Wednesday, 25 April 2012

Roof access rooflight with quadruple glazing (Islington)

We pride ourselves with being able to offer the perfect glazing specification to achieve the desired levels of daylight, solar protection, heat & noise insulation in our thermally optimised rooflights.

Our F100 rooflight has such a comprehensive range of glazing options that we can always offer a solution to achieve even the most demanding requirements. For more details on our rooflight dome glazing options, please refer to our article: rooflight dome glazing options.

The Apollo Group are one of the UK's largest socially responsible contractors and they came to us for advice on a number of rooflight domes required for a new build Homes for Islington (HFI) social housing project, for which Apollo are main contractor. Apollo wanted to install the most thermally efficient flat roof rooflight domes available.

Our quadruple layer rooflight dome offers fantastic thermal efficiency

We offer our rooflights with fully substantiated total product U-values which are calculated according to the internationally recognised standard: EN ISO 10077-2:2009 - Apollo could therefore be 100% satisfied that the U-values we claim are completely verified. For more details on rooflight U-values, please refer to our article: Uw - the value which really counts.

We have supplied a number of quadruple layer rooflights for this HFI project, one was a roof access rooflight for a roof opening size of 900x1200mm. Supplied with quadruple layer domed glazing and our 400mm high insulated GRP upstand (other heights available: 150mm, 300mm and 500mm) this F100 rooflight dome has a total product U-value of just 0.94W/m²K and here is the data-sheet to prove it: U-value data sheet.

Equipped for roof access - with colour coded gas struts, an internal handle and lock.

Our F100 rooflight dome award winning (JEC Paris 2009 Innovation Award) patented framework is fabricated from a rigid PVC profile which is completely free of cold bridges. The framework also benefits from 2No. co-extruded seals for optimised thermal & noise insulation and reliable protection against driving rain.

Patented award winning framework.

Apollo's contracts manager commented on the ease of the rooflight installation: "...because the rooflight is delivered to site fully factory assembled and pre-mounted to its upstand, you literally just position the rooflight over the roof opening, fix it though the upstands foot flange into the roof deck - and job done!". Also, because our upstands are fabricated from fully pigmented & insulated GRP they can withstand the heat of roofing torches.

Thank you for reading this article, if you would like more information about our rooflights, the options for roof access or information about rooflight U-values - please leave a comment below, email us or call 01284 749051.

Wednesday, 11 April 2012

Pyramid glass rooflight case study (Beckenham)

We are delighted to report upon the installation of a couple of our aluminium framed pyramid glass rooflights to a domestic flat roof extension in Beckenham, Kent.


DVS' 30° pyramid rooflights on EPDM flat roof - click to enlarge

The building contractor, WES Construction Limited (WES) is a specialist installer of RubberBond Fleeceback - a high performance EPDM flat roofing membrane, and we were contacted to discuss the rooflight requirements. WES' clients liked the idea of installing pyramid shaped rooflights and so we were able to offer both 30° and 45° versions. They prefered the shallower inclination of our 30° pyramid - as it gave them the sense of additional height without compromising the view from the upstairs windows which overlook their new extension.

The 30° inclination does not obstruct the view from 1st floor windows

We agreed the final rooflight requirements with WES as being: 1No. 30° pyramid for a roof opening size of 1000x1000mm and 1No. 30° pyramid for a roof opening size of 1000x1500mm. WES' clients were specific about the finishing of the rooflights aluminium frames - not a problem when choosing a DVS aluminium rooflight. We can supply our rooflight frames: 

  • Mill-finish (natural aluminium),
  • Powder coated to a single colour or, 
  • Powder coated dual colour.

...and in any RAL colour. This is particularly useful for customers wanting to match the colour of their rooflight frames with the frames of doors and/or windows. We were asked to supply the rooflights dual colour powder coated with jet black RAL 9005 externally (to match with the roofing membrane) and pure white RAL 9010 internally.

Beautifully clean lines - just 38mm internal sight lines.

Both the building contractor and their clients are absolutely delighted with the installed rooflights. Following installation we asked WES for their opinion on our rooflights and here is what they had to say:

  • "The fixing detailing is absolutely brilliant".
  • "You couldn't beat the quality of these rooflights - some competing products on the market look DIY in comparison!".
  • "Our clients are over the moon with the rooflights".
  • "Well worth the money".
  • "I would have no hesitation in installing these rooflights on our future flat roofing projects".

If you have an old flat roof in need of re-roofing or if you are planning an extension in the South East London and Kent areas - why not give WES Construction a call on 020 8306 8699?

