Beyond Light: Insight into Roof Windows and Their Characteristics

There are several types of roof windows. To choose the ideal one for you, avoid limiting yourself to aesthetics. The energy savings you achieve—or not—hinges on their size, positioning, and installation.

The Different Types of Roof Windows

There are four core roof window types: 

• Top-hung and pivot roof windows

• Centre pivot roof windows

• Balcony windows

• Roof access windows

And then there are skylights.

Top-Hinged Roof Window

The top-hung roof window is distinguished by its opening system located on the lower part of the sash. It guarantees natural ventilation and a large amount of sunlight in the room in which it’s installed. It’s perfectly suited for lofts. 

Pivot Roof Window

The centre pivot window, also known as a pivot roof window, is centre-hung. Therefore, its hardware is located on the frame. Such a window type is especially practical if you want to position furniture beneath it given that its opening mechanism is a top control bar. 

Balcony Roof Window

The balcony-roof window is pretty self-explanatory, it’s a roof-positioned window that doubles as a balcony. In other words, it has a lower, vertically fixed sash, above which the upper half sash lines up with the roof’s angle. This means the upper sash can be opened with a handle located on the bottom end of the window. The primary advantage of this window is that it allows you to have a door to the outside world, with a breathtaking view.

Flat Roof Access Window

The roof access window is practically a window-door combo embedded into a roof. Its opening system is identical to that of a door, allowing you to easily access your roof. It can also double as an emergency exit, provided that it’s compliant with the building code.

Skylight: A Window Roof Alternative

A skylight is an architectural option that translates into creating a hole in the dwelling’s sheath to benefit from additional sunlight. More precisely, it’s a glazed cavity that transports and diffuses natural light in a room. 

Should a skylight appear to be the best option, bear in mind that potential buyers may prefer a more standard option, such as a centre-pivot roof window, for example. 

Choosing the Right Roof Window Type: Factors to Consider

Materials: Wood vs. Aluminum

In terms of window frames, PVC is the best insulator, most notably on account of its sealed chambers trapping air. 

Naturally, the insulation qualities of wood come up short ever so slightly to PVC. Wood is definitely more aesthetically pleasing, eco-friendly, and a sure, natural-looking asset that just can be done with PVC. However, bear in mind that wood requires care and maintenance. You’re surely not bypassing the need to sand and stain your wooden window frames.   

Aluminum-clad windows are primarily lacking in their insulation department. Well, older window models that is—newer models are designed in such a way as to break up thermal bridges. In fact, a non-conductive material is slipped between the window and the frame's profiles and sash. 

That way, you can choose freely between wooden, aluminum, or even PVC windows, all the while aiming for sufficient energy efficiency to limit your electricity usage.

What roof window size to choose?

The rule is rather straightforward: the bigger the room, the bigger the window should be.

However, there are exceptions to all rules, and scientists have determined that the ideal window size is based on the surface area. We’ll delve further into this at the end of this section.

The reality of the matter is, that everything depends on the room itself. In kitchens and bathrooms, it’s best to steer toward large-scale windows to better air out the space, mitigating condensation resulting from cooking or showering.

However, installing a big window in a bathroom isn’t a priority, as you don’t spend as much time in your bathroom as you would in your living room or kitchen.

Consequently, choosing a window size will also depend on the use of the space:

• Large windows: frequently used spaces

• Small windows: little used spaces 

Window costs are added to the above-mentioned factors. One large window can be rather pricey in and of itself compared to a smaller-sized window. 

Yet, there are rare exceptions to the rule previously mentioned at the beginning of this article. Some rooms are unconventionally shaped, maybe L-shaped, which may get better sunlight via several smaller windows rather than two big ones. 

As we stated at the beginning of this section: scientists have determined the ideal window size for a loft. The latter should measure 7.6% of the room’s total square footage. With that in mind, focus on dormer roof windows, as these are three times brighter than the latter. 

With size comes positioning.  

Where and how to position a roof window? 

