Building Homes or Extensions/extending roof


i have a ranch home.  I want to add on add 10' to back of garage.  i want to follow the roof line (4/12 pitch)  can i set on top of old wall and sister to existing rafters (2x8)?



James, that would be normal and proper.  The stud wall should be more than adequate for the load.  If you continue with the 4in12 and go out 10, your outer wall will be 40" (3'4") lower.  If you have composition shingles, they need usually a 3in12 minimum which is still 30".  Many patio roof type roof extensions get much closer to flat which will require hot tar, modified bitumen, or TPO type roofing.  If you do go that route, take extra caution where the low slope meets the existing, because maintaining that joint waterproof is difficult.

If I've not understood your intent, please feel free to send me another question.


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Dan Griffin


I can answer almost all questions related to the total construction process. My expertise is in commercial construction, though I can field most any residential question. I have hands on experience in concrete, heavy equipment, masonry, all phases of carpentry, interior finishes, and I am fairly strong in mechanical and electrical.


I have over 20 years experience as a commercial carpenter and commercial construction superintendent. I have another 20 years experience in facility management for a major school district.

My favorite hobby for he past 12 years has been singing bass in a The OkChorale men's barbershop chorus and the Mature Moments quartet.

I hold a Bachelor's degree in English and Math. I have completed many continuing education hours in the building trades. I hold a Master Carpenter card from the AGC, Associated General Contractors.

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