lead valley detail on warm roof.

Joined
18 Apr 2020
Messages
59
Reaction score
2
Country
United Kingdom
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
 

Attachments

  • IMG_4491.JPG
    IMG_4491.JPG
    65.3 KB · Views: 484
Sponsored Links
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.
 
Sponsored Links
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.
 
Last edited:
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.
 
Last edited:
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....
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top