Re-using holes in joists...

[Myles]

The regs on where you can and cant drill holes in joists are quite clear, but what about if rewiring for a material change of use where new regs must apply? Would it be okay to rewire through holes which no longer comply? The holes in question are closer than 0.25 of the span to the wall.....but drilling new ones would theoretically weaken the joist even more! Tried to ask NICEIC tech line and was on hold for 40 minutes.....so gave up!

What d'ya reacon??

Thanks,

Myles

 

[eskimo39]

I reckon the NIC techline is taking the mickey

Not sure about about any guidelines but surley from a common sense purpose you could never be wrong to reuse them. Unless of course you have a magic machine which can refill the holes and make them as good as new.

 

[Myles]

Indeed I can't see why not too, cheers. To drill new ones to satisfy regs would be cutting off nose to spite face

 

[eskimo39]

It would also weaken the joist even more.

 

[Notsosmart]

As long as they are at least 50mm from the top or bottom.

I have seen rewires that have used the long defunct notches on the top of the Joists....I also found a stetson & spurs lying about..

 

[Des 56]

The distances in the building regs are probably to prevent weakening of the structure
If they exist already,then drilling more will add to that weakness

My take on it is that you are making use of existing, albeit non compliant holes,a sensible decision
I cant see any reasonable building inspector making noises about it
If they are too close to the tops of the joist,I would expect that they would need plating however

 

[Guest123]

I would agree.

You aren't damaging the intergrity of the joists anymore than they already are by re-using these holes. As long as they are not directly under the niling points for the floorboards then I would be quite happy.

 

[andyb]

You can use redundant notches as long as the cable is mechanically protected. You can even make new notches, plumbers do it all the time.
You can buy metal plates that cover the notch from any wholesaler.

 

[sparks1234]

Be honest here.

If you are doing a rewire with beds, wardrobes, chairs etc etc. who does carry out holes as per the guidance?

 

[padmore12345]

you can reuse old holes or notches but they may need to be mechanically protected eg by metal plates if less then 50mm from top or bottom of joist. you can reuse them under the guise of part A (structure)of the building regs, you shouldnt make a structure any worse then when you found it, ie weakening the joists further by adding extra holes.

 

[theleshollis]

I asked my ELECSA rep about re-using notches when I was assessed, he said that they could be used but must be protected by a 3mm steel plate. The joist plates I have are about 1.5mm, so I reckon 2 ofe these would have to be used to comply.