How to choose a roof access window: size and pitch

The roof access window is a pitched-roof window that opens wide enough for a person to pass through onto the roof covering. In the collection the sizes are 55 × 118, 66 × 98 and 86 × 87 cm and the frame is in wood or white PVC. To choose, start from the pitch of the roof (from 15° up to 55° or 70°, depending on the model) and from the position of the opening.

The types

• Insulated roof access window: it has thermally insulating double glazing and is used above all to reduce heat loss. Examples are the FWP U3, the FWP U5 and the PWP U3.
• Roof window: the generic name for models with no other specification, such as the WLI.
• A.1 standard roof window: the standard version of the A.1 series, see the A.1 standard WLI.

The difference between the codes lies in the frame material and the glass: in the data, wood is natural and PVC is white.

How to choose by job

• Unused loft, to be inspected from time to time: a standard roof access window is enough, with side opening and the opening close to an access ladder.
• Lived-in or heated loft: choose thermally insulating or super-insulating double glazing, so as not to lose heat.
• Damp rooms such as a laundry or bathroom in the loft: white PVC is easier to clean, while wood needs more care with the finish.
• Steeply pitched roof: check the pitch range on the data sheet, because the models cover different ranges (15°-55° or 15°-70°).
• Maintenance of chimneys, aerials or panels: position the window close to the ridge and close to whatever you need to reach.

The features to look at

Dimensions. The sizes in the collection are 55 × 118, 66 × 98 and 86 × 87 cm. To get through with tools or wearing a helmet you need a comfortable opening: do not look only at the light that comes in.

Pitch. The installation range is 15°-55° or 15°-70°. Measure the roof slope with an inclinometer before ordering.

Double glazing. It can be thermally insulating, super-insulating or fitted with toughened outer glass. Toughened glass withstands impacts better, which is useful where hail or debris are a risk.

Material and colour. Natural wood or white PVC. The waterproof flashing is grey-brown RAL 7022.

Warranty. The data show 5 years; always check the conditions on the data sheet of the model.

How to use it safely. Before going out, open the sash all the way, rest a stable ladder inside and climb up with your tools in a rucksack, not in your hands. Always work clipped on when on the roof: if the roof covering has no lifeline, install one before organising any job. After going out, close it properly, because a dirty seal or a sash that is not fully shut lets air and water through.

Common mistakes

• Using the roof access window as an anchor point. It is not one: on the roof you work only connected to a lifeline or to certified anchors.
• Going out onto the roof without opening the window completely. You risk losing your balance or hitting the sash.
• Choosing only according to the light. If you need access, the usable size of the opening is what counts.
• Fitting it far from a ladder. A window that requires a jump or an improvised foothold is dangerous.
• Choosing the flashing without looking at the roof covering. Tiles, sheet metal and pantiles need different flashings.

Frequently asked questions

Is a roof access window different from an ordinary roof window?

Yes: it opens in a way that allows passage onto the roof covering, whereas a centre-pivot window is designed above all for light and ventilation.

Can I go out onto the roof through an ordinary roof window?

Only if the model is designed for roof access. Check the data sheet or ask the technicians.

How big does it need to be?

Big enough to get through comfortably with the tools you carry. Start from the opening available between the rafters.

Do I need a fixed ladder?

Preferably yes, or at least a stable ladder close by. Ask the AMES technicians for advice.

Can I leave it open for ventilation?

It depends on the model and on the opening lock: if the sash does not stay in place by itself, do not leave it open in wind or rain.

How often should it be checked?

At least once a year, and after hailstorms or heavy thunderstorms: seals, waterproof flashing and hinges.

You will find the models available in the Roof access windows collection: ask the AMES technicians for a quote or for advice on choosing the size and flashing.