Roof Window - U Value

[Barney12]

Hi Guys

 

Just a quick sense check?

 

I'm intending to fit the following windows:

 

VELUX GGL UK04 2066 White Centre Pivot Window Laminated - 134cm x 98cm.

 

Its a triple glazed unit with a quoted U value of 1.0. On the basis that the roof makeup is actually 0.1 then clearly there is a drop in efficiency here. But enough to worry about?

 

I can get better (0.8) but I'll need to compromise on size and the cost rockets.

 

Lastly has anyone fitted the insulating collars supplied by Velux?

https://www.roofingsuperstore.co.uk/product/velux-bdx-uk04-2000-insulation-and-underfelt-collar-134cm-x-98cm.html

I cant seem to find any real detail about their make up.

 

TIA!

Edited March 6, 2017 by Barney12

[ProDave]

I would be interested in how you find the insulating collar. Particularly with a roof with counter battens then battens, almost all of the thiickness of the roof window will be outside the insulated makeup of a warm roof, so I feel it needs something. However if that skinny black thing in the picture is the "collar" it looks a rather pathetic attempt and I feel it should be possible to DIY something better. On the one I have done so far (cheap 3g window I would not recommend) I made a surround out of 20mm wood fibre board that was left over from cladding the back of my garage. Certainly better than nothing.

 

I found you have to pay a lot to get much under 0.9 U value for a roof window. Have a look at the eye watering price of the 4g Facro offering.

[Barney12]

Looking at the install guide it really doesn't look much and is only I would guess 50mm x 100mm

No idea of material, there are scant details of any technical nature.

 

[Barney12]

This image doesnt give much away either. The wood in the image is the actual window frame.

 

[Mr Punter]

I had some 3g Velux fitted with the insulating collars.  They seem a good design.  For the difference between 1.0 and 0.8 over a small area I doubt it would be worth bothering with any better.

 

Also, the 2070 code you quoted is for double glazed.  The 2066 is the 3g. 

[Mr Punter]

The insulating material is a grey coloured foam.

[Barney12]

2 minutes ago, Mr Punter said:

 

Also, the 2070 code you quoted is for double glazed.  The 2066 is the 3g. 

 

Sorry, good spot. Lazy copy and pasting! I've edited the original post.

Edited March 6, 2017 by Barney12

[Oz07]

keylite have that expanding foam collar as standard

[Dudda]

I first fitted a 3G Keylight window in my house which has a motor last summer and a u-value of 1.0. Think it's 960x1600mm or similar. The foam perimeter is more of a marketing thing than anything useful I found. Same for the quick 'flick' install. I had to get another 2 in November and wanted the same size so went with velux but didn't go automated and instead spent the money on the higher spec glass which gives a u-value of 0.8. Its the GGL PK10 - 62. Didn't bother with the insulated collar and instead made my own from left over insulation.

 

I did look at the 4G fakro ones but they're huge money and for curiosity I got a quote for the velux 5G passive certified rooflight. Whatever you're thinking sit down and then double it!

 

Edit: Fakro do a U6 which is comparable to the velux I got and a U8 thermo which is the even more expensive 4G.

 

This is my research from the time but presume it's still current as it's not long ago. Didn't want to post price column.

 

Company    Rooflight    Uw (W/m²K)    Ug (W/m²K)    Size
                
Fakro    FTT U8 Thermo    0.58    0.3    940 x 1400
Fakro    FTT U6 - 09    0.81    0.5    940 x 1400
Velux    Passive Rooflight    0.51        
Velux    GGL PK08 - 62    0.83    0.5    940 x 1400
Velux    GGL PK10 - 62    0.83    0.5    940 x 1600
Velux    GGU PK08 - 62    0.81    0.5    940 x 1400
Velux    GGU PK10 - 62    0.81    0.5    940 x 1600
Keylight    Triple Glazed    1.00    0.6    940 x 1600

Edited March 6, 2017 by Dudda

[JIH]

I used Velux insulated recessed slate flashing kits for my 2 C04 Velux roof lights.  Grey coloured foam collar as @Mr Punter says. All worked fine.  Think there are some videos  buried in their website regarding fitting.

[Barney12]

15 hours ago, Mr Punter said:

The insulating material is a grey coloured foam.

 

Thanks! Managed to find a picture in the end.

[Barney12]

I really shouldn't have started researching rooflight installs. Its another bloody minefield of information and confusion.

 

why do Velux specify such a large opening? This seems incredibly thermally inefficient when you have an insulated roof structure (Such as the one from MBC)? Am I missing something?

 

Edited March 7, 2017 by Barney12

[Cpd]

I think its to make sure you can fit it in square, what i did was to make the gaps large enough to get some 20mm calotex around all sides and with room to foam it in as well, i then fitted the windows, checked that the frames were sqaure to both the roof and just as importently to the glass units ( put the unit in and make sure it has an even gap between the frame and glass unit) tighten it all up and then seal it all up from the outside ( in my case it was some foaming and breather membrane ) then its back inside and finish foaming the gap between the insulation and rafters, cut back, tidy up and retape vcl. I am not saying this is the propper way as i did it without researching...... But it did give me a well insulated and sealed window that has given me no problems in the last five years. 

[Mikey_1980]

We have the 3G automated Velux Integras on our build with the thermal collars, Installation was very simple and they work reall well and we have had no issues now they have been in 12 months. We have 8 in total installed in our build.

 

Also you can special order them to have painted wood internally any colour and the outside any RAL colour if you want to them to match other windows.  Ares are all RAL 7016 externally and painted white wood internally to match our internorm windows.

Edited March 7, 2017 by Mikey_1980