9 Things to Consider Before Installing a Roof Window

Roof windows and skylights are fantastic additions you can use to brighten up the inside of your house. Increasing natural light should make your house look more luxurious and make your property more valuable. 

However, before you run to the store to buy Velux roof lights or brand-new roof windows, there are a couple of factors that need evaluation to make the final decision. Here are the top seven things you need to know before installing a roof window.  

Not All Roofs Can Feature a Skylight


The first thing you should consider before installing a roof window or a skylight is whether your roof is designed in a way that enables such an installation. Typically, there are no problems with finding a product that will fit with the structure of your roof, but skylights have more requirements. Roof lights are installed at the roofline beneath the roof shingles and the sheathing, so you need to consider the two types of roof framing most commonly used: 

  • Truss-framed type – named after triangular units they are made of, trusses can’t be cut after installation, so a skylight can compromise the integrity of your roof.
  • Stick-framed type – they are built with individual rafters that are spaced up to four feet apart. They are better suited for skylights, less risky because of the additional space to cut and fit a skylight. 

When you are preparing to install a window or a skylight, make sure to check whether your roof can handle it.  

The Right Size


Skylights and roof windows come in a wide range of shapes and sizes, choosing the right dimensions for your home is essential. The most common size is 34,4” by 23,62”, and it is usually installed between rafters at 23,62 inches. However, you should choose the size that will provide as much light as you want without overheating your rooms in the summer. Typically, you can look for non-standard window sizes in online windows stores like, but if you can’t find the right size, you might need to consider custom windows or skylights.

Glass vs Plastic Glazing 


When it comes to glazing, typically there are two types you can go for, glass and plastic. Skylights and roof windows glazed with glass tend to be more expensive than their plastic alternatives. Glass offers a better view and more light. Plastic can become discolored over time and scratches may appear, but it is a lot cheaper. 

The Perfect Location 


When you plan to install a roof window, you should take some time to think about where you want to place it. You should decide on how much solar heat and the light you want to let in. Installing your windows on a north-facing roof should provide a consistent amount of natural light all year. But if you are interested in saving more energy, installing your windows on a south-facing roof is the right course of action. 

Remember About Energy Efficiency


Even the highest quality roof windows and skylight will result in some energy waste. In the summer it should result in additional heat, and in winter in letting the warm air split up. If you don’t mind these conditions, then you can start installing your windows. Also, when you are shopping for a product, make sure to purchase the unit with the best insulation and energy-saving properties. This way, the additional windows shouldn’t affect your energy bills much. 

Fixed vs Vented


Did you know that you can choose to ventilate your house through your new roof windows or skylights? You will be happy to know that there are vented ones out there that can improve the air circulation in your house. However, vented ones are more expensive and more vulnerable to leaks, but if you want to improve the ventilation, it is a risk worth taking. 

Any Additional Features?


These products come in a variety of designs, and it is your decision to choose one that suits your house the most. You can get a curb mounted window that is fixed into a box structure or a deck-mounted window that is installed directly on the roof deck. You will also need to decide between the tempered glass, which shatters into small pieces when it breaks, and laminated glass, which forms larger pieces that are held together by a thin film, or go for a plastic finish that is cheap but vulnerable to scratching.

Site Delivery and Storage


Before the day of the window installation comes, you need to transport it to the site safely and store it undamaged for as long as needed. Some manufacturers offer free delivery, so if you can, choose the next-day delivery option to minimize the storage requirements on-site. 

Do not underestimate the weight of a roof window. A skylight can weigh anything from 60 to 300 pounds and more depending on the type of glazing and size. You might need to consider renting a lift for difficult to access locations or bigger units to ensure safety. Check with Health and Safety if you need any mechanical assistance or more professionals at the site. There is no such thing as too much caution. 

The Right Time for Installation 


When you plan to install one, you should factor in timing. The best weather to install a skylight or a roof window in is during summer days when it’s relatively dry. However, most of them can be installed all year round. Because the main installation season is summer, you can try to install in the winter to get charged less for the installation, but you risk it being delayed due to weather conditions. 

Final Thoughts

Installing a roof window is a relatively complicated process that requires a lot of research to meet the challenges of the decision-making ahead. However, once you establish what kind of effect you are looking for, the choice becomes pretty straightforward. Make roof windows a stand out feature of your house and let in as much light as possible. 

About Jeanette Iglesias