Ceiling/Downlight Problem

[actionjackson]

Hello all,

I have a current post in the electrics forum but have been advised i need to move the discussion over here to the building experts

Basically I'm attempting to install downlights in my 7yr old first floor flat which has a twin skin plasterboard ceiling.

I'm pretty sure its fixed to the joists using this stuff -

http://www.british-gypsum.com/produ..._profiles/gypframe_sound_insulating_bars.aspx

The problem i have is that one of the bars is not running parallel to the wall and although all my spacing etc was correct 2 of the holes are sitting over the bar!

Untitled

• actionjackson
• 15 Oct 2010
• 2

Please don't shoot me down for asking but can i trim the bar around the hole to fit the 2 lights or should i leave well alone? Unfortunately i have no access from above.

Neil

 

[geordiejoiner]

I would not mess about with this metal work as it is part of the sound reduction system between your property and the one above.
These resilient bars are also supporting the plasterboards of your ceiling and are quite thin so cutting into them would weaken that area. Go to the side if you can.

 

[alittlerespect]

Hi

My main concern would be that the twin layers of plasterboard are there to act as a 'fire break' between the floors of the building and by cutting the holes in the ceiling you will have significantly reduced the resilience of the ceiling structure to resist the passage of fire.

2 layers of plasterboard will give around 1 hours fire protection, cutting the holes will have significantly reduced this protection.

You may also find that you start to hear noises that you hadn't heard before as the plasterboard would have absorbed a certain amount of the lower frequency noises, but cutting the holes in the ceiling will have acted as something akin to leaving a tap running although instead of water you will have noise coming through.

Regards

 

[actionjackson]

Hi

My main concern would be that the twin layers of plasterboard are there to act as a 'fire break' between the floors of the building and by cutting the holes in the ceiling you will have significantly reduced the resilience of the ceiling structure to resist the passage of fire.

2 layers of plasterboard will give around 1 hours fire protection, cutting the holes will have significantly reduced this protection.

You may also find that you start to hear noises that you hadn't heard before as the plasterboard would have absorbed a certain amount of the lower frequency noises, but cutting the holes in the ceiling will have acted as something akin to leaving a tap running although instead of water you will have noise coming through.

Regards

Hi,

Fair points but i should have this covered. The downlights are acoustic rated/90 min fire rated/moisture seal rated/IP65 all to British Standards.

Neil