Technical FAQ's

Does the Conservation Rooflight^® comply with the new Building Regulations?

Yes. We anticipated the arrival of the new Part L requirements and increased the specification of glazing to the Conservation Rooflight in order to bring the thermal performance of the Conservation Rooflight into line with the new Regulations.

What are the maximum allowable U-values in the new regulations (1st October 2010)?

AD L1A: Conservation of fuel and power in new dwellings.

Requirement: 2.0 W/m2K

If the Rooflight is tested in a position other than vertical the above value is adjusted by adding the following values as per BR 443.

Inclination of Roof	U-value adjustment, (W/m²K).
	Double Glazed	Triple Glazed
>=70°	0.0	0.0
<70 and >60	0.2	0.1
<= 60 and >40	0.3	0.2
<=40 and >20	0.4	0.2
<= 20	0.5	0.3
Table 1.

Exception: none.

Exemption: none.


AD L1B: Conservation of fuel and power in existing dwellings.

Requirement: 1.6 W/m2K

If the Rooflight is tested in a position other than vertical the above value is adjusted by adding the following values as per BR 443

Exception: Where the replacement windows are unable to meet the requirements because of the need to maintain the external appearance of the façade or the character of the building, replacement windows should meet a centre pane U-value of 1.2 W/m2K.

Exemption: Buildings which are;

• Listed in accordance with section 1 of the Planning (Listed Buildings and Conservation Areas) Act 1990;
• In a conservation area designated in accordance with section 69 of that Act; or
• Included in the schedule of monuments maintained under section 1 of the Ancient Monuments and Archaeological Areas Act 1979.
• carports

AD L2A: Conservation of fuel and power in new buildings other than dwellings.

Requirement: 2.2 W/m2K

If the Rooflight is tested in a position other than vertical the above value is adjusted by adding the following values as per BR 443

Exception: none.

Exemption: none.


AD L2B: Conservation of fuel and power in existing buildings other than dwellings.

Requirement: 1.8 W/m2K

If the Rooflight is tested in a position other than vertical the above value is adjusted by adding the following values as per BR 443

Exception: Where the replacement windows are unable to meet the requirements because of the need to maintain the external appearance of the façade or the character of the building, replacement windows should meet a centre pane U-value of 1.2 W/m2K.

Exemption: Buildings which are;

• Listed in accordance with section 1 of the Planning (Listed Buildings and Conservation Areas) Act 1990;
• In a conservation area designated in accordance with section 69 of that Act; or
• Included in the schedule of monuments maintained under section 1 of the Ancient Monuments and Archaeological Areas Act 1979.
• Used primarily or solely used as places of worship
• Stand alone building with  floor area less than 50m2
• Carports
• Temporary building with a planned time of use less than 2 years

Can I specify/use Conservation Rooflights^® without having to do a complex calculation for Building Regulations?

Yes. Because the Conservation Rooflight^® U-value falls within the Building Regulations requirement it can be used without complex heat loss calculations, as long as the area of windows, doors and rooflights to an extension or new building is no greater than 25% of the total floor area. This proportion can be increased but a more complex ‘balancing' calculation between the areas and U-values of the floor, walls, roof and windows/doors/rooflights would be required to show compliance with the Regulations. Lower U-values in some elements can be used to balance higher U-values in others, or permit an increase in the area of windows/doors. In cases of replacement of existing rooflights the Regulations are satisfied if the replacement rooflight complies with the 1.6 W/m2K figure - which the Conservation Rooflight^® does.

If a property requiring rooflights is Listed, in a Conservation Area, or National Park - does this make any difference to the new U-values required?

Yes. There are special provisions in the new Regulations permitting latitude in the U-values of new elements added to historic buildings.
This may also include parts of an extension where it is desired to match an existing feature. The Conservation Rooflight^® in any case complies with the new Regulations, so there would be no need for a relaxation in order to use them to historic property.

What is the guarantee period for Rooflight Company products?

All Rooflight Company products have a glazing guarantee period of 5 years from date of purchase and the frame and silicone are guaranteed for a period of 12 years from the date of purchase (terms and conditions apply). See below for more information on the guarantees for each product.

The Rooflight Company's product guarantees:

Rooflight	Glass	Frame
Conservation range	5 years	12 years
Studio range	5 years	12 years
Replica	5 years	12 years
Plateau	5 years	12 years
Pyramid	5 years	12 years
Polyedge	5 years	12 years
Lantern	5 years	12 years
Specials	5 years	12 years
neo™ Steel	5 years	12 years
neo™ Fortecom®	5 years	10 years

How much do your rooflights weigh?

 

Each rooflight size and type has a different weight. The weight of each rooflight size and type is shown in the products section on this website.

How do you support your rooflights?

 

All our rooflights for pitched roofs are supported directly on and fixed to roof joists. The sizing and spacing of roof joists is frequently a matter of what is given by the existing structure in instances where rooflights are installed to existing roofs. In new roofs the roof joists can be optimised or placed so as to facilitate ease of rooflight installation. In all instances the sizing of the roof joists to support a rooflight should be advised by, or checked with, a structural consultant such as a consulting structural engineer. The Rooflight Company Plateau's, Pyramids and Lanterns are supported on up stand kerbs.

