Mortar fillet to sandstone wall

[Fubble]

Hi all, I have a mortar fillet over some leadwork slotted into a sandstone wall but it has come away from the wall after a few years, probably caused by rain.

Any advice on replacing the mortar fillet would be very helpful. How long should a fillet last? Thanks.

 

[George_engineer]

You would be better off redoing the leadwork - presuming the fillet was done because the lead was failing.

A mortar fillet isn't a good way to do a watertight abutment and it won't stick for very long if it's sat on lead.

 

[Fubble]

Thanks for your comment. I probably didn't explain well enough. The leadwork forms part of a box gutter and the upper edge of it is slotted into the sandstone wall and then covered by a mortar fillet. I think the lead is good and slotted well enough into the wall but it's the mortar fillet above it sealing it to the wall which has come adrift after not very long.

 

[jj4091]

The lead should be secured with lead wedges so you only need to keep the water out, which you can do with a good quality mastic, if is as it sounds ie the slot that the lead goes into. The mastic will allow the lead to expand and contract where cement will not without cracking itself. Photos might be helpful.

 

[Fubble]

Thanks for that idea using a flexible mastic. It makes good sense. Anyone else care to comment?

 

[ree]

OP,
If, as it seems, you have sheet lead turned into a brickwork bed & pointed with S&C mortar then its wrong.
Its best to point the lead turn with any of the Leadmate etc sealants available.

 

[Charlie George]

OP,
If, as it seems, you have sheet lead turned into a brickwork bed & pointed with S&C mortar then its wrong.
Its best to point the lead turn with any of the Leadmate etc sealants available.

Since when? who says it wrong? nothing wrong with mortar if done correctly, just noticed your from the US you may not know about UK practices

 

[Charlie George]

Poster #7,
I did, I said its wrong in Post #6.
Post #6 is not a geographical location.
The OP said: "it has come away" - ie its failed.
The typical cause of failure is expansion & contraction of the lead. So lead sealants such as Leadmate that can accommodate movement are better to use.

Poster 8
I will nip up on my roof to remove my 40 year+ old sand and cement pointing,
the typical cause of failure could also be the person doing the work, nothing wrong with using Leadmate, but to suggest mortar is not suitable is plainly wrong as it's still widely used and approved by BC and the like.

 

[Fubble]

I was the OP. The mortar fillet which failed was done in the traditional UK manner by an experienced tradesman but came adrift after only 3 years or so. The question in my mind is whether best practice nowadays would be to use a flexible mastic and protect that with a mortar fillet.

 

[Charlie George]

I was the OP. The mortar fillet which failed was done in the traditional UK manner by an experienced tradesman but came adrift after only 3 years or so. The question in my mind is whether best practice nowadays would be to use a flexible mastic and protect that with a mortar fillet.

To be honest , without seeing it nobody can give a definitive answer, the way you describe it as a fillet seems to suggest a large amount of mortar on top of the lead and not just in the lead slot, leadmate would be used on it's own in the narrow slot the lead sits in, no need to cover with mortar, and make sure the lead is firmly fixed.

 

[Fubble]

That's exactly how it was - a mortar fillet sitting on top of the bent lead with some mortar in the wall slot. It came apart and rain got into the slot and ran down underneath causing a bad leak into the house. I want to make sure it doesn't happen again so I'm inclined to fill the slot with mastic and - belt & braces - put a mortar fillet on top. Thanks for your comments.

 

[ree]

OP,
Perhaps what you describe as a fillet is the angular shape of a length of mortar pointing thats come out of the bed on top of the "turn"as the lead pulled away?

Whatever, there's no need for using mortar over sealant.
If the chase/slot is cleaned out, and is 25mm deep, then sealant can fill the slot & the 20mm turn can be pushed into it, & smoothed off afterwards.

 

[Fubble]

Yes. The fillet is triangular in cross-section.

 

[ree]

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