# Black Dirt around recessed lights



## godthe (7 Jan 2011)

I had an extension built 2 years ago and I have insulation between joists in the ceiling. There is no insulation near the recessed lights ( fire hazard ) and there is now a black rectangle of dirt around the lights. The walls are insulated with insulated plasterboard and they are pinned to the wall with metal mushroom type pins. There is also a black mark where these pins are. Can anyone tell me the cause of this and a remedy please.


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## dublin5guy (7 Jan 2011)

More than likely its caused by a draught within the ceiling void around the light fitting which is pulling dirty air and depositing it around the light fitting. A second possibility is heat scorching, but you would probably have an acompanying smell. Have it checked out by a professional electrician if you are worried


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## onq (7 Jan 2011)

Hi godthe,

This could be as dublin5guy suggests and I would certainly eliminate alternative causes where possible..

However his suggestion doesn't seem to address the wall marks and even your ceiling problem may not be straightforward and could have other causes.

With due respect therefore to dublin5guy, I offer the following advice for your consideration.

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The Ceiling:

Assuming the lights are circular a rectangular black mark on the ceiling may be caused by the outline of the uninsulated space between the joists.
If so this in turn may suggest damp  caused by condensation occurring on surface the affected section of plasterboard around the lights, which would act as a cold spot.
The local heat effect caused by the light ceases when the light is turned off, but the cold bridge remains, and the air in the room will still be carrying water vapour which may condense on the cold surface.
Black mould may then grow on the surface betraying the damp

Test:

Remove one light fitting, make good the hole and install insulation over it and repaint the ceiling to see if the mark re-occurs.

Remedy:

If it does, consider removing the downlighters, making good an insulating all the holes and replacing the lights with surface mounted fittings, making sure the roof void is properly vented in accordance with the Building Regulations F 
-TDG F 2009 Diagram 11 P. 28 or
-TDG F 2002  Diagram 6 P. 11

They are very similar in relation to this matter.

Alternatively you could leave as is using an insulated box [made from timber perhaps] with vent holes in it to keep back the insulation but prevent heat build up.
The holes should be positioned to vent easily to a minimum 50mmm clear space away from the insulation - typically in the top of the box.]
Repaint as required and monitor.

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The Wall:

The marks on the wall may be related to cold bridging again causing a local cold spot leading to condensation and damp but I wouldn't have expected a mark to show through on insulated plasterboard. It depends on whether the fixing comes through the insulation to the back of the plasterboard I suppose.

Alternatively the marks on the wall could betray a damp wall behind the insulated plaster board, whether caused by condensation of water vapour or damp ingress from the external wall.

If the condensation behind the plasterboard is severe the conditions  behind the board may look similar to damp ingress through the wall.

In such conditions the metal connector could either be attracting the condensation and transmitting to to the plasterboard where it comes through, or it could be transmitting water ingress.

If the kitchen is in the extension and if its not well ventilated you can experience a build up or water vapour in the air that can exacerbate the incidence of damp around any cold spot.

To deal with water ingress examine the wall, trace the leak [which could be down to the render, a movement crack, improper capstone or eaves or gutter or parapet gutter details - a hole slew of them] and repair. The cavity will usually dry out with time.

To deal with condensation getting behind the insulation you could seal the surface and any services penetrations and reduce the water vapour in the room air.

One option might be to install a good MVHR system if you want to keep the place sealed.
Install a good kitchen hood and extractor if not and ventilate manually [open windows].

Repaint as required and monitor.

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                                     as a defence or    support  -     in     and    of        itself  -         should          legal             action        be           taken.
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## godthe (7 Jan 2011)

Thank you both for your swift replies.
On the ceiling the marks are indeed the area around the lights which are not insulated. The temperature on the black marks are lower than than other areas of the ceiling. I presume the black marks are therefore dampness. The remedy i presume is to remove the lights, insert insulation into the areas, make good the holes and replace with another form of lighting.
With regard to the walls, the heads of the plasterboard fixings do indeed finish flush with the plasterboard. The marks on the wall are the same size as the head of the fixings.  I presume these marks are also dampness. I am not sure what i can do about this


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## onq (7 Jan 2011)

Apart from considering the suggestions I made in my post, you mean? 

