Flashing mortar

ollieu1900

Hey, 

How important is the mortar/sealant over lead flashing. Is this what makes it waterproof or is it cosmetic? 

stuart45

Sealant is the best, helps make the joint waterproof.

NSG666

Important as it helps hold it in place but as Stuart has said lots of people now use something like lead mate sealant.

ollieu1900

What does the majority of the waterproofing? Would missing mortar cause a severe leak? Or is it more of a backup to the lead being wedged in place? 

stuart45

The flashing that goes into the wall is known as a cover flashing which goes over things like soakers, or the front apron, back gutter of a chimney etc. It does not stop water getting into the joint where the lead is tucked in. When the mortar drops out the flashing can become loose, but even if it does not the water can still enter at that point.

ollieu1900

stuart45 said:

The flashing that goes into the wall is known as a cover flashing which goes over things like soakers, or the front apron, back gutter of a chimney etc. It does not stop water getting into the joint where the lead is tucked in. When the mortar drops out the flashing can become loose, but even if it does not the water can still enter at that point.

Ahhh ok I understand. Cheers!

Long story short my dad had a leak and the only area that doesn't look particularly watertight is a section of flashing with missing mortar about 2 inches long. 

It's alot of water though ..enough to blow the plasterboard. Seems like alot of water to go through a small gap! No problem with the roof though as have tested it and it only happens on strong winds which would indicate water being forced through a gap? 

NSG666

Is this post linked to these?

Opinions on stormdry/masonry cream — MoneySavingExpert Forum

Cavity wall leak. — MoneySavingExpert Forum

ollieu1900

NSG666 said:

Is this post linked to these?

Opinions on stormdry/masonry cream — MoneySavingExpert Forum

Cavity wall leak. — MoneySavingExpert Forum

Nope not linked to this. They are me yes, sorry for posting twice about the same issue didn't realize I had done, but that and this are not connected. 

Jeepers_Creepers

The quality of the flashing job can vary. I know little about this apart from examples I've seen, and some have been set in quite deep - I'm guessing over an inch? - and also have a upwards fold-over in the lead which makes it thicker, more likely to be held in securely by the mortar, and also acts as an extra barrier to penetrating water. I've seen others going in not much over a half-inch deep, and flat.

I can imagine that, if there's missing mortar, any rain running down that wall and hitting that gap will follow the underside of the brick and end up inside the gap, and very likely behind the lead.

It's certainly the obvious thing to sort first. Also worth prising out any further loose mortar, and using the proper sealant.

stuart45

The main problem with lead flashing is not going in deep enough. Lead chocks were traditionally used to hold them in place, but these are often used now.
Hall Clips (britishlead.co.uk)

travis-powers

stuart45 said:

The main problem with lead flashing is not going in deep enough. Lead chocks were traditionally used to hold them in place, but these are often used now.
Hall Clips (britishlead.co.uk)

Used these yesterday absolutely brilliant!
 It’s always best to use a lead sealant as lead moves and can cause mortar to crack and fall out especially where it laps.
 The trouble today is a lot of lead work is done by roofers and not by leadworkers.