Chimney Queries

[chuckalicious]

Hello all.

I have a Victorian sandstone house which has a 5 pot chimney stack which is in need of repair.

The people who had the house before us pretty much ignored the fact that it needed repointing and so over the years the stone work has been abused by the weather and is in a poor state in parts. The cope is also a bit tatty.

I do not know the full extent of the condition because the the roofline is fairly high so I have not dared go up my self.

I had one roofer go up last year to patch up what he could from the side he could access from a ladder. He rendered over the bad stonework and pointed what he could get access to.

From what I can see the pots could do with being re-seated and I imagine the flashing could do with getting replaced as well.

I do not know what condition the cope is in.

The fireplaces get a reasonable amount of sand coming down them, which I assume means the stone is in a bad way?

More recently I had the same firm come back round to quote for proper repairs. They said that they'd need to rebuild the whole thing in brick (as sandstone would be prohibitively expensive).

Quote was £2255 exc VAT to erect scaffold, take down chimney below roof level, rebuild in brick, put existing cope and pots back on and double render it.

Now, if that's what needs to be done then fair enough, but I'm wondering if something like this is worth repairing instead of rebuilding, replacing the bad bits and retaining what I can.

I have the money to do the replacement, but I will need to apply for planning condition to my council before I can go ahead, whereas I think with a repair I wouldn't need to as I'd be retaining as much of the original chimney as possible.

In your experience, if the stonework has been neglected for some time and is crumbly in places, should you take down and completely rebuild?

Don't have any photos at the mo I'm afraid.

 

[Alastairreid]

If the sandstone on the chimneyhead is worn away then the bridges separating the vents probably will be as well. This is all the more critical if the flues are in use.
A smoke test on each flue will determine if any of the bridges have collapsed or have perforated.
A visual inspection from above is the best way to ascertain their condition.

Patching up sand stone with mortar is a hash up as the sandstone will erode away around it leaving leaving a protruding patch of mortar.
Lime mortar is the proper way to do remedial works on sand/limestone.

A pic would help though it does sound like a rebuild.

Out of interest why do you need PP to rebuild existing.

 

[chuckalicious]

Ok - I had suspected as much. I know lime mortar is the right thing to use and I think that was used with the patch job where practical. I was aware at the time that it was very much a patch job to tide it over until I was able to deal with it properly - this house has cost a lot of money so far and I'm trying to get things done as and when I can.

Regarding PP, I live in a conservation area and when I asked the council if I'd need PP, they said yes as I'd be taking down a sandstone one and putting up a brick and rendered one. This has been done in a few of the houses round about me, but it's not to say that they'd still allow it, so best to go through the proper channels I guess.

 

[chuckalicious]

Also one of the fires is used each winter and I haven't seen anything untoward smoke wise as I have looked in the past.

I have also noted that there is no visible damp/water damage inside or outside the property. I imagine some water is getting in, judging by the state of it, but not to the extent of some of the postings I've seen here with people having water ingress via a chimney stack.

I'm sure it's just a matter of time though.

 

[Alastairreid]

When you get the work done put vented caps on the the unused vents..

Untitled

• Alastairreid
• 17 Jul 2009
• 20

 

[chuckalicious]

Will bear that in mind. Those look quite interesting.

 

[chuckalicious]

Ok, here are some photos of the chimney. Looking at it this morning it's not as bad I thought - in my opinion - you may disagree

Unfortunately the side that I think is in the worst condition is the one you can't see clearly as I cannot get a view.

See what you think - comments appreciated.

Untitled

• chuckalicious
• 27 Apr 2011
• 1

Untitled

• chuckalicious
• 27 Apr 2011
• 1

Untitled

• chuckalicious
• 27 Apr 2011
• 1

Untitled

• chuckalicious
• 27 Apr 2011
• 1

Untitled

• chuckalicious
• 27 Apr 2011
• 1

Untitled

• chuckalicious
• 27 Apr 2011
• 1

 

[chuckalicious]

Just so you get an idea of where the chimney is in relation to the house, you can see it in this photo, just peeking above one of the windows.

Untitled

• chuckalicious
• 11 Feb 2011
• 2

 

[Alastairreid]

Its in better condition than i imagined.
The blocks are in a reasonable condition considering their age and the weather conditions in Stirling.
If it was my chimney i would re-bed the cans if required (checking out the bridges at the same time) repoint with lime mortar and reface any badly worn stonework.
The leadwork may or may not need replaced.
get a few estimates.

 

[chuckalicious]

Thanks again for the input. That is also what I was thinking.

My issue is with replacing the stone - I assume the ideal thing to do would be to replace it with new sandstone? I would assume this would be very costly, or at least that's what I was warned by the company that said it should be rebuilt.

I will get some more people round to look at it then and see what they think. I suppose getting a couple of blocks of sandstone replaced may be cheaper than removing and rebuilding the whole thing...

 

[chuckalicious]

Sorry - I note you said "reface" not "replace" - how is that done?

 

[Alastairreid]

Sandstone surface repair

These are cosmetic stone repairs that are carried out to stone masonry that has suffered some form of superficial deteriation. The repairs are undertaken in-situ using repair mortar, this means minimal disruption to the building or structure.

Stone repair mortar is available in different forms but can be largely classified as below:
Natural stone repair mortar

A combination of natural hydraulic lime, blended sands/aggregates and clean potable water. This can be mixed by the stonemason or specialist on site to suit particular conditions, strengths and colours of stone masonry. It is not recommended that ordinary portland cement is used in the repair of sandstone as it does not allow the stone to breathe and will be significantly harder than the stonework, potentially causing problems as it cannot expand and contract at the same rate as the surrounding area.
Synthetic sandstone repair mortar

Typically manufactured in a laboratory using a mixture of polymers and aggregrates . They are lightweight and extremely fast drying. Where invisible stone repairs are required the mortar can be dyed or stained to match adjacent stone masonry.
Structural sandstone repair

Structural repairs are undertaken where cracks in stone walls, lintels or window cills threaten the stability of the masonry and it is not practical to replace the damaged stone.

Slots are cut into the cracked stone member and a combination of epoxy resin injection and stainless steel reinforcement is used to pin the two cracked pieces of stone masonry together. To complete the repair the slots are filled by indenting or surface repairs.
Cast sandstone replacement

Where replacement with new natural stone masonry is not a practical option, replacements can be reproduced to match the original masonry in natural stone artificial stone.
The new masonry is cast from a synthetic mortar or natural hydraulic lime mortar. The mortar is mixed or dyed to match the colour of the surrounding area so that the sandstone repair is barely seen when complete.

 

[chuckalicious]

Thank you again. That was very useful.

I shall call a few more people in my area and see if any of them would like to take a look and quote.

 

[Alastairreid]

Good luck.

 

[chuckalicious]

Ta. I'll try and update this thread when I have more info. Always useful for someone else's reference.