What's best ? Lead sealant or Mortar

[JasonF]

Hello all, Next week if it's dry! I'm planning to repoint the lead flashing on my garage, I've always used mortar but is lead sealant better ?
Thanks for any advice, atb Jason

 

[Notch7]

I prefer lead sealant -which just grey silicone.

 

[Mojo12345]

I had lead sealant on my new roof seems to be solid so far

 

[Alastairreid]

Lead sealant as it is low modulus and flexible.
Mortar can crack and fall out with differential movement.

 

[johnny2007]

Sealant.
I was converted after having to repoint all of my lead.
Couple of years later needs doing again in points.
Before anyone says, the lead is held in place very firmly by lead clips.

 

[Leofric]

Sealant.
I was converted after having to repoint all of my lead.
Couple of years later needs doing again in points.

that doesn't sound a good recommendation if parts needed doing again after just 2 years , no offence but that might have been the workmanship.

 

[johnny2007]

I meant to say that the mortar had failed.
I noticed that cracks appeared a couple of years later on the south side, where sun shines all day (when we get sunshine in England...)
Nothing on north side where mortar is still perfect.
So i re-re- pointed with lead sealant.
The pain was to clean the joint.

 

[datarebal]

make sure the chase is free from dust and dirt before using lead sealant. if you dont you will end up with the sealer stuck to the lead and not the bricks.. there by trapping water behind and in

personally , i prefer mortar, deep ,damp joint firmly packed.
if the flashing is turned in with a roll back then you can slip a length of building paper over the lead, then pack point the joint in mortar.
trim of paper after . leads free to move and mortar stays bonded to masonry.
rare to see this these days

 

[johnny2007]

Nice one.
Never seen this myself.
If I ever have to repoint lead I will try this.

 

[JasonF]

Datarebal, interesting way of doing it, I think I'm going to use mortar this time, the weather has been so wet and I don't think the lead sealant will stick. Thanks for your reply

 

[Milleniumaire]

I realise it has been 10 years since the last post, but I've just searched for what is better to seal lead flashing; mortar or lead sealant and got this post.

I've just had a roofer round who recons the reason my extension roof is leaking is due to the use of lead sealant rather than mortar. He went up and had a look and said the lead sealant is coming away in places and should be removed and redone using mortar to give a better seal. I went up onto the extension roof after him and couldn't find any issues with the lead sealant, so not really sure what he is talking about. The extension was built 8 years ago and has only just started allowing water through, but no idea how it is getting in!

I'm reluctant to have him remove all the existing lead sealant and replace with mortar if lead sealant is actually a better product!

 

[Nige F]

some roofers are also tarmac drive layers

 

[johnny2007]

I personally think that either methods are equally effective.
What's important is to clip the lead properly in the joint (25mm deep) and avoid stretches over 3 foot long.
If you can't see the lead sealant deteriorating, tell the "roofer" to get back on his horse and do one.
Somehow, roofers seem to be the profession with the most improvised cowboys out there.
In the past few years I've come across so many and not a good one, not one.

 

[Milleniumaire]

I personally think that either methods are equally effective.
What's important is to clip the lead properly in the joint (25mm deep) and avoid stretches over 3 foot long.
If you can't see the lead sealant deteriorating, tell the "roofer" to get back on his horse and do one.
Somehow, roofers seem to be the profession with the most improvised cowboys out there.
In the past few years I've come across so many and not a good one, not one.

I always find it difficult to trust what a tradesman is saying when I don't know them or haven't used them before. This guy was recommended to me by a friend, so better than just selecting someone from the internet!

I did call him to discuss how he would re-point the flashing and asked if he would remove all the leadmate first as this was my concern given I couldn't see any obvious issues with it.

He explained that the leadmate was quite deep in the joint, so he wouldn't remove it (as that would be a much bigger job), he would point over it to give additional protection. I asked why not fill the joint with more leadmate and he explained that if it was a brick house, this wouldn't be an issue, but as it is a random stone built house, leadmate doesn't always stick to the stone as well as mortar does.

Pointing the flashing is only part of the job I'm hiring him to do, with the main job being to re-point a valley that has crumbling 24 year old mortar.

As he is not removing the existing leadmate, I'm not as concerned as at least it still has that protection and just maybe the additional pointing will actually stop the occasional leak in heavy rain, for which a cause has never been determined.

 

[johnny2007]

I always find it difficult to trust what a tradesman is saying when I don't know them or haven't used them before. This guy was recommended to me by a friend, so better than just selecting someone from the internet!

I did call him to discuss how he would re-point the flashing and asked if he would remove all the leadmate first as this was my concern given I couldn't see any obvious issues with it.

He explained that the leadmate was quite deep in the joint, so he wouldn't remove it (as that would be a much bigger job), he would point over it to give additional protection. I asked why not fill the joint with more leadmate and he explained that if it was a brick house, this wouldn't be an issue, but as it is a random stone built house, leadmate doesn't always stick to the stone as well as mortar does.

Pointing the flashing is only part of the job I'm hiring him to do, with the main job being to re-point a valley that has crumbling 24 year old mortar.

As he is not removing the existing leadmate, I'm not as concerned as at least it still has that protection and just maybe the additional pointing will actually stop the occasional leak in heavy rain, for which a cause has never been determined.

Pointing over leadmate = recipe for disaster.