value.

Ken