Sheathing garage

[jimmiedee]

Im tired of looking for a stud every time I want to fasten something to the wall in my garage and being limited by the position I can put it. I want to sheath one wall, maybe two in plywood on the inside It has been suggested to me that ths may be against code and be a fire hazard. I dont see how as the wall will still be covered in 5/8 drywall. I havent been able to get a response from local city authorites on this. Any info would be greatly appreciated.

[Edwin Pawlowski]

Building codes usually call for a 5/8" covering of drywall or fire rated material. On top of that, we, as a society of homeowners, put paneling, pegboard, paper covering, all sorts of decorative material. drapes, etc.

My garage is detached. I insulated it, put up drywall, but in some areas I put plywood or pegboard over the drywall for the convenience of hanging. I don't give a damn about codes, it works. I don't see it as a safety issue but I take normal precaution of electrical, tools, liquids etc. That, IMO, is a far greater danger than a piece of plywood to hang tools.

[tbasc]

The code requirement that I know of is a fire separation between house and garage. That leaves the other wall free for what ever you want.

As Palowski notes, real world arrangements includes all kinds of flammable materials.

TB

[Goedjn]

As long as you cover it with a fire-rated depth of sheetrock, you should be fine. It used to be that if you had 3/4" of wood, you didn't need sheetrock at all, but I don't know if that's still the case. (In a single dwelling unit, that is.)

[Goedjn]

Oh, by the way: If you want a cheaper way out, you could just run ledger-board the whole length of that wall at two or three heights. If you put a back-bevel or ship-lap along the to edge, you can even hang things like cabinets that way.

[Pete C.]

If the ultimate wall surface is 5/8" firecode drywall it will not make any difference fire rating wise if there is a layer of plywood between the drywall and the wall studs (other than the increased cost). The drywall provides the fire rated protection for the plywood just as it does for the studs.

Pete C.

[jimmiedee]

The plywood would be on top.

[Pete C.]

Wrong, put the plywood behind the type X drywall. You maintain the fire rating and the ability to attach shelving or whatever at any point. There is nothing to be gained by putting the plywood as the exposed surface and you loose fire rating.

With plywood on the exposed side, it can be ignited readily since it has no fire protection and it then provides a fuel source that could burn long / intense enough to defeat the rating of the type X drywall behind it and ignite the studs or rafters on the other side. With the plywood behind the sheet of drywall the plywood receives the full protection of the drywall.

Pete C.

[buffalobill]

you could search google.com for your city and state building codes but it may take some time to narrow this down. many cities and states have strict regulations on this to reduce the spread of fire. depending on the size of your town, sometimes it may be easier to drop by the permit office and inquire of a building inspector regarding your type of construction at your particular address.

[Tim Mulvey]

Why would he lose the fire rating if his wall assembly, (5/8" drywall on both sides of studs), is still intact?

[Pete C.]

By putting a large quantity of unprotected fuel in direct contact with the rated wall?

Pete C.

[Goedjn]

A sheetrock wall covered in plywood takes longer to burn through than a sheetrock wall not covered in plywood.

[Pete C.]

Quite possibly, however the burning plywood fuel attached to the wall will in all probability burn through the sheetrock on the ceiling and ignight the joists or rafters above far more rapidly than say some burning boxes on the floor of the garage.

Pete C.

[Goedjn]

My impression is the opposite. If the plywood on the wall isn't constantly heated by an external flame, it's likely to just go out. Plywood backed by sheetrock doesn't burn worth a damn, and the fire-rating of the ceiling assumes direct contact with an open flame anyway. My guess is that the plywood will improve the performance of the wall, contribute toxic gas and smoke to the room it's in, and not noticably affect the ceiling.

1/2" exterior grade douglas-Fir plywood has a flame spread rating of about 140. (ASTM-E-84)

I don't know what the numbers mean, (Inches per hour, maybe?) but according to this site:

is a limiting number.

In any case, if OP is worried about it, beyond code-compliance, he could always paint the resulting plywood with flame-retardant paint.

--Goedjn

[jimmiedee]

Finally got a reply from local government on this. Plywood actually makes the wall have a better fire rating although it does add to available fuel in case of a fire. plywood attached to sheetrock does not burn as readily a a piece just stored in the garage. Anyway installed the plywood Saturday an first thing I noticed was how much quieter it was when the HVAC came on, not just in the garage but in the whole house.