chimney flashing? is it needed?

[jungle_jim01]

Last summer we had our roof replaced, with breathable membrane and slates. The roofer didn't put any flashing in. I remember the time he mentioned that the membrane tucks underneath the coping stones so no edge flashing was required...sounds ok and works fine....apart from working on the attic i've discovered a leak. It's coming in along the bottom of the chimney stack where his cement fillet has opened slightly. I'm getting back in touch with him but does it need a flashing? Traditionally what method would have been employed? When we moved in the roof was very old and didn't have any flashing.

Thanks

 

[Lime]

Of course you need flashing.
The membrane is not supposed to take any run off except in emergency or extreme conditions.
There is a guide on leadwork available. (Free to read online)
I suggest you read it and familiarise yourself with the various terms and methods used together with other details such as lead thickness etc.

http://www.docstoc.com/docs/7248211/THE-GUIDE-TO-GOOD-LEADWORK

When we moved in the roof was very old and didn't have any flashing.

Nothing new about shoddy work, it has always been done if the roofers thought they could get away with it.
(after all, how would you know if you had not been up in the loft?)

 

[Flyfisher]

I have a little experience of cement mortar as flashing . . . . . it's hopeless!

The photos below show the result of a chimney with only cement flashing. Basically, the cement mortar cracks and the water gets in. Leave it long enough and this is the result.

After repairing the roof, I wasn't going to allow the lack of proper flashing to compromise the job. I'm sure a mortar flashing would last for a few years but I'm rather hoping to live longer than that and I have no desire to revisit the roof in my lifetime, hence the lead flashing in the second photo.

Incidentally, don't be tempted to plug the leak from within the roof. This had been done on our roof and only served to trap the water from below causing it, presumably, to pool around the wooden structure of the roof and cause the damage shown.

 

[jungle_jim01]

Thanks for the replies. That looks like the way forward. I've emailed the roofer in the hope we can work something out. Meanwhile i'm using lime mortar to plug the crack in the hope it will provide a better a seal...just need to hope the weather doesn't go too cold in the next week!

 

[Lime]

Looking at the picture of the chimney reminds me.
Under that lead should be lead "soakers" (see online guide) that interleave with each tile.
Soakers are often not installed because they cannot be seen without removing the lead you see in the picture.
i.e. the roofer gets away with using less lead!
Soakers are very important.
Make sure your roofer knows that you know about them and tell him not to forget to install them!

 

[middi]

Looking at the picture of the chimney reminds me.
Under that lead should be lead "soakers" (see online guide) that interleave with each tile.
Soakers are often not installed because they cannot be seen without removing the lead you see in the picture.
i.e. the roofer gets away with using less lead!
Soakers are very important.
Make sure your roofer knows that you know about them and tell him not to forget to install them!

"Soakers" are absolutely necessary with "welsh" or "peg" tiles where the lead can actually be hidden away from view altoghether.
With " pan tiles" it is not absolutely necessary as there is no break in the lead where it is " chased " over the ridge of the tiles.
As to the original post:- yes you need lead protection and on no account should one rely on the breatheable felt.

Middi

 

[Feltwell]

Cement mortar flashing is hopeless. If the roofer thought this was acceptable I'd be very careful about the standard of any remedial work he does for you now.

Sometimes the soakers are (just) visible - with plain tiles they can sit under the tiles and lap up the wall, with a piece of shaped lead coming down the wall and largely covering them but not extending over the top of the tiles. The membrane can also be lapped up the wall under the lead, for an extra layer of protection.

 

[middi]

cement mortar can be used to good effect above carefully undelaid soakers which have been chased just above tile level into masonary.

it has a good aesthetic appearance (but no real weatherproof quality).

The lead would be totally invisible.

 

[Penners]

I've lived in several houses that had mortar flashing around the chimney. Every one of them either had leaks when I bought the place, or developed leaks later.

Get the builder to do the job properly.

 

[robgil]

I think a flashing chimney is a great idea. Especially round here with all these low flying war birds from the surrounding air force bases . And at Christmas as well, you would be the envy of the entire street.

 

[middi]

I think a flashing chimney is a great idea. Especially round here with all these low flying war birds from the surrounding air force bases . And at Christmas as well, you would be the envy of the entire street.

Especially if it supports one of those extra large pots. :wink:

Middi

 

[FamilyWiggs]

I think a flashing chimney is a great idea. Especially round here with all these low flying war birds from the surrounding air force bases . And at Christmas as well, you would be the envy of the entire street.

Rob, are you trying to displace Penners from his perch? Havent you got any work to do??!! :wink:

 

[Penners]

Seconded.

I'm the self-appointed weak-joke-merchant around here, and don't you forget it.

 

[jungle_jim01]

Thanks for all the replies....you might be onto something with flashing chimneys!
Just wondering if anyone's had experience doing their own flashing?...i suspect this is a job for the pros?

Cheers

 

[Penners]

i suspect this is a job for the pros?

Definitely. Unless you have experience of lead work, flashing a chimney should be left to an expert, in my opinion. Cut your teeth on something a bit less complex.

The results of getting the job wrong could be hugely more expensive than the cost of having it done professionally.

 

[robgil]

Seconded.

I'm the self-appointed weak-joke-merchant around here, and don't you forget it.

Well i shall be the weak end joke merchant then.

No you dont have to be a Pro to go flashing but i would try not to work the same street as them , you might scare away their clients and you dont want half a dozen angry Pro's chasing you down the street mid flash.

 

[chuckey]

My house had it's clay tiles replaced with concrete interlocking tiles about 40 years ago. Instead of flashing the roofers used little bits of concrete tiles and a 2:1 cement mix to form fillets at the base of the chimney stacks. All of them have cracked and let in water. The first one that failed I repaired using "Flashbanding" using the primer and so far its lasted over ten years. Next door a roofer sort of did some lead work by letting the lead into the side of the stack and folding it over the surface of the slates, looks awful and it relies on the cast in grooves in the top of the tiles to stop the water running underneath the lead!!
Noticed the same problem on the front stack last October, Phoned a roofer still has not arrived. When the weather improves, I'll get on with it :-(
Frank

 

[MatthewC]

Thanks for all the replies....you might be onto something with flashing chimneys!
Just wondering if anyone's had experience doing their own flashing?...i suspect this is a job for the pros?

Cheers

You don't say where you are, Jim, but if you're anywhere near Oxfordshire I can recommend a roofer who did some excellent lead work on my new roof recently. See my blog, but it was difficult to take good photos of flashing. [Stop thinking innuendo, Penners!]

Matthew
http://houseintheenchantedforest.blogspot.com/

 

[jungle_jim01]

Matthew, i've been following your blog with interest...an amazing project! Thanks for the contact offer but i'm up tut north in Yorkshire (whitby) so a bit of range of the roofers in your neck of the woods.

Nobody's mentioned a lime mix instead of cement...would this provide a better seal as any cracks would close up again? not ideal i know but just pondering.

 

[middi]

Nobody's mentioned a lime mix instead of cement...would this provide a better seal as any cracks would close up again? not ideal i know but just pondering.

NO it wouldn't

Middi