Tying a gable roof into an existing roof is a long expensive project usually undertaken only when there is a major addition or renovation to a house.
Extending existing gable roof.
For pitched roofs outriggers can be supported on the top of the gable wall end framing and extend back to the next truss or to a rafter.
In the past i ve built ladders out of the same size rafter material and lagged screwed them into the gable rafter and then cut the sheathing back and re lay it after the extensions were added.
In any case the structure that the shed roof is leaning on is an existing roof typically a gable roof with a ridge and a steeper slope than that of the shed roof.
Then load bearing roof beams fixed to the trusses are extended in the same way.
You will need building help and a large construction dumpster for debris.
This may require removal of a second rafter.
That s a simple low cost solution that can tie in well with the main house.
Attaching near the eaves.
Where the overhang created is more than 450 mm and the roof is constructed with rafters the outrigger may need to extend back at least 900 mm.
Add gable extension on existing roof we are re siding and re roofing so i thought now would be a good time to add them.
You may need a structural engineer to help with design of trusses and rafters.
With the roof pitch the same it doesn t matter if the new addition is slightly off in height or lined up front to back because you re going over or under the old roof.
But it is important that the roof pitch is exactly the same as the existing roof because you will see it from one roof to the other if it isn t.
However for larger extensions you ll need to hire a professional to get up there and remove large portions of the roof before extending the overhang.
Extending a gable roof can be tricky since it involves working on the roof but you may be able to do it yourself if you only need to add 1 2 2 inches 1 3 5 1 cm.
How to extend gable end roof overhang.