rafter span, spacing, and to-plate joinery

[Oarvander]

I'm adding an enclosed porch to my house. I am questioning the engineering in my rafter spanse and the joinery used at the top plate junction.
I will be framing it with timbers. The rafters are 6"x6" and will span 10' to the beam and then overhang a further 4'. The pitch is really slow at 3/12. I wanted to use 6"x4" for rafters, but have found 6"x6".

So my questions are:

1. can 6x6 span 10' (taking into account the 4' overhang)?

2. would i be able to space the rafters out further than 2' and what would be the max.(although i know this will complicate sheathing)?

3. what are some rafter-to-plate joinery options besides the step-lap for my design?

thanks
cheers

[James Eggert]

Take these questions to whomever engineered your design.
ONCE you get those answers, you need to have your "found" 6x6s graded to determine it's capacity.

Besides the fact of no drawing, few structural questions get answers because of a lack of provided info, as well as not knowing the integrity/knowledge of the framer nor have you even posted where this is being built. A lot of difference between Michigan and South Carolina as to framing requiements.

Try a search for framing info and you'll get a feel of how this works!

[Oarvander]

I didn't have an engineer draw it up.

What do you mean by 6X6 'graded'? A measure of the strength of the wood?

I'm located in Chatham, Ontario, Canada; about 1 houu east of Detroit.

I'm not worried about requirements (by-laws) as of yet. I'm just interested in timber framing logic as well as any general engineering science. I will see if what I have fits requirements next.

[Oarvander]

Thanks Bill. Ya, you may be right about the chimney load issue. I guess, I was thinking that what I wanted to do would be the simple way - killing two birds with one stone - the chimney acting as a timber, but it turns out there may be more issues this way.