safetywalls
I'm about to drill some 5mm diameter x 35mm deep holes to support a new curtain rail and when I used a voltage/metal detector to check for cables etc. it gives an alert for the entire surface of the wall. Is this possible and does it mean there may be a problem with the electrics in the flat?
Possible things I have thought of are:
The detector isn't calibrated correctly. I have calibrated according to the instructions
The wall paint is conductive.
What should I do?
TJIs of some sort making it virtually certain that the wall is not load bearing. The same joists are holding up the same second story over the same span beyond this wall.
If the wall was a properly built load-bearing single-top-plate wall every stud would be exactly under a joist. Its not load-bearing.
Luckily your mount has slots for the bolts so you have a bit of room to work. Get another (stronger, higher quality) lag bolt and put it in right beside the broken one.
Leave a tiny bit of room between them if you can, but make sure it still solidly hits the stud.
Predrill the hole. To find the right size, hold the bolt up behind your drill bit. The drill bit should cover the entire shaft, but not the threads. Make sure you drill to the same depth the bolt will go to.
Rub the bolt threads on a candle or bar of soap to lube it up a little if you think it is going to be hard to drive in again.
Drive the bolt in slowly. Don't use a drill unless it has a low torque screwdriver setting. You might want to tighten it with hand tools anyways so you don't risk snapping this one too. There probably isn't room for a third try!
Best Answer
If you're using a metal detector maybe your wall is plaster on wire lath, there's such a thing as electric heat elements embedded in walls or maybe steel studding. You need to know what your wall construction is, and do you mean 3.5mm holes for screws?