Wonky chimney

[hyraxbefud]

Hi all,

Just ahead of getting a structural engineer’s view, how urgent (or not) would you consider repairs are to the attached chimney? And how intrusive might they be - repair or replacement?

Building is late 18th / early 19th century.

Answers on a postcard!!

 

[malcolm]

4 inch lean? It's a lot. Mine was only a 2 inch lean. You wonder how it has managed to get to 4 inches of lean with the mortar joints in the bricks seeemingly filled with mortar. Chances are the mortar was eroded to nothing in the past like mine allowing the chimney to move, then it was repointed.

Rule of thumb for a reasonably well pointed chimney is you don't want the center of the chimney at the top to go past the edge of the chimney at the bottom as it'll probably fall down. Maybe do something before that to allow for wind loading.

It's not nice. Monitoring the lean is the important thing - if it is still moving it's likely a problem. If it starts to lean more it needs rebuilding with the original bricks and lime mortar.

 

[Kearn]

Rarely seen a decent age narrow stack that hasn’t got some lean on it… salts/expansion/erosion and a few other factors, based on the prevailing wind direction, where the stack leans into the wind.

Some measurements and further info here…

Chimneys and Flues - Russell Taylor

And a good old lean here on our brewhouse…which hasn’t been helped historically by a slight drop in the gable rubble stone after the brick stack was added a few hundred years ago.

 

[hyraxbefud]

Thanks both!

In all honesty it is getting me down a bit - this feels like a hobby that requires deep pockets.

Seriously considering whether to proceed with the purchase in light of the chimney wonk and a “dishing” roof (and a host of other issues).

Where dishing might be explained away by some historic over engineering, I don’t think I can get away from the blatant angle of the chimney and expense and time of getting LBC, proper contractors + scaffolding to sort it out.

Regretfully (perhaps) we have fallen in love with the property!

 

[Kearn]

Does your surveyor not have any drone shots from closer/above to fully assess the condition? Hard to say from those images alone…

A dishing roof due to over engineering. How do? Any pics? What is the structure inside and type of roof build?

IF the chimney needed remedial work, and that work was rebuilding, you’re probably looking at dropping and rebuilding about 10x courses. Not more than a couple of days work, but… the scaff costs will be in the 1000s, and while you’re up there you’ll notice the whole thing could do with repointing, the flashing probably wants to be renewed in lead, and and and …. Especially if you’ve some roof structural challenges.

 

[Alex_]

We bought our property with a stack with less of a lean than that but nevertheless the surveyor recommended an immediate rebuild after purchase. He was right. The brick just crumbled when touched. Better to fix than have fall on your head.

We negotiated a significant discount on the purchase price given the remedial works required, including chimney. Not quite enough as it turned out, but wasn't enough over to feel annoyed about. So I'd recommend negotiating a discount for all the issues identified in the survey and then assuming it will cost 50% more than you get discounted to fix. Just to prepare yourselves for the worst.

 

[montyjohn]

Thanks both!

In all honesty it is getting me down a bit - this feels like a hobby that requires deep pockets.

Seriously considering whether to proceed with the purchase in light of the chimney wonk and a “dishing” roof (and a host of other issues).

Where dishing might be explained away by some historic over engineering, I don’t think I can get away from the blatant angle of the chimney and expense and time of getting LBC, proper contractors + scaffolding to sort it out.

Regretfully (perhaps) we have fallen in love with the property!

The dishing roof wouldn't bother me.
It's common, and provided the wood isn't falling apart not usually a problem.

I have dished roof ridges, it's part of the character.

I also have four chimneys, one in each corner, and they are all leaning into the prevailing wind. The one that leans the most, if it fell would land in the middle of the house,
And these are monster chimneys. About 4.5m above the eves so there isn't an easy solution.

I haven't got up there yet to measure the lean, but the ratio is less than yours and I'm doubtful it's an issue at the moment.

Yours looks worse, but cheaper to resolve and it wouldn't put me off. I wouldn't have thought rebuilding a chimney like for like would trigger LBC but check with the conservation officer (if you can)

I've often wondered if it's possible to grind out the mortar, and hammer wedges in (somehow without destroying the brick). Do this at every course to correct a lean. Probably wouldn't work but given my situation find myself trying to find innovative solutions.

Or the nuclear option, put some rebar down the flue and fill it with concrete. It would probably kill my conservation officer. He was worried about me fitting radiators.

 

[stuart45]

They sometimes strap and brace stacks as a temporary measure. In the USA, they build them like that in some regions.