Add sister rafters in large garage?

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Aug 23, 2023
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Specifics: 95 yr old garage, double brick walls, 27' deep x 42' wide. Load bearing wall slightly more than half way across the 42" and an approx 12"x12" split (2 - 6"x12") support running the width of each half. Rafters are 2x6x16 on one half of garage and 2x8x16 in the other portion (other side of wall). Roof has a slight pitch of about 1' 10" across the 27'.

I love in the northeast where we get a decent amount of snow. On average we often have 3 feet on the ground for a lot of winter. 7 years ago we got hit with a blizzard and received 8+ feet of very heavy snow in a little more than a day. 2 days later it was 65 degrees and it melted quickly. Water was trapped in the snow and a couple of rafter cracked. They were supported pretty quickly and the next day I added sister rafters the full 14' of the rafters in the back of the garage. It went great and no additional issues.

Last winter, we received 7+ feet of snow (in a day and a half) twice. I was able to get the garage roof shoveled off for the first storm but not the second. I noticed no problems, no rafters cracked, etc in the front half rafters that do not have the sister rafters attached.

My question, would it be worthwhile to add sisters to the front half of the garage? Would simply using temporary posts instead of sisters work?

Photo 1 is the portion with the added sisters, #2 and 3 the front end without sisters at the front end of the garage.


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