Sub base for panneling ?

[ScottA]

My current plan is to use 1/8" mahogany plywood as panneling in part of our cabin. I'm wondering is anyone knows if 7/16" OSB would work as a base to attach the mahogany to using finnish nails and glue? I can't see any reason why not but I thought I'd ask just incase someone else knows something I don't. I've seen a product that uses what looks like a laminate of OSB and mahogany for panneling but it's expensive.

[MountainDon]

The only problem I could see is with moisture causing delamination of the OSB. I don't know if that is likely.

It also occurred to me that commercially available panel laminates are normally over plywood or MDF (medium density fiberboard. I've never seen OSB used in those type of finish products. That could be for reasons other than durability; maybe because of surface smoothness.   

[PEG688]

  You could use OSB , I know it's very cheap right now , a little under $6.00 a sheet here at Home Despot.

  You'll need to glue the paneling to it as with 1/8" sheet goods you'll get little long term holding strenght out of finish nails on that paneling.

With that in mind IF I wasn't going to use 1/2" CDX which would be a better choice to use IMO , and went with the OSB , I'd nail the OBS to the studs with the rough side exposed , this will allow the glue ,( I'd suggest Const. adhesive , or liquid nails , which is sort of expensive  Const. Adh. in smaller tubes ,) to get some bite into the OSB. I'd either do lots of lines close together or I'd insue the sheet of finished paneling fit right as in a dry fit , then I'd spread glue on the back of the paneling with it on saw horses and use a knotched trowel to do a "full spread" of glue on the back side of the 1/8" stock then stick it to the OSB use a few as possible nails to hold it while the glue drys.

You could IF possible have some scrap 1x4 that you could screw over the paneling to act as clamps then remove them the next day after the glue dries, that many be over kill and not really be practical.

 
But sure you could use OSB.


G/L PEG

[ScottA]

Thanks Peg thats what I had in mind. I get OSB for less than 6 bucks a sheet and the mahogany is about 10 bucks a sheet. With a solid base there will be no need to hit studs with the panneling and will reduce waste.

[PEG688]

The only problem I could see is with moisture causing delamination of the OSB. I don't know if that is likely.

How wet will it get inside?

It also occurred to me that commercially available panel laminates are normally over plywood or MDF (medium density fiberboard. I've never seen OSB used in those type of finish products. That could be for reasons other than durability; maybe because of surface smoothness.   

  OSB has a rough and a smooth side. The rough side generally is "UP / exposed " on a roof so the roofers don't slide off , the smooth side is sort of waxed so it goes "out" on side walls to shed rain a bit better. Until it's covered or the building is in the dry.

   But yes, it's a not the best choice for under paneling , but it is cheap!!

Life is some times a compromise.



 

[PEG688]

With a solid base there will be no need to hit studs with the panneling and will reduce waste.

  I'd still think you'd want to hit the studs underneath the OSB with you paneling nails , even if the substrate was CDX IF I where nailing the paneling up I'd hit the stud's. If you can rig up some sort of clamping system to apply pressure at the paneling joints while the glue cures  , MAYBE , you could get away with not hitting the studs. Remember IF you laid-ed out on 16"OC or 24" OC your sheet goods will land on stud's if you start out on lay out. Other than a small rip to start and finish off in the corners you should have little waste.

Now if your stud layout was willy nilly you've learned a lesson about  careful layout procedures.


   

[MountainDon]

If there's space above and below the mahogany panel areas to drive a long screw into the studs or whatever is real solid back there, you could use 2x4 pieces to "clamp" until the glue sets.

[ScottA]

I wonder if contact cement would work? There would be space to do that Don. There will be a 2' wide band of sheetrock above the paneling btw.

[Don_P]

I'd use the notched trowel technique PEG suggested but use parquet floor glue, in the flooring aisle at the big box. I've used spring sticks across the room before to clam stuff to walls. Basically something like 1x4's slightly longer than the span jammed between uprights that prevent scarring of either wall. Jam in as many as you need and walk away for a week.

OSB is actually more stable than ply and should make a fine substrate. I've used it several times under 3/4" panelling just so I could break anywhere and do patterns.This steel studded wall was first covered in osb then drywall above and hickory panelling glued and nailed below. The wineroom in the same house had ambrosia maple flooring that I glued down with parquet floor glue.


My FIL built our motorhome from the chassis up. He used what turned out to be a starch based glue mahogany panelling inside and under the fiberglass outside. It worked fine till we lived in it through a winter in the Black Hilld with lots of propane use and moisture. The whole thing basically delaminated, veneer sheets peeled right off the walls and the glass let go. Our humidity level was sky high but just figured I throw it out there.

[PEG688]

I wonder if contact cement would work?

  Contact bond is poor "glue ",  except of use with P.Lam. and there it's still marginal in many ways.

  I could go into a long explanation as to why , but it would be #1 Long , and #2: over most folks heads as to the "why".

  Trust me on this one contact bond would be a very poor choice for this application. 

   

[PEG688]

OSB is actually more stable than ply and should make a fine substrate.