Roof window placement is extremely important in terms of luminosity. The higher the window is placed on the roof, the more light will seep in and the better it’ll filter through a space.

A north-south facing window is also significant in its sizing. Full-on, south-facing windows can be smaller yet bring in just as much sunlight as bigger, north-facing windows. Therefore, it’s important to factor this into your decision-making process during the construction. As such, you can install several small-sized, south-facing windows that will provide you with as much natural light as large, north-facing windows, for the same price.

And it doesn’t end here. Studies have shown that the window’s frame placement plays a critical role in mitigating thermal bridges. In other words, when windows are installed in clay block walls and the frame is positioned outdoors, rather than indoors, heat loss related to thermal bridges is lessened by 75%. More precisely: 

• 75% devoid of insulation 

• 71% with insulation above the frame

• 58% with window frame insulation

How to Pick the Right Blinds for Your Roof Window

Blinds aren’t solely for aesthetics—they’ll also ensure better window insulation. Even if you choose to purchase double- or tripled-glazed windows filled with argon gas, neglecting to install a blind would be a mistake. 

In fact, blinds actively regulate heat transmission from one setting to the next (exterior to interior during summertime and interior to exterior during winter). 

Moreover, blinds shield you from wandering gazes and too much sunlight. To ensure you’re selecting the right blind, ask yourself whether you want one that’s:

• Manual 

• Motorized 

• Solar 

In terms of the safest choice, that would be the manual blind. With the latter, there’s no risk of motor failure.

Other criteria are added to the mix, as you can also choose a blind that’s: 

• Insulating 

• Roller 

• Insulating and/or pleated roller 

• Venetian

• Solar 

• Screen

Ultimately, your choice will be based on your needs and preferences. Said statement also applies to colour choice, with the main options being:

• Red

• Yellow

• Green

• Blue

• White 

Naturally, when it comes to colour, you should ensure that it suits the primary aesthetic and overall décor found inside, more than how the blind or shade will look from the outside.  

Pros and Cons of Roof Windows

The primary purpose of a roof window is to allow natural light to filter into a dedicated space in your house. However, the only hiccup with these windows is that, during summertime, they tend to heat the interior space, while allowing heat to seep out during winter, causing discomfort.

To offset said drawback—or at least partially so—you can add window treatments (blinds, shades) as an alternative to an air conditioner. In terms of cost-effectiveness, said factor is measured through indoor lighting needs. For example, it was determined that in a school, 50% of the electricity consumption resulted from classroom lights remaining turned on throughout the day. It’s important to consider the latter factor should you work remotely.

As for potential heat loss occurring throughout the winter period, it all depends on the window installed. Heat loss rests on several factors:

• Cavity size between the glazing and shutter

• Air leak rate through the cavity 

• Window’s installation angle 

• Window’s installation method

• The trim along the window frame

• The insulation found around the window’s perimeter

• Amongst others

Insulation and installation alone can reduce the linear thermal transmittance by 60%. The impact of insulation and installation quality were precisely measured. Therefore, in a 525-square-foot attic (160 m²), the junction where the window and wall meet may be responsible for 40% of the heat loss. Once improved, this loss is limited to 23%.

To better manage thermal bridges, refer yourself to ISO 14683, the international standard on such matters.

How to Install a Roof Window in 5 Steps

Step 1: Cut out the opening 

If the future window hole hasn’t been cut out of the roof yet, outline its positioning. To do so, grab ahold of some adhesive tape and mark the window’s position, most notably the top and bottom frames, then mark the rafter to ease the roof-cutting process. 

Make a hole in your roofing from the inside of your house. Start by cutting the centre-positioned rafter, then install new rafters before removing the slates or tiles. Once these steps are completed, you can cut the battens. 

Normally, the window manufacturer provides an installation guide. The latter will detail how to install the new battens and, should they be necessary, where to position the counter battens.

With each new step, feel free to check the levels to ensure the work done so far is well-levelled. 

