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Flat Glass Rooflight Buying Guide

Flat Glass Rooflight Buying Guide

Flat Glass - What You Need To Know

There are probably more options of Flat Glass Rooflights on the market than any other type of Rooflight or Roof Window, so when it comes to choosing the right one it can be a bit of a mindfield. I think it's safe to say that the majority of people looking to buy are comparing aesthetics and ultimitely, cost. But there are some vital points that you should be checking when purchasing your new skylight as not all Glass Skylights are the same. So lets break it down and cover each point in this guide. The things we will be looking at are:

Glazing - Double Glazed, Triple Glazed? It goes much deeper than that!

Fixing - How the unit is fixed is really important and not all Flat Glazed Rooflights are installed the same way.

U-Value and G-Value - U-Value is something you have probably come across, but how important is G-Value?

Manufacturer - A really important point to cover and why you should always make sure you are purchasing from reputable and well established manufacturers.

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Glazing Options - Flat Glass Rooflight Buying Guide

Glazing - What Differences Are There?

OK, now there are many Glazing options available in the manufacturing of Glass, but lets take the most widely used options used for Flat Glass.

Firstly, Double Glazed and Triple Glazed. Now typically, going with Triple Glazed over a Double Glazed option will give you better Insulation (Keeping the heat in) and better Sound Insulation. But is it as good as it sounds? A lot of people will be side tracked as soon as they see the words 'Triple Glazed' but you want to be comparing the Glass spec itself. For example not all Double and Triple Glazing is the same in terms of Glass Pane Thickness and Cavity Thickness. You may be looking at two rooflights, both Triple Glazed, but they may have two very different specs, lets take an example;

Triple Glazed Rooflight 1 - 6mm Outer Pane / 16mm Spacer / 6mm Center Pane / 16mm Spacer / 6mm Inner Pane
Overall = 50mm

Triple Glazed Rooflight 2 - 6mm Outer Pane / 12mm Spacer / 4mm Center Pane / 12mm Spacer / 4mm Inner Pane
Overall = 38mm

Now both of these Rooflights will boast Triple Glazing, but clearly there is a difference in terms of Performance. And this goes for when comparing Double Glazed with Triple Glazed, as a good spec Double Glazed Skylight can often perform as well as that of a low spec Triple Glazed.

So check the Glass Spec! You will want Toughened Glass, ideally at least 6mm (Sometimes 4mm will suffice on a smaller window) Anything over 2m2 and you should be seeing glass panes increase accordingly, if they dont, be wary! Bowing and sagging of Glass is very common on large units and a good manufacturer will know exactly when to increase Glass thickness or install a glazing bar for support.

Laminated Inner panes are there for Safety! In the event that something breaks the glass, it's to stop everything falling through. Laminated Panes also adds to cost, so if you are weighing up the cost of units and one has the laminated inner pane, bear in mind that the extra cost is for safety! Currently all of our Flat Glass Skylights offfer Laminated Inner Panes as standard.

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Flat Glass Rooflight Buying Guide - U-Value

U-Value and G-Value - What do I need to know?

If you are not sure what a U-Value or G-Value is or want to know more about this, then we do have a guide. See the button below!

Most suppliers and manufacturers will give you the U-Value, lower the number, better it is at keeping heat in. Brilliant! Thats all I need to know!

Wrong. G-Value is extremely important especially if you plan on going BIG! G-Value in short is the heat buildup through the glazing. A bit like the Greenhouse Effect.

If I give you an example; I had a customer not too long ago who spent nearly £4000 on glazing for her new single storey extension. She purchased the rooflights from a local company who hadn't explained to her the importance of Solar Heat Gain. Each Rooflight was around 2.5m2, totalling around 10m2. The extension was south facing and had that glorious sun beating down on it throughout the day. There was so much heat buildup that her lovely new laminate flooring started to warp in a matter of days under the immense heat! Really! I am not making this up!

So as you can imagine, the heat buildup is huge if not controlled!

So if you plan on going big with a Rooflight or plan to install multiple Rooflights into one area, you need to speak to us about Solar Control Glazing, Tints or Blinds.

What is a U-Value?
Flat Glass Rooflight Buying Guide - Fixing Detail and Manufacturers

Fixing Detail and Manufacturers

The one thing I can't stress enough is purchasing a Rooflight from a reputable manufacturer, The Skylight Company have hand picked the UK's leading manufacturers to work with as well as manufactured our own Permaroof Glass Edge Rooflight.

The one thing I have seen over the last few years is a huge increase in Glaziers jumping in to the Flat Glass Rooflight market. With no real experience in the manufacturing of Rooflights or without testing their Rooflights in all conditions, we have customers coming to us for replacements all the time.

Our Flat Glass Skylights have all been tested. All sizes and specs we offer have been put through stringent testing.

It's vital that Flat Glazed Skylights have adequate Glass Spec and Fixing detail.

Something you will find when purchasing cheap glass rooflights from glaziers or inexperienced manufacturers.

1. Inadequate Glass Spec - Bowing, Sagging or Cracking can occur
2. Weak or No Fixing detail - Some Rooflights I have seen require no fixing, just sealant. This is bad design and the sealant will perish over time meaning the Rooflight is a hazard!
3. No Warranty

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Always purchase from a trusted manufacturer and supplier.

Let us do all the work of making sure you are getting the best Rooflight for your money. The Skylight Company have been dealing with Flat Glass Rooflights since 2013 and some of our manufacturers have been in the business for over 30 years, so you know that you are in good hands.

We offer Rooflights from VELUX, Whitesales, Brett Martin, Permaroof UK and more!

Call us today with your requirements and we can help you get the right Flat Glass Skylight for your needs.


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