Narrowest drill dia...
 

Narrowest drill diameter plasterboard type fitting

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Hi, it’s for an old (1970 house with a plastered ceiling)  that has just been deartexed and reskimmed and repainted, experience has taught me  it often crumbles when you try to screw into it so after a drill fitting as that appears to work (starting with 2 or 3 mm then sizing up) smallest  I can find is 6mm drill hole (Fischer plasplug), it’s for a smoke alarms so no real weight, anybody know any really narrow diameter fixings 

 

thanks

 

 
Posted : 08/04/2025 2:39 pm
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It's just a smoke alarm, just fix it with 2 woodscrews it'll be fine. Never plugged any of mine and none fallen down....yet

 
Posted : 08/04/2025 3:38 pm
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I've used those Fischer plaster plugs, since moving into a new build. As above if you're worried about their larger diameter plain s ress or a couple of fisher duo power should be fine for a smoke alarm.

 
Posted : 08/04/2025 6:50 pm
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Knock on till you find a joist, innit

 
Posted : 08/04/2025 6:58 pm
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5mm rawlplug uno are the smallest I’ve ever bothered using. Generally seem to get on well with the uno plugs  

 

https://www.toolstation.com/rawlplug-uno-universal-contract-wall-plug/p81139

 
Posted : 08/04/2025 6:59 pm
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if it’s just a smoke alarm does it matter if you get a bit of crumble - it’s going to be behind the smoke alarm 

 
Posted : 08/04/2025 7:09 pm
 pk13
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10mm sq Valero sticky  pads are amazingly strong.

And before anyone says not fire safe ect the smoke alarm should have done it's job wayyyy before it melts the sticky pads

 
Posted : 08/04/2025 7:12 pm
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Posted by: bigginge

5mm rawlplug uno are the smallest I’ve ever bothered using. Generally seem to get on well with the uno plugs  

 

https://www.toolstation.com/rawlplug-uno-universal-contract-wall-plug/p81139

 

i use these Yellow ones for anything light weight (and sometimes probably heavier weight than I should 😂).

I actually bought a big multipack of about 4 different sizes years ago that have kept me going, very handy to have on the garage shelf.

 

 
Posted : 08/04/2025 8:00 pm
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Things like these are really good in my experience:

Plasterboard fixings

But, total overkill for a smoke alarm!

either use a wood screw self tapped into the board, and don’t crank down on it, or any small plastic plug. 

 

 

 
Posted : 08/04/2025 8:23 pm
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You may well get very small plugs in the box with the alarm

Personally I just screwed straight into plasterboard, no probs in my 80s house

 
Posted : 08/04/2025 10:16 pm
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Those Fischer Duo ones are the best. 

 
Posted : 09/04/2025 7:16 am
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Walldog screws would be my choice. Designed to hold without a plug or pilot hole and have a sharp deep thread. They also hold on brick and concrete with a pilot hole (again no plug).

They are designed as fire safe fixings but appreciate that's not required here.

https://www.screwfix.com/p/dewalt-wall-dog-phillips-countersunk-self-tapping-multipurpose-screws-6mm-x-32mm-100-pack/4017p

 
Posted : 09/04/2025 7:29 am
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Id just atick it to the ceiling.  Thats what the fire ser ice did when fitting tbem in my stair

 
Posted : 09/04/2025 9:48 am
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Yep, all my smoke detectors are just stuck on with 3M command strips

 
Posted : 09/04/2025 9:52 am
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I make sure I always have plenty of Fischer Duopower plugs in 4,6,8mm.  Yes they're pricey but they take all the thinking out of a job. Saving time and worry.

 
Posted : 09/04/2025 10:15 am