If these are the mushroom headed fixings I've seen there may not be much of a cavity behind to gather moisture,,
It may simply be a the steel head making cold bridge attracting moisture in the air resulting in bmack mould.

If its a painted wall, then epainting with a washable vinyl matt or silk paint and washing with anti-bacterial soap may allow you to maintain a good appearance without constant repainting.

If its papered, again a washable paper will help.


ONQ.

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All advice on AAM is remote from the situation and cannot be relied upon                                                      as a defence or     support  -     in     and    of        itself  -         should           legal             action        be           taken.
Competent legal and building professionals should be asked to advise in                                                      Real Life with  rights    to         inspect     and       issue         reports    on      the                    matters    at           hand.


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## godthe (7 Jan 2011)

ONQ, 
Could I use led lights in the ceiling with insulation surrounding.?
The wall fixings are the mushroom headed ones and the plasterboard would be tight against the walls
Thanks again for your help


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## onq (7 Jan 2011)

godthe said:


> ONQ,
> Could I use led lights in the ceiling with insulation surrounding.?



Nope, 'fraid not.
The lights in the ceiling need the insulation pulled back as you have already done.
Allowing the insulation closer to the light risks heat building up not only around the light fitting but also around the transformer.

Putting a ventilated box around the light fitting it will keep insulation away with no possibility of creep.
The transformer should be laid on plasterboard to allow it to radiate heat freely.



> The wall fixings are the mushroom headed ones and the plasterboard would be tight against the walls


The wall fixing are a cold bridge I suspect - if there was damp there  would be a "ring" centred on the head and you're only seeing a dark spot.


> Thanks again for your help


You're very welcome.



ONQ.

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All advice on AAM is remote from the situation and cannot be relied upon                                                       as a defence or      support  -     in     and    of        itself  -         should            legal             action        be           taken.
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## kbie (8 Jan 2011)

onq, what do you think of the system in the link below for the recessed problem

[broken link removed]


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## onq (8 Jan 2011)

kbie said:


> onq, what do you think of the system in the link below for the recessed problem
> 
> [broken link removed]



Well, let's see what the blurb says:

==========================================================================
*Fire, Vapour & Thermal Seal Cap
for Loft Void Protection

60 minute fire rating*​

*Ideal for use with Loft Insulation

Easy to install - pass cabling through the cover by piercing with a sharp instrument or pencil,
 place over the downlight and seal with mastic. No screws or clips required*



_Overcomes thermal and vapour transmission to loft voids when recessed lighting is fitted_
_Eliminates  condensation on roof timbers and thermal loss from living areas from  warm air passing through or generated by the light fittings_
_Maintains  sufficient air space around the fitting to allow continuous roof  insulation to be laid directly over light fittings without overheating  or damage to the lighting_
_Easy to fit, simply seal with general purpose mastic_
_Tested  and approved by the Lighting Association, helps meets building  regulations as well as NHBC and other insurers' requirements_
_Manufactured from inert mineral fibres which are rot, corrosion and vermin resistant_
_Designed to resist the formation of water droplets_
_Durable lightweight construction will not put any significant load on the ceiling_
_Fire tested to BS 476 Pt.21_
==========================================================================

Before I make any comments - a disclaimer:

The below is not an expert opinion nor have I tested this product or have any experience of it or read any tests on it or reviews of it.

This is just a common sense assessment by someone who has over two decades of experience of assessing materials and components and reading marketing blurb, post-qualification.

What I offer below is fair comment in the public interest and without empirical testing which may contradict what I say.

