Chimney venting

[housewinnie]

Hi again, I will post pics next time im up there, but raining again, scaffolding all done so getting ready to start, the flashing and pointing etc.

My question is we have fireplaces in the bedrooms which have had the dampers sealed up, which i plan to unseal and open. On top of the chimney the bedroom side has no pot and has just been flaunched over and sealed. My plan is to remove and redo the flaunching and add just what I think is called an elephants foot, not going to add a pot but just sit the elephants foot and flaunch around it.

Good idea or not?

Cheers again all

 

[a twig]

An elephant's foot is intended to go into a pot, wouldn't suggest flaunching around it.

If you already have the scaffold etc in place, I don't see the point in skimping on the £30 or £40 on a pot. It also then means if you (or anyone else) decides to use those flues in future then all they have to do is remove the foot. We re-opened a chimney here and were very grateful to the previous owner who had taken this route!

 

[housewinnie]

OK, but the flues are from the bedrooms and will not be used for a fire.

Thought it would be fine to flaunch around an elephants foot.

 

[a twig]

I think that's the point though isn't it - while you don't want to have a working fireplace in a bedroom now, future you or a future owner might? Maybe in 20 years we will all be install hydrogen fuel cell powered heaters in our fireplaces which need venting?

If you really don't want a pot, then you may as well leave the existing sealed flaunching and put an airbrick in the stack a few courses below where it is sealed, or even more expediently, a neat arrangement of 1" holes drilled through with insect mesh fixed over them - I think someone on here did that, Ivor maybe?

 

[housewinnie]

One more question, Am going to flaunch with Lime do I do a scratch coat or do it in one go?

Cheers again

 

[malcolm]

Use concrete for chimney flaunching. It's more weather resistant than lime and the flaunching doesn't want to breathe as it would let more moisture in than it let's out.

It's worth looking up flaunching on the Internet. It should be a few inches thick with falls and not the mess that modern builders will make.

 

[housewinnie]

Ok cheers Malcolm, when you say concrete assume you mean normal Portland mix, once done is it worth using a waterproofer sealant on the flaunching? cheers again Mark

 

[malcolm]

I think I used ballast in mine like you would use for a concrete floor. The larger ballast allows a thicker application and prevents cracks better than something like sharp sand.

Bung it on in one go in a fairly dry mix and let it dry a bit before final toweling. I wouldn't use any sealer.

 

[Lacan07]

Use concrete for chimney flaunching. It's more weather resistant than lime and the flaunching doesn't want to breathe as it would let more moisture in than it let's out.

It's worth looking up flaunching on the Internet. It should be a few inches thick with falls and not the mess that modern builders will make.

Thanks Malcolm, I didn't know this.

 

[stuart45]

Ok cheers Malcolm, when you say concrete assume you mean normal Portland mix, once done is it worth using a waterproofer sealant on the flaunching? cheers again Mark

If using concrete, a 10mm gravel is easier to get a good finish with.
Nowadays, a high bond DPC is used under the flaunching, as fine cracks develop in mortar and concrete in time.