What is the purpose of window stops?

Window stops play an important role in windows and doors. They serve several key functions that improve the performance and usability of windows.

What are Window Stops?

Window stops, also known as window restrictors or limit stops, are devices installed on windows that limit how far a window can be opened. They are typically small metal or plastic fittings mounted along the bottom or side of a window sash.

There are a few common types of window stops:

Limit stops – These allow windows to open only to a certain point, usually 4-6 inches.
Casement stops – Used on casement style windows to control the swing range.
Tilt stops – Prevent casement or awning windows from tilting too far inwards.

Sash stops – Stop double hung windows from opening too far and potentially coming off the frame.

Window stops are integrated into the window hardware and are either built-in features of the windows themselves or added on components. They are typically adjustable, so the limited opening can be customized as needed.

Safety Functions of Window Stops

One of the main purposes of window stops is to improve safety:

Fall prevention – Window stops can prevent people, especially children, from falling out of open windows. Limiting the window opening size reduces this risk.
Intruder prevention – By limiting how far a window can be opened, stops can deter a potential intruder from gaining access into a home. This makes it harder to enter even if a window is left open.
Injury prevention – Stops prevent windows from opening wide enough for people to inadvertently walk into. This helps prevent injuries from striking the edge of an open window.

Fall Prevention

Falls from windows are a leading cause of unintentional injury, especially for young children. Studies have found:

Each year around 3,300 children are treated in emergency rooms in the U.S. for injuries related to window falls.
75% of window falls occur in children under the age of 5.

Falls typically happen from the first or second story of a building when a child leans on or climbs up to an open window.

Properly installed and used window stops can greatly reduce the risks of falls. Building codes often require window stops on windows above the first floor to improve safety.

Intruder Prevention

While window stops will not fully prevent break-ins, they can deter intruders by making windows harder to access. Key factors include:

The limited opening size, usually 4 inches or less, is too small for a person to squeeze through.
Stops make it hard to cut screens or tear windows off tracks from the outside.
Would-be intruders seeking easier entry points may avoid windows with visible stops.

Along with locks, alarms, and other home security measures, window stops provide an additional layer of protection against unwanted entry.

Functionality Benefits of Window Stops

In addition to safety, window stops provide other useful benefits:

Increased weather resistance – Stops limit air infiltration from the outside, keeping out drafts, wind, and precipitation.

Noise reduction – Less window opening means interior noise stays in and exterior noise stays out better.
Increased security – Stops add security by preventing windows from being forced open wider from the outside.
Operational control – Stops allow control over the opening and closing of a window for ventilation or cleaning.

Weather Resistance

Window stops improve a window’s weatherproofing by limiting air leaks. This provides benefits such as:

Reduced drafts for greater comfort.
Less precipitation entering around edges of the window sash.

Decreased loss of indoor heated or cooled air.
Lower energy costs from less need to maintain desired temperatures.

Tightly sealed windows with well-fitted stops can make a home more comfortable and energy efficient.

Noise Reduction

Restricting window openings also helps block exterior noise sources. This creates a quieter indoor environment in locations like:

Urban areas with traffic sounds.
Homes near airports, trains, or noisy commercial districts.

Residential streets with considerable daytime traffic.

For maximum noise control, sound-dampening windows and additions like double panes help too. But window stops play an important role in keeping noise out.

Increased Security

Window stops add security beyond just deterring potential intruders. They also:

Prevent windows from being forcibly opened wider from outside.
Reduce ability to tamper with or disable window locks.
Keep windows firmly positioned in tracks and frames.

Along with locks and other security equipment, stops make it much harder for windows to be compromised by an intruder attempting to gain entry.

Types of Window Stops

There are many different types of window stops available. The most common options include:

Sash Stops

Sash stops, also called sash limiters, are commonly used on double hung windows. They are small metal teeth that insert into one side of a window frame. When the window is opened, the teeth catch the bottom sash and prevent it from opening too far.

Material – Typically steel or zinc-plated steel to prevent corrosion.
Location – Inserted into the top rail of the bottom window sash.
Benefits – Inexpensive option that’s simple to install. Adjustable teeth allow custom opening size.

Casement Stops

Casement stops control the swing range on hinged casement and awning style windows. The arm mechanism that opens the window has an integrated stop.

Location – Built into the window arm hardware mounted on the sash.
Benefits – Precise control of opening angle. No additional components needed.

Considerations – Must be properly calibrated and can wear out over time.

Limit Stops

Limit stops allow a window to open only a limited amount, usually 4-6 inches. They are installed on the window tracks or frame.