Maybe but OSB 7/16" can become OSB 3/4" if you subject it to the wrong conditions.

  If that place , Scott's could be kept "dry" and heated like a house particle board the high density stuff not cheap underlayment "normal" Home Despot off the shelf stuff, would be even a better choice. It or MDF,  make excellent substrates for certain things , glue soaks in deep and the bond of white glue / carpenter glue into either is excellent. So it depends on what your gluing  / doing and what the exact conditions are.

All that being said , sure OSB is in certain conditions more stable than CDX. But CDX will hold a nail better than OSB , a nail driven thru OSB almost acts like it's been "waxed" which I think it has been when driven thru OSB and they pull out like they where waxed.

  My first  choice if I where laying this paneling would be 3/4" CDX IF I intended to nail without regard to stud layout.

  But then like I said life is a compromise. I don't have to like that , but it is a reality!


 

OSB is $hit mostly , I'm not a fan of it at all. Like Hardi siding,  it has it's place in the building industry , BUT it or they are far from the "Best choice" if money is not the main / pressing / dominate  issue.

  It also  will off gas as will most man made products a bunch of nasty crap into the building , also in a fire man made products are heath risks to fire fighters , but then if your house is on fire you generally have bigger issues!

       

[MountainDon]

OSB is actually more stable than ply and should make a fine substrate.

That's why I had my concerns about the OSB. If one ran into extreme humid conditions like Don P did.....

[ScottA]

I don't see moisture ever being a real issue. I'll use construction adhesive and clamp it while it drys.

[PEG688]

I don't see moisture ever being a real issue. I'll use construction adhesive and clamp it while it drys.

  My concerns are based on not remembering if your place is a full time/ generally heated  deal or a cabin, unheated most of the time, place. Thats my moisture concern. Unheated during a long damp period could and would swell every thing thats wooden in the place to some extent.

   

[ScottA]

It will be a full time home and heated and cooled year around.

[Don_P]

I knew a bit, knew where a bit more was and googled a bit, file this under "more than you ever wanted to know about OSB"

This is a short piece on formaldehyde emissions from structural panels;
http://www.apawood.org/pdfs/managed/J330.pdf?CFID=3288805&CFTOKEN=40193100
(it will require registration to view, but that site is ok and has alot of good info)
Basically OSB exceeds every formaldehyde regulation worldwide, they ain't the problem.
After getting the casts off following a bad fall back in '79 I ran a high frequency glue press for awhile using urea formaldehyde, press opened and I got hit in the face by a blast of steam and formaldehyde. Kinda neat machine, it was basically like a 20KW college FM radio station that broadcast its signal through the wet gluelines from one platen to the other. That excited the water molecules in the glue and 30 seconds-1 minute later, poof the glue was set. The thing could light a flourescent tube held near it. I quit after becoming sensitized to formaldehyde. It was bad enough that for some time after that on jobsites I had to prop open the outhouse door and make very quick trips in there. I've never reacted in a house and am in there when offgassing should be at its worst. In a fire the contents are typically the problem. The glues used in panel manufacture use far less formaldehyde than the urea formaldehyde interior glue we were using on cabinets and furniture.

This is a good general pdf on osb and its manufacture;
http://www.apawood.org/pdfs/managed/W410.pdf?CFID=3288805&CFTOKEN=40193100

OSB is stiffer than plywood and arrives flatter, I gave up on plywood some time ago after replacing sheet after sheet when they got wet. We had multiple delams caused by dry spots in the glueline and warpage. Where an entire section of a plywood sheet lets go when wet a single chip of osb might delaminate. Yes the early stuff was pretty bad, it has improved with each "generation" of the product, plywood has continually gotten worse IMO. I have to beat together warped plywood subfloor every time, almost always with a helper standing on the back of the sheet to hold the warp down, advantech or any osb for that matter takes one or two licks and no helper.

The bearing capacity of a dowel type fastener in osb is the same as in a structural1 plywood panel, 4650 psi. Typical plywood has a dowel bearing capacity (a nail in shear) of 3350 psi. Withdrawal numbers are not available for either panel alone, this is not a structural application. The nail is to hold alignment until the glue sets. There is a small amount of wax used with the resin during manufacture to help with moisture repellancy. My ceilings have 2 layers of foam under the rafters with osb screwed through that to the rafters. 3/4" T&G is then trim nailed to the osb, no glue, nothing but 16ga trim nails in osb, been there for years.

Am I saying PEG is wrong... hardly, read this;
http://www.rci-online.org/interface/2003-06-haughton-murphy.pdf
Basically osb is slower to adsorb water but once its inside it tends to stay there a whole lot longer. That is its Achilles heel. We are into our high humidity time here, wood products are metering ~14-16%, pretty well below what it takes to cause problems as long as I don't have a leak. PEG lives in a rain forest over the water, that is quite likely going to tip the balance.

Some folks call OSB "old sh###y board" or "vertical mulch" others swear by it. Anyway, not trying to do anything but present a little info and hopefully a balanced view so you can decide what makes y'all's world go round.

Course, theres nothing like diagonal boards