Would you cap a chimney?

[oxalto]

I have a large masonry chimney stack in the centre of my house and 5 fireplaces which flow into this space. Currently the chimney is open and, when it rains, a surprising volume of water makes its way down the chimney (particularly into the living room!). The chimney is original, but none of the fireplaces is. The one in the upstairs bedroom has been bricked up, and one on the ground floor has been hugely vandalised, now leaving a tiny space equivalent to a very small Victorian bedroom grate. This room is going to be my in-laws bedroom (as they need ground floor living). 2 more have been rendered unusable by a new main staircase from ground floor in the living room to 1st floor rising alongside them. This leaves me with only one in the music room (or 2 if I open up the upstairs bedroom) which we might like to function as intended. My old house had open fires which, whilst looking lovely, were very poor in efficiency and, of course, required maintaining.

We lose a lot of heat up the chimney, particularly in the living room and do not need open fires to supplement the heating in any of the rooms. I am therefore inclined to cap the top of the chimney and prevent the water coming down. There is sizeable air flow around the house through a large number of other drafts so I think that the house would still breathe. I think that the capping would also be easily reversible in the future. I would most probably board over the 3 fires other than the music room one (which is at least Victorian rather than hideous modern) and ought, I think, to include an air vent.

Does anyone have any advice or thoughts as to the pros and cons of following this course of action, please?

p.s. Anyone able to help tell me how to add photos to my previous post?

 

[AMc]

How to post pictures
http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=9077

If you don't want to use the fireplaces then replacing the chimney pot with a vented one is reversible in the future and will stop almost all rain entering. The pots look like a conventional chimney pot with a pottery cowl on the top - either with holes all around or a curved 'tile' over the top.
That sounds like what you would need to do - a decent roofer could do it and it shouldn't be very expensive - keep the original pot.

You can also fit a chimney balloon to reduce the amount of air rushing up the chimney, they have a small vent to allow some air to move to avoid condensation and damp. I don't know how 'long term' they are but you don't want to completely seal the stack or you may end up with some damp issues.

 

[FamilyWiggs]

Yes - this sounds like a sensible move, but you need to maintain airflow through the chimney once capped to prevent damp/condensation problems in the chimney and the rest of the house.

I haven't checked but I'm sure change slike this are covered in building regs. Any decent roofer should be able to advise.

 

[Flyfisher]

I would cap unused chimneys, but not with anything that would restrict the airflow; it's wide to maintain some ventilation in the chimney stack.

We also had problems with crows/rooks dropping sticks down our open chimneys but some added mesh seems to have mostly stopped that particular nuisance.

Any decent roofer should be able to advise.

. . . or chimney sweep.

 

[Feltwell]

If you've still got the original chimney pots in place and they are secure and in OK condition, you can just get a "pepperpot" cowl put in the top. That's what I did with mine. Very easy to reverse in the future if you wanted to use the flue again, plus of course you keep the original pot.

http://www.roofingsuperstore.co.uk/...s/clayware/fluvent-terminal-180mm-spigot.html

As others have said, maintaining some airflow up the chimney is important. You should also get the flues swept if they look like they need it. Damp and old soot can apparently cause problems by producing an acid substance that can affect the brickwork.

 

[oxalto]

Many thanks for the comments and also help with pics - I'll have a look at how to post them in detail later!

One slight spanner in the works is that I don't actually have any chimney pots, just a stone clad rectangle with brick topping. Without looking directly down it, I can't tell if it has 5 separate flues or one large one into which they all flow. I rather suspect it is the latter. That's certainly how it looks looking upwards from the largest one on the ground floor. Do I have to rethink?

Clearly I should leave some sort of air flow, from what has been said. Can it just be a small vent or does it need to be larger? Would I get a damp issue if the source of damp (the rain) were stopped? Perhaps I need to have an aired space anyway. I'm interested by the balloon idea. If this were lower down the chimney then I could presumably vent above it slightly, but without loosing heat from the lower part.

Does anyone have an idea of how to create the cowl effect but on a brick rectangle?

 

[stephenh]

The classic way to cap off a chimney with no pots is to cover the stack with a 50mm deep concrete slab - (coping stone from builders yard / cast it yourself ?) If it is a couple of inches bigger all round it looks quite good.
Before you do this , cut out 2 bricks and fit a terracotta 9" x 6" air vent at a high level in one of the sides.
Now install plaster 9 x 6 airvents in each of the blocked up fireplaces.
You only need a trickle of air through to keep the flue dry.

With chimney pots you just put terracotta mandarin hats on.

Always it is the access that is awkward....

Good luck

 

[Flyfisher]

I'm interested by the balloon idea. If this were lower down the chimney then I could presumably vent above it slightly, but without loosing heat from the lower part.

I've used a chimney balloon, but only to prevent downdrafts (as the associated small) during the non-winter months when a chimney wasn't being used. They are intended to be inserted into the flue from the fireplace as a temporary measure. "Chimney reversal" is fairly common when a chimney is totally cold, as they usually are during most of the year.

I don't think I'd use one when decommissioning a chimney for any length of time though. Anyway, if you're thinking of boarding up the fireplace, there's really no need for a balloon as well - just fit some sort of trickle vent into the boarding. But if you're thinking of leaving the fireplace open, then a balloon could work quite well - together with some form of rain-cap for the stack as well.

 

[oxalto]

Thank you everyone - I think that stephenh's solution sounds like the perfect one for me. I shall see if I can find some pleasant coping stone that already happens to be the right size, add the vent and set the cap on a bed of lime mortar. I'll then board up and vent down below, keep the one nice(ish) fireplace on display (which already has a soot flap which can act as ventilation) and then all is well, asuming that the builder doesn't destroy the tiles! Before this, I might have it all swept out one last time, though!

Is this a job for a specialist roofer or a careful builder?
Would they need a scaffold or just some ladders?
It sounds like it could all be done in a day with careful planning. Am I wrong?