Block and Tackle Window Balance Systems Explained

The block and tackle window balance is one of the most widely used balance systems in single and double-hung windows. The balance system is the mechanism that allows you to easily open or close your windows. There are three other types of window balances and understanding how each work will help you make informed decisions when it comes to buying new windows or balances. In this post, we’ll explain everything you need to know about the block and tackle window balance.

For information on other types of balances take a look at our Window Balances 101 post.

Table of Contents

What is a Block and Tackle Window Balance?
Pros and Cons of Block and Tackle Window Balances?
How Do I Know Something is Wrong with My Window Balance?
How to Repair or Replace a Block and Tackle Window Balance
Which Window Brands Have Block and Tackle Window Balances

What is a Block and Tackle Window Balance?

^{Caldwell Series 300 ⅝” Channel Block and Tackle Window Balance.
Image Credit: Window Hardware Direct↗}

Block and tackle window balances are also known as channel balances. Like most other window balances, block and tackle balances are located in the window jamb. This device includes a combination of two or more pulleys, a cord, and a spring contained within a “U” frame channel. The “U” frame is a long square container with one open side (pictured above). Some block and tackle systems also have “wings” which are small plastic attachments at the end of the “U” frame.

Styles for block and tackle balances vary depending on what type of sash they will be operating. Some block and tackle balances are designed for tilt sashes and others for side load sashes. A tilt sash is one that can be unlatched and tilted toward the interior of the home for easy cleaning while a side load sash doesn’t tilt and is loaded in or out of the sash from one side.

Modern wood windows usually use block and tackle balances but they can also be used in aluminum, vinyl, and composite frame windows.

^{Image Credit: Screen capture from JELD-WEN YouTube video↗}

How do block and tackle balances work?

Block and tackle balance systems use an extension spring force to counterbalance the weight of the window sash. The pulley and cord system control the tension in the spring as the sash moves up and down in the frame.

^{Image Credit: Family Handyman↗}

We’ll use the terminology from the graphic above to illustrate the parts of the block and tackle window balance. As you can see the channel or balance cartridge encases the balance system. In the image, you see a clip on the left, the “S-clip,” the clip is attached to a holding pin that is connected to a tensioning spring. The tensioning spring is connected to a pulley block with two pulleys and nylon or synthetic cord threaded through. One end of the cord is at the pulley block and the other runs through the locking terminal.

Tilt-sash windows use balances similar to the one pictured above. Not pictured is a pivot shoe. In tilt-sash windows with channel balances, a clip is attached to the end of the cord that runs through the locking terminal. That clip attaches to the pivot shoe which connects to the sash allowing the window to move up and down and tilt-in for easy cleaning.

Non-tilt windows with block and tackle balances have a hook at the end of the cord that runs through the locking terminal. When the block and tackle system is engaged the hook slips into a slot near the center of the window jamb extending and stretching the cord. This balance moves with the window sash and doesn’t have a pivot shoe.

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Pros and Cons of Block and Tackle Window Balances

Benefits of block and tackle window balances

Can handle heavy window sashes
Long-lasting system
Easy to replace the balance

Drawbacks of block and tackle window balances

Window units with this system leave wiggle room for the sash so the seal is not as tight compared to windows with other balance systems
Lots of breakable parts
Block and tackle systems are durable but can fail after time, the biggest problem is that parts are specific to the window at the time they are made. Finding the parts can be a challenge 20-30+ years down the road

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How Do I Know Something is Wrong With My Window Balance?

You’ll know something is wrong with your window balance when the sash begins to feel heavier as you lift or close the window. Continuing to use the window as it becomes more difficult to operate can make the problem worse. On the plus side, removing the sash and identifying the problem should be relatively easy.

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How to Repair or Replace a Block and Tackle Window Balance

This type of balance has lots of moving parts - the clips, spring, cord, and wings (plastic end caps) can all fail. Before you remove the sash and balance, try spraying the lubricant in the jamb. If the window is still difficult to operate, remove the sash and balance to identify the problem. In situations where parts are broken, some parts can be replaced or you can replace the whole balance.

If you can identify and source the original parts of your window, balance replacement should be easy. Follow the steps below to remove and replace your block and tackle window balance.

Instructions for a sideload/non-tilt window
Instructions for a tilt-sash window

INSTRUCTIONS FOR REPLACING A BLOCK AND TACKLE BALANCE IN A SIDELOAD/NON-TILT WINDOW

Step 1: Remove the sash

Popout the two takeout clips at the top of each side of the window frame (you may need a flat head screwdriver for this)
Lift the sash evenly, a couple of inches above the takeout clips (this will also disengage the balance from the sash)
Push the sash in toward one side of the jamb, pull the other side of the window out of the jamb

^{Image Credit: Brennan Enterprises}

Step 2: Remove the old balances

Remove the spring-loaded balance slowly to prevent it from popping out at you.

Pull the balance down and out of the takeout clip
Pull the balance back up to disengage the balance’s lower hook from the frame of the window

Repeat step 2 for both sides of the jamb.

Step 3: Replace the balance

Place the lower hook into the slot near the center of the frame
With the hook engaged, push the balance down so that the top part of the balance engages under the takeout clips

Repeat step 3 for both sides of the jamb.

^{Image Credit: Brennan Enterprises}

Step 4: Replace the sash

Place the sash into the jamb above the takeout clips
Slip one side of the sash into the jamb, far enough to clear the opposite side
Slide the sash into place and lower the window
Push the takeout clips back into a flat closed position

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INSTRUCTIONS FOR REPLACING A BLOCK AND TACKLE BALANCE IN A TILT WINDOW

You’ll need some tools for this process

A hook or pliers to remove the cord from the pivot shoe
Phillips head screwdriver
Flathead screwdriver (in case you need to remove the pivot shoe)

Step 1: Remove the sash

Unlock the window and lift it up a few inches
Engage the tilt-in latches and tilt the window toward you
Twist the sash to disengage it from the pivot shoes

Step 2: Remove the old balances

Take your hook tool and attach it to the terminal clip
Pull the clip out from the pivot shoe and guide it back up to the rest of the balance
Use the Phillips screwdriver to remove the screw attaching the balance to the frame
Remove the balance

Repeat step 2 for both sides of the jamb.

Take a look at the condition of the pivot shoe, if it’s broken it will need to be replaced.

Step 3: Replace the balance

Place the replacement balance into the jamb and secure it with screw
Use your hook tool to pull the terminal clip down and reattach it to the pivot shoe.

Repeat step 3 for both sides of the jamb.

Step 4: Replace the sash

Place the sash back into the pivot shoes and tilt the window up into the jamb

The window should now open and close smoothly.

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Which Window Brands Have a Block and Tackle Window Balance?

Block and tackle balances are one of the most common balances used by window manufacturers today. The list below identifies the windows we sell which feature block and tackle (channel) balances.

Andersen E-Series Double Hung Windows
Andersen A-Series Double Hung Windows
Andersen 400 Series Woodwright Double Hung Windows
Andersen 400 Series Double Hung Windows
Andersen 200 Series Double Hung Windows
Andersen 100 Series Fibrex Single Hung Windows
Milgard Ultra Series Single Hung Windows
Milgard Essence Series Double Hung Windows
Milgard Trinsic Series Single Hung Windows
Milgard Style Line Series Single Hung Windows
Milgard Thermal Break Aluminum Series Single Hung Windows