Shallow pitch rear extension

[Sonnypaul]

Morning all, have another extension coming up and the architect has designed a 15 degree pitch ( mono pitch )

197x47 rafters and tops to be bird mouthed (proberly 2 inches )

However I want to birdmouth the bottom end of the rafter but not sure wether to take 1 inch or 2 inches out?

Any ideas on what distance I should aim under the upstairs window sill, how much lead upstand etc

Thank you

 

[freddiemercurystwin]

150mm in an ideal world. For clarity you're being paid to do this right? Don't take it for granted that the tiles the arch has specified will cope with that pitch, check it yourself and get the lap right too or you'll be coming back to fix it.

 

[Sonnypaul]

150mm in an ideal world. For clarity you're being paid to do this right? Don't take it for granted that the tiles the arch has specified will cope with that pitch, check it yourself and get the lap right too or you'll be coming back to fix it.

Hi freddy thanks for replying.

So 150mm down from the sill will be to the top of the rafter? Then Battern and tile and lead on top of this, I'll proberly have to cut the lead right under the sill then. Want to have about a 3 inch upstand of lead.

If I fixed my pole plate at 150mm Down from the sill do you know a quick way to scribe my rafter with a 2 inch birdmouth.

Cheers freddy