Looking for smoke alarm with 120mm+ diameter base

[reubin78]

Moved into a property that has a papered hallway and landing ceiling. Stuck to the papered ceiling are two old smoke detector bases - measuring 120mm diameter.

I've tried to remove a base but gave up as its clear it will result in some/all of the paper being damaged/removed.

Plan B is to try and find two battery powered smoke alarms with bases that cover the area. Tried a few shops but they only seem to stock smaller sectors.

Any ideas? Need to have a base larger than 120mm.

Thanks for reading

 

[OwainDIYer]

You can buy MDF or ply circles from craft shops/ebay etc in almost any size example

If you are putting in new smoke detectors I think they now have to be mains and interlinked to comply with Building Regs?