News & Events
How Roofs are Prepared for Skylights

How Roofs are Prepared for Skylights

If you have never had rooflights installed on your property, it is only natural to be curious about the installation process.

As the country's leading skylight installer, Natralight has over 30 years of experience of transforming domestic and commercial properties. Here we are going to summarise the installation process.

Measuring the Opening 

The first step when you have decided to purchase a flat-fixed rooflight is to have the structural opening measured where your rooflight will be installed. You should allow for 5mm tolerances all around which allows the bottom pane of the rooflight to fit smoothly into the opening. 

For a standard unit, the top pane would have a black 100mm overhang all around on the top pane, which would make the top pane an overall size of 1200mm by 1200mm. Our team of installers are able to increase the size of the overhang if required if the upstand width is wider.

Preparing Your Roof

Structural glazing silicone is used to bond the double/triple glazed sealed units to the top pane which forms your skylight. The rooflight IGU is secured onto the timber kerb built by your roofer as part of the roof's construction. 

The timber upstand needs to protrude 150mm above the roof with a pitch of 6 degrees, which is sufficient to allow water to flow down. 

Rooflight Installation 

The last step to finish the roof before installing your skylight is applying your roof covering up to the side of the upstand which makes it weatherproof. 

The timber upstand should protrude at least 150mm above the roof and the pitch should be 6 degrees, sufficient to allow water to flow down. Before sealing the product with silicone, water can be applied to test the flow off of the water. If pooling occurs a higher may be needed. 

Bottom pane needs to be supported on 4 sides once it is set in place, the aluminium angle can be fitted before the plasterboard and covered with plasterboard or fitted after the plasterboard. Another way to support the rooflight is to add a timber batten with an aluminium strip on the top. 

A compatible Low modulus silicone will be applied as per silicone supplier's datasheet to the top of the Upstand firmly placing the skylight onto the upstand. Pressure needs to be applied all around the 100mm overhang which ensures the silicone spreads and seals any gaps then finish off the silicone all around with silicone tool. Once cured a structural silicone will be applied to the bottom aluminium angle trim flat surfaces which firmly fits them in place. Any excess silicone will need to be wiped away using a finishing tool.

At this stage of the installation, the bottom and top panes should be supported. Sealants compatible with the top of the upstand, aluminium angle trim, glass, setting blocks and silicone need to be used. Some sealant suppliers may require a primer to be applied to surfaces. 

Get in Touch with Any Questions

If you have any questions about the installation of rooflights, please contact us today. 

Keep up to date with our latest projects on our Instagram feed.