Garage roof structure

[pjcloninger]

I don't have any pics of this but I will try to explain it the best I can. The garage of this house has a gable roof just your typical A frame. The roof is famed with rafters and every rafter has a collar tie on it, also this is brand new framing. My question is about the ceiling joists. There are only four joists at the front of the garage where you can put the track for a garage door. Everything else looks fine as far as the faming goes. Are the collar ties enough to prevent spread or should there be ceiling joists on all of the rafters? I hope I explained this good if you have any questions please ask.

[Bruce Thompson]

I assume you have no sheetrock on your garage ceiling. ??

I'd like to have a little more info. How big is your garage? What is the pitch of your roof? What sort of roofing material is on top? Is the roof decked with plywood or OSB or not at all?

Thanks
B

[Larry D. Kage]

Originally Posted by pjcloninger

Are the collar ties enough to prevent spread or should there be ceiling joists on all of the rafters?

Often ceiling joists are installed on every other rafter set when a ceiling is not being applied that needed more nailing but having no ceiling joists except on one end doesn't sound right...I guess pictures would help. Is that possible?

[Kenton H. Shepard, CMI]

Collar ties alone are not enough to prevent walls from spreading.
Unless the garage has a structural ridge, posted to the foundation at each end and designed to carry the weight of the entire roof (usually a gluelam, sometimes several microlams glued and nailed together) rafter ties tying the lower ends of the rafters together at the wall top plate are required.
Typically installed every other rafter. Typically 2x6 but should be bigger if they plan to use it for storage.

[Robert J. OConnor]

Originally Posted by kshepard

Collar ties alone are not enough to prevent walls from spreading.
Unless the garage has a structural ridge, posted to the foundation at each end and designed to carry the weight of the entire roof (usually a gluelam, sometimes several microlams glued and nailed together) rafter ties tying the lower ends of the rafters together at the wall top plate are required.
Typically installed every other rafter.

Right on the money ... although using rafter ties at every other rafter usually requires a bolted connection at the rafter/tie heel joint and any joist splices due to high loads (look at IRC Table R802.5.1.9 to get an idea of the ridiculous number of nails that would be required ... unless there is not any heavy snow loading, and it's just say a 20 psf roof live load).

JMO