Attic flat- there’s a lot of wasted space behind the knee walls in our condo- would like to build some shelves/ cabinets into these areas. The easiest way would be just to buy some cabinets and set them into framed openings, but it occurs to me that there may be an issue, as you would then not have fire protection; the cabinets would be unprotected wood, breaking the ‘envelope’ of 5/8 rock which covers the framing- any of you kind folk know how this is handled in the code?
Edited 6/24/2007 3:52 pm ET by PGproject
Replies
We run into this in commercial building when recessing large autowasher boxes, & drinking fountains.
The drinking fountains are usually set in a framed & rocked cavity, while the auto washer are covered on the back with rock & then set into the studs.
If you were to order your cabinets 1.5" smaller than the stud bay you could wrap them with 5/8" rock & fire tape them, that would still give you your one hour rating.
Since you're in a condo, you may have fire protection issues if your attic space is shared by another unit(s). You may also have some wiring issues if any wiring runs in walls where you want to put cabinets. You'll certainly have to deal with insulation since you probably have at least R-19 (maybe higher) behind the knee walls.
Read your CC&R's to find out what you can (and can't) do and have a chat with your homeowners association. Off-hand, I can't see any insurmountable problems.
Thanks, Dave- no shared attic, as we are the entire top floor of the building. Also, no insulation, though we'll add it where possible when the wall is opened.
With most codes it's ok to put a cabinet in an unrocked opening since the construction of the cabinet will resist fire spread.
In your case I would build an outer box with ply that insulation is then applied to the outside of. The cabinet is then set inside the box.
Best of luck
Beer was created so carpenters wouldn't rule the world.
know how this is handled in the code?
Well, to answer Code questions, sometimes the best thing to do is go to your city's web page, and look for Planning & Development, or Engineering, or the like to see if they have a link to the Code used in the City. (Or, even better, a Municode link--search functions are so nice.) That's going to be the standard the BI will use.
Since you have cleverly filled in your Profile, I can know you are in the Bay Area. That means you may have more restrictive fire codes than I am used to. It can also mean that the "grandfather-ing" to severly limited, too.
So, that could mean that you might have to "re-kneewall" to enclose the new cabinetry spaces to achieve mandated fire protection (or lease/habitation space seperations). But, really, only your AHJ (authority having jurisdiction) can say for sure.
Worst case would be if you have to maintain a "rated" seperation, as that means the joy and fun of fire caulking and rated mud & tape on the joints. The framing is simple enough, frame to fit the new casework. Then get the framing inspected. Put up the wall board, and have that inspected--that usually being the pain in the behootie.
Since you say the space is "wasted" behind the knewwalls, is this a shallow or a steep-pitched roof? If, as I'm going to surmise, this is shallow, let me offer that it's tough to use casework shorter than 2' or so. So, you have to cipher where the back of the casework will hit that 2' point, and that will "set" the depth you can use (generally). That will often set up a situation where a slide-out is better than an open shelf sort of situaltion. Not a bad idea, when you get the walls open to run a circuit for lights for the cabinets, even if only "puck lights" as adding light will help a room seem roomier.