If I tie into a 6/12 pitch roof with 2×6's. Will I be able to span a concrete slab of 11' 6"? I will be setting 4×4 post every 6' with 2 2×6's with 1/2" osb sandwiched between them as the form to set on top of post. My plan is to add 2×6 supports on to the top plates of the existing house wall where the 2×6's intersect with the walls.
Wood – use 2“x6” as roof rafters for porch addition over concrete patio
additionroofroofingwood
Related Solutions
As @TheEvilGreebo mentions, 2x6 is not enough for a floor that will be used as "habitable space". I know because when I remodeled my attic to convert it to a bedroom, the existing 2x6 floor joists (over a very similar span) were not enough and I had to sister them all.
At a minimum you will need to check with your local (municipal or county) building department. They should be able to tell you what you need.
It might be easier to get a structural engineer or architect to come out and tell you what to do. If they are not drawing up plans you might be surprised that their prices are quite reasonable (they should be able to give you a quote for what it would cost for them to come out and generate a report up front). It will also help when you get your building permit to be able to submit the report written by a certified professional to the building department.
I would say that it depends on the drip-edge and how the fascia are laid out on the edge. Galvanized drip-edge should easily span a 5/8" gap, and will certainly be less waste than flushing up the sheathing and cutting off 15" for starter courses. It mainly depends on having the drip-edge supported on both sides and having adequate room for nailing it down.
This will work:
This won't:
Related Topic
- Span of roof rafters, how to fix improper structure
- Wood – Rafter tie sizing
- Wood – Pergola 13×15 floor space what is 2×6 WRC maximum span
- Convert timber roof rafters to trusses
- Can a curved shed roof design use corrugated metal roof panels lengthwise horizontally
- Strange Roof Framing – Are these ridge supports temporary
Best Answer
It looks like the answer is "probably not." If this calculator from the American Wood Council is to be believed (and if my assumptions about your materials and load are correct), the max span is about 10ft for a pine 2x6.
This table agrees that 10-12ft is the max span for typical grade lumber, at typical spacings, for a 5psf dead load.
While your particular circumstances might come up with slightly different numbers, I'm going to bet that you're in the vicinity of the max span for that material. How closely you want to shave that risk is up to you.