Green Building Forum - Flat roof light

Flat roof light

SarahLW — Fri, 01 Mar 2019 15:45:43 +0000

Hello
Does anyone have any experience of a company called roof maker based in Leicester?
I am looking at their triple glazed ultimate flat roof light which they advertise at a u value of 0.2.
Was just hoping for some feedback on them before putting in an order. I am in dorset so is a long way to go and look at the showroom

Flat roof light

snyggapa — Fri, 01 Mar 2019 16:41:27 +0000

no experience of any but this forum:

http://periodproperty.co.uk/forum/viewtopic.php?f=1&t=16577

gives these multiple recommendations https://www.therooflightcompany.co.uk/all-products/conservation/ - and recommended by longstanding forum members rather than accounts just setup to recommend a product 8-|

Flat roof light

Simon Still — Fri, 01 Mar 2019 17:05:39 +0000

Can't recommend them specifically but they have been going to all the homebuilding shows for years so they're not some fly by night company.

We had a flat 3G walk on rooflight supplied by our window/structural glazing company. There's not a lot to a flat rooflight - it's a 3G unit with a larger (to overhang the upstand) and stronger outer pane (more so if it's to be walk-on). they're almost certainly buying in the glazing and getting a good U value for the pane is easy and pretty much anyone can supply you that.

The frame/upstand/installation detailing is the key thing - if you're comparing to other suppliers get the upstand detailing they supply/expect you to build.

Flat roof light

Doubting_Thomas — Fri, 01 Mar 2019 17:44:49 +0000

I think roofmaker are probably no different to most suppliers but the thing to establish early on is whether that's the 'whole window' u-value (Uw) or just the value for the glass unit (also known as Ug, not to be confused with g-value).

The frame in any double or triple glazed window will lose far more than the centre of the glass, so it's in their interest to tell you the better number.

I suspect 0.2 W/mÂ²K is the glass unit, but how readily they admit this will usually tell you all you need to know about the company.

Flat roof light

djh — Fri, 01 Mar 2019 19:42:10 +0000

Posted By: SarahLWI am looking at their triple glazed ultimate flat roof light which they advertise at a u value of 0.2

Where do they make that claim, please? Assuming you mean https://roof-maker.co.uk/ I can see 'U-values as low as 0.5w/m2k' along with an offer of triple-glazing but I suspect even that is a Ug value (and probably a Ug value in vertical orientation at that).

A U-value of 0.2 is totally impossible to my mind. Especially for glass.

You should be looking for a Uw value. That is, a value for the whole rooflight including upstand, measured in a horizontal position.

Flat roof light

tony — Fri, 01 Mar 2019 21:24:54 +0000

3g unit sat on a kerb upstands set to falls

Flat roof light

Beau — Sat, 02 Mar 2019 12:34:33 +0000

Posted By: snyggapano experience of any but this forum:

http://periodproperty.co.uk/forum/viewtopic.php?f=1&t=16577" rel="nofollow" >http://periodproperty.co.uk/forum/viewtopic.php?f=1&t=16577

gives these multiple recommendationshttps://www.therooflightcompany.co.uk/all-products/conservation/" rel="nofollow" >https://www.therooflightcompany.co.uk/all-products/conservation/- and recommended by longstanding forum members rather than accounts just setup to recommend a product 8-|

We have rooflights from them and I would recommend avoiding them. Very solid steel frames but therein lies the problem. The steel goes from inside to outside so no thermal break. We get ice on the frames in cold weather and terrible condensation in the bathroom. How they complied with the regs for U values at the time is beyond me.

Flat roof light

jfb — Sat, 02 Mar 2019 15:38:49 +0000

Beau that is interesting to hear. I have been seriously considering some of their roof lights though probably the Neo range not the conservation one.

Out of interest does your house have mechanical ventilation? Mine are for a barn conversion with MVHR so that should mitigate some of the condensation risks and they are not in a bathroom, just bedrooms.

Flat roof light

WillInAberdeen — Sat, 02 Mar 2019 16:58:44 +0000

Hi Jfb, if the steel is cold enough to freeze, then the room air dewpoint would have to be kept below 0degC to avoid condensation. No MHRV is going to keep it that dry in the UK climate, and if it did it would feel uncomfortably dry.

