Wood burner squeeking flue when windy

nazuro4013

Hello, we have a rather annoying squeeking sound coming from the wood burner flue. The source of the sound seems like it's coming from around a foot or two above the ceiling. The flue then goes up through the bedroom (boxed in corner) and out the roof. 

I've a quote for:

-£680+vat to fit 2 x bracket in the room above and make good but there are no guarantees that this will work

-Plastering £170+vat  

But I wanted some advice please as to whether any thoughts if this would work or any other solution like perhaps replacing the chimney cowl with something better? (with a cherry picker presumably as it's 3 storeys high)

Pictures attached here and short 15 second clip of the sound attached on imgur. 

https://imgur.com/a/pJfsmqT

Thank you in advance!

victor2

How old is the burner and when was the chimney last swept?

If it's a noise that wasn't there originally, that may be all that's needed. Could the soot by the cowl be from burning unseasoned wood? 

nazuro4013

victor2 said:

How old is the burner and when was the chimney last swept?

If it's a noise that wasn't there originally, that may be all that's needed. Could the soot by the cowl be from burning unseasoned wood? 

Hello Victor, thank you for your kind response. We moved into the house only 2 years ago (and noticed the sound soon after). I think it is about 10 years old - not sure as to the sweeping status. We don't use the burner and don't have any current plans to. 

The squeeking is accomponied by a lot of wind in the void itself (I can feel it when standing on the ladder next to the removed ventilated firestop spacer). The sound seems to be coming from maybe 2 feet above this so I thought perhaps a bracket is loose or something. Should it be getting that windy in there in the first place though? I wonder if the cowl is the thing causing the issue and letting too much wind in.

Thank you

victor2

You could just ask what it will cost to replace the cowl. Probably won't need anything more than ladders. Might be difficult to find someone prepared to do it though, as it's a small job. Would the people who've quote to fix the flue internally do it?

WIAWSNB

I would agree with their diagnoses - it sounds like a vibrating part of the flue is causing a small amount of metal-to-metal movement. I'm guessing the most likely point will be where two flue sections join. Or, a loosely-fitting existing bracket.
You have a clear shot of the external flue - could you set up your camera on a tripod or similar so it's fixed, and video it during wind to try and detect any tiny shakin'?
If the whole external section is vibrating, that would likely discount it being just the cowl.
So, if you can detect the external section shaking/vibrating at the rate of the sound, that'll almost certainly be your answer, and ditto the solution.
With that amount of external flue without external support, I'm guessing there must be a hefty bracket or two immediately inside that roof to steady it. That would be my first check - are they solid and secure? If there is only one bracket holding that last external section, then add another, and space them as far apart as possible - that should hold that section steady, instead of providing it with a 'pivoting' point for transferring any movement.
Is the bedroom taking up the pitched roof, or is there a loft space? If a loft, get in there and take some pics, and try and replicate the noise by push&pulling the flue there.
The 'sound' might be coming from just above that ceiling, and the guilty joint could be ditto, but the cause will likely be from much higher up - so sort the cause by dampening that movement as soon as it comes through the roof.
I guess it would be more costly to add a support brace to the external section? 

nazuro4013

Hi both

Unfortunately, not possible to get up to the chimney with ladders due to it being three storeys high and tight to neighbours house. We did previously have scaffolding on for solar panel install and I had this Wood Burner company round to inspect the chimney, and he said he couldn't see any issues with it.

It's been windy today. I've had a look outside and I cannot (to the naked eye) see any movement of the chimney.

I've put my hands up in the ceiling and been able to move the flue side to side a few mm each way and am unable to replicate the squeeking sound.

Attached image of the bedroom above. I think the squeeking sound is coming from roughly in the orange square, not higher. I was wondering whether I just cut a 30x30cm square out and attempt to tighten whatever's there myself, and put an access hatch in to save on expense.