For more information about our range of rooflights please refer to our website, email us or give us a call on 01284 749051 - and we'd be delighted to offer you all the advise you need.

Tuesday, 10 April 2012

Rooflight dome glazing options.

At DVS we are absolutely passionate about daylight and we work very closely with architects to ensure the desired levels of daylight, solar protection, heat & noise insulation are achieved when specifying our rooflights.

Our F100 rooflights have such a comprehensive range of glazing options that we can always offer a solution to achieve even the most demanding specifications.

We offer our F100 rooflights with the following main glazing options:

  • Double layer domed glazing.
  • Triple layer domed glazing. 
  • Quadruple layer domed glazing.
  • Double layer domed glazing with 16mm 6-ply multi-wall polycarbonate.
  • Double layer insulation glazing (glass).

Each of these glazing options has its own unique attributes, and these are detailed below:

Double layer domed glazing:

Heat transmittance (glazing only) Ug: c. 2.6 W/m²K

Sound index Rw, P: c. 24dB

Light transmittance: c. 73%




Triple layer domed glazing:

Heat transmittance (glazing only) Ug: 1.9 W/m²K

Sound index Rw, P: 24dB

Light transmittance: 64%




Quadruple layer glazing:

Heat transmittance (glazing only) Ug: 1.6 W/m²K

Sound index Rw, P: 24dB

Light transmittance: 64%




Double layer domed glazing with 16mm 6-ply polycarbonate:

Heat transmittance (glazing only) Ug: 1.3 W/m²K

Sound index Rw, P: 24dB

Light transmittance: 40%




Double layer insulation glazing:

Heat transmittance (glazing only) Ug: 1.1 W/m²K

Sound index Rw, P: 38dB

Light transmittance: 78%




All of our domed glazing options can be supplied either clear or opal. We usually recommend opal glazing, as it provides a more evenly distributed natural daylight which is dazzle free. Rooflight domes have "self-cleaning" properties, mainly due to the excellent water run-off from the domed glazing, but opal glazing makes for an even lower maintenance rooflight as any (inevitable) dirt/debris is much less noticeable, particularly useful if the rooflight is being installed onto a roof with difficult or no access.

The quoted heat transmittance values above, relate to the glazing only and therefore do not reflect the overall thermal performance of the entire rooflight. We also supply fully verified total rooflight U-values which are calculated according to the internationally recognised standard EN ISO 10077-2:2009 and this takes into account the glazing, frame profile, the upstand and area to give the complete U-value of the product. For a  detailed explanation on rooflight U-values, please also read our news article: Uw - the value which really counts. Our triple layer F100 rooflight dome supplied with our 300mm high insulated upstand for a roof opening size of 1000x1000mm achieves a complete rooflight U-value of just: 1.1W/m²K refer to data sheet: F100 rooflight dome total U-value data-sheet.

Thanks for reading our article, for more information about our range of rooflights please refer to our website, email us or give us a call on 01284 749051.

Friday, 6 April 2012

Rooflight dome case study (Lincoln)

The landlord of a residential apartment block invited us to offer our advice on the replacement of a couple of old rooflights on one of his rented properties. The apartment had a bitumen felt flat roof that was much in need of replacement.

Old felt roof with rooflight domes.

The existing rooflights were extremely thermally inefficient; not only were the seals so ineffective that there was a noticeable draft, but there were some serious cold bridging issues. Massive amounts of condensation collected on the glazing, frame and the inside face of the upstand, a sure sign that the cold external temperature was able to travel through the rooflight structure and when the warm air inside the property touched the rooflight surface the moisture in the air then condensates. In fact, these rooflights were so poorly insulated that on very cold days the condensation actually turned to hoar frost!!


Existing rooflights - so poorly insulated that hoar frost can clearly be seen on the INSIDE (click to enlarge).

The plan was to strip the existing roof covering back to the joists, re-insulate the cavity, replace the roof deck and rooflights and then re-weather the roof with a seamless GRP roofing finish. Prior to contacting DVS, the landlord had been speaking with some competitors who had offered to only replace the upper part i.e. just replace the rooflight dome and fix it to the existing upstand. We advised against this, and instead strongly recommended that the entire rooflight structure ought to be replaced, to get the maximum benefit. The fact that the existing upstands were so poorly insulated and the re-roofing works involved stripping back to the joists - we felt it would have been bad practice not to recommend this. We offer our rooflights with a fully insulated (foam filled) GRP upstand, and we know through independent testing that our F100 rooflight dome with upstand exceeds the Building Regulations Part L requirements - our rooflight structure is free from cold bridges.

