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Bricking up a fireplace - Ventilation?


Steve1309

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Hi, I'm bricking up a fireplace in a bungalow. It's a 1970s build and a small living room fireplace which I think has only ever had a gas fire. The gas pipe comes up from the floor in the middle of the fireplace. The chimney is lined with a round (pipe) liner of concrete/clay material? Question is, do I need to leave a hole when bricking up for ventilation? If so, what does this ventilation prevent and wouldn't it cause a draft into the living room?

Thanks for your advice.

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Yes,I believe it should be ventilated with an air brick which could be covered with a Louvre. You could minimise the downward draft of cold air by inserting a chimney balloon prior to closing the opening off. This should still allow enough air flow in the stack. My old chimney sweep told me that a virtually free alternative was to to stuff newspaper into a bin bag and place this in the flue. 

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Ventilation is intended to prevent the risk of condensation within the chimney. 

My understanding is that being in the middle of the house would reduce this risk significantly in any case as there are no cold walls. 

There are other posts on this when I was researching a similar question. Is it capped at the top? If so do you know with what? 

 

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  • 1 month later...
On 17/01/2023 at 07:19, larry said:

Ventilation is intended to prevent the risk of condensation within the chimney. 

My understanding is that being in the middle of the house would reduce this risk significantly in any case as there are no cold walls. 

There are other posts on this when I was researching a similar question. Is it capped at the top? If so do you know with what? 

 

 

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The builder has just removed the vented plasterboard on the former fireplace and plaster over the whole wall. The chimney is on an external wall. I think it should be ventilated to prevent condensation but the builder says no. SOS! Where is the other thread please. 

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This was a thread I started: 

 

In the end I vented it externally through the solid wall and and blocked up the internal opening. It's now got wood fibre insulation fixed to the whole wall and I'm in the process of making a hash of the lime plaster finish over the top :)

 

Key question though - is the chimney capped at the top - and if so with what? If somebody's just stuck a slate over the top (for instance) then ventilation at the bottom won't make a big deal of difference - you might need to vent to the loft as well (or I guess externally, further up the chimney to keep air flow).  And - is it dry in its present state? 

 

If it's a downstairs room and you've got suspended floors I guess you could also vent through the subfloor but I suspect there are risks doing this and would defer to others' advice. 

 

If you vent externally remember to drill the holes slighly angled to avoid rainwater running in to the chimney.  I made my ventilation with a few 25mm holes and then fitted of these wedged in through those holes  https://www.manthorpebp.co.uk/wall-floor-ventilation/weep-vents/refurbishment-weep-vent-2 (terracotta ones though on a brick backing so they aren't very visible). 

 

 

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Is this forum not a fan of filling the chimney full of EPS beads and ventilating only the chimney stack if still present?

 

Perhaps not an option for the OP depending on diameter of the flue, but to leave a space for colder air to circulate would seem unfortunate.

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34 minutes ago, Sparrowhawk said:

Is this forum not a fan of filling the chimney full of EPS beads and ventilating only the chimney stack if still present?

 

Perhaps not an option for the OP depending on diameter of the flue, but to leave a space for colder air to circulate would seem unfortunate.

I'd be a fan if I didn't hate ladders :)

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