Valley help! Urgent

[Cabbyfan]

Hi everyone. Me again !

The good news is I have most of a roof now but I'm stuck on the best way to build my 2 valleys . First plan was to use a grp valley but I think this wont work as the valley doesn't go to gutter level.

Can anyone advise ?

My builder says I need to lay 6x1 treated board direct on the felted rafters to support a lead valley which to be fair does sound better but never done lead work. The height of the 1 inch board worries me too in terms of tlies. .. they are Marley Ludlow Majors.

 

[noseall]

This is how you prep a valley....

Roofundercanopy1

• noseall
• 29 Oct 2017

Go for a dry valley and throw that one in the bin.
This is one we refurbished because the wet valley was rubbish....

Dryvalley

• noseall
• 2 Nov 2017
• 1

 

[noseall]

You will be better using a 450mm x 450mm code four lead soaker where the valley nips onto the tiles.

 

[^woody^]

The valley board should be flush with the top of the trusses/rafters, not on top of them.

 

[noseall]

The valley board should be flush with the top of the trusses/rafters, not on top of them.

Correct.

We make ours wide enough so that they support the valley and catch any batten ends that fall short of a rafter.

 

[^woody^]

Correct.

We make ours wide enough so that they support the valley and catch any batten ends that fall short of a rafter.

Yes you posted a good picture in the past iirc

 

[Cabbyfan]

Thanks chaps. Had a lot of Googling and opinion seems to be 6mm marine ply on top of rafters/felt or 12(or15)mm set in between rafters on battens. As my valleys are 2.5m long and dont go all the way down the roof presumably if I use lead I can dress the bottom of the lead over the tiles at the bottom of the valley (which is about 1/3 of the way down my roof...

I am very uneasy with my builder saying 1" x 6" on top of the rafters, just looks wrong to me but I am not a builder !

 

[catlad]

You can use the builder advice for lead.
You will have to knock the odd lug of the tile to make them sit better in the valley.
I would follow Nose advice if I were you.

 

[^woody^]

but I am not a builder

Is your builder?

 

[John D v2.0]

Is your builder?

Not all builders are equal. I could call myself a builder and have a go!

 

[garyo]

I am very uneasy with my builder saying 1" x 6" on top of the rafters,

I would be too. Having just done two, it's already hard enough getting the tiles to sit nicely without the added challenge of having the valley sat 25mm too high.

 

[Doggit]

Go for a dry valley and throw that one in the bin.

Not seen that before Noesall, how do you do a dry valley.

 

[noseall]

Not seen that before Noesall, how do you do a dry valley.

Easy peasy. Same as a regular GRP valley without the crazy mortar or the ugliness.
They will not bend though so you have to use lead over the fascia kick etc. Your tile cuts but up to the central upstand.

 

[wessex101]

New one on me too, looks tidy.

 

[Blagard]

As my valleys are 2.5m long and dont go all the way down the roof presumably if I use lead I can dress the bottom of the lead over the tiles at the bottom of the valley (which is about 1/3 of the way down my roof...

One other point is that if you do use lead don't lay that 2.5m in one piece it expands and contracts a lot so you need the laps to allow that to happen or it will split. See
http://leadsheet.co.uk/home/lsa-pocket-guide/pitched-valleys/