Can I nail the lead flashing under UPVC windows?

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Hi,
My lead flashing will go directly underneath my window on my new extension roof.
Underneath the window I have constructed a wooden box section as it was previously tiled.
Is it OK to fold the lead under the UPVC window sill about 20mm and then fix it using galvanised nails to the wood section below? - I'm assuming under the sill it wont get wet? Or is there a better way to secure it (silicone/lead mate) ?

Thanks!

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Mine is. Nailed exactly into the wood frame where you marked yours.

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Thanks Notch. Can you let me know how that would work?
I have managed to slide some 300mm dpc right under the sill and will have that under the lead flashing going onto the roof underlay.

Cavity tray?
 
It's wrong .. possibly does not come into it.

It should have cavity trays too..

Nailing through the exposed upstand ..geez
 
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The only other way is to remove the window, fix the lead and refit the window?

The nails will be right up under the plastic window sill so unlikely to get any water on them unless it's splashback?

How does lead get fitted under sills normally as I don't really want to bang a roll of lead in to keep it there as it might shift the window...

It's wrong .. possibly does not come into it.

It should have to trays too..

Nailing through the exposed upstand ..geez
 
The lead should go through under the cill turned up on the inside..a tray.
There should be cavity trays along the full length of the roof.
B c should pull you on it , rightly so
 
The lead should go through under the cill turned up on the inside..a tray.
There should be cavity trays along the full length of the roof.
B c should pull you on it , rightly so
A cavity tray will serve zero purpose beneath that window.
 
What would be the best way without removing the window to fit a tray? I will keep this in mind as no doubt the windows will all be replaced in 5 years or so.

I have pushed some DPC under the window sill and this will direct any water onto the roof felt that gets passed the lead (not at edges of the window though)

Would using leadmate stick the lead to the bottom of the UPVC sill? I could also use lead straps to hold the bottom of the lead from slipping down the roof if nailing it is a bad idea...
 
Thanks Notch. Can you let me know how that would work?
I have managed to slide some 300mm dpc right under the sill and will have that under the lead flashing going onto the roof underlay.

A cavity tray can't be used below the window, but there should be one across the roof....building control sometimes insist, especially if when there is a big opening and a steel.


The window kind of is the cavity tray - where a cavity tray reaches a window opening, the construction detail is that tray should continue across the opening - if necessary by use of a lead tray that returns up the sides and meets the cavity trays.


It's up to you....many jobs will be fine. I've done jobs where the upstairs window has leaked into the cavity causing damp on the plaster below.

If it's mostly wall in the extension below, you could batten and use foil backed plasterboard - that keeps plaster away from potentially damp bricks.
 

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