Blocking up chimney flue question.

[OpenToSuggestions]

Hi all.
I moved into my current home in the summer.
The gas fire was not plumbed and was broken.
I have replaced it with an electric fire and need to block up the flue as I lose no end of heat through it and can always hear any wind howling down it.

I plan to put one of those flue balloons up it. It is a flue that is built into the cavity wall and I don't have a chimney breast. Do I need to worry about damp at all?

 

[Nightglow]

Most will allow for a little ventilation, so you shouldn't have a problem & get the right size for your chimney.
Chimney here, I just used a strip of mdf 12mm against the flue before inflating balloon to give a small gap.

 

[Maccapacca]

I'd sheet over with a piece of insulated plasterboard and install a hit and miss vent http://www.sdslondon.co.uk/hit-and-miss-vents.html to suit.

But I can pick up small pieces of plasterboard myself from site, you don't want to be buying a full sheet so anything you can pick up with some solid insulation on the back like MDF

 

[MikeTimbers]

I read it's vital to put a flue at the bottom to prevent damp build up and also to ensure the chimney pot is one that prevents rain getting in.