Step 2: Prepare the window

To install a new window, you first need to remove its sash. Then, position the brackets on the frame. Follow along with the manufacturer-provided guidelines to avoid any confusion. 

Step 3: Install the window

The frame must be placed onto the rafter, supported by brackets. Once the frame is level and centre, go ahead and secure it in place.

Secure the sash while ensuring its control bar is positioned outward and placed on the frame. Close the window to ensure it's straight.

Step 4: Finishes

To complete this step, you must remove the previously installed sash to affix the gutter. Then, position the waterproof underfelt collar against the tiles and secure it around the window’s frame.

All the other elements (apron, etc.) used to dress the area around your roof window should be meticulously carried out, according to the provided instructions manual.

Before relaying the roof tiles, add the foam gasket strip, and then you can retile.

Step 5: Reaffix the sash

Now you can reaffix the window sash as per step 3.

Your window is now installed. Keep in mind that your window’s insulation capacity is a direct result of the installation quality. Therefore, if you’ve never installed a window before, let alone a roof window, it may be best to go through a professional installer.

How much does it cost to install a VELUX window?

Between $500 and $3,000 for the material. To this, factor in the installation cost, meaning between $2,000 and $6,000 more.

Accessories to Upgrade Your Roof Window Experience

Roof window accessories are mainly centred around the window’s opening and closing mechanism. To maximize fresh air intake, you have to be able to safely open your open. With roof windows, it’s not always as easy as it might seem. 

Amongst the accessories designed to facilitate window maneuvering, there are hook poles and adapters. Adapters are positioned on the blind’s handle and the hook pole will trigger the control bar.

Another option is to remotely control everything. If your window is out of reach and manually operating it isn’t ideal, you can also add a motorized feature to your roof window. Electric motors, as well as solar-powered ones, are retailed with several window models.

To avoid any unforeseen circumstances resulting from a motor outage and having a permanently open window, it might be best to opt for both systems.

What are some of the safety accessories available?

A roof window will always pose safety issues, especially when it comes to children. While they may not be able to open the window themselves, windows may be hazardous once opened to allow fresh air to filter in.

This is all the more true with a balcony window or a roof access window, which might provide breathtaking views, but are basically a doorway onto nothing but a void. To prevent any catastrophes, several accessories are made available: 

• Window opening control device with lock and key

• Lock and key hardware

• Push button lock 

This last accessory is especially helpful to prevent break-ins, and the first two are rather useful to prevent children from fully opening the window, or preventing the window from opening at all.

Naturally, the safest option remains the limit device. The reason for that is if you were to open the window to let in a bit of fresh air, and the sole safety is the lock, yet the sash is still tipped open, the slightest wavering of a watchful eye might result in an accident.

Roof Window Curtains and Shutters

Curtains and shutters aren’t solely for aesthetic purposes, especially when it comes to roof windows. During summertime, if you don’t have any shades, shutters, or curtains, 76% are the sun’s rays will filter through the pane’s double-glazing, transforming into heat once settled. 

The worst part is that, even with curtains or shutters, the US Department of Energy has determined that 75% of Americans leave their shutters or curtains in the same position throughout the day.

In other words, they’re pointless in terms of energy savings. Here are the best practices to keep in mind:

• Winter: Open the window early in the morning to benefit from the sun’s rays.

• Summer: Leave the blinds shut, except for those that aren’t directly in the sun's path. 

If you have motorized curtains and shutters, you can do even better by programming them to open and shut based on the heat felt within the room and the amount of daylight filtering in.

Light, Space, and Savings: The Crux of the Roof Window

Roof windows are so much more than just a natural source of daylight—they’re an essential feature when revamping your home's aesthetics or the overall functionality of your interior. Choosing the right type of roof window mandates factoring in the positioning, design, materials, and featured technologies, upgrading the benefits in terms of natural daylight and thermal comfort. By integrating roof windows into your renovation or construction project, you’re essentially steering yourself toward an eco-friendly approach, on account of lessening artificial lighting and heating needs, as well as creating an overall more pleasant and healthy setting.