drafts through downlight installation - any solution?

[sim17]

This is somewhere between roof building, insulation and lighting installation, thought I'd try here if any good people have ideas or experience on this.

I had a new single story lean-to extension built several months ago. Am now in the first winter with it. The roof has 150mm insulation (100mm Kingspan plus 50mm insulation backed plaster board), as specced by architect and builder, to meet current build regs. I have a couple of veluxes and some glass doors to the extension - I paid more to get good insulation rating on the glass.

On the electrician's advice, flush fitting tilt downlights were installed in the roof, 8 of them. I have CFL lamps, GU10 fitting, cut out is I think something like 80mm. The electrician said insulation would have to be cut away above the lights, so there wouldn't be heat buildup, even though CFL. Fair enough.

The disappointing thing is that there is a draft (or in this weather frankly it feels like little jets of cold air) coming down around the tilt part of the fitting. The light fits into the cutout snugly, but it is air actually coming through the fitting, through breather holes in the top and then around the CFL lamp into the room. The air flow under the tiles, on top of the insulation is creating a pretty strong cold flow down into the room.

Is it possible to get a replacement fitting which will provide a more air-tight fit? I understand the top of the light must have air around it (in my case that = open to outside temperature under roof slates and roofing membrane, that is the way the electricians fitted them. But is there such a thing as a fitting that will better seal the room while allowing the required ventilation above for safety?

I did also wonder about condensation - the temperature difference between the top of the light and the room when heating is on strong, people in room, means that the metal surrounds on the fittings get wet with condenstation, one of them even dripped! There isn't a leak, have had loads of rain and no problem at all, it is temp difference and condensation.

If I was doing it again I would not fit downlighters! As installed they seem to negate the efficiency of insulation required by building regs, and also money spent on decent glass! I'm a bit confused as to why the electrician specified them, he knew I was aiming for decent insulation. Although it was a case of the team fitting them being different from the gaffer who specified...

Any ideas?

 

[sim17]

Just a quick note to add: I've seen the loft cap and downlighter hood things in lighting suppliers, that are fire and vapour specified. Only thing is there is no space to fit them - the lights go into 150mm deep insulation directly behind plasterboard, on top of which there is less than 50mm gap to roof membrane and tile. And anyway, not possible to get access to the above insulation area without pulling all the roof tiles and membrane off! Lights went in at second fit, after the plasterers had finished and everything else was built. Electricians drilled cutout from beneath through the insulation.

 

[ban-all-sheds]

The disappointing thing is that there is a draft (or in this weather frankly it feels like little jets of cold air) coming down around the tilt part of the fitting. The light fits into the cutout snugly, but it is air actually coming through the fitting, through breather holes in the top and then around the CFL lamp into the room. The air flow under the tiles, on top of the insulation is creating a pretty strong cold flow down into the room.

That is entirely to be expected, and one of the reasons why it is almost, if not completely, impossible to install recessed lighting into roofs like that.

I did also wonder about condensation - the temperature difference between the top of the light and the room when heating is on strong, people in room, means that the metal surrounds on the fittings get wet with condenstation, one of them even dripped! There isn't a leak, have had loads of rain and no problem at all, it is temp difference and condensation.

Also entirely to be expected, and another reason why they can't be installed in a roof like that. You'll probably find that as well as it dripping into the room you're getting condensation on the actual roof itself, so you do need to sort this as left unchecked that could lead to rotting and structural damage.

As installed they seem to negate the efficiency of insulation required by building regs, and also money spent on decent glass!

Presumably the electrician signed a document to say that the work complied with the Building Regulations? You might like to start thinking if you should make that come back to haunt him.

I'm a bit confused as to why the electrician specified them, he knew I was aiming for decent insulation.

Because he's an incompetent t**t who is no good at his job.

Any ideas?

IP rated bathroom lights should stop the worst of the draughts, but they might not stop water vapour getting up into the cold space and they'll still leave you with compromised insulation overall. And they will still get cold so you may still get condensation dripping from them.

Really the best solution is to get rid of them, reinstate the insulation and the vapour barrier and make good the holes in the ceiling. IMO the electrician should pay for all that.

 

[sim17]

Hmmm. Was hoping to avoid the extreme option of reversal.

Yes, the work is certificated (Part P). I didn't engage electricians - all work on extension done through builder under fixed price, he got the trades in. Have building regs sign off from LABC too.

Hopefully the risk of condensation on roof timbers is minimal as the lights are lower temp CFLs, not Halgoen, are positioned midpoint between rafters and will all be at least 25cms from any timber, and there does seem to be good ventilation flow on the cold side between the tiles and the insulation.

Will look into IP rated bathroom lights as you suggest - thanks. Although I suspect I wouldn't be allowed to fit them under regs? Or is it direct replace of a fitting, not a new circuit installation.

Trouble reversing the work even if at installer's cost is the amount of hassle, mess and disruption in the house...although I suppose the cutouts could perthaps be patched neatly without replastering the whole ceiling. Then I have to get alternative wiring & lighting installed

 

[sim17]

thinking back I have a feeling recessed downlights may have been specced on the architect's design. The builder/electrician may point the finger at him. Still, you wouldn't expect someone to just fit knowing it could be a problem.

If shallow sealed LED fittings of the same diameter were available, perhaps they could be fitted under some sort of cap restoring say a third of the insulation, a fire retardent casing, and minimal necessary ventilation all taking place on the warm side. If anyone knows of such a fitting.... or perhaps I am dreaming now.

