In article ,
Dean writes:
Great. Thank you all for the advice.
I'll forgo the lime and builders sand and go for a cement, sharp sand
render, 1:4 (?) with some plasticiser.

That's a very strong mix for this purpose, in my opinion.
I'd go with a max of 1:5, and possibly even 1:6.
I haven't done anything this exposed though.

Regarding poor pointing, shouldn't repoint first then render? If I render
over the raked out pointing, will this make the render too keyed-in to the

Too keyed-in? What do you think is going to happen?

brickwork? Though I like the idea of raking out the bad mortar then doing
the repointing and render as a single application.

As far as I can tell the chimney has no ventilation whatsoever. I think
it's capped at the top but haven't gone up high enough to check yet. I
looked on Google Earth but it wasn't clear ;-) Whatever, I will go for
ventilation top and bottom as suggested.

One other thought - don't assume any structural integrity
of the chimney until you have verified it. i.e. don't assume
you can hang off it, support a ladder against it, or anything
like that, until you have established it's not just a pile of
bricks with no bonding. I noticed when my scaffolders were
working near mine, they treated it like it was a pile of
children's building blocks, which I guess a good number of
the chimneys they deal with are. (Fortunately, mine wasn't
bad at all.) Personally, I would only work from scaffolding.
I wouldn't dare put a ladder up against a chimney anyway,
although I have seen builders do so.

--
Andrew Gabriel
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