Types – Plastic, nylon, or metal placed on side, bottom, or top of window.

Benefits – Prevent window from opening too far. Easy to install and adjust.
Location – Top or bottom window track or frame, or on window sash.

Vent Stops

Vent stops are a type of limit stop. They have an adjustable block that slides into the window track and prevents the sash from passing by a certain point.

Materials – Plastic, nylon, aluminum
Benefits – Low cost, easy DIY installation, and adjustable venting
Considerations – Only compatible with certain slider window designs

Choosing Window Stops

Important factors to consider when selecting window stops include:

Window Type – Match the stop design to the window, for example sash stops for double hung windows.
Opening Size – The needed opening limit will dictate the stop style.

Location – Consider if stops should be at the top, bottom, or side of windows.
Ease of Use – How stops mount and whether they are adjustable or fixed position.
Visibility – More visible stops add security, less visible provide a better look.

Budget – Costs range from cheap plastic stops to higher priced metal stops.

Consulting with a window installation specialist is recommended to ensure ideal stops are chosen for the windows and needs of a home.

Installation of Window Stops

Window stops must be properly installed for maximum effectiveness and safety. There are a few potential methods of installation:

During Window Installation

Having stops fitted when new windows are installed is the most common approach. This allows stops to be integrated into the window framing and hardware.

Professional installation ensures correct placement and function.
Required for built-in stops like casement arms and some limit stops.

Aftermarket additions may not fit or function as well.

Aftermarket Add-On Products

Many stops like sash stops and vent stops can be added to existing windows. This allows stops to be retrofitted.

Enables installing stops on windows that don’t have them.

Less costly than window replacement.
Proper measuring and fitting is essential for performance.

DIY Installation

Some basic stop types like sash stops are easy for DIY installation. However, some considerations apply:

Only certain stop models are truly DIY-friendly.
Proper tools and know-how are needed for best results.
Professionals should handle any installation uncertainties.

Overall, having stops installed by experienced window installers ensures they are positioned and adjusted correctly.

Building Codes for Window Stops

Model building codes provide requirements and best practices for the use of window stops. Codes help ensure proper application for safety.

International Residential Code (IRC)

The IRC includes the following provisions related to window stops:

Stops must be installed on windows above the second story where the opening is more than 72 inches above grade. Exceptions are made for some egress and rescue windows.
All stops must limit the openable area to less than 4 inches unless equipped with breakaway stops.
Windows in lofts used as sleeping rooms must have stops if more than 36 inches above the loft floor.

International Building Code (IBC)

The IBC states:

Opening limits of 4 inches unless equipped with breakaway stops.
Egress windows below the fourth story can have openings of up to 8 inches.

Any stops must be releasable or removable from the inside without need for keys or excessive force.

Always check local codes for any additional window stop requirements. Some jurisdictions require stops on all windows regardless of height.

Replacing and Repairing Window Stops

It is important to address any window stops that become damaged or defective. Potential issues requiring replacement or repairs include:

Stops that break, crack, warp, or deform.
Fittings that come loose from the window.
Corroded, rusted, or painted over pieces.

Stops that no longer hold position properly.
Broken or malfunctioning window crank arms.

Replacing worn non-functional stops restores window security and safety. Some tips:

Use exact replacement parts when possible.
Adjust, tighten, and lubricate stops to potentially fix issues without replacement.
Ensure all window hardware is in good condition when replacing stops.

Have professionals make repairs for optimal results.

Regular inspections of stops every few years will identify any in need of repair or replacement to keep windows safe.

Removing Window Stops

In some cases, it may be desired to remove window stops altogether. Reasons can include:

Replacing stops with a different style or opening size.
Removing stops from windows that pose little fall or safety risk.
Increasing ventilation and airflow through window openings.

Enabling easier emergency egress from windows if needed.

Any removals should be done with caution:

Assess if stops are mandated by local codes before removing.

Consider fall and intrusion risks before removing stops.
Use care not to damage windows or frames when taking stops off.
Fill any holes and repair frames left by old stop hardware.

It is often smart to replace stops with more suitable options rather than permanently removing stops altogether.

Conclusion

Window stops serve vital roles in limiting window openings for safety, security, weather resistance, and functionality. Different types are available to suit all window styles and needs. Proper installation and maintenance are needed to keep stops in good working order. Building codes provide requirements for the use of stops to prevent falls and intrusions based on window heights and locations. Speak to window professionals to ensure the optimal window stops are utilized in a home.