Lead gulley leaks when heavy snow thaws

[quisquose]

Consider trace heating for the outlet area - have a google

I did consider something called Guttermelt when I was googling "ice dams" last year, and it does seem that trace heating is popular in Canada/Scandinavia, but I'm not sure if I could justify the cost if all that would solve it is some tape across the overlay or peeling back the step and putting in some splash laps.

I've just been in the attic now, as the damp patch has reappeared after this mornings snow and this evenings thaw. I'm now pretty convinced that it's capillary action that's the problem, and furthermore think it's happening at the top of the lead rather than in the bottom and jumping up the step.

I'm not too happy about the damp patch on our ceiling, but I'm quite enjoying the puzzle tbh. What do you think my chances if I peel back the step and curl the lower lead over at the back and top?

 

[^woody^]

It's very easy to nit-pick someone else's work from photos, and how it should be done, or how we might have done it, but that is a tidy job by someone who seemed to know what he was doing.

Never the less it is still leaking, but even the best tradespersons can make a mistake, or some specific circumstances can catch anyone out

These gutters are not resistant to standing water or melting snow, and capillary action is a likely cause at that joint.

A bead or two of quality mastic sealant within that lap should be a good enough, very long lasting repair. Otherwise, it's a case of re- making the joint with some 'anti-capillary' measures

 

[quisquose]

It's very easy to nit-pick someone else's work from photos, and how it should be done, or how we might have done it, but that is a tidy job by someone who seemed to know what he was doing.

Never the less it is still leaking, but even the best tradespersons can make a mistake, or some specific circumstances can catch anyone out

These gutters are not resistant to standing water or melting snow, and capillary action is a likely cause at that joint.

A bead or two of quality mastic sealant within that lap should be a good enough, very long lasting repair. Otherwise, it's a case of re- making the joint with some 'anti-capillary' measures

I have to remind myself that I actually watched the guy at work, and fed him cups of tea. He was about 65 years old, and been a plumber all his life. He fetched out the perished lead that was installed in 1933. It came out in just two huge pieces, there was only one step, and the lead was nailed all the way along. Even this managed to last 60 years before it failed on the previous house owners.

I remember him telling me how he was putting in an extra step, making them deeper, overlapping over them, using three sheets of lead, using a neoprene expansion joint, and using fewer nails, with only the top sheet nailed at the valley end. He might not have been up to the standards of some people, but from my casual observation I thought he did a sound job, particularly compared to most roofers in the Yellow Pages.

Anyway, after staring at this for the last hour in the dark with a torch, I think I've actually sussed it.

This is the left side of the gulley.

• quisquose
• 4 Feb 2013
• 1

The overlap here, about a metre from the end is where the water is getting in after snow. I...

Looking at the 1st photo again, and from what I've just observed from watching the thawing snow, I think it's the arrangement of tiles that the problem. It's not the plumber's fault, but the cowboy builders who put the tiles back after the plumber had left. Although I couldn't see it directly, I can sense that the snow sat on the tiles is melting through the gaps between the tiles and landing straight on the top of the lead where the red mark is. I don't think capillary action is even required, the water is just slipping through the two layers of lead from the top.

This should be a easy fix, but open to suggestions.

 

[ladylola]

I've made and fitted snowboards on many gutters like these. They were common years ago but nowadays they normally are omitted probably because of the cost.
Basically they are something like a duckboard made to the size of the gutter bay and are generally constructed out of treated 4x2 and tile lath.
They work by holding snow above the gutter so the gutter is free to work as it should and preventing a build up or ice dam in critical areas.
I have to agree with the advice here too especially the comments about the fixings.
Just re reading your last post about where you think the water is coming in at the top of the lead. Might be a daft question but there are eave tiles fitted aren't there?

 

[quisquose]

I've made and fitted snowboards on many gutters like these. They were common years ago but nowadays they normally are omitted probably because of the cost.
Basically they are something like a duckboard made to the size of the gutter bay and are generally constructed out of treated 4x2 and tile lath.
They work by holding snow above the gutter so the gutter is free to work as it should and preventing a build up or ice dam in critical areas.
I have to agree with the advice here too especially the comments about the fixings.
Just re reading your last post about where you think the water is coming in at the top of the lead. Might be a daft question but there are eave tiles fitted aren't there?

I have thought about snow boards. The house used to have them all around the house, the rusty brackets are still there, but previous owners removed them. I wish they hadn't because the snow slipping off the roof took a length of plastic gutters with it last year.

Anyway, as for eave tiles I doubt it. All the tiles used are the same type of Rosemary tiles. I wouldn't know an eaves tile if it fell on my head tbh.

 

[cotswoldbuilders]

An eaves tile is slightly shorter in length and fitted directly under the first row of tiles.
In effect you should see a double row of tiles.

 

[quisquose]

An eaves tile is slightly shorter in length and fitted directly under the first row of tiles.
In effect you should see a double row of tiles.

There's no eaves tiles then, as you can just make out from the 4th photo posted up.

Could that be the problem?

 

[cotswoldbuilders]

On your last photo looking along the valley, it seems like theres no under eaves.
It would be a good idea to fit them, I wouldn't have thought you have enough lap over the lead, ie the 2nd row might only just be covering the lead upstands.

 

[quisquose]

On your last photo looking along the valley, it seems like theres no under eaves.
It would be a good idea to fit them, I wouldn't have thought you have enough lap over the lead, ie the 2nd row might only just be covering the lead upstands.

This is the conclusion I am coming to. You can see far more in the dark with a powerful torch than you can during the day.

A job for a nice day methinks.

 

[noseall]

I can see an eaves lathe in the image posted above. This then runs out as the lead creeps higher. I imagine looking at the proximity of the lathes above that it weathers adequately.

Think about it. The top edge of the lead is never more than 100mm or 4" away from the nearest lathe above - just like with the roof tile coursing above.

Therefore there will always be the required (2.5"or 60mm) headlap.

 

[^woody^]

I've actually sussed it.

Maybe.

Its hard to tell with out seeing it, but yes if laps aren't full and compete then water can get through

The gist of it is to make sure tiles lap the top of the lead, and top of the joint. If the tiles don't or can't, then use another piece of lead under the last row of tiles or above it and under the second row as a sort of big lead tile

And mastic where need be!

But also check out some images of an eaves tile arrangement to see how it should be

 

[noseall]

I doubt it is a tile lap issue.

 

[palaceray]

If the problem was because of no eaves being fitted or insufficient lap over the lead then there would be a problem whenever it rained especialy if it was windy.

 

[noseall]

From the end of the gulley

• quisquose
• 4 Feb 2013
• 1

Image from 2012 whilst we were having the ridge tiles rebedded

.

In this image there is actually a course of tiles missing on the left! Also the eaves lathe (shown in other photos) has not been used either. This isn't not how the roof was left was it?

 

[noseall]

...Or, they have used the eaves lathe and then missed the course of tiles directly above the eaves lathe.

Either way there is a course of tiles missing in that image.