Cant find a common agreement on insulation & down lights....

[Rodders66]

Hi All,

I'm kind of hoping to get confidence in my decision to have spots fitted into the ceiling of our new extension, but keep coming across different advice...help would be welcome!

We're looking to fit 12 LED spots (Aurora Pro 6w) into a lean-to pitched roof, split into two circuits on dimmers. Room is 7.5m x 3.5m

There are Velux windows (3) and there will be 100mm Celotex between joists with 50mm underside of rafters, plaster board to be fitted as finished ceiling...roof is vented between tiles and Celotex.

So, I was going to have holes into the Celotex at 12 positions, the holes being double diameter of light fitting and with about 25mm gap between the rear of the light fitting and the face of the Celotex. There would be at least 25mm of Celotex left in bottom the pocket that is created which separates the LED from the vented roof.

I appreciate it will compromise the thermal integrity, but have seen arguments and statements from various LBC guys accepting that it's not the end of the world in terms of thermals, especially given the use of Velux...is this OK?

Does anyone have an input on the level of protection that's needed from a fire safety perspective, ie...the distance around the fitting?

Any input very welcome.

 

[flameport]

I appreciate it will compromise the thermal integrity, but have seen arguments and statements from various LBC guys accepting that it's not the end of the world in terms of thermals, especially given the use of Velux...is this OK?

Ask whoever is doing the thermal calculations for the build. Any holes or reduced thickness of insulation must be included in those calculations, and if the thing as a whole complies with the required standard then not a problem.
Just hacking big holes in insulation which was intended to be a continuous piece is not acceptable, as it obviously will not meet whatever specification it was intended to.

ie...the distance around the fitting?

Depends on the particular light fitting. Ask the manufacturer.
Some can be completely covered with insulation. Others require a substantial space both around and above.

 

[Notch7]

Have you considered shallow downlighters such as the inceptor micro or nano?

https://www.downlights.co.uk/click-nano-led-downlight.html

I guess your roof is built -otherwise maybe you could consider a warm roof instead. (the ventilation is achieved below the tiles by counterbattening. Construction details are available from tyvek.)
There are 2 types, supported and unsupported types -thats the membrane.

http://www.dupont.co.uk/products-an...lications/warm-pitched-roof-construction.html

 

[ban-all-sheds]

We're looking to fit 12 LED spots (Aurora Pro 6w) into a lean-to pitched roof, split into two circuits on dimmers. Room is 7.5m x 3.5m

Have you wondered if needing 12 lights in a room that size is a pretty damning indication of how poor they are at lighting up rooms?

 

[Rodders66]

Hello & thanks for the feedback gents...

I have had reservations on 12 units, and originally was looking at 8 which I've seen in a friends similar size room. But, I like a really bright room and my thought was I can always dim them if required.

My roof is all up etc...and I hadn't considered shallow down lighters before. What are the downsides / benefits I should know about?

I just had a quick look at the link sent, and although the slim fit are obviously smaller and lower power don't you have the same problem in encasing the fitting etc...with with similar arguments?

 

[ban-all-sheds]

I have had reservations on 12 units, and originally was looking at 8 which I've seen in a friends similar size room.

Have you wondered if needing 8 lights in a room that size is a pretty damning indication of how poor they are at lighting up rooms?

 

[Rodders66]

Helpful Ban-all-sheds...not!

Please don't feel you need to add any other comment, I'd hate you to waste your time..

 

[mrcrow]

My living room is similar to yours and I have 2 rows of 5 across at 1/4 points along the length
They are 5W daylight GU10
And give sufficient lighting
Cheers
GEOF

 

[Rodders66]

Thanks MrCrow

Did you fit them into an insulated ceiling ?

 

[mrcrow]

Thanks MrCrow

Did you fit them into an insulated ceiling ?

yes...the ceiling is to my house loft so its really well insulated...
i put protective covers over the lamps to hold the insulation off them, they run pretty cool though...one can touch the bulbs from the living room and are just warm
also
i have a non insulated suspended ceiling in my garage...and have 3 5W GU10 leds down the middle of the garage
the garage is 5m long and 3m wide...the lamps are cool white so have greater lm values
cheers
geof

 

[Rodders66]

The sparky will do first fix and route the lighting ring around the rafters etc before the insulation goes in, therefore leaving tails for each down-light. How do I allow for the tails to be in the correct position within the insulation...both the 100mm between rafters and 50mm bottom side of rafters?

Do I simply cut a 100mm diameter hole through both sheets in the correct position then drop the tails into the hole, then slide the 100mm diameter & 50mm thick plug I've just made, onto the tails by making a small 'cable hole' in the middle of the plug.Then push the plug up into the 100mm diameter hole in the ceiling all the way back until it's at the back of the hole in the ceiling. Then seal any small gaps where the cable goes through the 'plug'....if you get what I mean?

Or am I really over thinking this?

 

[phatboy]

You are going to create cold spots on your ceiling, and will probably get moisture around them.

If you cannot maintain the insulation above them, you need slimline or surface mount units.

They aren't really 'spot' lights in a lot of cases now - they have a very wide beam angle. Or you can get 100mm round ones that are 12mm deep, which which will avoid the need to cut up your insulation. Just need to find a place to fit the drivers....

 

[Rodders66]

The roof is vented, so in principle there's a void above the insulation and moisture shouldn't be an issue I believe...but maybe that's not correct?
Or are you suggesting that the moisture would be inside the pockets I make within the insulation?

I'll look at the surface mounted units if they provide the same amount of light...

 

[ban-all-sheds]

You've got a new extension with a cold-deck flat roof?

Dear God.

 

[Rodders66]

Ban all....

You don' t like my posts ...please block me ...ignore me...do something else with your valuable time...someone somewhere must need your expertise and wisdom with a big serving of arrogance ...so please for the love of God find something else to do.