All About Basement Windows: Types, Sizes, Ventilation, and Protections

Written By Adam Paul - Waterproofing Expert

Basement windows are small openings in the basement wall that allow light and ventilation into the darker, more enclosed areas. They should be placed according to standard codes such as "IRC" in the USA and "Building Regulation Part B" in the UK. There are six main types of basement windows: hopper, awning, sliding, egress, casement, and glass block windows. Basement windows have six main parts: frame, head, sash, rail, sill, and glass panels.

The standard basement window size typically falls between 24 to 48 inches in width and 12 to 36 inches in height. The minimum size of the basement window size is 720 square inches. All of the basement window sizes should be higher than that. The recommended sill height of the basement windows should not be more than 44 inches. The recommended minimum clear opening height for a basement egress window is 24 inches and the recommended space in front of a basement window is at least 36 inches As well as the recommended space above the basement window is typically at least 6 inches.

Basement windows are made mainly using these 5 materials: vinyl, aluminium, wood, fiberglass, and glass blocks. In order to enhance the functionality, aesthetic appeal, and privacy, basement window treatments are used. The most used basement window treatments are window covers, curtains, and blinds. Basement windows should be faced according to the space's functionality, comfort, and energy efficiency. Hence the most suitable directions for the basement window are south and east. Water leaking from the basement windows should be stopped by following effective ways to minimize the water impact and damage to the basement.

If you do not place a basement window it is a code violation, if the basement is used for living purposes, such as a bedroom, office, or recreation area. For the basement windows, grates are not essential. In order to increase the aesthetic appeal and reduce the cost, fake basement windows are used. Basement windows consist of exhaust fans in order to improve the air circulation and control the moisture in the basement mostly

What are the Basement Windows?

Basement windows are small openings in the basement wall in order to allow light and ventilation into the darker, more enclosed areas in the basement. Basement windows consist of six main parts: frame, head, sash, rail, sill, and glass panels.

Basement windows are mainly of 9 types: hopper, awning, sliding, egress, casement, glass block, double hung, fixed, and tilt and turn windows are them. The six major advantages of basement windows are increasing natural lights and ventilation, energy efficiency, enhanced safety, increased home value, and aesthetic appeal of the home. Hence basement window is an essential opening in the basement as well as basement sho

Basement windows can leak water and moisture inside the basement rain and snow season. In order to protect the basement and reduce the humidity, basement waterproofing is essential.

What are the Standard Guide for Basement Windows?

In both the USA and the UK, there are specific building codes and standards that govern the installation of basement windows, particularly when they are used as egress windows (for emergency exits).

USA Basement Window Standards

Country: United States (USA)
Guidance: International Residential Code (IRC)
Section: IRC Section R310
Important Facts:

Minimum Opening Size: Net clear opening at least 5.7 square feet (0.53 square meters), except for windows located at ground level, which can be 5 square feet.
Minimum Height and Width: The opening must be at least 24 inches in height and 20 inches in width.
Maximum Height from Floor: The bottom of the window opening must not be more than 44 inches from the floor.
Window Wells: If the window is below ground level, a window well must be installed with a minimum area of 9 square feet and a minimum horizontal projection of 36 inches.

UK Basement Window Standards:

Country: United Kingdom (UK)
Guidance: Building Regulations
Section: Part B
Important Facts:

Minimum Opening Size: Egress windows must have a clear opening of at least 3.6 square feet (0.33 square feet) and a minimum dimension of 1.5 feet in either direction.
Window Wells: Similar to the US, if the window is below ground, sufficient clearance must be provided to allow an escape route.
Maximum Sill Height: The window's sill height should not exceed 44 inches from the floor level to facilitate easy exit in emergencies.

What are the 6 types of Basement Windows?

The 6 types of basement windows are hopper windows, awning windows, sliding windows, egress windows, casement windows and glass block windows.

