Building Homes or Extensions/framing


Hi Dan:  I'm building a porch roof.  It's gabled but blends into a flat roof at the front of the house.  I built a 80" long by 48" wide box above the door and am framing the gabled roof on top of that.  I didn't have any problem with the rafters above the box but I can't seen to figure out the formula for making the cuts in the rafters that blend into the flat roof. Any suggestions?  Thank you for your help.

Terry, I don't quite understand the dilemma.  When all else fails, take a 2x4 and butcher whatever you need to butcher to get it to fit somewhere close to what you are doing.  Lay another scrap on the roof and mark your sacrificial board.  If the problem is at the ridge, same exercise.  Use a speed square to check the angle or pitch of the line you've drawn to get what you need for the rest of them.

I suspect you will find that if the ridge cut is 4in12, the bottom cut will be at or close to 12in4.  Hope this helps.

Building Homes or Extensions

All Answers

Answers by Expert:

Ask Experts


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.

©2017 All rights reserved.