hole size for expansion bolt

[ny_bygg]

I want to mount an M12 expansion bolt in concrete, how big should the drill hole be? Should I use a 12mm drill bit or larger?

 

[andersmc]

If the thread is M12, then there is a sleeve outside the thread, so the hole must reasonably be larger. I would guess 14mm, but the easiest way is for you to measure your specific expansion bolt.

 

[Bubblaren]

For the anchor bolts I've used, the drill diameter is the same as the thread (M12 - drill 12 mm). Otherwise, the manufacturer should have it on their website. I checked on Hitachi's website http://www.hitachi-powertools.se/db/repository/x1801201117193.pdf

 

[Alfredo]

I am so boring that I say: read the manufacturer's instructions. Should be on the packaging or on a data sheet that can surely be found online.

 

[whork]

14 mm would probably apply if you were going to use chemical anchors to secure the bolt forcefully, but if it's an expansion bolt, you should go for 12 mm.