Leaking slate roof with lead valley

14 Oct 2012
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United Kingdom
Hi everyone,

I've just signed up for advice on a leaking roof.

First the house/roof: 3 storey, 1850s terrace house in Clapham, London. House is 5.5m wide, 9m deep. Roof is a slate roof, not steep at all (loft is around 1m high) with a valley in the middle, draining at the rear of the house. The valley is lead, in 5 sections, with 5cm steps. Valley is about 4 feet wide at the front of the house, 1 foot wide at the rear. Valley barely slopes. The last two sections have pools of water as the roof has sagged over the years. These sections have had the joints Acropol-ed some years ago, with evidence of old leaks.

The valley leaked in the last (rear) section. Roofers came round, charged 2000 pounds and put in new lead, elevating the higher end to stop the pooling. This reduced the leak in the last section, but now water leaks from the wooden boards supporting the lead in the 2nd last section. The roofers came back, charged another 1000 pounds to reset slates around a Velux window, but still without fixing the leak. They then came back again with a quote for 16000 to redo the whole roof, generously discounted by the 3000 we'd already paid them to 13000.

This is where I need some advice:
- for the amount originally paid (3000), should I expect the leak to be completely fixed? The original work was the roofer coming round to inspect the leak, saying X needs to be done and this is how much it will cost. From my perspective, I paid for the leak to be fixed, which it isn't.
- assuming the roof needs to be replaced (which I doubt), what would be a fair price range for redoing the valley in lead, membrane, battens, slates, etc?
- is lead the best material for this? The roof valley is completely invisible from below. How about a single piece of EPDM instead of all the lead work?
- suppose we redid just the valley, in say EPDM instead of lead. Is this feasible without touching the existing slates?

Thanks in advance for your advice! Any roofers serving the Clapham area wanting to take a look and quote for fixing it are also most welcome.

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If you have already paid them £3000, and they still have still not sorted the problem, get someone else would be my advice.
The price seems very steep considering that there is not a lot of slating and the only large outlay is for the Lead gutter.

I do not think it would be practical to do the gutter in EPDM

If you would like me to have a look for you and give you a quote or some advice send me a message with your phone number and i will give you a call.

Ray Fordham,
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Is there historicaly , a lot of leaves on the roof , requiring removal each autumn ? I see some debris in the photos . It has been known for a lot of fine debris to get under those splash laps in the lead bays and water can draw up them by capillary action , particularly if there isn`t an anti. cap. groove dressed into the lead :idea: The devil is in the detail . Apart from that it looks like a good one . NigeForest ;)
Looks like it's not the original roof. Cement fibre slates, concrete ridge... Very common in London.Leakage is unlikely to be via slates. Lead bays require close inspection... but not by your previous guy.
Some of lead looks ok.. but dont like the sound of acrypoled!!

We just carried out some corrective slate/lead work at your local church tower over looking the common.

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