swindmill

My attic is partially finished and I plan to add a walk in closet in the unfinished portion. I'll be cutting out a section of drywall where the doorway to the closet will be. The closet will run down the middle of the attic, where the ceiling is highest. I'd like to avoid framing a ceiling for the closet, using the roof joists to attach the drywall so that I can retain all the ceiling height possible. My question is, for the side walls, can I run a bottom plate along the subfloor and then attach the studs to the ceiling joists rather than using a top plate? I'd then run 2x4's along the ceiling joists in line with the studs to create an A frame. I'm sorry if this is a confusing description, but if anyone follows me, please let me know if this will work.

Wuzzat?

http://www.ci.auburn.in.us/departments/bpd/buildingcodeoverview/Unihabitable%20with%20limited%20storage.pdf
It seems to work as long as you don't exceed 10 psf with your storage. Figure 35#/ft³ for the lumber dead load. What's your OC spacing?

GBR

"add a walk in closet" ---- requires floor joists, not ceiling joist table as shown.

"roof joists to attach the drywall " ------ you need to furr down the rafters for the required air space baffles and insulation for your area: Insulation Fact Sheet

"then attach the studs to the ceiling joists rather than using a top plate" ---- the top plate creates a fire block that you must replace if omitting.

Be safe, Gary

Wuzzat?

You know, by using through bolts I guess you could have the closet both
hanging from the roof rafters and
supported by the attic floor joists, but
analyzing the max live load for that configuration would be pretty difficult.

Can you post photos or drawings?

What truss design do you have?
Google Image Result for http://www.classictruss.com/art/truss_configurations.gif

swindmill

I appreciate the advice so far. I think I'll need to post pictures of the space in order to properly advise as to what I'm working with. I think my main concern is whether the attic floor joists are capable of holding the load as they are currently constructed. The house is 110 years old, and the truss design is simply an inverted "V" with the one board running down the center. I'll post pics as soon as I can.

Wuzzat?

I think by putting a concentrated load [you!] at midspan and measuring the resulting deflection, the strength of your existing structure can be calc'd.

It's a "Kingpost truss"; that should be easy to analyze.

swindmill

How do I measure the deflection? I've walked around in the attic numerous times while removing an old chimney in preparation for the closet. I know it can hold myself and a large pile of bricks, but I don't know what the deflections is.

Wuzzat?

From the floor underneath.
With the load in place measure the exact ceiling height. Then remove the load and look for an additional fraction of an inch in height.
I usually clamp two scrap sticks together and set this composite pole to the exact ceiling height when loaded, and then eyeball the gap that results when the load is removed.

For L/Δ = 360, for a span L of 15' [180"], Δ = L/360 = 180/360 = 1/2" when under the design live + dead load, but this is for a distributed load. A concentrated load gives you different results but I think it can be still be used to figure the equivalent dist. load.

swindmill

This project has been pushed back a bit, but a friend and I have started the planning. We are concerned that the floor isn't strong enough as it is. We were both in there and it was a little bouncy. I've added some pictures in case it helps with any of the questions I've posed.





Where the door to the bedroom will be, and where chimney was removed: