Recommend chimney cowl?

[joe-90]

Yes I do think you are weird. My advice is based on 1000 years of houses in the UK. 80 million chimney pots that don't have problems. If you put a cowl up then you risk condensation in the chimney which manifests itself as damp on the chimney breast in the bedroom. Read through the forum and you'll see.

BTW, what problem does the OP have? I can't seem to find it.

In my opinion there are better ways of spending a thousand notes - and it may bring condensation problems with it. Still, it's the OPs choice. As long as he's aware of the risks - then let him get on with it.

However, I'd advise him to look out of his bedroom window first and see how many open pots there are out there.

 

[noseall]

I agree with Joey on this one.

People see damp patches on a chimney breast and automatically assume flashing leaks or rainwater flue ingress. As is often the case, flue masonry that has been saturated with hygroscopic salts is largely to blame.

In reality, the amount of rain likely to fall into a flue is either evaporated naturally by the updraught or lies harmlessly on the flue masonry until evaporated.

Put it this way, if i wanted to collect rainwater, putting a bucket at the bottom of an open flue will be the last place i'd look.

 

[Alastairreid]

It is only relatively recently flues have in general ceased to be used for what they were originally designed for, ie coal,peat,logs etc (solid fuel).
The heat kept the flues dry and moisture free by being in regular use.
Yes chimneys have been in use for hundreds of years..but they were being used for what they were designed for.

In response to joes 80million chimneys, i have no idea of the figures but i do know an unused and uncapped vent does result in rain penetration which will lie on the bridges not always evaporating..Especially in areas of higher rainfall, this will eventually cause damp ingress to any adjacent rooms. This will occur over a period of many years.
Also in older properties where the stacks and bridges were built from lime mortar the the damage caused by rain, frost, freezing and thawing cycle causes the lining and bridges to crumble ...again over long periods of time.

I have removed hundreds of chimneys over the years which have been sodden and rotten with collapsed bridges caused by rain penetration.
I have also removed nests which have over the years accumulated to a depth of several feet.

Geography and rainfall would also be mitigating factors.

So in my opinion logically.... capping the vents makes more sense than leaving them open.

By the way Joe if i look out of my window mostly all of the chimneys are capped....And i would love to get a grand for fitting a cap on a chimneyhead.

Noseall: The scenario with the bucket i assume would be on the chimneyhead as opposed to the bottom of the flue. And the bucket would be full after a decent rainfall.

I dont disagree condensation can be an issue but on the balance of probabilities and many years of on hand experience on dealing with these issues i would always cap an redundant vent.

 

[noseall]

in areas of higher rainfall, this will eventually causing damp ingress to any adjacent rooms. This will occur over a period of many years.

No it won't.

9" solid external masonry is saturated every time there is wind blown rain - then it evaporates.

If this were the case the every solid walled home will have damp problems when ever there is driven rain.

However, they do not.

Also, many real fires are/were left unused throughout the summer but you don't see folks running up ladders in order to prevent rain ingress.

 

[Alastairreid]

External masonry walls are.....errrm on the outside...Which get dried out naturally.....Chimney vents are....let me think...inside a dark damp flue

And i stated this action occurs over a long period of time...

 

[joe-90]

And i stated this action occurs over a long period of time...

Tell us more Alastair. How long? What action? Why is it that most houses don't have the problem when they all have the same stack?

 

[Alastairreid]

And i stated this action occurs over a long period of time...

Tell us more Alastair. How long? What action? Why is it that most houses don't have the problem when they all have the same stack?

Depends on the design of the chimney,height of stack, where bridges fall, if the vents are on an external wall, fabric of building ie sandstone limestone,Location etc.. The variables are endless.

There are a many reasons which should be taken into consideration when diagnosing..including condensation issues.
I would never however suggest leaving a redundant flue uncapped.

 

[Alastairreid]

Several feet of water? FFS - what a load of rubbish.

That data was provided by the BRE.

http://www.bre.co.uk/page.jsp?id=1710

 

[catlad]

I guess Alastair, you just have to have seen it many times before what problems develop over time on an uncapped chimney that is no longer in use.

 

[Alastairreid]

I guess Alastair, you just have to have seen it many times before what problems develop over time on an uncapped chimney that is no longer in use.

Especially the climate we get on the west coast of Scotland.

 

[noseall]

The argument as to whether a chimney needs or does not need capping off, is one that could be batted back and forth forever. Some flues may benefit and some may not. It is not a cure all panacea for all chimneys.

However, as Joey has pointed out, there are trillions of uncapped chimneys that not only are healthy but are thriving upon being left open.

The argument about vast amounts of water being allowed in each time it rains is hilarious, especially the bucket in the garden analogy.

 

[Alastairreid]

The argument as to whether a chimney needs or does not need capping off, is one that could be batted back and forth forever. Some flues may benefit and some may not. It is not a cure all panacea for all chimneys.

However, as Joey has pointed out, there are trillions of uncapped chimneys that not only are healthy but are thriving upon being left open.

The argument about vast amounts of water being allowed in each time it rains is hilarious, especially the bucket in the garden analogy.

Not an argument..more a debate.

I agree, there are millions of uncapped redundant vents throughout the land, i also think being uncapped accelerates their decay from within which does not become apparent until the dampness starts to become evident. (proactive maintenance comes to mind).

Joes stance on condensation always being the issue is where i was trying to redress the balance.

 

[joe-90]

The point I was making is that capping chimney pots can be an expensive issue when factoring in scaffolding etc. If it aint broke - then don't fix it.

You still haven't answered why you think some chimneys suffer when others don't - even in the same row. They all get the same amount of water down them.

Still, it appears that you cap hundreds and make big money out of useless repairs - so I'm sure you will push it - just like damp contractors do.

 

[Alastairreid]

Still, it appears that you cap hundreds and make big money out of useless repairs - so I'm sure you will push it - just like damp contractors do.

Nope!! we remove them.

Your questions have been answered.

And you do not need a scaffold to put a cap on a chimney the same as you dont need a scaffold to clean or put aerials on them.

 

[joe-90]

You do to remove them. You haven't answered any of the questions. I guess you can't.