We are able to propose clear structural width and length dimensions for all standard rooflight types, and offer such in the form of diagrams with proposed clear structural width and length dimensions. In all instances the sizing of the structural members themselves should be checked by a structural consultant as set out above.

What do the size dimensions of your rooflights mean?

 

We quote the sizes of our rooflights as clear structural widths and lengths. This is the clear opening that is required within the roof structure in order to install the specific rooflight. Along with the clear structural dimensions we also provide clear viewable widths and lengths. This relates to the unobstructed clear viewing area visible from the inside of the building when looking outward.

What roof pitches are your rooflights suitable for?

 

Flat rooflights can be installed on a flat roof with a pitch between 3 and 5 degrees. The 'normal' range for a pitched roof is between 17.5 degrees and 65 degrees. Between the pitches of 5 degrees and 17.5 degrees, special measures should be taken at the abutments of the rooflight to the roof finish to ensure that the abutments are weathertight. We are able to advise on appropriate detailing, please contact Customer Service and ask for the Renee detailing

 

What makes your rooflights different from others?

The Conservation Rooflight^® is the original low profile skylight with an authentic traditional appearance. It features a robust steel design with protective layer and polyester powder coating. The glazing is divided by real glazing bar(s) and the Rooflight can be installed flush to the roof.

The casement has fine detailing with a minimal perimeter edge measuring just 3mm. In addition to this, the standard colour and texture of the paint have been chosen specifically to reduce reflection, resulting in a less conspicuous appearance.

Our rooflights are designed to the highest standards of safety and comfort. The BRE 6375 Weather Tightness Test: Part 1: 2009 test results can be viewed here:

The Conservation Rooflight^® - View PDF

The neo Rooflight (steel) - View PDF

The neo Rooflight (Fortecom) - View PDF

What is the difference between the Conservation Rooflight^® and cast rooflights?

 

The Conservation Rooflight looks exactly like a Victorian cast iron rooflight, but under the surface it is very different indeed. Cast rooflight types are very simple in their detailing on account of the fact that they must be pulled from a mould. The simplicity of the detailing makes such rooflights susceptible to draughts in strong wind and leakage in deluging rain quite apart from their susceptibility to condensation. They may look 'correct' from the outside but cast rooflights may be hard to live with on account of the weathering and condensation problems inherent to the design.

Conservation Rooflights are made in a very different way, in order to get over the potential for weathering and condensation problems with castings. They are fabricated of folded and welded sheet steel, which is subsequently primed and then polyester powder coated after the unit is made. The use of relatively thin folded sections makes it possible to achieve complex details that are better at keeping the weather out than the simple sections of castings.

Aren't metal rooflights susceptible to condensation, like metal windows?

 

Yes, unless they are fitted with a thermal break or a thermal lining device such as our Thermoliner^®

In fact condensation is more problematic on a rooflight than on a vertical window because the condensation drips or runs down onto wall and floor finishes instead of just lying on a cill and evaporating like condensation on a vertical steel window. It is for this reason that steel windows were commonly installed with quarry tiled cills. The only effective answer to condensation on any metal window or door is a thermal break or a thermal lining that works. Our Patented

Thermoliner is exclusive to the Rooflight Company. It uniquely does not set out to prevent condensation it allows condensation to occur in a controlled manner out of sight of the rooflight user. It drains any condensate water out of the building via small drains at the rooflight cill.

 

Do you do flashing kits?

Please see our flashing kit page of contact Customer Services on 01993 833155 for more information.

Do your rooflights have trickle vents like other windows and rooflights?

The whole of our rooflight is a trickle vent, according to Building Control officers we have consulted.

This is because in their view the means of ventilation is 'controllable and secure' when a winding device is used to open it. This means that under normal circumstances a Rooflight Company opening rooflight can be used as a trickle vent providing 'background ventilation' to a habitable room in accordance with the requirements of the Building Regulations. In fact most of our rooflights can provide considerably greater than the current open area requirements of the Building Regulations - 8,000 sq. mm. Some Building Inspectors interpret the Building Regulations differently, however, and it is recommended that they be consulted on the specific type and location of the rooflight proposed before relying upon the rooflight as a sole means of providing background ventilation to a room in a Building Regulations application.

 

How do you clean your rooflights?

With a cleaning tool optionally available from us.

All of our standard rooflights for pitched roofs can be cleaned from inside with a cleaning tool. Rooflights that are longer than a CR-13 need to be opened further to achieve this, and we are able to supply ironmongery that can achieve the required opening in these instances.

What are your payment terms?

We accept most credit and debit cards for full settlement in advance for our rooflights, or payment against a Pro Forma invoice. We can issue a VAT invoice upon request. Alternatively Rooflight Company rooflights may be obtained from major Builders Merchants.

Do you do Egress Rooflights?

Yes. We do a range of Egress / Access rooflights for pitched and flat roofs, more information can be found in our ‘products' section.

Can you do different coloured rooflights?

Yes. We can offer any available RAL colour in addition to our standard colours (please note: this does effect lead-time and cost).