Insulating an unused chimney – Singletrack World Magazine

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We’ve had the fireplace made into a box (we’re not using it so no wood burning stove), and a c-cap fitted to the chimney pot.

Over the weekend we also had a heat survey done on the house, and one of the points made was the draught from the chimney. A closure plate(?) is fitted as the ceiling to the fireplace box and it has a vent grill in.

What would be the best way of insulating that doesn’t create a panic over potential damp/condensation in the chimney?

We had lined up our chap to change the c-cap and on his suggestion put some insulation in, to counter the bongo drum noises amplified down the chimney when it rains. Would this sort it, or are we best looking into something like a Chimney Sheep or balloon instead above the fireplace (assuming plate can be removed to access)?

The heat surveyor mentioned something about insulating at the top or at the bottom but not both.

I’d line it with the cheaper stainless liner and pour pumice from the top to insulate it all making sure the chimney is capped properly

You never know you may want to reuse the flue sometime in the future or if you sell the property on

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I filled a bin bag with left over loft insulation (the horrid glass fibre stuff) and rammed it up the chimney. Stuck a length of PVC waste pipe next to it for ventilation.

No damp so far!

A chimney sheep?

Chimney Sheep® Draught Excluder

We’ve had the fireplace made into a box (we’re not using it so no wood burning stove),

Not sure if your type is welcome here.

Chimney balloon.

Won’t a chimney sheep or balloon just stop the draught from your room, which might encourage damp? Would there be any way to get the chimney to pull air from under the floor space, or an air brick on the outside of the building, rather than your living room? You could then fit a chimney sheep or even block up the grille in the sealing plate.

Chimney sheep is breathable.

Certainly no damp here

Resisted the chimney balloon for that reason though.

Makes a hell of a difference.

i used a chimney baloon, it was horrible. In the rain it sounded like drumming and amplified any wind noise from outside. Italso went flat every year.

Instead i just stuffed it with rockwool.

Possibly a silly thought: Could the chimney be re-used as part of a heat recovery ventilation system?

When I looked at this it was suggested to add an air brick in the attic (assuming it is a vented space) and fill with loose fill insulation below that line.

The principle being that any moisture still getting in at the top despite the cap is wicked away by the airflow through the attic.

I just installed a Chimney Sheep in the end.

Thanks all for the thoughts. Certainly sounds more straight forward to opt for a chimney sheep install if the closure plate can be removed, but for peace of mind given what the heat loss surveyor said I wouldn’t want that as well as some insulation up near chimney level (though I’ve struggled to find any info on the ‘dangers’ of insulating bottom and top).

Hopefully the chimney sheep at the lower level will also sort the rainfall drumming noises!

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