Fitting an M12 coachbolt - do I drill 12mm hole?

[diyAlex]

Hi, just about to use some coach bolts to join some timbers. I'm going to use M12 bolts - do I drill 12mm diameter holes for this? Or actually, will I need to drill 13mm diameter?

I don't want to drill too big such that the head + nut starts sinking in. But also I don't want to drill too small such that I'm using a hammer to get the bolts through in the first place!


cheers!

 

[freddiemercurystwin]

12mm bolts will fit through a 12mm hole, nothing wrong with a good tight hole though is there?

 

[foxhole]

Use washer under bolt head and nut to reduce sink in .