Chimney vent

[davidor]

It is always suggested that when blocking up a fireplace, a vent should be put in to prevent condensation and damp.

I have a 1970s brick-built house with two chimneys going up the middle, which I no longer use. If I block off the fireplace AND cap the chimney, does it still need ventilation?

2nd point: the pots are short clay pipes about 12inches in diameter. To cap them off I thought of cutting a bit of ply, putting a bit of wire through the middle and dropping it a couple of inches down the pot with the wire tied to a small bar across. then filling the top up with cement, leaving a domed top. Is there a better way to cap off the chimneys?

 

[Lower]

i believe that if there is not risk of water getting into a chimney, ie its properly capped, you don't need to vent it at the bottom.

 

[masona]

Is there a better way to cap off the chimneys?

Yes, I wouldn't use cement just incase it ever need in service again, the quickest and the cheapest way is here. Having said that it's best to have a vent chimney cap type and a open/shut vent shutter on the chimney breast below as it's a very cheap way of dealing with ventilation or condensation problem.

 

[snowgatehead]

I would agree. A disused chimney flue will need ventillation so that moisture can escape, and not condense on the flue walls.

As the previous poster said, you ccould buy a capping cowl.

Or, you can remove the chimney pot & using a peice of upside down half round gutter / cast half round pipe, cement that on the chimney stack upstand, so that air can circulate & stop rain from entering.