Attention all flashers...

[Penners]

... that got your attention, eh? However, I do need some advice about flashing, please.

I've got a chimney problem. The usual thing - damp appearing in the ceiling that abuts the (plastered) chimney breast in an upstairs bedroom. We've had lots of heavy rain recently, so that's obviously exacerbated the problem.

In the photo below you can see the face of the chimney where the leak is - it's the one in shadow, facing the right of the picture, with the ridge running up to it. As you can see, the flashing around the chimney doesn't run above the last ridge tile, but underneath it (I don't know whether it's intact underneath the ridge tile, but I assume so). Between the top of that ridge tile and the face of the chimney there's a small fillet of mortar. (Please scroll down - there's more text below the picture)

Is this the normal method of flashing between a chimney and the ridge of the roof? My instinct says that it would better to have flashing cut into the mortar course above the ridge tile, running across that full face of the chimney, and for this flashing to overlap the top of the ridge tile generously.

Any advice or opinions would be very welcome, please.

 

[Lynn]

like this maybe...

 

[Penners]

Yes, Lynn. That's sort of what I had in mind (although the picture is a little difficult to make out). But I might overlap a bit more over the ridge tile.

What do others think, please?

Is that copper flashing? I don't think it's very common in this country - lead is the norm. I suspect it has a bit less "springback".

 

[Mark]

I agree that it seems wrong but I dont think it should matter - IF the mortar is sound on the ridge tile. The flashing is really to cover the joint of the roof and wall. I know that we have a similar arrangement, and that we had a leak but the roofer found that the ridge tiles were just sitting on - there was no bond on between the mortar and the roof tiles, if you prodded one it moved. Could be the same?

 

[Penners]

I dunno, Mark. The ridge tile bedding mortar looks pretty sound.

Thanks for your thoughts, though.

 

[Nemesis]

I appreciate it's hard to tell from a pic, but are you sure that's not a crack in the bedding mortar - at the right hand side of the final ridge tile?

 

[Penners]

I thought you had eye trouble?! But I think you might be right. Do you think that would be enough to cause a leak? It doesn't look like much.

 

[Nemesis]

I have a new flat screen monitor and my reading glasses on.

It's worth considering... if you look at where it is rain may be oozing in to the crack, then under the lead, then into the join between chimney and roof.


Nice roof!

 

[Penners]

Yes - it's just about the only part of the house that was in a decent condition, when we bought it. It was probably what swayed our decision. You know what they say about a good hat and good boots...

...in this case, one out of two ain't bad.

 

[Lynn]

Seems like a small bit of cricket flashing over the ridge tile

cricket flashing:

 

[Penners]

Looks good, Lynn. I'm surprised that the cricket flashing doesn't pass under the tiles above the chimney. How is water prevented from creeping underneath it?

 

[Penners]

Actually, now I look again, I suspect there may be a second layer of copper underneath the tiles. Is that right?

 

[Lynn]

here's a better angle:

 

[Lime]

I thought this might help.

It is from a free handout called "the Cookson guide to good leadwork" that I picked up in a local builders merchant.

You will notice that the lead is run under the ridge and has a welted edge on it.

(the clips are stainless steel.)

Second image added to show soakers.

 

[middi]

Penners, it is difficult as you know to establish how water is gaining entry by looking at the nice picture, any small crack or mortar separation in conjuction with not enough dept of lead in the brick joint could create the problem. Also the tendency of roofers that use the method of "one piece" lead under the ridge tile is quite rare, they usually cut the led and overlap it under the ridge tile. Judging by the lead on the surface tiles I will bet that no lead soakers also mortared in the bricks have been used . This would guarantee that no run off or wind swept rain from the tiles side could gain entry.

On an old peg tile roof like yours the ideal method would be to individually bed the lead soakers under every tile and about 3/4 of an inch into the shimney stack, this done correctly would eliminate the need of any exposed lead or any mortar above the tiles at all and it looks the part.

A small amount of motar bed at the tiles edging agaist the stack is quite acceptable. - NO LEAD SHOWING-

This exposed lead business is an accepted norm by roofers because it is reasonably quick to install, and, especially on an old building such as yours with those pegs, there is no total guaranty that it will not leak

If you need to get up there to sort the problem out, be a devil, take it all off , a bit more time, and do it properly.

Oh...., Do I love it when other peoples chimneys leak around the exposed flushing , thank God is not mine

 

[Penners]

Many thanks to everyone for their responses.

Lime - those diagrams are very useful, particularly the one showing treatment of a ridge. It seems to confirm my fears about the way my ridge has been done. And it gives a clear view of how it should be done.

Middi - despite your schadenfreude ( :wink: ) thank you very much for your thoughts. I can assure you that I won't be going up there to do the work myself. I'll tackle most things, but at my age I don't do heights! I understand what you're saying about a technique that leaves no lead showing, but actually I don't mind the look of lead flashing; it's quite attractive.