Wood Framed Commercial Bldg - Cathedral Ceiling

[bpstruct]

Have a seemingly trivial question. Don't do too much work with wood, so I apologize in advance. I have a building where the owner wants a cathedral ceiling...no ceiling joists/rafter ties. The rafters will sit on glulam beams on each end and probably a glulam ridge beam. The ridge beam frames into a gable end of the building. I have been reading that I need to balloon frame up to the ridge beam, which makes sense. Don't want that weak joint at the top plate. Figure I'll strap across the posts to keep the top plate (chords) continuous across. Since there is an entry on this end, I can't directly support the ridge beam by a continuous post. Thinking I'll have built-up posts or "stud packs" on either side of the entry. Then I'll place diagonals in the plane of the gable end wall down from the ridge beam to the juncture of the top plate and continuouse built-up posts. Is this the best way to do this? Also, I am thinking that the best way to do the posts is by building them up thereby eliminating weak joints at "splices". I would envision staggering the studs as required to offset individual joints. Would appreciate feedback. I can send a sketch tomorrow if necessary. Not in the office right now.

 

[abusementpark]

How high is the ridge? I would use continuous studs if possible for the "stud packs".

Not sure if I understand the part about diagonals.

 

[bpstruct]

Regarding the stud packs, what would you do if the length is to great for continuous studs? I think that I can get them to work as single pieces given where they will be, but it seems like it would behave as continuous anyway if joints in the individual studs are offset. Regarding the diagonals, the intent is to have something directly beneath the ridge beam that extends down at an angle to the continuous studs. Maybe the end rafter carries over to the continuous studs?

 

[dik]

Can you use scissor trusses? or if you use ridge beam and joists, then you require a tie at the ridge. How high is the wall? You may have to use deeper wall studs...

Dik

 

[msquared48]

Never heard the term "stud packs". Are you referring to multiple stud columns?

If that is the case and the columns have to be longer than 12 to 16 feet, you may want to consider using glulam members for the columns. Depending on the tributary area for wind, you may want to do this anyway considering the possible need for locally deeper wind beams.

As you suggested, a sketch would really help here.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dik]

as Mike noted... or LVL's or PSL posts... Check the CWC site for a publication titled, "Tall Walls"

Dik

 

[BAretired]

Provide a sketch with dimensions. It is too easy to misinterpret your situation from a verbal description.

BA

 

[bpstruct]

Thanks for all the feedback.

Forget the "diagonals". I am planning on using a transfer beam to support the glulam ridge beam. Although I'm not sure about the connection.

Also, thanks for the recommendations about the posts (lvl's, glulams, etc.). But, if solid sawn works, would a built-up stud pack be considered continuous (if the builder can't get 20-foot sticks)?

See attached.

 

[asixth]

Just by reading your post it sounds as though you have a fairly good handle on it already.

You might be able to laminate the studs together (maybe 3 or 4 studs).

 

[dik]

You may need more framing on either side of the windows, and your top plate may be a problem... both for lateral loading...

Dik

 

[BAretired]

I agree with dik. Use full height framing each side of each window.

I would omit the double plate shown and use a sloping double plate under the rafters plus a single horizontal plate above the windows.

Builder should be able to find 20' long Timberstrand, Parallam or similar material. If not, use Glulam.

BA

 

[bpstruct]

Thanks. Was planning on using the double top plate as the chord for the diaphragm, so I will need to figure out a splice detail for a sloped top plate.

 

[msquared48]

Doesn't look like much lateral capacity either unless you use Simpson StrongWalls or the like.

I agree with the full height studs at the end of the window headers too.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[abusementpark]

Never heard the term "stud packs".

I prefer the terms "ganged studs" or "stud posse."

 

[BAretired]

How about multiple studs?

BA

 

[dik]

or a flock... <G>

Dik