==========================

I have a difficulty accepting these claims because, as far as I know; -


vapour transmission is unaffected by any component which fails to seal the light fitting to the ceiling.
You can't achieve a 60 minute fire rated seal to the top face of a plasterboard ceiling using general purpose mastic.
General purpose mastic cannot eliminate condensation on roof timbers.
Inert mineral fibres cannot eliminate condensation on roof timbers.
You can't achieve 60 minute rating on a cap detail if the ceiling only has 30 minutes fire resistance - the additional 30 minute rating is meaningless.
The component is not designed to resist the formation of water droplets - they are unlikely to occur merely because the component is under a layer of insulation.
Cannot see how the detail assists with heat dispersal, whatever about overheating - heat is contained by the detail while overheating is a condition resulting in outbreak of fire or light fitting failure.
This detail promises nothign in relation to the overheating of the transformer, which was the only culprit in the sole instance of attic fire that I have investigated.
==========================

So I can't see all these claims being true.

While the blurb says "Fire tested to BS 476 Pt.21", this doesn't offer much in the way of assurance in and of itself.
You'd have to know the exact test and test conditions to understand what was tested and how relevant this might be to the installed detail.

Now don't get me wrong, a properly installed fire rated cover can assist in reducing fire risk.

In this case I cannot accept the claims made, particularly re; -
- the lack of any requirement to install using intumescent paste
- the lack of ventilation around the fitting and
- the lack of any strategy for the transformer.

Pass.

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                                        as a defence or       support  -     in     and    of        itself  -         should             legal             action        be           taken.
Competent legal and building professionals should be asked to advise in                                                        Real Life with    rights    to         inspect     and       issue         reports    on        the                    matters    at           hand.


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## godthe (8 Jan 2011)

The lights I currently have in the ceiling are 50w 12v Dichroic with the 2 small pins. If i was to change these to 220v GU10 L.E.D bulbs which are only 7w would this work as there won't be a transformer and little or no heat from the bulb


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## onq (8 Jan 2011)

The object of AAM is to offer gereral advice.
The advice is offered in good faith, remotely and there are unknowns.
Thus I am not in a position to answer your queries in detail - read my sig file below.

Please read my replies again and you will see there are several overlapping issues with downlighters.
I am happy to point the way towards solutions and general principles, but I cannot solve these problems for you.
As you can see from the above and my other posts on AAM on the subject of downlighters, they are troublesome things and issues surrounding them can be complex.

These issues can include compromising the fire sealing of building elements that need a minimum of 30 mins Fire Resistance to allow people to escape from the building, including the 1st floor and attic construction.
The attic construction is not specifically requested to have 30 mins FR but it follows that if the roof collpases within the 30 mins then the 30 mins FR for the 1st floor cannot be achieved.

Cutting holes in ceilings compromises the Fire Resistance.
It also allows water vapour in the air to migrate around the voids in the structure and in the attic, with serious implications for timbe framed houses.

Finally the installations themselves can be a source of fire risk, either directly or through igniting combustibles adjoining them through heat build up.
Both house fires I have inspected were caused by transformers, one under the timber ground floor and one in the attic.
The attic transformer served downlighters.

I'm afraid that's all I can offer you in the way of advice short of being appointed to come out and inspect.
Perhaps others will offer you more advice.
Also you could try www.boards.ie
Construction and Planning forum.

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                                      as a defence or     support  -     in     and    of        itself  -         should           legal             action        be           taken.
Competent legal and building professionals should be asked to advise in                                                      Real Life with  rights    to         inspect     and       issue         reports    on      the                    matters    at           hand.


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## godthe (11 Jan 2011)

Thanks to all for your help. 
Regarding the ceiling lights i think i will disconnect them and put insulation in through the holes for the recessed lights. I will then look at alternative lighting.
Regarding the cold bridge caused by the pins on the wall i think all i can do is clean the spot on a regular basis.
Once again thanks guys for your help


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## Petermack (11 Jan 2011)

onq said:


> Nope, 'fraid not.
> The lights in the ceiling need the insulation pulled back as you have already done.
> Allowing the insulation closer to the light risks heat building up not only around the light fitting but also around the transformer.


