Can You Get Sunburnt Through Glass?

The benefits of natural light are clear as day. But can you get sunburnt through glass? Discover everything you need to know from the experts at Cantifix.


19 Feb 2023


Simon McAuliffe

Sun shining through clerestory glass

For thousands of years we, as humans, have worshipped the sun…

After all, the great big ball of fire in the sky grows our crops, warms our skin, and, according to a recent study, makes us significantly happier. When the sun shines, we – and our pets – seek out the sunniest spots to relax. And if the sun isn’t shining, we’ll undertake pilgrimages abroad to find it.

We’ve written extensively about the many benefits natural sunlight can bring, including improving our circadian rhythm, boosting vitamin D levels, reducing mould, and increasing energy efficiency. 

But it’s no secret that there are dangers associated with unprotected exposure to sunlight. Sunburn is the quickest illustration of that fact, causing our skin to turn red, blister, and become sore if we haven’t applied enough suncream or sought shade quickly enough.

Sunburn is unlikely to last longer than a few days, but the danger of long-term health concerns may also cause us to think twice about spending too long in direct sunlight. 

We may even retreat indoors, safe in the knowledge that the sun’s harmful rays can’t penetrate the bricks and mortar of our homes. But what about the windows? Can you get sunburnt through glass? Can you get a suntan through glass? Does it provide UV protection like suncream, or do the rays pass right through?

In this guide, we make the answers as clear as day when viewed through Cantifix’s solstice glazing.

Let’s start with the sciencey bit.

What causes sunburn?

Sunburn is caused by overexposure to ultraviolet radiation. When our skin cells receive too much of it, they become damaged. The warm redness of sunburn is our body’s natural response to that damage.

We typically associate the word ‘burn’ with heat, for example dipping our toe in a hot bath or touching a pan that’s been cooking. But sunburn is not caused by heat – anyone who has been skiing on the snowy slopes will know that it doesn’t occur exclusively at high temperatures. You are just as likely to get sunburnt in temperate or freezing conditions as you are in hot ones.

Sunburn is, therefore, more accurately described as sun damage.

To better understand how the damage occurs and what you can do to protect yourself from it, we need to differentiate the three forms of UV radiation. All three are parts of the electromagnetic spectrum, but their penetration abilities and effects are what sets them apart from each other.


UV-C radiation is the most dangerous form of UV. But it is also the one about which you have the least to worry. While UVC can cause severe burns, it is entirely filtered out by the earth’s ozone layer and other atmospheric protectors.


UV-B radiation passes through the earth’s outer atmosphere and penetrates the epidermis, the surface layer of the skin, but goes no further. UVB is the primary cause of sunburn and skin cancers, but UVB is also very beneficial to the body.The rays interact with a protein called 7-DHC in the skin to create vitamin D3, essential for healthy bones.

The DNA in our skin cells is very efficient at dealing with UVB radiation. 99.9% of the rays’ energy is converted into heat, and it’s the 0.1% leftover that causes damage, eliciting an inflammatory response from our immune system. We’ll talk more about this a little later on.


Whereas UVB rays are stopped by the epidermis, UVA can penetrate through it and into the dermis, the layer of skin in which new cells are produced. Those new cells can become prematurely aged, causing wrinkles to form on the skin. 95% of the UV rays that reach us are UVA. The remaining 5% is UVB. UVA’s enhanced penetration is what allows it to pass through glass.

In short, UVC is nothing to be concerned about, UVA and UVB can cause long-term skin conditions, but it is solely UVB rays that cause sunburn. 

UV-Burn, UV-Ageing.

Can you get sunburnt through glass?

You can get sunburnt through glass, but the chances of it happening are minimal. Plain glass filters out approximately 97% of the sunburn-causing UVB rays, but the remaining 3% can still cause sunburn if you are exposed to them for long periods.

Comparing glass to the protection we receive from UVB-blocking sunscreen, which we’ll talk about in a moment, the rating would be somewhere in the region of SPF 30. That means glass provides approximately 30 times your body’s natural resistance to sunburn.

Sunburn-causing UVB isn’t the only factor to consider. Between 50 and 70% of UVA rays, responsible for some serious health conditions related to exposure to UV, pass through glass. As the symptoms of UVA exposure are not as obvious as the sore sunburn associated with UVB, you may be experiencing detrimental effects without knowing it.

Laminate glass, with its extra layer of plastic that keeps the glass in place if it breaks, filters out all UVB rays (meaning no sunburn) and up to 99% of UVA rays. It is the most effective for stopping sunburn through glass, but might not be the most practical for your next project.

Sun shining through clerestory glass

Can you get a suntan through glass?

Yes. You can get both suntan and sunburn through glass. While 97% of the UV-B rays that cause suntanning and sunburning are filtered out by glass, the remaining 3% can cause both phenomena if you are exposed to glass-filtered sunlight for extended periods.

