cables in attic

[JACKC]

What are the regs for routing cables in attics please, mine are just laying across the joists. I want to board up the loft but cables in the way. Told to disconnect , drill joists and reconnect. OSG does not mention routing in attic space.
Would welcome any thoughts before I foul up.
Suspect not allowed to drill attic joists (Nail plated joists )and a case of rewiring and routing correctly. Also can you tell me what book to read explaining all of this to me.
Many thanks.

 

[JohnD]

How deep are the joists?

If you decide to counter-batten them (look it up on "search" here) then the cables can safely go in the gap between the new timbers.

 

[Adam_151]

I hope your are not planning on drilling preformed roof trusses

(they are made to such tight tolerances that drilling holes in them cannot be recommended!)

[I have once but a 5mm dia hole right at the top of one, almost like a very small notch for a speaker type cable - but if you want to route T&e you are going to need much bigger holes than that...]

 

[HDRW]

I hope your are not planning on drilling preformed roof trusses

(they are made to such tight tolerances that drilling holes in them cannot be recommended!)

[I have once but a 5mm dia hole right at the top of one, almost like a very small notch for a speaker type cable - but if you want to route T&e you are going to need much bigger holes than that...]

You realise that the best place to drill is right in the centre of the height of the beam? Since the top is in compression and the bottom in tension, the middle is "neutral", that is contributing little to the structural strength. By notching the top (I know you didn't say that!) you are reducing the width of the wood at that point and providing a point for a crack to start.

Assuming the OP is talking about lighting cables, he'll need about a 10mm hole, and as you say, that may weaken the truss too much, but the centre of the height is certainly the place to do it if he going to do it!

Cheers,

Howard