Lead Sash Weights

Lead sash weights are counterweights used to balance traditional sliding sash windows. They are installed inside the window frame and connected to the moving sash with cords running over pulleys. Their purpose is to counterbalance the weight of the window, allowing it to open, close and remain in position with minimal effort.

Lead sash window weights are particularly suitable for timber sash windows, period properties and restoration projects where space inside the window frame is limited.

To calculate the correct sash window counterweights, first determine the weight of the complete window sash, including the timber frame and glazing. In a traditional system with two counterweights, each weight should generally be approximately half the total sash weight.

For example, a sash weighing 12 kg will typically require two counterweights of approximately 6 kg each. Small adjustments may be necessary depending on the window design and whether it is the upper or lower sash.

Correct balancing prevents the window from dropping, rising unexpectedly or becoming difficult to operate.

When choosing replacement lead sash weights, measure the existing counterweights or the available space inside the sash box. The most important measurements are the weight’s diameter or cross-section, length and total mass.

The replacement weight must move freely inside the frame without touching the surrounding timber or interfering with the pulley mechanism.

If you are replacing missing sash weights, measure the sash itself to calculate the required counterbalance. Our team can help you choose the appropriate lead weight dimensions for your window.

At Sash Weights London, we supply round, square and rectangular lead sash weights for different sash window constructions.

Our range includes square profiles from 25 mm × 25 mm to 57 mm × 57 mm, round profiles including 32 mm, 38 mm, 45 mm and 50 mm diameters, and rectangular options such as 45 mm × 35 mm, 50 mm × 25 mm and 60 mm × 30 mm.

The ideal shape depends on the sash box dimensions and the weight required to balance the window. Browse our round lead sash weights, square lead sash weights and rectangular lead sash weights to find a suitable profile.

Yes. At Sash Weights London, we offer lead sash weights cut to size to suit individual window requirements. Our cutting service is available at no additional cost.

Cut-to-size counterweights are particularly useful when restoring Victorian or Edwardian sash windows, replacing missing weights or working with narrow sash boxes where standard lengths may not fit.

Selecting the correct length and weight helps ensure smooth movement inside the frame and reliable window operation.

Both materials provide effective counterbalancing, but lead sash weights are denser than steel sash weights. This means lead can provide the same counterweight in a smaller volume, making it particularly useful for narrow sash boxes and traditional timber window frames.

Steel weights are a practical alternative where sufficient space is available and steel is preferred for the installation.

The best choice depends on the required counterbalance, available cavity dimensions and the construction of the window. We supply both lead and steel sash window weights.

Yes. If your existing sash window weights are slightly too light, lead add-on weights can provide additional counterbalance without replacing the main weights.

This solution can be useful following glazing replacement, timber repairs or other modifications that increase the weight of the sash.

We offer lead add-on weights for fine-tuning traditional sash window balance systems. Always check that the combined weight and length are suitable for the available space inside the sash box.

A traditional sliding window sash generally requires two sash weights, one on each side of the frame. Each weight is connected to the moving sash by a cord passing over a pulley.

A traditional double-hung sash window with two independently moving sashes will normally require four counterweights in total.

The upper and lower sashes may have different weights, so each should be measured and balanced separately to ensure correct operation.

The price of lead sash weights in London depends on their size, shape, length, weight and the quantity ordered.

Smaller counterweights generally require less material, while larger or heavier weights have a higher material cost. We offer a range of lead sash weights for individual replacement projects and larger professional orders.

You can browse our products online to compare available sizes and prices. We also offer bulk discounts for customers purchasing larger quantities.

You can buy lead sash weights in London from Sash Weights London, located at 14 Gorst Road, London, NW10 6LE.

We supply round, square and rectangular lead counterweights, replacement sash weights and cut-to-size solutions for traditional sash windows.

Orders can be placed online, with collection from our London premises or courier delivery available. For information about collection arrangements and shipping, visit our ordering and delivery page.