Extension roof

[Suffolk build]

Hi all just resigned up again after a long while off the forum . I have recently been helping my brother out a timber framed extension onto the rear of a bungalow. So here goes ! Bungalow has hipped roof . New ridge board ran through level with existinng. New roof to run through at existing pitch inline with old roof. Engineers drawing shows lay boards on old rear section rafters with diminishing rafters new to old . Old roof timbers are 100 mm and new are 150 we are worried about the height matching with the old . Hope this makes sense any feedback very gratefuly recieved.

 

[bobsuerita]

size of timber wont make any difference just sit new wall
unless new extension is same width in which case sit new wall plate say 50mm lower so you dont end up with too big a birds mouth

 

[^woody^]

If ceiling height (ie plate height) needs to match the main bingalow, then you will need to have deeper notches on the new deeper rafters.

If there is a downstand between rooms and no flush ceiling this wont be noticable, but even 50mm difference can sometimes be perceived within a room.

Otherwise, redesign the roof for smaller rafters.

 

[noseall]

oops