When selecting a rooflight for your property, there are various technical aspects that need to be considered. Among these, one key decision you'll need to make is whether the manufacturer provides pricing based on internal or external measurements. While this may seem like a minor detail, understanding the difference can have a significant impact on both the aesthetics and the cost of your project. In this blog post, we’ll break down the differences between internal and external measurements for rooflights and explore the advantages of choosing a manufacturer who prices based on internal measurements - the glass you see.
What Are Internal and External Measurements?
Before diving into the benefits of choosing one over the other, let’s clarify what internal and external measurements refer to in the context of rooflights:
- External Measurements – These measurements include the entire area covered by the rooflight assembly, which means that the size will include the frame that surrounds the glass.
- Internal Measurements are the dimensions of the hole in your roof – the part that you actually see from the interior of the building.
For example, if you have a rooflight with an external dimension of 1000mm x 1000mm, the internal measurement – the area of visible glass – may only be 850mm x 850mm, depending on the size of the frame.
Why Does the Measurement Type Matter?
The choice between internal and external measurements can make a substantial difference in both the cost and the visual appeal of your rooflight.
1. Cost Efficiency
When comparing rooflight prices, it’s important to know whether the size refers to internal (hole) dimensions or external (overall) dimensions. Many manufacturers price based on external dimensions. At Roof Maker we always quote on internal hole size, timber to timber.
By choosing a manufacturer that prices according to internal measurements, you ensure that your listed size reflects the visible hole size, giving you more daylight for your money. A rooflight priced externally will not be comparable in size and will lead to a smaller window and less light.
To get the best value, always check whether the size refers to the internal or external measurement. This simple distinction ensures you’re paying for the light you want.
2. Better Transparency
A manufacturer who prices based on internal measurements is usually more transparent in their pricing. You’re being charged for exactly what you’ll get – more glass and light. This type of pricing also aligns with customer expectations, as it’s the visible glass that matters most when it comes to the rooflight’s performance and aesthetic appeal.
When pricing is based on external measurements, it can feel misleading, as you might be led to believe you’re getting a larger rooflight than you actually are.
3. Aesthetic Considerations
The glass is the focal point of a rooflight. It’s the part that lets in natural light and provides an unobstructed view of the sky, so many homeowners and architects prefer to focus on the glass area itself when making decisions. Internal measurements directly relate to the amount of visible light that will enter the space, as well as the open sky view. Choosing a manufacturer who prices based on internal measurements means you’re paying for the glass you see – not the extra frame or surrounding structure that doesn’t contribute to your view.
On the other hand, external measurements often overestimate the actual usable or visible area. This is because the frame and mounting system take up space so the hole in your roof ends up being smaller.
4. Efficient Use of Space
A rooflight’s primary function is to allow as much natural light into your home or building as possible. By choosing a rooflight based on internal measurements, you ensure that you are maximising the amount of glass installed, which translates to more daylight and a brighter, more inviting space.
When choosing a rooflight, understanding the distinction between internal and external measurements can have a profound impact on your decision-making process. By selecting a manufacturer who prices based on internal measurements – the glass you actually see – you are maximising your space’s light and aesthetic appeal, all while ensuring cost-efficiency and value.