flat roof advice

[george765]

Hi,
Not built a flat roof before, so help from experienced builders would be much appreciated.
Drawings attached show the blockwork I have ready for a flat roof to be fitted.
a structural engineer has looked and said no steel is needed and just to 'double-up' the joist going across the opening.
I plan to clad the roof with celotex EL3000 130mm then fit a rubber membrane covering.
The roof will also need an opening 1500x1000 for a velux flat roof skylight.
.
some questions...

Do the joists going from/to the left and right walls need to rest on both leafs of the concrete block cavity wall ?
Do I need a timber wall plate on top of both walls ?
what size timber should I use for the wall plates ?
what size timber should I use for the joists ?(I was thinking 170x50)
should I use straps to hold wall plate to wall then screw joist to wall plates or use straps from the joists to the walls ?(I've seen these in builders merchant). These would also then secure the wall plates to the top of the walls.
How should I finish the opening at the top ready for upvc windows/doors ?
How should I fix the double timber at the front above the opening ?
should thes two timbers be bolted together ?
any sketches would be really helpful.
.
thanks in advance for your help
George

Untitled

• george765
• 16 Jun 2012
• 1

Untitled

• george765
• 16 Jun 2012
• 1

 

[catlad]

Well George I hope you are having better weather than us if you are working outside. I can't see anything amiss with your plan, but I think you should strap your wall plate down on the internal wall before putting on the joists. Finish the joists were you like but you will need something to attach fascia boards to, most flat roofs joists are flush with external brick work then fascia.
I think bolting your timber together in this instance a bit over kill I would just get some large screws. largest flat roof skylight velux do is 1200x1200.

 

[george765]

thanks catlad, thats helpful
george

 

[noseall]

100,000 replies!!!!!!!!

 

[george765]

too many questions ?
questions not clear ?
wasnt a great responce was it noseall
anyways... if you noseall, why diidn't you chip in ?

 

[noseall]

too many questions ?
questions not clear ?
wasnt a great responce was it noseall
anyways... if you noseall, why diidn't you chip in ?

Sorry George, i was referring to the post count in the building forum and i happened to post the 100,000th reply!

I just chose your thread as the sacrificial lamb.