Holes - sealing and integrity etc...

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dixon9

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When drilling through ceiling (plasterboard for example) when dropping/running cables to switches in cavity between brick and stud/plasterboard do you seal the hole?

Same for outside lights for example - drilling through brick and cavity...

What

 
When drilling through ceiling (plasterboard for example) when dropping/running cables to switches in cavity between brick and stud/plasterboard do you seal the hole?When dropping cables down stud wall use say 20mm wood bit no need to seal hole. Just as long as each rooms ceilng and floor is made good and there is no direct opening from one floor to the next so as to reduce risk of fire spreading. i think you only need to worry about hole reseal if you are bashing out bigger holes or in places like apartment blocks when supply cables are going up through each floor in service cupboard.Same for outside lights for example - drilling through brick and cavity...

I normally just seal hole on outside with silicone sealant and also drill at a slight downwards angle.

What
 
Also forgot to say, I dont think your Part P assessor is going to be taking up the floor to see what holes you have made.

He will be more interested in health & safety, safe isolation, testing, paperwork and general competency in following regs.

If say you do a consumer unit change and its not the neatest he cant really say anything just as long whats done is correct, ie cables terminated and identifed correctly.

 
Ok...thanks for the answer.

So, as a general rule, ceiling holes (as in the example above) 20mm with no sealing/grommet etc is fine.

And sealant on brickwork for outside lights.

 
Yes thats right, i have never seen holes in stud walls(looking from above into top peice of wood) or small holes in ceiling when for example in a cupboard made good. The only exceptions are when you are making larger holes with your hammer or taking trunking etc straight through.

 
If it helps I showed my assessor a two way outside lighting circuit and he got me to take the front of the light switch off to make sure i'd used grommets and sealed the hole in the brickwork ... also asked what i had considered when drilling through an external wall ..

 
Sealing holes is more about maintaining the integrity of the building and its characteristics more than anything else.

Drilling through an external wall would require you to maintain the damp proofing more than anything else, drilling through a ceiling would require you to maintain the sound and thermal integrity and if applicable the fire integrity.

Holes should be sealed if any of the buildings characteristics could be changed by introducing an opening.

A fire boarded ceiling or wall will have a weak point at the point of the hole you have made, so it would be common sense to reseal that hole so it provides the same overall protection it would have done if no hole was present.

Drilling through external walls are best done at a slight down angle to prevent rain from entering, and be sealed with silicone to prevent water from breaching the cavity by cappilary action along a cable etc etc.

 
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