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oscar1962@charter.net 07-19-2009 11:44 AM

Screened in porch
 
I have a question on building a gable roof, I installed rafters (2x6) on a 2x8 ridge beam 14'-4" length, width 13'-1" of wall. Do I have to put cross ties and how many. I have 11 rafters on each side 16" on ctr. Pitch is 4-12. The lenght of rafters is about 8'. I took the design from family handyman mag. They didn't show cross ties.

glennjanie 07-20-2009 05:19 PM

Welcome Oscar:
We are happy to have you.

The roof framing, decking and shingles create quite a load with a downward pressure. The rafters transfer that load to the walls in an outward pressure. You could build it without cross-ties and see if it tries to 'squat'. In that case you could add 3/8" cables on 4' centers to stabilize the walls.
Or you could use collar ties about 1/2 way up the rafters.
Glenn

GBR 07-22-2009 06:43 PM

If inspected, rafter ties at the plate line- 1x4's every 4' on center are required. Collar ties hold the ridge/rafters together in a high wind. If you have the headroom, use rafter ties.
Be safe, G

oscar1962@charter.net 08-02-2009 11:45 AM

I built it all ready and the walls didn't bow out or squat but I am going to put rafter ties every 4' @ 1 x 4 anyway for saftey and can I do the same for collar ties.
The wall has a top plate and bottom plate of 2 x 4 and the beam is 2 - 2 x 6.

GBR 08-02-2009 07:24 PM

The rafter ties(on the walls) are required at 4' on center, minimum code. You can put them on every one if you so desire. The collar ties may not be required as they hold the roof rafters/ridge together at the peak from separating in high winds/uplift pressures. The walls will bow when you get any snow load with a 2x4 wall, 13' long, that is guaranteed. Don't forget the H-clips, or H- 2.5, at every rafter, both sides: H Seismic and Hurricane Ties

Be safe, G

oscar1962@charter.net 08-04-2009 05:22 PM

So if I put the rafter ties every 4' then I should be OK. Is this the same as ceiling joist. Are they nailed to the plate or the rafter or both.

GBR 08-05-2009 10:28 PM

Nailed to the rafters: Single Family Residential Construction Guide - Roof And Ceiling Framing
Be safe, G


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