How Many Windows Do I Need for my Extension?

Optimising your light intake may not be the first thing on your mind when planning an extension. In all likelihood, it won’t have even cracked the top twenty. However, it is commonly understated how important a healthy amount of vitamin D is for the body – especially now that more of us than ever are working from home.

Windows are key here, not only for this all-important light but ventilation as well. Done right and with the correct number, you’ll find them to be a key component of any bright and inviting conservatory or loft conversion. Typically, this can be achieved with a combination of varied sizes and gradients of windows, though the exact design may elude you. In this brief guide, we’ll be giving you a few clues on how to transform any extension with stunning natural light.

Benefits of Natural Sunlight

If you’re not convinced of the importance of sunlight (beyond just needing it to brighten up your interior), below we’ve taken the liberty of compiling just some of the phenomenal additional benefits.

1) Strengthens Your Immune System

Vitamins offer hundreds of health benefits, from converting food to energy, repairing cellular damage and – yes – boosting your immune system to fight off disease and infection. Vitamin D is essential for this and, as we all know, there are few easier ways to get it than with sunlight. Increase your exposure to sunlight and, in turn, you increase your body's natural defences.

2) Improves Mental Health

There is a science behind why we feel better when the sun is shining. Beyond simply the warmth, sunlight also boosts the amount of serotonin in your body – a chemical which improves focus, reduces stress and all in all, helps to calm the nerves. Waking up to a room full of natural light then is one of the best ways to get your day off to a great start.

3) Helps Maintain a Regular Sleep Schedule

Serotonin isn't the only chemical that sunlight effects, however. An hour or so of natural light in the morning can also greatly help regulate your circadian rhythm. In other words, when to increase and decrease your melatonin. This, in turn, helps to control when your body feels tired – making sure that you can sleep when you need to, and wake refreshed the next day.

What Roof Windows are Available?

Fortunately for all the interior designers out there, roof windows are wide and varied both in style and function. Different windows and glazing provide different benefits as well as varying degrees of light exposure. Here are just a few that you can choose from.

Roof Lanterns

As the name suggests, roof lanterns offer not just a phenomenal amount of light transmission but also a unique styling sure to add a touch of gravitas to any building. Whilst on the pricier end of the roof window spectrum, they provide complex designs which project light further and often come supplied in pre-assembled kits to help with their installation.

Skylight Windows

Compared frequently to lanterns, flat roof skylights offer a similarly impressive amount of light, though lack the above's intricate designs. All the same, these less obtrusive models are typically preferred for more minimalist extensions, with easier installations and smaller price tags to boot. You’ll also find them far more suitable for pitched roofs.

How Many Windows Do You Need?

So, now for the big question. How many of the above do you actually need? Well, as you might imagine, the answer is not so cut and dry. To make a complicated issue simple, let’s start with coverage. Generally speaking, you will need your glazing to cover around 15 – 20% of your extensions floor space – this will provide at least enough light to cover the whole room. A very simple way to get an exact surface area is the following equation:

 Floor Space ÷ 5

For example, if your extension had a floor space of 40 square meters, you would need around 8 square meters of glazing across all your windows. That being said, how you distribute that, where you choose to install them and where your extension is actually located are all additional factors to consider.

Lofts Extensions

Loft extensions are perhaps the simplest when it comes to windows as an installation in your roof's current structure will be all that is required to introduce some more light. This, as long as there is enough headspace and no alternations need to be made, can be a relatively inexpensive process. Naturally, not all lofts offer a suitable amount of space for this and may not feasibly suit a new window. In these cases, the next step to take is a dormer extension.

Ground Floor Extensions

You have a bit more choice when it comes to a ground floor extension, especially when it comes to roof lanterns, however, you also need to take into account every other source of daylight. This includes any sliding doors, bi-folds and any other vertical windows you have planned. In many cases, a singular roof lantern or skylight may be all that you need, though it is also important to keep location in mind.

Rear extensions tend to push daylight away and so may need a combination of vertical and pitched windows to increase the output. Whereas building in a well-lit spot may require the opposite. In both cases, the key is ensuring a good volume of light at all times of day to limit your reliance on electricity and save you some money on your bills.

Do You Need Planning Permission?

When it comes to windows, planning permission is fairly straightforward, if not the same in every case. You DO NOT need permission when replacing windows of a similar size and appearance. However, you DO need permission if any of the following is required when building:

• Fitting a skylight or rooflight protruding more than 150mm beyond the plane of your roof slope
• Fitting a skylight or rooflight that is higher than the highest point of your roof
• Fitting an upper-floor side elevation window that can open and is not obscure-glazed (unless that opening is 1.7 meters from the floor of the room)

If you are unsure whether or not your particular project requires planning permission, read our guide on planning permission for windows.

Design Inspirations

Picking out your windows is only the first step. When installing and once installed there are a few more tips that can help maximise their utility. First of which is their location. Naturally, light will flood in from wherever they are fitted so take the time to carefully consider where they are needed most. Light can be a brilliant attention drawer, so installing one right above a feature, perhaps a photo wall or dining area, will make that space stand out from the rest.

Another effortless way to improve your interior is with window frames or, as the case may be, without. Opting for smaller frames offers an immediately modern feel, not to mention limiting any hindrance in the path of the light. Best of all, you can enjoy stunning views without the distraction.

Any Questions?

Whether you are looking to replace an old window, fit a roof lantern, or are looking for some advice on finding a pitched or flat roof window to suit your needs, our award-winning customer service team is here to help. Get in touch on 01295 56565 or use the chatbox below.