Drilling Hole in Joist (Attic Trusses)

[AndyScholes]

Hello

I'm currently looking to install 6 spots in my downstairs room - replacing an existing pendant light.

My house is made with engineered attic Trusses. It's like a big bungalow with an upstairs / downstairs and loft space - although the upstairs rooms have sloped walls.

I'm trying to figure out my options for routing new cable. It's a downstairs room with limited access from above. To get access would mean moving a lot of stuff + it's a plywood floor so would need to start cutting holes out of it.

I'm fairly certain that with Attic trusses that I should not put any holes in them for cabling. I'm wondering if the same applies to the joists between each truss? Could I put a small hole through the middle of them?

I've attached a picture, the joists are substantial and run from the full height of the void - so no gap above / below.

If I can drill through them I'm thinking I can get cable for each row of spots back to the wall and from there route the cable in the safe zone along the top of the walls.

Thanks
Andy

 

[chivers67]

watch this

 

[AndyScholes]

Cheers - decent video that.

I know the regs for drilling joists - I just don't know what the regs are for my joists. I'm guessing my joists are engineered - so different rules.

 

[sparkwright]

Send more pictures, taken further back, so we can see the whole thing.

 

[Sureitsoff?]

Surely the joists between the trusses are just effectively large noggins so a 20/25 mm hole will not affect the strength

 

[AndyScholes]

Surely the joists between the trusses are just effectively large noggins so a 20/25 mm hole will not affect the strength

That's my thinking

I don't see how it can impact the strength. But even on the video above it says different rules apply for engineered joists .. and I'm guessing it is engineered as I know the Attic Trusses are and in the picture you can see it's got that big metal plate thing on it attaching it to truss (maybe that's normal though).

That joist is full height 9inch.

 

[AndyScholes]

Send more pictures, taken further back, so we can see the whole thing.

I'll take a few when I get home tonight although not sure it will show you much more - if you step back from that picture that's just me looking up through the ceiling.

 

[AndyScholes]

Here's another picture - not sure if it's much help.