Few questions about a new roof

[Ian H]

Morning,

We are extending the roof on our semi so it covers an existing flat roof, at the same time we are converting the loft and having a dormer on the back like this:

The plans we had drawn are like this:

Sorry about the reflections.

My questions are:

Would a professional roofer remove the old hip from the rear and leave the front one there or remove both?

Would you remove the purlin on the front and fit a wider one onto brickwork each side rather than joining another on the existing 4x4 timber structural post?

Could you use a bigger rafter and do away with the purlins altogether?

How would the new ridge beam RSJ connect/sit at the party wall/chimney end?

Would anyone local to Rochdale like to quote me for the roof work?

Thanks

 

[freddiemercurystwin]

All questions for your SE really.

 

[Ian H]

Would be if I had one. Could anyone recommend one in Rochdale ish? The guy that did the drawings recommended a mate of his but I'd rather pull my teeth out.

 

[John D v2.0]

There's a limit to how far timber can span without a purlin, you can increase the section sizes up to a limit, but after that the wood itself becomes too heavy to support itself even if you could somehow lift it up there and were happy to buy it.
But a good SE would have some suggestions to solve it other ways. And should provide you with details of all fixings and connections and even methods of installing it (due to cdm safety rules he can't just specify a giant beam that would be dangerous and let you get on with it)

 

[Ian H]

I've spoken to a SE and he is going to do the calculations and the details.

He sent me an initial drawing which had some things on which I would have never thought of so I'm looking forward to his completed work.