Blocking for roof brackets
Hello all,
I’m wanting to build a covered entry on a new building with brackets supporting the roof, like the one Gary Katz built for FHB “Building Craftsman Style Brackets”. The article mentions securing the brackets to 4×4 backing, but I have not been able to find any more information on exactly what is required for backing in the wall framing.
The building is in snowy Manitoba, climate zone 7A and has 2×6 walls with 2″ of exterior Rockwool. The roof will be 3 feet deep and 7 feet wide with a 6:12 slope. I would like to avoid thermal bridging as much as possible, so I do not want to overbuild the blocking.
Does anyone know where I could find more information on what is required for supporting the brackets and how to keep it as insulated as possible? Any information would be much appreciated.
I tried posting this once before with a link to the article, but it never made it out of GBA review, so I’m trying again without the link
Thanks,
Chris
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Replies
I would look at securing the backing with one of the system designed to attach deck ledger boards to walls with rigid insulation.
Two options are:
https://deckbracket.com/
https://www.strongtie.com/deckconnectors_decks/bvl_plate/p/bvlz
Depending on where the porch is, if there is interior walls on either side of it, one option is to cantilever a beam from the inside to support the roof. You would then add the corbels as decorative non-structural trim.
Here's the article: https://www.finehomebuilding.com/project-guides/siding-exterior-trim/building-craftsman-style-brackets.
Unless the roof is fully self-supporting, the brackets need to support at least part of the "gravity load"--the weight of the roof--and also the horizontal or lateral load pushing the bottom of the brackets inward as the roof tries to rotate itself off the side of the house. In most cases it's best to have what I think Gary is describing, a vertical framing member running from bottom plate to top plate, large enough to handle both the vertical and lateral loads.
In a pinch, on several occasions I have used blocking between existing studs instead. First I confirm that the framing is in good condition and large enough to handle the load. (If you don't have experience in making that assessment, find someone who can.) I use Simpson's concealed flange joist hangers installed on the stud faces and drop the blocking (solid 2x or LVL) into the hangers.
Chris,
You need to be a bit careful with these. I have had no trouble using brackets to support roof overhangs, but for even small roofs such as you are proposing I've had my building inspector require an engineer's comfort letter.
Thank you all very much. These replies are very helpful! I think this clarifies it enough for me to sketch something to ask the inspector about.