Covering up OSB - thoughts?

[John Pariseau]

I built a workshop a few years ago, and have been slowly chipping away at different aspects of it. I'm at the point now where I need to tackle the interior walls. This may seem unnecessary, but I need to get the walls covered before I can finish my electrical.

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This is the second floor - first floor is concrete but the walls are identical in construction. The sidewall girts are 2" thick. Top and bottom of the girts were left rough sawn, but the wood facing the interior was planed smooth.

I had a variety of ideas for the inside walls - one was to break up pallets and use the wood on the walls. After collecting, moving, tearing apart 20 or more I realized it was a very unrealistic idea, and abandoned it. "Luckily" I happen to have enough 3/4" rough sawn white pine to side the entire building (was originally going to be the siding), so have enough for the interior.

So - was hoping to get some advice on how to go about this next phase.

Right now, here's what I'm thinking:

Plane one face of each board to get a flat surface
Rip each board edge to get a set of standard width boards (I have an assortment of 12", 10", 8")
Using an appropriate construction adhesive, apply boards horizontally to the OSB

Questions:

Should I shiplap the boards? The sheer amount of wood needed to be cut feels daunting. I have a Craftsman 100 table saw (1950's era) + dado stack, router+table but it's a basic model with just a 1/4" collet

Which side should face inwards? Originally with the pallet wood I was going to leave it rough. I like the rough-sawn contrast, but it might be a dust collection nightmare.

I'll have to do some testing, but would you glue rough side to OSB, or smooth side?


Thanks for any suggestions/ideas.

[Zachary Hoyt]

I would use nails or screws to hold it to the OSB or through to the frame in addition to or instead of glue, but I would be leery of glue only, especially if you are going to attach anything to the walls. I got an invalid attachment message when I clicked the link in your post, so maybe I am not understanding something that would change the situation. I recently made some shiplap edges on ash boards to make a new basement hatch cover for the living room, and I got good results by cutting with a regular blade from the side and then from the edge. This means two cuts but it seemed easier than using a dado blade or a router bit. I set the depth so that I didn't have to move the fence or change the blade height. I just made one cut, flipped the board around and made the other one.

[Mel Fulks]

Smooth side showing . You don’t need “ thousands of of dust caches ….dust will find lots of hide-outs anyway.

[John Pariseau]

Here's the inside, not sure why the previous image didn't load. If I had to use screws, I was hoping I could "panelize" the boards somehow and screw into the top/bottom girts - it's about 18" between the girts. I'm loathe to screw into the OSB - there is a self-healing vapor barrier on the outside, I'd prefer not to screw through or into it.

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[John Pariseau]

I would use nails or screws to hold it to the OSB or through to the frame in addition to or instead of glue, but I would be leery of glue only, especially if you are going to attach anything to the walls. I got an invalid attachment message when I clicked the link in your post, so maybe I am not understanding something that would change the situation. I recently made some shiplap edges on ash boards to make a new basement hatch cover for the living room, and I got good results by cutting with a regular blade from the side and then from the edge. This means two cuts but it seemed easier than using a dado blade or a router bit. I set the depth so that I didn't have to move the fence or change the blade height. I just made one cut, flipped the board around and made the other one.
My general plan for the walls - build shelves that hook into the upright posts from behind - it was one fatal flaw in my wall system I hadn't really considered - I should have used a thicker plywood rather than OSB. I'll get over it eventually, but at the moment I do not want to put screws in my beams/girts except for electrical and permanent fixtures.

[Jim Becker]

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

[John Pariseau]

A different option would be to mud/plaster the OSB surface between the timber frame structure and just paint it.
That sounds interesting - but does it require wire lathe?

[Jim Becker]

That sounds interesting - but does it require wire lathe?

Since the OSB has a relatively rough surface, you may be able to get away without lathe, especially using drywall mud. It would not be hard or expensive to do a test with some scrap OSB and some boards to simulate the girts, etc., so you can be sure that the process is clear.

The reason for this suggestion is both cost and because it would emulate a very traditional look.

[John Pariseau]

Since the OSB has a relatively rough surface, you may be able to get away without lathe, especially using drywall mud. It would not be hard or expensive to do a test with some scrap OSB and some boards to simulate the girts, etc., so you can be sure that the process is clear.

The reason for this suggestion is both cost and because it would emulate a very traditional look.
I have enough wood on hand to cover it without purchasing any - but I would have to spend time and money (electricity) to process the wood. I am intrigued, though, and have enough scrap of everything - quite possibly some drywall mud as well (the powdered stuff, right?).

