Advice : Valley gutters, lead and felting

[Neil]

Hi all

The felt on my 3 year old pitched roof has failed in several places adjacent to the leadwork of a valley gutter and the recent heavy rains have allowed water through to the ceilings beneath. The felt that the builder installed looks to me the sort of quality that would be more suited to a rabbit hutch with large areas of it now very brittle. I will have to refelt and I am looking for some advice on the correct construction method to create a watertight seal about the valley. The present felt is lapped over the top of the lead to the valley ( by about 10cm ) and then a mortar fillet between the top of the felt and the underside of the roof tiles. To my untutored eye it appears to be easier to create a lasting seal by carrying the felt underneath the lead ( which will mean stripping the lead and then reinstalling after the felt has been replaced ) as the present system seems to rely entirely on the cement fillet not cracking at the junction with the leadwork. Should the fillet crack water is free to seep under the mortar and then on under the felt. Any roofers care to comment ?

Many thanks

Neil

[Andrew Gabriel]

I had one redone nearly 20 years ago -- it was 90 years old at that time. The lead had cracked over the years with temperature cycling and you could see light though holes in it from the loft.

A neighbour did it for me (he taught building). He fitted a plastic valley instead. I might not have this all remembered right, but I think there's a thick plastic sheet under both the felt and the valley gutter. The gutter then goes on this sitting in it's V timber support. The felt then lays slightly into the gutter. I don't think there's any mortar on mine -- the tiles are all cut to the angle of the gutter and just overhang into it. I can only see it by going up there on a ladder or from a neighbours garden, so it's not easy to look and see.

[Michael Mcneil]

I'm not a roofer but may I ask if you had any rain in the order of an inch or so in an hour or so recently?

Or to put it another way: An inch of rain falling on the part of the roof that drains into the valley and you want to duct under the lead into the masonry would dump how much water into your home in an hour?

Why not just take the lead off and spread the water around a little?

The felt is just a secondary failsafe. Look for damaged and/or missing tiles further up

That is the stuff they have used for decades. It does go brittle. It is reinforced with hemp if that helps.

Explain further please. You are stripping the roof because you are unhappy with the felt?

All pretty standard and good workmanship so far.

The roof is leaking further up by the sound of it. Get up to the ridge and see what you can see and post some pictures but you will save yourself a lot of heartache getting the original roofers to come and repair it. I doubt they will charge much more than it will cost you in the long run.

If you want to diy, I and not a few others will try to help.

Good luck.

[Paper2002AD]

I had the same problem a few years ago - it poured down the interior wall to the living room with disastrous results. The roof had been built with no valley protection at all, other than the felt under the tiles, which we all know gets brittle sooner or later.

The roofer sent by the insurance company fitted a glass fibre valley about a foot wide, laid on felt with the tiles replaced on top. Insurance covered one valley, but we paid the roofer to do the other one. No problems since, but I'm waiting to see how many neighbours eventually have the same problem.