valley / valley boards

evening all

im ian, 21 and have been a builder/bricklayer for 5 years.
recently left my firm to take on my first poject which is a garage and 2 storey exstension for my mum and dad. the garage is all compleate and i have come stucuk on the roofing of the exstension.

all the ready made trusses are on and the diminishing trusses.
im at the stage where the avleys need to be sorted. i wil be using grp valleys. i n\know the valley bards need to be put in but im unsure of how to do it. i also think there is somthing thta needs to go in that will support the end of my roofing batten.

here are the trusses fixed and how they are now




thanks in advance for any help
ian[/img]

I normally specify some 20mm board to support the valley. This is set flush with the top of the rafters, so you have to nail some support timber (bits of lath) to the sides of the rafters. The tile laths then just go over this onto the GRP valley.

Have a look at this page from the Marley Roofing Design guide - downloadable from the Marley roofing site

thanks woody, have you got a direct link to that marley page so i can have a read?

alsi anychance you could tell me what my next steps shoub going by the pics. eg what i put and where i put it next next
thanks
ian

you should also fix a 4"x1" thrust batten under/against each diminishing truss.

The document should be on the Marley website its called " Concrete tile and slate design guide " mine is a 2002 edition.
But similar details should be on the Redland site too

If you can't find it email me (addy in profile) and I'll send you a pdf copy - but its nearly 4mb

Your next step is to get something like 6x1 or wider board and cut this to fit between the rafters running down the valley - these will be parallelogram shaped. You do this for each side of the valley - ie existing roof rafters and new trusses

Bear in mind that these boards have to be wide enough as you will be fixing the lath to them. Too narrow, and your tile laths will have nothing to fix to

Then you need to fix a piece of lath to the inside of each rafter for this board to sit on so that the boards are flush with the top of the rafters. As per the page in previous post

Then lay the valley felt. Then fix the valley support laths running up the valley. Then fix the GRP trough. Then lap the main roof felt over the trough, and then tile etc.

You may be better off getting a dry fix trough as then you don't have to point the valley . This has an upstand down the centre and gives a nicer line, IMO

thanl alot for the help.
so the valley boards go in between the rafter then rather than on top?
ian

If they go on top they will kick the laths up and you wont get the tiles flat

thnaks woody