replacing lead valley on pitched roof what grade of lead?

15 Mar 2009
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United Kingdom
Hi I know nothing about roofing and need some advice!
I have a pitched (London) roof with a lead valley down the middle. A few differnt roofers have given me quotes saying that there are cracks as whoeever originally put the valley in used poor quality/ thickness of lead and so the lead has shrunk back and now there are cracks. I have one small leak that comes through upstairs bedroom during heavy rain.

I have had a few quotes and all of them are differnt in price ranging from 2 grand to 5 grand! I have no idea who to go with as nobody can recommend anyone to me.

Apparently there is a certain grade of lead that should be used (grade 4 or 5 or something?)

What grade should be used and how do I know that the person doing the job actually uses that grade?

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Hi. The code (thickness)of sheet lead used, is dependent on the length and breath of the valley being lined. From what you describe the failure is due to over sizing bays (term to describe each individual panel that makes up the valley) If the bay is to big for the code of lead fitted failure will occur due to metal fatigue caused by expansion and contraction. To overcome this the decking to the valley is stepped, these steps are set out in relation to the code of sheet lead to be used. EG. Code 5 step at approx 1.8 m but code 8 at 2.8 m.
The max width is also addressed and it may be required to fit wood core roll (expansion joint) as the valley increases in width as it rises away from outlet.
Because the failure process can take years to show, it is most important to get it right at the design stage. Either research it your self via the Lead Sheet Association tech details or contract a sheet lead worker who can design and fit for you. If carried out correctly it will last several lifetimes. Good Luck

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