Our sound advice and quality product secured us the order for the supply of the two F100 rooflight domes supplied complete with our 150mm high fully insulated GRP upstand, both equipped to manually hinge open for ventilation.

Our rooflights being delivered  - securely packaged ensuring they reach site in optimum condition.





Once the roofing contractor had stripped the existing roof, re-insulated and re-boarded - it was time to fix our rooflights. Our F100 rooflight domes are delivered to site completely factory assembled and pre-mounted to their insulated upstand - making site installation very quick, easy and trouble free.

The rooflight is fixed through the upstands "foot flange" into the roof deck at approximately 300mm centres:

The roofing contractor securing our rooflights to the new roof deck.

Once the rooflight has been fixed to the deck, the roofing membrane needs to be applied to the roof and onto the upstands - with the GRP roof covering used on this job it really couldn't be easier as our upstands are manufactured from insulated GRP. Also, because our upstands are manufactured from insulated GRP they are completely seamless (jointless) so they are impregnable to water ingress.

The GRP material seals the upstand to the roof deck
The rest of the roof had the GRP roof covering applied

The finished roof with our thermally optimised rooflight domes - will ensure that the landlord and his tenants have a maintenance free roof for many years to come.


The finish roof with our F100 rooflight domes
Our F100 rooflight dome - internal view

Thanks for reading our article, for more information about our range of rooflights please refer to our website, email us or give us a call on 01284 749051.

Monday, 2 April 2012

Triple glazed flat roof rooflights

DVS' range of aluminium framed glass rooflights are available as flat (FE) or pyramid (FP) / hipped (FW) versions and can be supplied powder coated to any RAL colour. As standard, our glass rooflights are supplied glazed with a high specification double glazed unit: which includes an argon cavity, low E coating and warm edge spacer bar.

Our standard double glazed specification provides a centre pane U-value (Ug) of 1.1W/m²K and so when installed into our thermally optimised aluminium frame our rooflights total U-value is just 1.0W/m²K (*).

The following isothermal diagrams confirm the superb thermal performance of our aluminium framed glass rooflights - for an explanation of how to interpret isothermal diagrams please read our news article "Isothermal diagrams explained":


Isothermal diagram of our FE rooflight with double layer glazing - click to enlarge.
Isothermal diagram of our FP/FW rooflight with double layer glazing - click to enlarge.


We offer fully verified total rooflight U-values, so you can be absolutely certain of Building Regulation compliance. Our rooflights exceed the requirements of thermal performance set out in Part L when supplied double glazed, because our thermally optimised aluminium frame is decoupled with double polyamide inserts and continuously foam cored for increased thermal efficiency and glazed with high specification glass units as standard.

There are many well documented benefits of installing building products with lower total U-values. With ever increasing energy prices and governments across the globe introducing initiatives to cut CO2 emissions, installing a rooflight with as low a U-value as possible is a great choice for both the end user and the environment.

For even better rooflight U-values - we offer triple layer glazing with the same high specification features as our double glazing: including warm edge spacer bars and 2 x argon cavities. Our triple layer glazing specification achieves a Ug value of just 0.6W/m²K and is available with both our flat and pyramid rooflights:


Our FE rooflight supplied with triple glazing - click to enlarge.
Our FP rooflight supplied with triple layer glazing - click to enlarge.

When glazed with our triple layer specification our rooflight total U-value is reduced from 1.0W/m²K to 0.78W/m²K (*).

There are plenty of suppliers who offer triple glazing as an option with their flat roof rooflights and we would therefore urge you to request proof of their total rooflight U-values - it is only when armed with this figure that you can make a like-for-like comparison between suppliers. As we discuss in our news article entitled "Uw value - the value which really counts", some suppliers still just quote the Ug (glazing) value in their sales literature and arguments - which is wrong because it is a waste of time (and money) to install triple glazing into non or poorly thermally broken aluminium framework. Any rooflight supplier worth doing business with should be able to produce a data-sheet to substantiate their rooflights total U-value, we calculate ours according to the international standard EN ISO 10077-2:2009 and here's an example (currently in German text only): triple glazed total U-value data-sheet. We are working on translating this document into English - so here is a copy of the data-sheet for our F100 rooflight dome which we have already translated into English: F100 rooflight dome total U-value data-sheet.

* = the total rooflight U-value examples in this article are based on our FE rooflight to suit a roof opening size of 900x900mm supplied with our 150mm high fully insulated upstand.

For more information about our range of rooflights please refer to our website, email us or give us a call on 01284 749051.