Roof slope

[bowtiebubba]

Im a newby here and love this site. I need a little advice. I have a 30 x 40 pole barn which i want to build onto one side. I want this addition to have a leanto type roof on it. I have 2 questions.
1.What is the minimum slope i will have to have on this roof?
2.How do i tie the new roof with the old roof?

Thanks guys, any help would be appreciated.

 

[NHCharger]

Welcome to the site.
Need a few more details. How much snow do you get? How high off the ground is the edge of the existing roof? How wide will the leanto be? What type of roof is on the pole barn?

 

[bowtiebubba]

I live in N.E.Missouri, the last few years not very much snow at all,around here you just never know. The existing roof is 11ft.10in. off the ground. The existing roof is metal. As far as width of the addition, i wont to go as wide as i can, but i guess that would depend on the slope i need. Thanks

 

[mleichtle]

You can make the roof pitch what ever you want, but the structure under it needs to support it. Say you went with a 1/12 pitch you could go out 36' and the eave would still be over 8' of the ground (if the ground is flat), but it wouldn't be a clear span unless it was steel. your existing wall needs to support half of that span too, so that might need to be beefed up.

To tie it in, the easiest would be to tie it into the existing wall below the roof with flashing. I would think it be difficult to tie it into the roof cause of the pitch change (I'm assuming).

 

[NHCharger]

I agree with mleichtle. Would be a PITA to try and tie into the existing roof, especially with different slopes. You should drop down about 12" below the edge of the existing eaves. As far a slope on the new roof you should take into consideration that the existing roof will be dumping snow onto your new lower roof. Your going to want enough of a pitch to have that snow slide off, not sit there and overload the roof.
I would think a minimum 4/12 pitch would be needed. I guess it depends on how wide you want to make your leanto. Call the company that supplies metal roofs. They could probably give you some input on this.

 

[bowtiebubba]

I would like to make this leanto 20 feet wide. A question on the concrete floor. I know that if you put the building up first the poles are put in post holes. What if i pour the floor first do the poles set on top of the concrete? If so how do they attach?
Thanks again guys.