valley beam angle

[chirpychippy]

Hello everyone, may I ask a question about a cut n pitch roof I am about to do. As per usual the drawings are useless from the architect.

The main roof is vaulted internally whereby the supporting collars form the ceiling of the room, this roof is pitched at 37 degrees.

I am putting a timber framed 2.4 mtr by 800mm deep 2 storey bay on the front of the house with a 45 degree pitch gable roof intersecting with main roof. The underside of the ridge on the new gable will line up with the underside of the collars on the main roof.

My question is this, as I am intersecting a 45 degree pitch roof with a 37 degree roof, how do I workout the angles of the valley beams, please.

 

[foxhole]

Wrong section, try roofing?

 

[wrightwoodwork]

Make up the straight part of the cable roof as it is 45 your plum and seat cut will both be 45 then with straight edge and level. Level across to the main roof this mark will represent the top of the ridge line then if you have the main part of the extended bay Window formed sit a straight edge across to the main roof there is is no need to worry about the straight edge being level you are just putting 2 marks on the roof to ping a a chalk line on so ideally you want a mark near the bottom and a mark near the top. This will give you you you're valley line. To form the valley simplest way is with a lay board could be a piece of 6x1 when you fix it to the roof you want it to be approximately 15-18mm in from the chalk line so if you place a straight edge across it will touch the top edge of the lay board. Then from the common rafter nearest to the main roof measure 600mm put a mark on the ridge and put a cross nearest to the last common rafters so are marking 600 centers also do the same at the bottom on to the lay boards you do this simply by holding your tape out and sliding your tape up and down keeping it roughly level. The plum cut and seat cut will still be 45 on the jack rafters The only angle to work out now is the compound angle. The easiest way to do is for the first one is to cut you 45 plum and 45 seat cut then sit it place making sure parallel with you fast common rafters then with a rule or block of wood sat on the main roof bring it up to the jack rafter and mark a line this is your compound angle recut the seat with the compound angle also set a bevel to the the compound angle. Don't worry about going on to a different pitch roof your main worry is getting the valley lines right do that it will just fall into place. If you have a plan I will tell you what order to do things

 

[chirpychippy]

Thank you for your reply Wrightwoodwork and Foxhole, as suggested I am going to move this to the correct section and upload some drawings. Cheers