1. Location, location, location
It’s vital to choose the ideal place to position your roof windows at the design stage. Picking a place with optimum sunlight is great for reducing the need for artificial light, but it’s also important to consider the size of the windows and layout if you’re opting for more than one in a room. How many roof windows you install will have a dramatic effect on the finished aesthetic of the exterior of the property and the rooms themselves, so it’s important to ensure you’re happy with any plans before the build starts.
2. Thermal comfort
Roof windows are normally installed with a 20mm gap around the edge to allow for adjustments and ease of installation. This gap should be filled in after installation. If this area is not insulated, then this can lead to cold bridging and condensation on the frame of the roof windows. The gap between the roof and the window creates a cold section all around the frame due to the temperature differential between the outside and the inside. Eventually, this can lead to condensation and mould, which contributes toward heat loss.
Although you should always use products that meet with Part L requirements, this is not always enough to guarantee optimum thermal comfort. You should, more importantly, ensure a thermal collar is either part of the product, or that you purchase a separate thermal collar or insulating material after the window is installed to help prevent condensation and mould.
3. Flush finish and top handle
Large expanses of glass and roof windows which allow natural light to flood in are always going to enhance the kerb appeal of a property, but it’s the quality of finish and the extra details that often make a self-build project stand out.
If you’re installing roof windows, then it will be important to consider how these align with the whole building envelope. Products that protrude from the building may look cumbersome compared to those with a flush or less obvious finish. Similarly, opening mechanisms are important. When specifying a roof window, consider the opening options and how this will work from both an operational and aesthetic point of view.
4. Breath of fresh air
Another important performance consideration when it comes to specifying roof windows is ventilation and fire safety. As well as choosing the right roof windows to provide you with wellbeing benefits such as fresh air circulation, you can also opt for roof windows with smoke ventilation kits, which automatically open once the ‘break glass’ screen is broken, helping to dilute the smoke to allow for easier egress.
5. Ease of install
Whether you’re fitting yourself or using a trusted trade professional, you should always check that the roof windows you’re specifying have been designed with ease of installation in mind. The gap between as-designed and as-built is often caused by incorrect installation, and this isn’t always the installer’s fault, but is often due to poorly designed products. Looking out for patented design and installation features is a good start.