Covering up OSB - thoughts?

[Ron Selzer]

I missed any information about insulation being used, seems like you need to insulate the walls in SE Mich.
Would use foam insulation board over the 2x? and then strip the boards up and down, paint the foam where every board joint is so any gaps don't show. Butt the boards tight this time of year and loosely in Jan-March. Will get a small gap in the winter and close back up in the summer. Gives it a look that goes with all the exposed wood you have. Try one wall and look it over for a month or two before going any farther.
Just my thoughts, definitely like what you have done so far.
Ron

[John Pariseau]

I missed any information about insulation being used, seems like you need to insulate the walls in SE Mich.
Would use foam insulation board over the 2x? and then strip the boards up and down, paint the foam where every board joint is so any gaps don't show. Butt the boards tight this time of year and loosely in Jan-March. Will get a small gap in the winter and close back up in the summer. Gives it a look that goes with all the exposed wood you have. Try one wall and look it over for a month or two before going any farther.
Just my thoughts, definitely like what you have done so far.
Ron

It's already insulated (R40 / R20). I did what some refer to as "wrap and strap". My stackup is:

inside | Post | Girt (actual 2"x6") | OSB | impermeable vapor/water barrier | 4" rigid foam (two layers, taped and seams staggered) | rain screen gap | furring strip | housewrap | siding | outside

I should have just bought SIPs, but I thought I was saving myself money - ha! That's another story for another time... This assembly eleiminates any thermal bridging except at the window boxes, each screw that holds the foam/cladding up.

[John Pariseau]

The key thing is - whatever I do on the inside cannot restrict the OSB from drying out. That is, I shouldn't cover it with something that would trap moisture.

[Maurice Mcmurry]

The key thing is - whatever I do on the inside cannot restrict the OSB from drying out. That is, I shouldn't cover it with something that would trap moisture.

This is exactly why mud over wood is not a standard application. The wood will expand and contract relative to humidity and temperature.

[Tom M King]

When I mask bare wood for new plaster work to adjoin, like all the trim in the 18th and 19th Century houses I work on, I put a thin area of shellac on the wood for tape to stick to. Once finished, I go back and scrape the shellac off. It comes off pretty easily, but has protected the wood from soaking anything up.

http://historic-house-restoration.com/Plaster.html

[Tom M King]

If I was going to cover the OSB in your building with wood, and mill the boards, I'd make a modified tongue and groove design with uneven depths of the sides of the grooves. The part of the groove that covers the show side would be longer to hide medium crown staples nailed though the longer side of the tongue. Not sure if words draw that picture. I don't do much drawing. Most such designs are in my head, and just made as needed.

In other words, it would look like regular tongue and groove, but no fasteners would show in the joints at any time of year.

Senco staples have the most reliable glue on the legs that I have found, and would hold a lot better than nails, or brads in the OSB.

[Tom Bain]

This is what I’ve been doing … slowly … as I accumulate “scrap” cutoffs (don’t know why the photo is upside down). I just plane them down to the same thickness and face nail them to the OSB. Eventually the whole shop will be covered but may take a while.

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[John Pariseau]

This is what I’ve been doing … slowly … as I accumulate “scrap” cutoffs (don’t know why the photo is upside down). I just plane them down to the same thickness and face nail them to the OSB. Eventually the whole shop will be covered but may take a while.

Nice! Are you grooving your boards?

[Curt Harms]

A different option would be to mud/plaster the OSB surface between the timber frame structure and just paint it.

I had the same thought but it would depend on how John feels about drywall work. Applying the mud should go pretty fast but there may be quite a lot of sanding if he wants a nice finish. Would the OSB swell from moisture and become rougher when applying drywall mud? I've never tried it.

[John Pariseau]

I had the same thought but it would depend on how John feels about drywall work. Applying the mud should go pretty fast but there may be quite a lot of sanding if he wants a nice finish. Would the OSB swell from moisture and become rougher when applying drywall mud? I've never tried it.

I would forgo the nice finish - might be nice to have some light trowel marks to make it not look like drywall - I have a particular distaste for drywall. As for swelling - dunno. The only way to find out will be when I do some tests. It is an exterior rated OSB, but still, I had moisture get into a section of it when I was doing my siding and had to replace it (granted, it was exposed with water splash back for a long time).

[Tom M King]

Plaster is not going to stick to it long term. Lath is used because it needs something to help hold it in place. It will bond to masonry, but not level surfaced wood, even rough wood like the rough side of OSB.

[Tom Bain]

Nice! Are you grooving your boards?

No, I just leave a small gap between them for expansion/contraction. Haven’t had any issues.

[Maurice Mcmurry]

Dryvit is a sticky flexible plaster like coating. It is typically applied over fiberglass faced foam board and fiberglass mesh. I suspect it contains fungicide, mildewcide, etc and would not be something for indoors. It sticks to everything and does not like to come off.