I am thinking of using OSB Sheathing as ceiling in my converted gas station home but am concerned about the VOC output and my 2 year old son... would this be safe? or safe if sealed? thank you.

OSB burns great!

I'm pretty sure 7/16" OSB functions as a 15min. thermal barrier, equivalent to 1/2" drywall. If you are concerned about off-gasing and the health effects don't use it. If your home is well ventilated with fresh air, it may be ok. It's a judgement call.

I have seen OSB used many times for walls and ceiling finish in non-traditional projects. It is common place as liner panels for 'office spaces' in ag and lite commerical buildings. Give it a coat of good quality interior stain and a poly seal coat and can become downright pretty.

In a word, NO THis from Wikipedia--- In homes, the most significant sources of formaldehyde are likely to be pressed wood products made using adhesives that contain urea-formaldehyde (UF) resins. Pressed wood products made for indoor use include: particleboard (used as sub-flooring and shelving and in cabinetry and furniture); hardwood plywood paneling (used for decorative wall covering and used in cabinets and furniture); and medium density fiberboard (used for drawer fronts, cabinets, and furniture tops). Medium density fiberboard contains a higher resin-to-wood ratio than any other UF pressed wood product and is generally recognized as being the highest formaldehyde-emitting pressed wood product. Other pressed wood products, such as softwood plywood and flake or oriented strand board, are produced for exterior construction use and contain the dark, or red/black-colored phenol-formaldehyde (PF) resin. Although formaldehyde is present in both types of resins, pressed woods that contain PF resin generally emit formaldehyde at considerably lower rates than those containing UF resin. NOTE, OSB (oriented Strand Board) is intended for exterior use. THough it emits less than some it does emit. As to it being a thermal barrier just like sheetrock. You need to check with your insurance agent before you give advise like that. It is a contribution to a fire--not a barrier. Show me the certification for that statement!

mgerety, Take a look @ Huber Engineered Woods web site and you'll find all the info you need. Research article RE: California acceptance is very detailed. You need to look closely at what is allowed in the way of coatings for OSB materials. There are some out there that want their products to breath and a coating may void any warranty. If your local rep. gives you the OK, I'd get that in writing.

I'd have to check my IRC, but I remember having this discussion about wall coverings and fire barriers in another thread.

Posted By jusaxeme on 09/15/2009 7:30 AM

the IRC says thermal barrier, not fire barrier

The term "Thermal Barrier" does refer to the fire "resistance" capabilities of a specific material.

I'm pretty sure 7/16" OSB functions as a 15 minute thermal barrier, which would be equal to ordinary 1/2" gypsum wall board. So that means where ever ordinary 1/2" gysum wall board can be used, 7/16" OSB can be used in its place, when required to meet a 15 min. thermal barrier.

However, the company that manufactures the 7/16" OSB has to have a test that proves this or it can't be used in that capacity.

It's funny that people automatically assume any 1/2" gypsum wall board functions as a 15 min. thermal barrier, the fact is that if a company hasn't had their board tested and certified, it may not. Likewise, with OSB, there is cheap uncertified OSB that uses less glue with flakey/dry surfaces and certified OSB that uses the right amount of glue and is smooth, dense and uniform. In the end, you get what you pay for. Beware of deeply discounted materials.

Below is the section of the IBC that prompted me to make the above statement.


2603.4.1.5 Roofing. Foam plastic insulation under a roof
assembly or roof covering that is installed in accordance
with the code and the manufacturer’s instructions shall
be separated from the interior of the building by wood
structural panel sheathing not less than 0.47 inch (11.9
mm) in thickness bonded with exterior glue, with edges
supported by blocking, tongue-and-groove joints or
other approved type of edge support, or an equivalent
material. A thermal barrier is not required for foam plastic
insulation that is a part of a Class A,BorCroof-covering
assembly, provided the assembly with the foam
plastic insulation satisfactorily passes FM 4450 or UL
1256.

Because I'm in the SIPs business as a designer, I have to keep track of where my foam plastic insulation is in a building and wether it needs to be separated from an interior. 7/16" OSB would meet this criteria for this specific case. The codes are very complex and a lay-person, has to be careful how they use building materials in relation to the code and fire safety.