Hopper windows: Hopper windows open inward from the top. It helps to control the airflow into the basement. Due to the compact and small size, hopper windows are suitable for lower basement walls. Hopper windows are tightly sealed when closed. Hence, it provides excellent insulation to the basement.
Awning windows: Awning windows open outward from the bottom. Hence it is important for basement ventilation during rain. Awning windows are highly recommended for basements that need prolonged weather protection due to rain. Awning windows are tightly sealed when closed; hence, they provide excellent energy efficiency to the basement.
Sliding windows: Sliding windows open horizontally. Hence, sliding windows are easy to operate. Sliding windows are suitable for wide window spaces in basements. Due to the sliding mechanism, they have lower maintenance routing compared to other types of basement windows.
Egress windows: Egress windows should be placed according to the approved building codes for emergency exits in habitable basements. Egress windows are larger than most other types basement windows due to their escape requirements.
Casement windows: Casement windows are hinged on the side and swing open like a door. Casement windows provide maximum ventilation compared to other basement window types. Casement windows are excellent for energy efficiency and security in the basement due to tight seals.
Glass block windows: Glass block windows provide privacy and security without sacrificing natural light in the basement. They are highly durable and resistant to breaking. Glass block windows are often used in unfinished or utility basements for additional insulation.

What are the Standard Basement Window Sizes?

The standard size range for basement windows typically falls between 24 to 48 inches in width and 12 to 36 inches in height. The size of the basement window depends on the type and function of the window.

Small basement windows are compact in size, cost-effective and consist of basic functionality. Hence small size basement windows are important in areas where space is limited or where minimal light and ventilation are needed

Large basement windows are larger in size and it helps to allow more natural light and ventilation into the basement space. Large basement windows are highly recommended for the living space in the basement.

What is the Basement Window Size Chart?

The basement window size chart is a chart that is prepared by multiplying the width of the egree window and the depth of the egress window. The area of the window chart is denoted by the square inches. The recommended minimum area for the basement egress window is 720 square inches (0.46 square meters). Hence every basement window size should be higher than this.

What is the Sill Height of the Basement Windows?

The sill height of a basement window is the distance between the bottom edge of the window frame (the sill) and the finished floor inside the basement. The higher sill height is prone to ventilation, while the lowest sill height cause many water and other problems.

The recommended sill height for egress windows should not be more than 44 inches from the floor. But in non-egress windows, the sill height can vary. The lower sill height improves natural light and ventilation in the basement.

How much Space is needed in front of the Basement Window?

The recommended space in front of a basement window is at least 36 inches. This clearance allows for easy opening of the window and ensures that occupants can safely exit through the window if necessary.

More space in front of the basement window increases the ventilation, sunlight and provides an escape route in emergencies.

What is the Minimum Clear Opening Width of a Basement Window?

The minimum clear opening height of a basement window is the unobstructed vertical dimension of the window when it is fully opened.

The recommended minimum clear opening height for a basement egress window is 24 inches. This height, combined with the required width, ensures that the window provides adequate space for emergency exits while also serving the purpose of ventilation and light entry in normal use.

How much Space is Needed Above the Basement Window?

The recommended space above a basement window is typically at least 6 inches. This clearance helps accommodate window frames and ensures that any necessary trim or drainage systems can function effectively.

What Materials are used for Basement Windows?

The most used material for basement windows are vinyl, aluminum, wood, fiberglass, and glass block. This material consists of availability, low porosity, higher water-resistant, pest and insect repellence, and resistant mold and mildew growth due to higher humidity.

Vinyl: Vinyl is a popular material for basement windows due to its low porosity and higher water resistance. Vinyl windows are easy to clean and prevent mold and mildew growth in the basement.
Aluminum: Aluminum is a non-porous window material that offers excellent water resistance capability, and it prevents moisture ingress. Uncoated aluminum basement windows can be prone to condensation, which may lead to mold and mildew growth if it is not properly ventilated.
Wood: Wood is a traditional material for basement windows. Wood provides excellent insulation. But wood basement windows are susceptible to water absorption if not properly treated. This can lead to mold and mildew issues in higher humidity conditions.
Fiberglass: Fiberglass is highly durable and has lower porosity and excellent water resistance to the basement windows. Fiberglass windows are resistant to mold and mildew growth and damage by the water due to their non-absorptive nature.
Glass Block: Glass block windows are often used in basements for privacy and natural light. They are non-porous and highly water-resistant, effectively preventing moisture intrusion. Hence glass block windows are highly recommended for the higher humid basements.