WIAWSNB

nazuro4013 said:

Hi both
Unfortunately, not possible to get up to the chimney with ladders due to it being three storeys high and tight to neighbours house. We did previously have scaffolding on for solar panel install and I had this Wood Burner company round to inspect the chimney, and he said he couldn't see any issues with it.
It's been windy today. I've had a look outside and I cannot (to the naked eye) see any movement of the chimney.
I've put my hands up in the ceiling and been able to move the flue side to side a few mm each way and am unable to replicate the squeeking sound.
Attached image of the bedroom above. I think the squeeking sound is coming from roughly in the orange square, not higher. I was wondering whether I just cut a 30x30cm square out and attempt to tighten whatever's there myself, and put an access hatch in to save on expense.

Ah, so the bedroom is in the roof space, so no loft.

Yes, that's what I would do. As I mentioned, the external part is quite long and unsupported (I'm not saying that's an error), so any vibrations in it would transmit downwards to the sections behind that boxing-in. 

The only problem with your idea is that you haven't a clue where the 'fix' needs to be! You may be lucky and find a joint where the noise is - and good chance - in which case a bit of sealant and a tightening of the screws could sort it. Or you may realise that it's a lack of bracketing/bracing further up, in which case a second 'hatch' would need cutting.

If you are going to DIY this, then get yourself a craft knife, and mark out a suitably-sized panel that you are going to cut out. Not sure which side to tackle - perhaps the socket side, whichever one you reckon will be less obvious.

Bear in mind there will most likely be a timber stud in the external and internal corners, so I'd mark 2" inwards, and draw your hatch. Don't skimp on the height, as it'll make no difference when it comes to repairing it. I'd go a good ~450mm high.

Begin to cut through using your knife, but only go 2 or 3mm deep at a time - don't overdo it. Also hold the blade at a good 30-40 degree skewed angle inwards, so you end up cutting out that panel with a nice bevel around the edges, one that'll stop it from falling inwards! And, when you come to replace it, a bead of filler along the mating edges, and it pressed gently into position until a straight edge on the outside surface to show when it's perfectly level, will do 90% of the work for you. (Or you may wish to add a batten across the opening on the inside - we can tell you how to do this.)

Oh, and there are cables running behind there, so don't let your blade go deeper than the actual plasterboard - just keep extending the blade each cut, until you cut neatly through. 

You have now't to lose. 

If you cannot repair it yourself afterwards, then a plasterer will sort it easily for you. 

Follow your gut - you think it's coming from a certain 'orange' point, so I would cut through there. 

You can't see that far up from below at the moment, to see if there's a joint there? 

 

nazuro4013

Thank you so much!

I managed to hoover some cobwebs and get a clearer picture. Must be one of these things  causing the squeek. Do you think it will simply be a case of tightening, or can I put some non combustible material between so that metal is not touching metal?


On a slightly unrelated topic, the soundproofing between bedroom and living room is near non existent. Can hear conversations happening in the living room and the sound seems to mainly eminate from the corner where the flue is. Can we lift the carpet in bedroom and put some kind of non combustible insulation around to lessen that sound transfer?

WIAWSNB

Away at the mo so can't see pic on big screen. But very good chance you can sort this from that access.
These look like toggle clamps - ie the sections have a round collar going around the outer flue, and a toggle clamps tightens it. These might be adjustable.
Do some googling for flues, and see how they are joined.
I also see no issue with packing around with insulation, but it needs to be fully heat resistant - glass or rock wool at a guess, but research. That should also reduce sound travel.
Worth a try first? It can always be pulled back out if not successful.
Pack firmly around the reachable 2' or pipe with insulation, using a stick. 

nazuro4013

Great, thank you! I'm going to be cutting an 80cm high rectangle out of the plasterboard. Is that too much? It's difficult for me to be able to measure the correct required space to cut out. Would rather not have to cut two holes. 

WIAWSNB

It's no harder to patch a big panel than a wee one :-).
Remember the bevel, and cut a wee depth at a time.
Snap-off blade craft knife is ideal.
Once issue sorted, we can guide you on replacing it.
Watch out for wiring behind - set depth of blade to suit.