Despite being caused by the same thing (rays of UVB), sunburn and suntan are scientifically very different. When the rays hit our skin cells, a process begins called melanogenesis, whereby our melanocyte cells begin producing melanin pigment, a darker skin substance that can absorb 99.9% of radiation and transform it into heat. 

Freckles and moles are a smaller-sized concentration of melanin.

But the .1% of the radiation that is not absorbed and released as heat damages the cells’ DNA. In response, our body’s defence system dilates blood vessels to increase blood flow and bring immune cells to fix the damage. It is the dilated blood vessels that cause the pink or red colouring of sunburn.

Other types of sunburn...

Can your eyes get sunburnt?

Yes. Your eyes can get sunburnt through a process called photokeratitis. Sunburn affects the cornea (the layer in front of your pupil) and the conjunctiva (the protective layer covering the white part of your eye and your eyelid).

Instead of your eyes peeling like something from a horror movie, symptoms might include pain, redness, blurry vision, seeing halos and headaches. Symptoms typically last between six and 24 hours. If they persist for longer, seek advice from your doctor.

Can you get sunburnt on a cloudy day?

Yes, even on days when the sun is fully obscured by overcast conditions, you can still get sunburnt. The intensity of the UV rays that cause sunburn is reduced by the thickness and colour of clouds. But the risk is never eliminated.

According to the US National Weather Service, a cloudless sky allows 100% of UV rays to reach us, broken clouds 73% and overcast skies 31%. While the majority of those rays are likely to be UVA – which don’t cause sunburn but do damage the development and ageing of cells – there will still be some UVB rays that make it through the clouds, causing sunburn.

Can you get sunburnt while wearing sunscreen?

Yes. Sunscreen can provide your skin with additional protection from sunburn caused by UVB light, but even with the highest protection – SPF 100 – approximately 1% still reaches your skin.

Much like there is a difference between the different types of UV rays, there is also a distinction between the protection ratings that feature on bottles of sunscreen. SPF, meaning sun protection factor, refers to the potential to block UVB rays and has a number between two and 100. The number is how long it would take for the skin to redden compared with no protection at all. For example, SPF 15 will protect 15 times longer than the skin’s natural ability to do so.

UVA, as we’ve established, doesn’t cause sunburn. But it can cause other long-lasting health issues. Therefore, protection is required. That protection is illustrated by a UVA seal, indicating that the product conforms to EU recommendations for UVA protection. The ratings run from one to five stars correlating to the descriptions: minimum, moderate, good, superior, and ultra.

For maximum broad protection, your sunscreen should have both a high SPF factor and a high UVA seal.

In conclusion

Reading through this article, you may think you have no protection against sunburn, even indoors. The fact is that ordinary glass is not as effective as other building materials at filtering out both UVA and UVB light. That said, the benefits of brightening your next project with natural light far outweigh the risk of sunburn.

Instead of ripping up existing plans for an exquisite glass structure and replacing them with blueprints for a concrete, windowless box, you should take sufficient and sensible precautions to reduce risks associated with prolonged exposure to sunlight.

These might include:

  • Wearing sunscreen on bright days, even when you plan to stay inside;
  • Avoiding extended periods spent directly in front of windows;
  • Installing blinds which can reduce- but not eliminate – the incoming sunlight.


Most importantly, construction professionals and homeowners should discuss everything in detail with their glass supplier at the planning stage. Factoring in the potential (and unavoidable) risks of sun exposure is important, and glazing specialists like Cantifix will be able to advise you on the best solution when it comes to the design of your installations, and the best glass specification to use. 

Glass has been a core construction material for thousands of years, and modern architecture features more glass than ever before. If the risks of sun damage were too significant, this wouldn’t be the case. Being informed is the name of the game here: by arming yourself with the knowledge of how to enjoy a glazed installation safely – from a set of sliding glass doors to a complete glass atrium – you can reap the benefits that natural light has to offer, and transform the financial and aesthetic value of a property at the same time.  

If you want to minimise the risk of sunburn but maximise the benefits provided by natural light, speak to us today.

Fire-rated glazing is essential for any architects who are in the early stages of planning a project and need to incorporate health and safety fire regulations into their designs. Using fire-protective and fire-resistive glazing will help to slow or stop the spread of fire, by making glass panels more resistant to flames, smoke and heat.

But fire-resistant glass can only achieve its designed performance when it is part of a complete fire-resistant glazed system. This means that all component parts – such as the glazing seal, beads, fixings and frame material – must be compatible and work together to achieve the required performance, and must be referenced to appropriate and relevant test evidence.

It’s also vital that the fire-resistant glazed system is installed as tested and assessed by a competent authority. The glass must be tested and classified in its proposed end use application, for example as a screen, door, roof, floor or façade in a glazed system appropriate for that application.

Installation must be carried out by properly trained and competent individuals who can demonstrate the necessary knowledge and skills required to satisfy the third party certification schemes.

If you need help with specifying fire rated glazing for your next project, get in touch with us today.