 
Hi onq,

I thought the use of LED downlighters eliminated the need for a transformer.


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## Sandals (11 Jan 2011)

We have nine downlighters in kitchen, and five in hall, bungalow, recently insulated the attic and we sealed drainage pipe over the downlighters and put three litre drinks bottles over the top of the pipe.  

The transformer is outside the pipe and is covered with insulation.

We have alternative lighting in both rooms and so downlighters are never used, Is their a fire risk? Thanks.


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## Sconhome (11 Jan 2011)

Sounds like the lights and fixings are conducting cold (cold bridging) from the part of the building envelope outside the insulated zones. Any humidity in the house is condensing on the cold spot leading to dirt and possibly mold.

A very simple method of fire proofing and insulating downlighters is to use terracotta plant pots over the light fitting. Having said that you should all be on led bulbs to reduce both your light bills and to eliminate heat build up.


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## onq (11 Jan 2011)

Petermack said:


> Hi onq,
> 
> I thought the use of LED downlighters eliminated the need for a transformer.




Look at the broader implications.

Post #11 above sets some of these out.

The transformers are not the only issue here.

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                                       as a defence or      support  -     in     and    of        itself  -         should            legal             action        be           taken.
Competent legal and building professionals should be asked to advise in                                                       Real Life with   rights    to         inspect     and       issue         reports    on       the                    matters    at           hand.


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## onq (11 Jan 2011)

Sandals said:


> We have nine downlighters in kitchen, and five in hall, bungalow, recently insulated the attic and we sealed drainage pipe over the downlighters and put three litre drinks bottles over the top of the pipe.
> 
> The transformer is outside the pipe and is covered with insulation.
> 
> We have alternative lighting in both rooms and so downlighters are never used, Is their a fire risk? Thanks.




The transformer is covered in insulation?
Putting plastic near a source of heat?
Yes, I believe there is a risk.

What do the bottles do?
Is the pipe ventilated?

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                                       as a defence or      support  -     in     and    of        itself  -         should            legal             action        be           taken.
Competent legal and building professionals should be asked to advise in                                                       Real Life with   rights    to         inspect     and       issue         reports    on       the                    matters    at           hand.


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## onq (11 Jan 2011)

godthe said:


> Thanks to all for your help.
> Regarding the ceiling lights i think i will disconnect them and put insulation in through the holes for the recessed lights. I will then look at alternative lighting.
> Regarding the cold bridge caused by the pins on the wall i think all i can do is clean the spot on a regular basis.
> Once again thanks guys for your help



You could try the ventilated box fitting - it might reduce the heat loss to prevent black marks, also it would reduce the air movement near the uninsulated section of plasterboard - that might be enough to reduce condensation to stop the blackspot.

You could install a fire-rated cowl but seal it with intumescent paste - I have no faith in a fibre cowl - who would that stop either cold or hot fumes or smoke? You might need to look for another manufacturer I suspect.

But the risk will always be the transformer - lay it on something non-combustible, like a piece of plasterboard! Get one long enough to span the space between joists. That way evne if it compresses the quilt, it won't go below the joist depth.

You could also specify a cut-out transformer to prevent heat-build up, but if you want it to keep working and avoud heat build up, don't lay it on or cover it with, insulation.

One solution that deals with both venting the light and keeping the transformer off the insulation is to design the vented box surround so that you can rest the transformer on it. The transformer shouldn't block any vent holes.

Bit of thought needed, but it should be possible to do something with people on site who know what they're at.

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                                       as a defence or      support  -     in     and    of        itself  -         should            legal             action        be           taken.
Competent legal and building professionals should be asked to advise in                                                       Real Life with   rights    to         inspect     and       issue         reports    on       the                    matters    at           hand.


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