Loft wiring

[Sharpend]

Generally any roof supporting structures can not be drilled. 

 

[Sidewinder]

Generally any roof supporting structures can not be drilled. 

Really?

Are you sure?

 

[Sharpend]

So every building control officer I've ever worked with has said, so on the law of probabilities I guess some had to know what they were talking about! But then maybe it's just the general roof types we've done? 

 

[Sidewinder]

I had this very discussion with a BCO a few months ago, & he said exactly what you said.

Then I stated that it was OK to drill if it was done on the neutral axis.

At this point he was speechless.

He then went on to quiz me about neutral axes and beam loadings etc.

Once I had explained and answered his every question (even though I was not involved in "drilling" structural beams), then he relented and said, that, yes, if I did it my way then it was fine.

They do not allow it, because it is not done correctly, thus they find it easier to not allow it, rather than have to explain or get remedial works done.

Have you never seen a castellated beam?

 

[Manator]

I had this very discussion with a BCO a few months ago, & he said exactly what you said.

Then I stated that it was OK to drill if it was done on the neutral axis.

At this point he was speechless.

He then went on to quiz me about neutral axes and beam loadings etc.

Once I had explained and answered his every question (even though I was not involved in "drilling" structural beams), then he relented and said, that, yes, if I did it my way then it was fine.

They do not allow it, because it is not done correctly, thus they find it easier to not allow it, rather than have to explain or get remedial works done.

Have you never seen a castellated beam?

After a freshly submitted TMA I had the same discussion The BCO was dumbfounded when I presented my evidence.

 

[Andy™]

probably not used to anyone challenging them

 

[Sharpend]

yes, in metal beam only, not roof timbers. 

 

[Rob_the_rich]

yes, in metal beam only, knot roof timbers. 

Fixed that for you

I agree, it might be fine on paper, but somewhere along the line a judgement is made by a human on a natural material, guesswork really.

edit; castellated beams, as Ian Dury said "there aint half been some clever broad beans"

 

[dave2]

What do you think what cause most stress to a roof structure? A 10mm hole through each joist or a load of chipboard + extras on each joist.

Most engineered roof structures are designed for the roof covering only and not for boarding out lofts.

 

[Andy™]

and look at how many people have added boaring and store lots of stuff in the loft without anything falling down

 

[SPECIAL LOCATION]

There might be a couple that could be re-routed, but most run a pretty direct route from one point to another straight over the top of joists with not much slack.  I only want to put a few boards down, I didn't really want to get into replacing cables!!!

There can't be that many cables if its just an average domestic property.....

2 or 3 bedrooms..

Landing...

bathroom...

If your only putting a few boards down then I guess not every cable will need moving....?

Surely the cheapest solution is just get the few cables re-routed and save prating around with batten and spacers etc...

and have no risk of squashing a cable as they will all be out of the way.

opcorn

 

[steptoe]

There can't be that many cables if its just an average domestic property.....

2 or 3 bedrooms..

Landing...

bathroom...

If your only putting a few boards down then I guess not every cable will need moving....?

Surely the cheapest solution is just get the few cables re-routed and save prating around with batten and spacers etc...

and have no risk of squashing a cable as they will all be out of the way.

opcorn

The thing is,

Insulation depth.

I live in a 2&1/2 bed semi, have you seen that mess of cables on my gable wall,? :C

 

[SPECIAL LOCATION]

The thing is,

Insulation depth.

I live in a 2&1/2 bed semi, have you seen that mess of cables on my gable wall,? :C

Not much of an issue for lighting.....

1.0mm  worst case de-rated down to 8A enclosed in insulation in a stud wall....

or 1.5mm  down to 10A enclosed in insulation in a stud wall...

{method 103}

or if we go above a plasterboard ceiling under greater then 100mm insulation  {method 101}

we still have 10.5A or 13A to play with for 1.0mm & 1.5mm respectively.

Assuming were on 6A circuits here... Just re route and cover the lighting cables...

still can't see much of an issue....

From what the OP said I don't read this a shower cables....

Which would be a different ball game altogether.

Guinness

 

[steptoe]

Not much of an issue for lighting.....

1.0mm  worst case de-rated down to 8A enclosed in insulation in a stud wall....

or 1.5mm  down to 10A enclosed in insulation in a stud wall...

{method 103}

or if we go above a plasterboard ceiling under greater then 100mm insulation  {method 101}

we still have 10.5A or 13A to play with for 1.0mm & 1.5mm respectively.

Assuming were on 6A circuits here... Just re route and cover the lighting cables...

still can't see much of an issue....

From what the OP said I don't read this a shower cables....

Which would be a different ball game altogether.

Guinness

But how is the OP going to obtain anything more the 6" (if it's an old house, 100mm for a more modern house) of insulation if he boards directly onto his trusses or joists,?

Iirc recommended depths are 270mm or 10".