Boarding attic, wires over joists, advice needed.

[cctvtobeornottobe]

Hi there I’m boarding my attic and the wires are going over the joists,

I know I can chisel a grove in the chipboard board or take the wires out of light fixture.

I was just wondering would it be a bad idea just to made a grove in the top of the joist with a round rasp just big enough for the wire to sit in the joist below the board?

I know you can also drill hole in middle of joist just wondering is it a bad thing to make notch in top of joist?

 

[diditrain]

I would say it would depend upon how deep the joists are. They should ideally only be drilled or notched in certain locations. If you google, where to drill joists, you should find plenty of guides. You should consider using safe plates as well, if you go down the notching route.

 

[Lister1987]

You can get attic flooring stilts (around 3-4" in height) - mainly designed to stop compression of insulation fill but it'll also solve the wire issue

 

[Wilko]

Hi - I don’t run twin and earth cables in joist notches due to the risk of damage from a future nail or screw. Here’s an extract of the Electrician’s Guide to Building Regulations on the topic.

 

[Pete999]

Hi - I don’t run twin and earth cables in joist notches due to the risk of damage from a future nail or screw. Here’s an extract of the Electrician’s Guide to Building Regulations on the topic.
View attachment 57818

Are the rules you quote the same for rafters, joists are not the same as roofing trusses are they? just wondering, after all they are not as robust as floor joists. smaller in all planes especially in new houses.

 

[buzzlightyear]

The best way of doing it is to put some plant on timber over the cables, so you do not take the stress out.

 

[radiohead]

Don't notch roof timbers. Either use a proprietary packing device as suggested above or a cheaper solution is to batten off the timbers with some 2x1.

 

[telectrix]

Are te rules you quote the same for rafters, joists are not the same as roofing trusses are they? just wondering, after all they are not as robust as floor joists. smaller in all planes especially in new houses.

good point. i'd be wary of drilling modern roof trusses. the ideal way would be to notch and fit plates. that also means that the cables don't need disconnecting.

 

[Wilko]

Are the rules you quote the same for rafters, joists are not the same as roofing trusses are they? just wondering, after all they are not as robust as floor joists. smaller in all planes especially in new houses.

Hi Pete - I hope you are well .
The minimum depth for unprotected cable should still be 50mm below the surface, but you’re right the strength of the beam needs consideration, which would likely be on a scale of ok to oh dear .

 

[radiohead]

good point. i'd be wary of drilling modern roof trusses. the ideal way would be to notch and fit plates. that also means that the cables don't need disconnecting.

Roof trusses should not be drilled or notched.