On 22/03/2021 22:00, Vir Campestris wrote:
On 21/03/2021 22:13, alan_m wrote:

I also bricked up a chimney opening this morning after removing a gas
fire.Â* As I already had some sharp sand and cement from my previous
job I used a 4:1 mix to mortar in some bricks.Â* 11 hours later the
mortar is hard, although not fully dry. I put a pile of the mortar I
had left over on a sheet of plastic in the outside cold. This pile is
still very crumbly so an extra 15C of temperature has made a large
difference to the setting time, as expected.

Have you made provision for ventilating it?Â* (It's normal to leave an
airbrick at the bottom. For good reason)

ANdy

Yep, all my bricked up chimneys have a ventilation grill in the room.
I've used
tinyurl.com/3nsk36yk

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk