Trying to Add a Carport on a Social Security Budget

Reader BRIAN in WHITE CLOUD writes: “I am planning (hopefully as funds exists) a free standing 24 x 24 x 8 sidewall carport that will butt up to the front of our existing garage. I am planning to use 6×6 treated posts sunk to 48″ deep on a pad. I will also place (2) 1/2″ x 12″ long re-rod through the bottom of each post and add 2 or 3 bags of redi-mix around the bottom of each post. Spacing at 8′ on center with an engineered 24′ 4/12 truss notched into each post with a double 2×10 header notched into each post around the periphery of the building. 2×4 purlins on edge with steel roof. My question is 1. Does this sound structurally sound in Michigan or am I missing anything? 2) Should I add a post in center of truss span at each end? 3) Since we only live on SS I wish to try to keep costs down and wonder if I could downsize the posts to 4×4’s? Thanks!”

For sake of discussion I will assume “front” to be a gabled endwall. If so, and your existing garage is structurally sound, you can probably just add a ledger board securely attached, rather than needing another truss.

Provided this can be done, I would place four UC-4B treated posts at 12′ and 24′ from existing building (two on each sidewall) and entirely backfill holes with concrete (this is a roof only building, lack of concrete encasement will likely result in racking of building). No, these cannot be 4×4. Use a single truss on front endwall and a pair of trusses at 12′. 2x purlins, on edge, joist hung between trusses (or to ledger).

We could engineer and provide this building for you, utilizing site built trusses, to further reduce your investment, as well as it would be fully engineered. You won’t need to have headers (aka truss carriers) or a column at center of each endwall.