# How to add to existing L shape roof



## rocfrk (Jun 20, 2011)

I have an uncovered concrete patio off the back of my house I would like to cover. The cover I want is a cathedral that I would like to tie in straight back into the existing roof line similar to this (http://jhcustompools.com/images/District_G-20100908-00009.jpg). Problem is that the Roof would have to some how tie into the L shape on the left side. Is this possible. Are there any other options. I have see where the new structure was built higher on the L side and gutters were just added to the two roofs (see pic) but I would like to stay away from this if possible. Thanks for reading!


----------



## nealtw (Jun 20, 2011)

In the valley between the two roofs you build a deflecter. If you can picture a triangle of plywood pointing at the gutter and wider as it goes back over the house. Right where the two roofs meet you install a rafter with a 3/12 or a 4/12 seat cut  and what ever cut on the other end to fit the wall or roof at the other end. On each side of that one every 16" or 24" inches add another at the same level, each one will be short than the last.


----------



## TxBuilder (Jun 23, 2011)

nealtw said:


> In the valley between the two roofs you build a deflecter. If you can picture a triangle of plywood pointing at the gutter and wider as it goes back over the house. Right where the two roofs meet you install a rafter with a 3/12 or a 4/12 seat cut  and what ever cut on the other end to fit the wall or roof at the other end. On each side of that one every 16" or 24" inches add another at the same level, each one will be short than the last.



I agree with Neal. It's hard to explain in words, but hes on point here.


----------



## rocfrk (Jun 24, 2011)

I think I see what you are saying, Kind of like adding a sloping "wedge" or "shim" in between the two peaks cut to a point at the bottom.
I appreciate the help!!!


----------



## TxBuilder (Jun 24, 2011)

rocfrk said:


> I think I see what you are saying, Kind of like adding a sloping "wedge" or "shim" in between the two peaks cut to a point at the bottom.
> I appreciate the help!!!



Exactly like that! Let us know how it works out.


----------



## nealtw (Jun 24, 2011)

It is nice to be understud the first time out. But now theres more. These deverters are not the best looking part of the roof so we try to keep them as low as we can but they do creat a few problems. If one roof is higher or steeper than the other the water can run up and under the shingles on the lower roof, and with the amount of water in this area it will be the first to ware out. I would have a sheetmetal shop make one peice section for this with a raised rib at each valley. Extra big gutter and larger down pipe or evan two down pipes for that area.


----------



## nealtw (Jul 2, 2011)

The normal here for venting a valted or flat roof is to cross stap the roof with 1x4 or 2x4 and allow airflow from soffit to ridge above the insulation, on a flat roof you find outside air where ever you can.


----------

