Woodburner causing damp. The plot thickens, aagggghhh!

[yamin]

Mine is the message below regarding the sodden chimney breast that the builder thinks is because the flue needs back filling with vermiculite. Thanks again for the replies! Today I spoke to the man who fitted woodburning stove, and he had 2 cats to put among the pigeons

1. The twin skinned self contained flue that is using the chimney void is further contained within a pumice/anki liner that is already up there, the whole apparently surrounded by leca (?spelling? beads - much like vermiculite. This was already in the chimney, so previously lined.

2. He feels that the width of the chimney breast vs the width of the flue he utilised, indicates the presence of 2 original flues, with a divider, using the same chimney stack. This makes sense of course in a 2 floored house.

So, his suggestion was that the second, unused, flue, which presumably is NOT lined, is cold and therefore the condensed air leading to damp is coming from its ability to be warmed by the neighbouring used flue. This is complicated however by the fact that the other flue is lined (see above) and therefore should not be rising in temperature enough to affect the cold air in its neighbour!

This is all completely beyond me! I need a rub down with a damp edition of the radio times! In the meantime, I have given the builder the number of the fire man and asked that they talk, as hearing all this second hand through me, as you see here, is not terribly clear! Its so frustrating as I just don't know what solution to try. Backfill the empty flue? Put airbrick in at level of damp? (halfway DOWN breast of upstairs chimney breast). Whatever we do if its more than tuppence ha'penny it'll have to wait. Builder has suggested that I take a hammer and remove the sodden plaster, as its gypsum so not helping, and is so sodden it just won't dry now.

Any other comments welcome!

 

[Flyfisher]

It all sounds a bit complicated but my instinct would be to try to improve ventilation in the unused chimney. Have you established there is no rain ingress anywhere? Hacking off the ruined plaster also sounds like a good idea. I've done this on walls affected by bad guttering and everything dried out very quickly, but that only deals with the symptoms, not the underlying problem.

 

[Penners]

I agree with Flyfisher.

I presume that this disused chimney is blanked off over any old fireplace? Disused chimneys must be well ventilated, to ensure that they don't become damp. So you need to ensure that (a) the top of that chimney is capped with a ventilated capping device to exclude rain but allow air movement, and (b) there's a vent in the fireplace blanking off board, at the bottom of the chimney, to allow air to circulate throughout the stack.

It might also be worth opening up the old fireplace, getting the chimney swept, and clearing out any accumulated debris. Old chimneys have a nasty habit of having little ledges inside them, where soot and general debris can accumulate. And if rain then falls on this, it will become a permanently wet source of damp that can soak into the brickwork. The same can be true of accumulated debris at the bottom of the chimney - usually in the closed off fireplace.

 

[yamin]

Thanks again guys

Ventilation was mentioned, and I do think the bottom of the firplace is blocked off. Well I know it is. And I can see why ventilation is important - there are no airbricks at all. I would very much like to have the fireplace upstairs open anyway, so when I take off the rotten plaster I wonder if it might be worth exploring the opening, if it still exists. This is proving so helpful, to see the advice here - thank you!

 

[Pford75]

Yamin - Most of the fireplaces in our house were boarded over when we moved in. There was significant damp in many of the rooms.

We did exactly as Penners and Flyfisher have suggested....we open the fireplaces and had them swept. Some had birds nests...some had birds (dead ones) and one was even stuffed with sodden pages of a second world war newspaper. Within a few months, the damp had disappeared.

But do remove the gypsum plaster, it will slow the drying and needs replacing anyway

 

[chuckey]

I have more or less the same situation as you with one lined flue and a second unused upstairs flue that has got a really rotten divider between it and the lined flue. What I intend to do is to knock out a stone in loft to ventilate the unused flue. Putting an air brick externaly is a major job in a rock and rubble wall and could under certain circumstances (horizontal rain?) could allow water in. I was wondering about filling both the flues with pearlite, a, to further insulate the used flue and, b, to reduce the volume of air and hence the chance of condensation in the unused one.
Frank

 

[yamin]

Ok, so if its not too horrifying/rookie a question, whats the best way for a novice (bear with me, i'm trying to learn without going at it like a bull in a china shop, but being so young and naive its taking a while to get the skills!) to tackle opening up a fireplace? Presumably I shouldn't just take a sledgehammer to it, but on the other hand at some stage I have to breach the wall!

 

[Flyfisher]

Slowly and carefully is the basic answer, at least until you can clearly see the construction of the fireplace.

