Measuring a Kerb and Selecting the Right Size rooflight for your Project
The success of your roof light installation rests on getting the sizes right.
The amount of light coming into your project will be determined on the size of roof light you choose. An artist’s impression will go a long way to help you visualise the end result, but that is not the only time size will be an issue.
Let’s look at what happens once you have placed your order and we are manufacturing and processing your roof light for delivery, this is the time whether your working with a builder or self building you will need to construct the builders kerb.
It’s a common misconception that the roof lights simply fills a hole in your roof and also the reason why site delays occur. To comply with building regulations the roof light cannot sit directly onto your roof. All roof lights must sit on a builders kerb.
So why do you need a builders kerb ?
The builders kerb, also called an upstand is constructed on site to accept the roof light. It sits on your existing roof. It can be made of concrete, metal but almost always is constructed using timber and usually is 150mm high.
So there are two very important sizes :
Roof opening size and external builders kerb size
The roof opening size is the actual dimension of the hole In the roof of if it’s a new build the opening you need to create. This is the size you order when ordering size of your roof light.
The kerb size or upstand is the external size so we always refer to this as external kerb size.
We have illustrated below how each is measured in easy to understand pictures.