Mortar raking advice needed

[middleofafield]

So I need to set to and repair the mortar on out very leaky chimney. Haunching and flashing looks solid, but some of the pointing is quite badly cracked. I was going to use a 115mm rake on my grinder, but it's uneven stonework which is so proud I can't get the wheel in. So looking into grabbing a 9inch grinder, I can't find any raking discs below £100.

Does anyone have any ideas? The mortar is really tough stuff as well. The only option I can think is a stone cutting disc, but that seems a pain.

Cheers.

 

[robinbanks]

Picture would help. SDS with a chisel tip, hammer mode only?

 

[cdbe]

I'm not particularly risk averse but there no way I'd be using a 9" grinder on a chimney unless it was fully scaffolded to the extent that it was comparable to working on the ground.

You can get a mortar rake attachment for your grinder but it may not go deep enough.

In the old days we used a plugging chisel, otherwise as above, a slim SDS chisel or even a drill bit will usually break it out.

 

[middleofafield]

Yeah sorry a pic would help - see attached.

I did wonder about a 100mm attachment for the grinder, but still not sure it would go deep enough and I'm not too comfortable about putting a lot of lateral load on the tool. It will be fully scaffolded with two platforms so access is good, but I just can't find any 9 inch raking discs that don't cost less than the grinder!

I guess the only alternative is an SDS chisel, but it just seems a brutal way of doing it and I'd be afraid of damaging the stone. And as I say, the mortar mix in there is very hard - too hard.

 

[ree]

OP,
Just google "very thin 9" grinder blades" and you'll see a large choice. Most all of them at low to reasonable prices.
Some of the beds & perps on your chimney breast are extremely thin, & you'll possibly need a 9" blade to reach in to hack out 20mm - 25mm. for chases?

But, given your "very hard ... mortar mix" is it the masonry pointing thats the problem and not the flashing?
The cover flashing we can see seems to have been incorrectly fitted for those profiled tiles - and the little of the back gutter showing doesn't appear to be correctly fitted either?
Has the cover flashing lead been turned into a chase or is it merely "stuck on" with sealant?

You would need to lift the tiles surrounding the stack to see whats happening. If you lift the tiles then why not post pics of what you expose?
A pic of the top of the stack might also help?

 

[middleofafield]

OP,
Just google "very thin 9" grinder blades" and you'll see a large choice. Most all of them at low to reasonable prices.
Some of the beds & perps on your chimney breast are extremely thin, & you'll possibly need a 9" blade to reach in to hack out 20mm - 25mm. for chases?

But, given your "very hard ... mortar mix" is it the masonry pointing thats the problem and not the flashing?
The cover flashing we can see seems to have been incorrectly fitted for those profiled tiles - and the little of the back gutter showing doesn't appear to be correctly fitted either?
Has the cover flashing lead been turned into a chase or is it merely "stuck on" with sealant?

You would need to lift the tiles surrounding the stack to see whats happening. If you lift the tiles then why not post pics of what you expose?
A pic of the top of the stack might also help?

Ree, I appreciate your clear feedback. We've had two guys round to see it, and one lifted the tiles around the back and reported all was well. But they both said the issue was the pointing. I saw some of their pics and the cracks did seem quite bad. The quotes they came back with were stupid though and funds are very tight. I'm not averse to getting up there and doing my best, though I'm no expert!

The background is that this has been an issue for a while with damage to the ceiling and walls in the living room. We only just found this out as we moved in last year. Most of the time it's fine when it rains. The issue only really comes when the rain lashes down with the strong winds we get here, and only then when the wind blows on the back of the chimney. With heavy, steady rain there is no leaking at all, which is why I think it's not the flashing. In the roof area, the water is coming through the mortar joint, and not running down the face of the stone.

I will get up tomorrow and grab some closer pics for you if that's OK. As well as the guttering which does look odd I agree.

Many thanks again.

 

[^woody^]

A 125mm wheel will grind that out. Use it on an angle if need be. Or try a mortar rake on the grinder.

A 9" grinder used on that could give you some red stains on the stone.

But if the mortar is tough, it should not need re pointing.

 

[middleofafield]

A 125mm wheel will grind that out. Use it on an angle if need be. Or try a mortar rake on the grinder.

A 9" grinder used on that could give you some red stains on the stone.

But if the mortar is tough, it should not need re pointing.

It's deceptive I've tried lol! I don't like red stains but may have to take the risk. There are some nasty cracks in the mortar. The rest is rock hard. Probably a 3-1 mix.

 

[aveatry]

I'm sorry but I do not not see what the problem is with your pointing especially when you say it is very hard-- from the pictures I do not see an issue. Looking at your pictures I would be looking more closely at your flashing and the filling between the lead and your stone.

 

[middleofafield]

I'm sorry but I do not not see what the problem is with your pointing especially when you say it is very hard-- from the pictures I do not see an issue. Looking at your pictures I would be looking more closely at your flashing and the filling between the lead and your stone.

No, the main issue with the pointing is behind the chimney and at the top. I've seen the pics from the roofers who have been up there, but can't send my own until the scaffolding is up. But there are sections with some nasty cracks with 3-4mm gaps.

Attached is a pic one of the roofers sent me of the flashing exposed at the back. He said it was fine, but coated it in some marine gunk just in case. It made no difference.

@ree I've also attached a couple more pics of the gutter I promised, as well as a clearer pic of the flashing round the back when it's exposed. It does seem to be chased in.

 

[ree]

OP,
I would use a 9"angle grinder if it was natural stone but your last pics suggest to me that its faux stone made from concrete?
I dont understand why a 9" grinder would cause red stains on that faux stone or on natural stone?
You could use an 8mm x 150mm rake but only on soft mortar - or previously disc slotted mortar to clean out.

 

[middleofafield]

OP,
I would use a 9"angle grinder if it was natural stone but your last pics suggest to me that its faux stone made from concrete?
I dont understand why a 9" grinder would cause red stains on that faux stone or on natural stone?
You could use an 8mm x 150mm rake but only on soft mortar - or previously disc slotted mortar to clean out.

I presume he meant blood! Why not use 9" on false stone? But I guess the 9" is the only option I have

 

[ree]

OP,
Presumably pic 3 is showing the back gutter - and the back gutter is well wrong, useless for purpose.
What are the strands of stringy stuff on the left in pic 3?
Exposure means lifting all the tiles and the lead back gutter up and away - then taking a pic.
The cover flashing I referred to was the side flashing - that needs all the tiles touching it to be lifted & then pics?
The metal support bracket below the plastic gutter is not needed - a correct fitting or clip should be used.

 

[ree]

We dont yet know how the faux stone pieces, courses or panels was "put together" so best to wait before raking out until you post pics of the back of the stack.

Good shout about "blood".

 

[middleofafield]

@ree the stringy stuff is just cobwebs from under the lifted tiles. Do you mean the lead is not a single sheet? I'll get the scaffold put up and then come back with some better pics. But the reason I don't suspect the flashing is because heavy rain does not produce and leaks. It's only when the rain is blown by strong wind against the side of the chimney when it leaks. And then only leaks out through the mortar joints in the roof, and not down the face of the stone.