We went Tony's route: the joiner made a simple hardwood frame with a rebate round the top, mounted a dg unit in it, and the roofer made a flashing to go round it and wrap over on 3 sides. It needed to fit an odd shaped hole but didn't need to open or be stood on, otherwise we would have bought one. The glass had to be at a steep enough angle to shed wind-driven rain and snow. The timber sides were not thermally broken but we felt they were small enough not to matter, and there was no visible condensation.

Flat roof light

Beau — Sat, 02 Mar 2019 18:33:10 +0000

Posted By: jfbBeau that is interesting to hear. I have been seriously considering some of their roof lights though probably the Neo range not the conservation one.

Out of interest does your house have mechanical ventilation? Mine are for a barn conversion with MVHR so that should mitigate some of the condensation risks and they are not in a bathroom, just bedrooms.

No MVHR but MV in the bathrooms. Not sure you could avoid problems in cold weather regardless of internal RH. Condensate on the outer frame is not a big problem as this is caught by a liner which is fitted with a drain hole onto the roof. The biggest problem is the divider between the panes as again this is steel which goes from inside to outside. Condensate runs down this and then tracks into the room via the opening mechanism. Why they don't have the DG over this divider and plant on a muntin to give the same visual effect but with a thermal break is a mystery. Hopefully the Neo range is better though out

Flat roof light

jfb — Sun, 03 Mar 2019 08:19:00 +0000

Good to know thanks. The neo doesn't have a divider and has some anti condensation pvc coating so hopefully better.

Flat roof light

SarahLW — Sun, 03 Mar 2019 15:41:21 +0000

Thanks everyone that is really useful feedback, think you are correct they are only quoting the ug value.
They state an aluminium frame but canâ€™t see a thermal break shown on the drawing so guessing they have not really progressed.
Glad I asked the question so easy to miss things with all the decisions to make.

Flat roof light

SarahLW — Sun, 03 Mar 2019 15:44:47 +0000

Posted By: djh
Posted By: SarahLWI am looking at their triple glazed ultimate flat roof light which they advertise at a u value of 0.2

Where do they make that claim, please?

Can see it here https://roof-maker.co.uk/wp-content/uploads/2016/12/Fixed-Flat-4pp-WEB.pdf

Flat roof light

djh — Sun, 03 Mar 2019 21:03:15 +0000

Posted By: SarahLW
Posted By: djh
Posted By: SarahLWI am looking at their triple glazed ultimate flat roof light which they advertise at a u value of 0.2

Where do they make that claim, please?

Can see it herehttps://roof-maker.co.uk/wp-content/uploads/2016/12/Fixed-Flat-4pp-WEB.pdf" rel="nofollow" >https://roof-maker.co.uk/wp-content/uploads/2016/12/Fixed-Flat-4pp-WEB.pdf

Thanks for that link. I think it's either a misprint or an outright lie. Either way I wouldn't believe it. Since they claim "meets Passive House standards, with U-values as low as 0.2 W/mÂ²k" I would ask them to produce the PHI certificate. Since I don't think they will be able to do that, I'd ask for whatever certification they do have. PS note that reflex glass is part of the same company (the website redirects).

edit: the good news is that there clearly is a thermal break shown in that pdf.

Flat roof light

SarahLW — Mon, 04 Mar 2019 22:46:39 +0000

I have email to request the uw value.
I await their response but does put me off that itâ€™s not on the quote.

Thanks everyone for your input

Flat roof light

SarahLW — Wed, 13 Mar 2019 22:59:08 +0000

Just in way of an update, after several attempts, I have today been told that they canâ€™t supply the overall u value unless I put down a 20% deposit as itâ€™s a very complicated calculation depending on the size and installation angle of the window. Which would have been around Â£500.
They refused to supply an indicative value based on a standard situation.

I refused to supply the money and told them I would be spending my cash elsewhere.

Very peculiar.

Flat roof light

SarahLW — Wed, 13 Mar 2019 23:10:24 +0000

Really weird as found them on Passivhaus Trust website with overall u value of 0.93 with ug of 0.8
https://database.passivehouse.com/Media/certified_components_v2/certificate/pdf/roof-maker-ltd_fixed-flat_1153sk03_en.pdf
Flummoxed for an explanation