lead valley detail on warm roof.

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Can anyone recommend how to build up a lead valley on a warm roof? The roof is to be slated with 20" x 10" spanish slate. Tile battens are to be 25 x 50mm

Photo of my roof attached. (eaves trays were momentarily off when the photo was taken.)

options seem to be:

Fit the valley boards flush with the top of the counter battens (reducing the flow of any water on the membrane) then build a proper valley with tilting fillet and welt. Leave the membrane passing beneath.

Or carefully rip up the valleys and detach the membrane from the insulation and end this in the valley... (seems like a lot of remedial work!)

Or put the valley boards on top of the counter battens. like in the photo. The issue here is getting the valley boards strong enough yet thin enough to allow the fillets and lead welt within the 25mm thickness.. I'm not sure it's possible.

or some sort of hybrid solution featuring battens for strength between the counter battens then maybe a ply to flatten it?

Any help greatly appreciated.

Dan
 

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Carry on as is . you are looking for a problem that wont be there if your slater is competent. Is that a super foil BB I see there?
 
Valley boards need to be flush with the tops of the CB's, otherwise the valley will sit too high.
 
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Carry on as is . you are looking for a problem that wont be there if your slater is competent. Is that a super foil BB I see there?

Superfoil sf40bb.

no my roofer was incapable of installing the superfoil, so he has gone. I am just cracking on for now. I am a capable diy'er.
 
plan is to use code 4 lead. but with the 20mm boards i have currently. it leaves no room (height) for a fillet or welt to contain the water in the valley. (i am not a roofer) I am wondering whether running a wider valley width will contain the water flow without much welt or fillet.
 
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As I say , you are over thinking it.
Run a batten alongside the valley board . Cut slate battens tight to it .
Then slate it in .
 
Superfoil sf40bb.

no my roofer was incapable of installing the superfoil, so he has gone. I am just cracking on for now. I am a capable diy'er.
Good product . It's not rocket science to fit. What did you do when you went down past the plate?
 
plate?

The picture shows the eaves trays off. the original roof had some sort of sprocket kick at the bottom. originally i reinstated this kick, only to realise the tiles should be as flat as possible so Just adjusting the tilting fillet height then the eaves trays will be back on.
 
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Wall plate, what did you do with the insulation where the super foil passes over the roof plate onto the soffit area?
 
Wall plate, what did you do with the insulation where the super foil passes over the roof plate onto the soffit area?
It ends. And a breather membrane only (the black stuff) picks up the water, onto the sarking board then over the eaves trays....
 

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