 

[pjcomp]

Don't want to add to your woes, but the tilt downlights usually require a bigger cutout than fixed downlights, so replacing them might prove problematic.

pj

 

[PrenticeBoyofDerry]

The problem you have sim17, is that the insulation within the ceiling roof void has been compromised by the installation of downlights, as has the barrier the ceiling and insulation forms to prevent draft and moisture.
You have no access above and limited space, rectification will be difficult!
It may have been part p certified but what about part C paragraph 6.12, (avoidance of moisture transfer in roofs) and L1A Paragraph 51 (building The fabric of the building should be constructed so that there are no reasonably avoided bridges in the insulation layers)
I am surprised that BCs have signed this off.

I think in hindsight the advise given to install downlights, was ill-formed.

 

[ban-all-sheds]

Hopefully the risk of condensation on roof timbers is minimal as the lights are lower temp CFLs, not Halgoen, are positioned midpoint between rafters and will all be at least 25cms from any timber, and there does seem to be good ventilation flow on the cold side between the tiles and the insulation.

The type of light etc is irrelevant. The key issue is that fitting them has breached the vapour barrier which is supposed to stop warm moist air from the room getting into the cold space, where it will cause condensation.

 

[Chri5]

This type might suit, as you can see they don't have any air space, and although the drafts may sneek through there will be far, far less.

There not cheap, but the light is 50% better so you might get away with 5 or 6 and then bung up some of the existing holes.

http://www.tlc-direct.co.uk/Main_In...ownlights_Index/LEDlite_Downlights/index.html

Then there is the more standard GU10 fire rated, these ones have

The recent addition of Part E to the Building Regulations has presented the House Builder with
the problem of how to maintain acoustic integrity yet allow the installation of downlighters,
which by their very nature, must puncture the ceiling lining, which affords acoustic integrity.

The design provides a sealed barrier between the underside of the ceiling and its associated void area.
This clever design also incorporates intumescent materials which ensure the luminaire can withstand the onslaught of fire in accordance with the requirements of Part B of the Building regulations.

Thus from one simple to install luminaire the both regulations can be complied with, negating the need for separate fire hoods or a segregated ceiling void as requested by The Standard Robust Details.

About £10 each


http://www.tlc-direct.co.uk/Main_In...hts_Index/Fire_Rated_Downlights_Gu/index.html

 

[bernardgreen]

The cold draughts coming down from the lamps are the better way for the air to flow. The problem is when warm moist air goes up into the roof space, cools down and makes the space damp.


Chaning the lamps for air tight units is the easiest option if there is no access to the space above.

It is a pity, and often a cost to customers, that too many electricians concentrate on Part P and ignore the other equally important parts of the building regulations.

 

[ban-all-sheds]

It's more than a pity - it's a criminal offence, possibly two (the second being fraud).

 

[phatboy]

I would suggest, in my non-expert opinion.....

Replace the lights with LED ones which are very slim. Before you fit them in place, fill the hole with circles of Kingspan - maybe glue them in so they cant slip, although I doubt they would. You can then fit the LED fittings below them as they are so small.

As said, the tilting ones have larger holes, but you can get kits to convert, so the rim of the lamp will cover the larger hole.

 

[bernardgreen]

Not all LED lamps run cool. Some 240 volt LED lamps get hot due to the heat created in the driver built into the lamp itself. The driver is the thing that converts 240 volts AC to an LED compatible voltage / current.

 

[dhutch]

Not all LED lamps run cool. Some 240 volt LED lamps get hot due to the heat created in the driver built into the lamp itself. The driver is the thing that converts 240 volts AC to an LED compatible voltage / current.

Also, although the heat output from even half-decent high-power led's is less than there halogen counter parts, they must remain cool(er) in order to work. Aka, although the first of setting fire to the surroundins is less, the need to ventilate them often more. Hence as you will notice, most have large heatsinks on them.

I quite like the bar type fittings as an alternative to downlighters. Links for visulisation only:-

http://www.purple-pumpkin.co.uk/med...36e95/l/2/l2110_-_clear_chrome_3_spot_bar.jpg
http://www.wickes.co.uk/content/ebiz/wickes/invt/195268/Lazer-4-Bar-Spotlight_large.jpg

Daniel

 

[sim17]

Lots of help here, thank you.

Chris5 picture examples are ironic. The second £10 example seems to be what I have (I saved a box from the bin). Apparently fire rated and perhaps some acoustic rating. But doesn't see m to offer vapour control necesary. The LEDs are the sort of thing I wanted. I asked if LED s were possible. I was told yes but costs more. I said I'd source them if electrician would advise type. Waited. No answer. Time went on, lights holding up finish, and they came back and said easier if they sourced and fitted cfl gu10 types. ...

Those LED ones seem to offer more than just fire and acoustic, but th.e specs ban-all refers to as well. I'll try fitting a fewer number of those, with optional converter plate indicated to mount in existing wider cutouts. Can't do anything about insulation, as folk point out the driver will still need ventilation space.

That should provide vapour block. Then I'll ask a plasterer if he can do a neat patch over other cutouts swhere I'll remove some of lights, reinstate some insulation and block .

Am I ok with the unused tails on connector blocks pushed up above the insulation? I remember reading you shouldn't cover over joins in cable, is that a prob here? There are actually two separate light circuits so half can be switched on independently. If necessary I could isolate one cct from mains, but not ideal, would rsther not remove in that pattern.

As for blame and going back to the installers, the rave of going to builder, electrical install co. he used, then particular electricians and possibly architect, all of whom will point out BC signed off, the possible arguments and then if they put right having the disruption in the house around a room we've finished and furnished and live in... well if it was a renovation I didn't live in, yes. But as it is if there is a satis fix with leds, that is the much easier option.