Vermiculite chimney infill above a roofline lead tray.

[epsilonGreedy]

My question is related to the question just raised by @MortarThePoint. Once a tile-height lead dpc tray is installed and the build of the chimney continues up with bricks and flu sections up to pot height, should the remainder of the chimney void be filled with Vermiculite?

 

My concern is that the final top courses of the chimney above tile height will be exposed to the weather and prone absorbing rain. If the chimney void is filled it could act like a sponge.

 

Prior question:

 

Edited March 22, 2021 by epsilonGreedy

[MortarThePoint]

This was one of the main reasons I decided against saving some money by using vermiculite rather than the Isokern recommended Leca. In reality I suspect it's a non-issue though as the total amount of rain that's going in to your chimney pot is probably around 0.1*0.1*3.141*0.6 = 0.019m3 = 19litres/year (climate data [1] [2]). Across a whole year that's not much and averages about 200ml per rainy day which is a glassful.

 

You definitely need something surrounding your liner for support.

 

[1] https://www.metoffice.gov.uk/research/climate/maps-and-data/uk-climate-averages

[2] https://www.metoffice.gov.uk/research/climate/maps-and-data/uk-climate-averages/gcr9j7q0s

[PeterW]

2 minutes ago, MortarThePoint said:

suspect it's a non-issue though as the total amount of rain that's going in to your chimney pot is probably around 0.1*0.1*3.141*0.6 = 0.019m3 = 19litres/year (climate data [1] [2]). Across a whole year that's not much and averages about 200ml per rainy day which is a glassful.

How have you calculated that ..?? Assuming the pot is open..?? 
 

You need to fit a cowl to stop birds nesting and also keep crap out of the pot - they reduce the rain exposure unless it’s lashing sideways to probably a teaspoon. 
 

https://www.fluesystems.com/shop/Colt_High_Top_Birdguard_SF.html#SID=14
 

Shop around and you can get a Colt High Top for about £25. 
 

To make it neater, turn the stainless straps in on themselves and trap the ends with the band. Much easier to do when the scaffold is still up ..!

[MortarThePoint]

15 minutes ago, PeterW said:

How have you calculated that ..?? Assuming the pot is open..?? 
 

You need to fit a cowl to stop birds nesting and also keep crap out of the pot - they reduce the rain exposure unless it’s lashing sideways to probably a teaspoon. 
 

https://www.fluesystems.com/shop/Colt_High_Top_Birdguard_SF.html#SID=14
 

Shop around and you can get a Colt High Top for about £25. 
 

To make it neater, turn the stainless straps in on themselves and trap the ends with the band. Much easier to do when the scaffold is still up ..!

 

Yes I've assumed the worst case of it having a 200mm opening at the top.

 

We're planning to fit a wire Tepee:

A cowl with a lid would make a big reduction to the water entry.

Edited March 22, 2021 by MortarThePoint

[PeterW]

They are crap and stuff ends up in them. Have seen birds nest on them and sweeps push them out so a secured cowl is much better. 

[epsilonGreedy]

31 minutes ago, MortarThePoint said:

This was one of the main reasons I decided against saving some money by using vermiculite rather than the Isokern recommended Leca.

 

 

Hmm yes I take your point, my flu section below roof height is made from commodity Redbank sections which were the default available at my local BM. If I fitted a purpose made lead dpc tray with the inner 100mm upstand then I could build the flu using your choice of flu sections.

 

38 minutes ago, MortarThePoint said:

In reality I suspect it's a non-issue though as the total amount of rain that's going in to your chimney pot is probably around 0.1*0.1*3.141*0.6 = 0.019m3 = 19litres/year (climate data [1] [2]). Across a whole year that's not much and averages about 200ml per rainy day which is a glassful.

 

 

I suspect a chimney is going to pick up a lot more moisture from its facing bricks as the wind drives rain. My working hunch is that the chimney will absorb less water and dry more quickly if the final 18 brick courses of chimney above tile height surround a hollow void.

 

43 minutes ago, MortarThePoint said:

You definitely need something surrounding your liner for support.

 

 

Yes think you are correct, I was hoping to discover some purpose made metal support bracket/clamp that could be embedded in the brick courses and wrapped around the flu sections for lateral support.

[epsilonGreedy]

39 minutes ago, PeterW said:

https://www.fluesystems.com/shop/Colt_High_Top_Birdguard_SF.html#SID=14
 

Shop around and you can get a Colt High Top for about £25. 
 

 

Something like that would trigger aesthetic distress in my local conservation officer.

[MortarThePoint]

20 minutes ago, epsilonGreedy said:

 

Something like that would trigger aesthetic distress in my local conservation officer.

 

My honourary local conservation officer is in the kitchen having a cup of tea and not so keen on that type either

Edited March 22, 2021 by MortarThePoint

[Cpd]

1 hour ago, MortarThePoint said:

We're planning to fit a wire Tepee:

A cowl with a lid would make a big reduction to the water entry.

 

40 minutes ago, PeterW said:

They are crap and stuff ends up in them. Have seen birds nest on them

As Peter says they are crap and there are far better options, this is what I did with the one on my chimney!

 

[PeterW]

1 hour ago, epsilonGreedy said:

 

Something like that would trigger aesthetic distress in my local conservation officer.

So the CO can go talk to the BCO and get them to sign it off ..! Conservation officers are so far up themselves it is frighning ..!! It’s the only position that allows an unelected official to use their opinion .....! Everyone else has to use facts ... 

[epsilonGreedy]

2 hours ago, PeterW said:

Conservation officers are so far up themselves it is frighning ..!! It’s the only position that allows an unelected official to use their opinion .....! Everyone else has to use facts ... 

 

 

So true, our previous conservation officer instilled a degree of fear in the freeholders of the village not seen in England since Marcher Barons were overlords of the Welsh boarder counties in the medieval period.