A good first start is to remove any plaster to reveal the brickwork. This should reveal the original fireplace opening and the supporting arrangement for the bricks above the original opening. When you've identified the original opening and satisfied yourself about the supporting structure, it's a fairly easy and safe task to remove the bricks used to brick-up the original opening. The first few bricks are the most difficult to remove and a good hammer drill can be helpful.

The last fireplace I opened up turned out to be three fireplaces in total. The fireplace that was in current use, another one behind that, complete with a (disconnected) back boiler and the original brick-arched opening about 4 feet high. The fireplace in use was constructed with really hard cement and was a pig to remove but the one behind was built with a much nicer soft mortar and was quite easy to remove.

And further to Pford75's comment about birds nests, when we opened up another (unused) fireplace the chimney was pretty much totally blocked with birds nests and bird skeletons - probably right to the top of the chimney judging by the many wheelbarrows of stuff we removed!

 

[yamin]

Good grief! I hope I don't find such a winged graveyard. Can I remove bricks that are clearly below the line of the original opening safe in the knowledge that the original support will still be in place above the original opening?

Thanks, and sorry for the 20 questions!

 

[yamin]

3 fireplaces one behind the other? Thats amazing!

 

[Flyfisher]

In principle, yes, you should be able to remove all the bricks below the original opening. Think of the original construction; it would have been built with some sort of structure to support the wall above the chimney opening. Then, when bricked up sometime later, the added brickwork would not have been structural, so it should be able to be safely removed.

But, without seeing the fireplace it's impossible to be 100% certain, hence my earlier caution to start slowly and carefully. The key thing is to satisfy yourself about the integrity of the support structure above the original opening.

As for bird remains, if your chimney pot is capped then you may avoid that experience - but where's the fun in that?

 

[AMc]

I would start with a few test holes with a hammer drill and medium sized masonary bit near the middle, bottom of the suspected opening. Check the colour of the dust and the depth before the drill 'pops' into free space. You might be lucky and find it's just a bit of plasterboard, or it might be red brick, grey concrete block, rubble etc.
Once you've worked out where the opening is/what its filled with then remove the plaster outwards and upwards until you find the extent of the opening.
I wouldn't go swinging into it with a sledge hammer until you can be sure the chimney isn't being held in place by a few loose bricks, some plaster and habit (very much the worst possible case!).

It would also be worth familiarising yourself with the dangers of asbestos in old houses and take reasonable precautions to protect yourself when hacking into unknown substances.
http://www.hse.gov.uk/asbestos/

 

[yamin]

OM I never thought of this! This is a childrens playroom! Reading the website link, it seems likely that normal gympsum plaster skim will be OK, and ordinary plasterboard OK too, but I think I will get a face mask and follow the damping down precaustions as advised. I had heard to leave Artex well alone because of asbestos. Can't seem to establish how long I need to give a room 'clearance' to let any dust dissipate before allowing my children back in?

Is asbestos a common issue in residential homes, other than artex?

Thanks for the warning

 

[Penners]

I was wondering about filling both the flues with pearlite.... to reduce the volume of air and hence the chance of condensation in the unused one.

I'm afraid I very much disagree with that, Frank. The disused flue needs a good flow of air.

 

[Nemesis]

Is asbestos a common issue in residential homes, other than artex?

Some fool thought that using it in sheet form instead of plasterboard to make partitions (bathroom) and line wobbly walls was a good idea in my house.

 

[yamin]

Ah, nice! And how could you tell it was asbestosand not ordinary plasterboard?

 

[Penners]

This thread is worth reading: http://periodproperty.co.uk/forum/viewtopic.php?f=1&t=9814

 

[plumbers mate]

Anyone remember using discs of asbestos edged with a metal strip to heat pies and thinghs? When I was at College we all did this in our bedsits. You laid it on the gas ring (with the gas lit) put the pie directly onto it and put a bowl over the top. The pies warmed through lovely!
:shock:

 

[Penners]

Ah yes - I reemember eet well.

(Just call me Maurice)

 

[yamin]

all this talk of abestos really gave me the collywobbles! Never mind that at the moment I'm only stripping woodchip! Nevertheless I thought I'd observe some basic respiratory protection. NHS husband has neglected to liberate a mask for me, so I had to improvise. First attempt was an old stocking (black of course) pulled over my head. This lasted for all of 5 minutes, before the tightness round my neck made me think that husband would come home and find me unconscious, apparently the victim of some strange DIY auto erotic experience ( ). Seriously, for actual fireplace removal, would anyone wear a fully protective mask and suit? Or just look out for suspect boards etc?