I'm planning to add a lean-to to my 35' long shop, extending 12' out. I'm using 4x4 posts set in concrete at 12' spacing, with a 2x6 ledger board, 2x6 rafters, and 2x6 headers on the posts. The purlins will be 2x4 and I'll have a metal roof at a 2/12 pitch. We don't get much snow in northern Alabama, but I'm a little unsure if the 4x4 posts will really hold up at that distance. My father-in-law thinks it should be fine, but I'm feeling hesitant about such a large span for 4x4s.
1 Answer
How tall are your 4x4 post sections? They can warp and twist pretty easily, so you'll want to make sure you’ve got other framing attached to keep everything straight. Also, consider that at 12' spacing, each span will bear some serious weight, especially with wind or rain factored in. A single 2x6 header likely won’t hold up well; I’d suggest using 2x8 headers on both the front and back. Lastly, just so you know, putting those posts directly in concrete might lead to rot over time, even with pressure-treated wood.
They'll be 12' above ground. Thanks for the info! I'm definitely considering upgrading to 6x6 posts to avoid any future issues. I originally planned to concrete them in. What would be a better option to prevent rot?