Question for an experienced roofer, re: rafter ties
Hi there. My house is a 1700 sqft ranch with an attached garage circa 1964. It's basically a T shape. House front to back and garage off to the left with a fireplace room in the middle
My roof I believe is a 4/12 with 3' eaves. actually here's a pic from google... http://photos2.zillow.com/p_d/IS5gftsrkyiftv.jpg
My question is this...
The rear half of the roof has the ceiling joists and rafters parallel. The front half of the roof, the rafters are perpendicular to the ceiling joists.
The collar ties are there as they should be on the upper third every 4' ( maybe every other?, just didn't actually count but I know it's not every one) but on the front half of the roof shouldn't I have rafter ties spanning the width of the house to help against any outward wall pressure?
If I were to put rafter ties in, being a span of approximately 28' how much overlap would I need on the boards? I think I read somewhere one every 3 rafters on 16" oc spacing, vertically 2x4 or larger
Would love to hear from someone with real experience in this area
For reference this is basically how my roof is setup. Minus the purlins, wind brace, and props. We'll there is a prop, but in would assume it was put in later by a previous home owner.