What are the Basement Window Treatments?

Basement window treatments are solutions that are improved to enhance the functionality, aesthetics, and privacy. The most popular basement window treatments are covers, curtains, and blinds.

Basement window covers are protective barriers installed over basement windows to shield them from the elements, improve insulation, and enhance security. Basement covers can be made from various materials, including wood, metal, or plastic. Basement window covers help to prevent water infiltration, reduce heat loss, and deter unauthorized entry into the basement.

Basement window curtains are fabrics that are specifically designed for basement windows in order to resist water, sunlight, and water damage. Basement curtains enhance privacy, control light levels, and improve the overall aesthetic of the basement space.

Basement window blinds are window coverings specifically designed for basement windows. Basement window blinds are often made from materials such as wood, vinyl, aluminum, or fabric. They provide a versatile solution for controlling light, enhancing privacy, and contributing to the overall decor of the basement space. Basement blinds come in various styles, including vertical, horizontal, and roller blinds, allowing homeowners to select options that best suit their needs and preferences.

What Side Should the Basement Windows Face?

The direction of the basement window should be faced according to the space's functionality, comfort, and energy efficiency. These are the directions and benefits of basement window facings.

To improve the natural lights, basement windows should face to south. South-facing basement windows receive the most sunlight throughout the day, helping to brighten up the space.

To improve the ventilation, basement windows should face the east or west direction. But it depends on the region. These directions can enhance the ventilation, reduce moisture buildup and prevent mustiness in the basement. It helps to improve indoor air quality in the basement.

To improve energy efficiency, basement windows should be faced east direction. Warmth sunlight is received throughout the day without heating the afternoon. This balance can help regulate indoor temperatures, potentially lowering heating and cooling costs.

How to Stop Water Leaking from the Basement Windows?

Water leaking can be stopped from the basement windows by following 5 effective ways.

Install proper window wells and cover around basement windows that helps to prevent water from pooling near the window and keep debris and rainwater out.
Seal gaps and cracks on the basement window frame by using a high-quality waterproof caulk of weatherstripping to seal the openings on the frame.
Improve drainage (french drain) around the basement window to involve grading the soil away from the foundation, installing downspouts, or adding drainage pipes to redirect water away from the windows.
Use waterproof window flashings to create a barrier against water intrusion and direct any water that comes into contact with the basement window.
Regular maintenance of the basement window by checking any signs of wear, damage, or buildup of debris in the window wells and cleaning them regularly to ensure proper water flow away from the windows.

Is It a Code Violation Not to Have a Basement Window?

Yes, it is a code violation if there is no basement window in the basement that is used for living purposes, such as a bedroom, office, or recreation area. Building codes often require at least one egress window for safety reasons, allowing occupants to exit in case of an emergency. Basement egress windows is essential in areas prone to fires or other emergencies where quick evacuation is necessary.

Is Window Grates Essential for Basement Windows?

Window grates are not always essential for basement windows. But window grates enhance the performance of the windows by enhancing security by preventing unauthorized access through basement windows, protecting windows from debris, and providing an extra layer of security against water intrusion in severe weather or flooding.

What are Fake Basement Windows?

Fake basement windows, also known as false basement windows or window wells, are not real windows. Fake basement windows are installed in the basement to improve the aesthetic appeal and reduce the cost of installation.

Fake basement windows are designed to mimic the appearance of real windows without providing actual light, ventilation, or egress. Some fake basement windows incorporate built-in lighting, such as LED lights, to simulate natural light to the basement. These fake windows are made from materials like vinyl, fiberglass, or wood, designed to resemble traditional windows.

What are the Advantages of Basement Windows with an Exhaust Fan?

When the basement window is equipped with an exhaust fan offers these 5 advantages.

Improve air circulation in the basement
Control moisture in the basement
Reduce odor in the basement
Regulate temperature in the basement
Increase the energy-saving