[Maurice Mcmurry]

That is a great looking space! Decreasing fire load would be a reason to use plaster. Using sheetrock would be way less messy than plaster. The Timber frames I have worked on were done with SIS panels that were OSB on the outside and sheetrock on the inside.
For making your boards into plank paneling how about smooth side out with Dutch Lap?. I have made Dutch Lap with a molding head on a table s saw. It would be a lot of work. I think it looks nice. +1 for staples or pins rather than construction adhesive.

What bit to make dutch or cove lap siding? (https://sawmillcreek.org/showthread.php?232266-What-bit-to-make-dutch-or-cove-lap-siding)

[Jim Becker]

I have enough wood on hand to cover it without purchasing any - but I would have to spend time and money (electricity) to process the wood. I am intrigued, though, and have enough scrap of everything - quite possibly some drywall mud as well (the powdered stuff, right?).

You can mix your own or use pre-mixed. I suspect that mixing your own for the "big job" should you decide to go that way, is most cost effective. Check on what's most appropriate type for "skim coating"...there are different kinds of mud and I'm not very knowledgeable about what's best for this. But for your testing, use what you have to "paint" some osb with the mud to get a smooth surface (or even a "worked" looking surface for the appearance of old time) and go from there.

[Maurice Mcmurry]

I have found the learning curve for trowel trades to be quite flat. Plastering, stuccoing, or mudding that vault is not going to be easy. Even an experienced plasterer will mask all of the beams and floor so that the inevitable mess is easier to clean and the lovely wood is not stained. Joint compound is easier to work than plaster or stucco (mortar) because it sticks to the tools. Joint compound over OSB is not a standard application. If you go for a plaster look I suggest sheet rock. I have a good trick for creating a mud to wood corner that does not require J bead or L bead. I personally would rather work wood than plaster.

[John Pariseau]

I have found the learning curve for trowel trades to be quite flat. Plastering, stuccoing, or mudding that vault is not going to be easy. Even an experienced plasterer will mask all of the beams and floor so that the inevitable mess is easier to clean and the lovely wood is not stained. Joint compound is easier to work than plaster or stucco (mortar) because it sticks to the tools. Joint compound over OSB is not a standard application. If you go for a plaster look I suggest sheet rock. I have a good trick for creating a mud to wood corner that does not require J bead or L bead. I personally would rather work wood than plaster.
You mention "vault" - however I'm not doing the ceiling, just the walls. The ceiling is 2x6 T&G.

I, too, prefer working with wood - the only challenge for me is processing all the wood. I don't have a shaper - if I wanted to do any kind of lap it'd have to be done on my (small) table saw. I have some experience with mortar - I did a lathe/scratch coat/real stone veneer application on my foundation, as well as various repairs around the house. I don't think my first go at this would be perfect... and there will be a mess, but since I'm doing the work and I'm, shall we say, meticulous/particular, I would expect the mess to be kept to a minimum (but yes - lots of blue tape, drop cloths, etc...).


This is all good info!

- Plaster is very tempting, but then I have a lot of wood to "get rid of". Will do a test with some scrap OSB.
- Dutch Lap looks nice, but I would prefer a flat wall. I can do a simple lap with my table saw (per a comment above), not sure this is necessary.

The more I think of it, the more I like the idea of a plaster-style application. I found a technique in a YouTube video (admittedly YT isn't always the best source) where the guy uses concrete adhesive and mixes it with sheetrock joint compound. You might want to put your volume down before watching: https://www.youtube.com/watch?v=iEJPb-0heb8

And just reviewing different plastering techniques, one can apply a bonding coat of sorts and have a thin layer of plaster (ie, 3mm) without need of mesh. My main concern are any resins in the OSB that would prevent/reduce adhesion. I guess I have a lot more reading to do, but I don't have any deadlines on this phase.

[Maurice Mcmurry]

Plaster would be a good look. When I mud over wood I use bonder, self adhesive fiberglass mesh, and Durabond 90 followed by Stay Smooth 90 or Quick Set 90.
It is not an approved application and can fail in very hot, very dry, and/or damp environments. (I had a failure in a skylight trunk)

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I got zoomed in on your image and see the vault now. Again, what a cool room!

[John Pariseau]

I got zoomed in on your image and see the vault now. Again, what a cool room!
Thanks! I't s a bit, erm, excessive in some regards, but it's a very inspirational space, and I'd like to move my art supplies, tools and stuff to use it for projects.

[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.