rafter positions

[hog]

Hi all

I'll be framing my new extension roof this weekend. I have a couple of questions regarding the rafter positions, which the plans do confirm but I would appreciate a 2nd opinion as to whether best practice is being used.

I have the two gable ends already built and a 9x3 ridge beam, as spec'd. The rafters will be birdsmouthed over the ridge beam, and purlins added, again as spec'd. My questions are:

1. The plans show the front rafters laid directly facing/opposite the rear rafters (not correct terminology I expect, but hopefully gives you the picture). Should I rule any thoughts of having the rafters offset and to sit aside/overlap each other at the ridge? (As I mentioned the rafters will sit on top of the ridge beam). I understand that, for a wall plate there would be no choice in this, they are laid opposite. In my view, having the rafters opposite would be ideal as it allows each rafter to be skew nailed from both sides into the beam.

2. The plans also show a gap between the end rafters and the gables. Whether this is intended or not, is there any reason to having this? I saw on a previous thread it showed a preference for having this gap because it allows (for a flat ceiling) the ceiling joist to run flush with the wall and was preferred for supporting the ceiling plasterboards. With our vaulted ceiling the plasterboards will be screwed to the rafters so would this end gap be a hindrance? I would presume, with no gap, the rafter would be screwed to the gable as it couldn't be skew nailed from the gable side? Hope this makes sense.

Thanks in advance.
Hog

 

[tony1851]

1.You can do the rafters either way as you are using a ridge beam rather than ridge board.

2.By a gap, how much do you mean? Ideally, the end rafter should be as near as poss. to the gable wall, to make fixing the insulation and plasterboard easier.
Don't forget the lateral restraint straps, which should be noted on your drawing.

 

[hog]

cheers tony1851, much appreciated
for info I went with rafters facing opposite - this passed inspection OK

yet to nail the end rafters home but plan is to butt these right up to the gable blockwork and single-nail from other side, therefore no need for fiddly cuts of insulation like you say

noted your point on restraint straps, these are indeed on plans thanks