Dome Skylight Buying Guide

Polycarbonate Domes

Polycarbonate Domes offer a fantastic and cost effective solution to allowing natural light into your domestic or commercial building.

Dome Skylights are renowned for being extremely durable and long lasting, most likely to outlast the life of the roof itself. Polycarbonate is a group of thermoplastic polymers containing carbonate groups in their chemical structures, making it virtually unbreakable and up to 250 time stronger than glass when impacted.

But is the Roof Dome you’re buying made from Polycarbonate? We will move on to this crucial point in a moment!

Rest assured though that the Domes we supply at The Skylight Company are all manufactured from Polycarbonate and are all manufactured in accordance with European standards, they hold a CE mark according to EN1873.

We offer low cost Roof Domes for uninhabited spaces to thermally efficient Roof Domes to give the best performance for your home.

Dome Rooflights are available in various shapes and sizes as well as various ventilation options. Roof Domes can also be supplied with an insulated upstand or as a Dome Only to allow you to construct an upstand on site yourself.

Replacement Dome or New Rooflight?

This would be the first question you need to ask yourself when it comes to buying a polycarbonate dome. As this will often determine whether you are going to need a pre-formed insulated upstand or whether you need the dome only.

If you are replacing an old or damaged glazing, then you may want to be looking at purchasing a Dome Only. Replacement Domes are perfect as the majority of the time you don’t need to distrub the waterproofing and the new Dome can be secured directly to the existing upstand.

If you are unsure how to measure an existing upstand please contact us!

If you are looking at installing a new dome rooflight, then you will most likely want to choose a Fixed Dome or Opening Dome. These come supplied with an Insulated Upstand meaning you do not need to create your own. Everything is included and the flashing is usually created from the roof material itself.

Glazing Options & Energy Efficiency

Polycarbonate Domes usually come with 3 skin thicknesses. Single, Double and Triple Skin Domes. You can also purchase quad skin domes, but these are usually manufactured to order.

To put it simple, the more polycarbonate skin, the better the thermal efficiency.

Single Skin – Ideal for unihabited spaces, such as Sheds, Lean To Roofs, Porches. Single Skin Domes will give plenty of light but little insulation. Any heat build-up will most likely result in condensation issues.

Double Skin – Giving you better U-Value, halfing that figure compared to a Single Skin Dome. Double Skin Domes are ideal for replacement like-for-like Domes.

Triple Skin – New Builds will most likely require a Triple Skin Dome so that it complies with Part L of Building Regaulations. Part L will state that the U-Value needs to be a certain figure to comply and Triple Skin Polycarbonate Domes usually meet this requirement with a U-Value of 1.78w/m2k.

So to make it simple… Single Skin Domes for unheated areas. Double Skin Domes for like-for-like replacements. Triple Skin Domes for new builds.

Access or Ventilation – Do I need it?

So you have an idea on the size and skin thickness you want your new polycarbonate dome to provide, but what about ventilation?

First think about the area where the Roof Dome is being installed. Is it a Bathroom or Kitchen where there may be a lot of heat buildup or moisture in the air? Or is it in a room with lack of ventilation like Windows or Extractors? If this is the case then you may want to look at domes with ventilation.

So what are the option?

Trickle Vents – Trickle Vents can be installed in to a uPVC Insulated Upstand, this is done in the factory and is delivered with the vents installed. So if you are looking at getting a Dome Only, then you wont be able to have this option.

Trickle Vents give a small amount of ventilation, much like the vents you might find on other doors and windows in the house. Typically trickle vents are only an extra £35.00 so are a cost effective ventilation option.

Opening Domes – Domes that open for ventilation are either controlled manually, on a hinge and spindle or controlled electrically.

Manual Domes open around 400mm and give plenty of ventilation. If a manual opening dome is installed out of reach then we supply purpose made Operating Rods allowing for easier opening.

Electric Opening Domes are controlled by a Wall Mounted Switch or Remote Control, depending on the product.

But remember, you may or may not need ventilation and fixed domes will be a cheaper option. If you are unsure with you need ventilation then please do contact us.

Security and Safety – No matter what option you choose

I mentioned earlier about Polycarbonate and whether the Roof Dome you are looking to purchase is made from Polycarbonate… and there is a crucial reason why you should be asking this.

As we mentioned Polycarbonate Domes are extremely durable to impact, virtually unbreakable in fact. But there are materials that aren’t as strong including Acrylic for example. Acrylic and Solid Polycarbonate Domes are virtually identical visually, you would never be able to tell them apart… unless you attempted to break it. Acrylic is easily breakable and for this reason it makes the rooflight unsafe and not secure!

What also seperates our Skylight Domes from others is the patented security fixings that come as standard with every dome! That includes Square Domes, Rectangular Domes and Circular Domes. The fixings can’t be unscrewed once fitted making it tamper proof. A lot of cheap domes will offer just a fixing and washer that can be easily removed.