As a UK lead sash weights manufacturer, Heaps, Arnold & Heaps Ltd supplies lead sash weights and steel sash weights direct to timber window manufacturers, sash window restoration specialists, joinery contractors and architectural ironmongers across the UK.
Manufactured to order at our Rotherham facility from over 250 years of metallurgical experience, our sash weights serve both volume production for new timber sash windows and one-off restorations of period properties and listed buildings. Our window and joinery range covers two principal product types: lead sash weights in square, round and rectangular profiles for traditional sliding sash windows, and steel sash weights as the modern alternative to cast iron in three standard cross-sections.
Both are manufactured to order with no minimum or maximum quantities — single replacements through to full production runs.
Lead Sash Weights for Sliding Sash Windows
Lead sash weights are the traditional counterweight used in sliding sash windows, balancing the upper and lower sashes to allow smooth, controlled opening and closing.
We manufacture lead sash weights to order with no minimum or maximum order quantities, supplied to timber window manufacturers producing new sliding sash windows and to architectural ironmongers and restoration specialists working on period properties.
Lead sash weights are available in three principal cross-sections — square, round and rectangular — covering both standard imperial dimensions for heritage restoration and metric specifications for modern joinery production.
Square Lead Sash Weights
Square lead sash weights are the most commonly specified profile, suiting the standard sash box dimensions found in both Georgian, Victorian and modern timber sash windows. 
Available in:
– 25mm (1″) square lead sash weights
– 32mm (1¼”) square lead sash weights
– 35mm square lead sash weights
– 38mm (1½”) square lead sash weights
– 40mm square lead sash weights
– 42mm square lead sash weights
– 45mm (1¾”) square lead sash weights
– 50mm (2″) square lead sash weights
– 57mm (2¼”) square lead sash weights
– 63mm (2½”) square lead sash weights
Round Lead Sash Weights
Round lead sash weights suit narrower sash box configurations and are often specified for bespoke window restoration or specialist period property work where a circular cross-section is required:
– 25mm (1″) round lead sash weights
– 32mm (1¼”) round lead sash weights
– 38mm (1½”) round lead sash weights
– 45mm (1¾”) round lead sash weights
– 50mm (2″) round lead sash weights
– 63mm (2¼”) round lead sash weights
– 76mm (3″) round lead sash weights
Rectangular Lead Sash Weights
All lead sash weights are supplied with a 12mm central hole for sash cord fitting.
Steel Sash Weights — The Modern Alternative to Cast Iron
Steel sash weights are the modern alternative to traditional cast iron sash weights, manufactured to order with no minimum or maximum order quantities. As the supply of new cast iron sash weights becomes increasingly limited, steel offers a dimensionally compatible, cost-effective sourcing option for timber window manufacturers and architectural ironmongers. Our steel sash weights are available in three standard square cross-sections — 40mm (1¼”), 45mm (1¾”) and 50mm (2″) — across a comprehensive weight range from 6lb (2.7kg) to 35lb (15.8kg) and beyond. Any weight can be produced to specification in any of the three cross-sections.
Standard Steel Sash Weight Range
The choice typically depends on three factors: heritage compatibility, cost and weight density.
When to specify lead
When to specify steel
Bespoke Sash Weights & Counterweights
Beyond standard lead and steel sash weights, we manufacture bespoke window counterweights for unusual specifications — oversized commercial sashes, French casement balancing, sliding shutter mechanisms, and specialist heritage window types.
Our in-house extrusion, casting and machining capabilities support both one-off prototypes and production runs. For challenging restoration projects where the original weight specification has been lost, we can take measurements from a sample weight or sash box and reverse-engineer the correct weight, dimension and material.
Find out more about our wider construction lead products and manufacturing capabilities.
Why Choose a UK Manufacturer for
Sash Weights
No Minimum Order
Lead and steel sash weights manufactured to order with no minimum or maximum quantities. Single replacements for restoration through to full production runs for window manufacturers
Heritage & Modern
Traditional imperial dimensions for period restoration alongside metric specifications for modern joinery. We support both heritage craftsmanship and contemporary timber window manufacturing.
Direct from manufacturer
Working direct with the UK manufacturer means faster turnaround, technical advice on weight specification, and no distributor mark-ups on bespoke profiles
Bespoke Capability
In-house extrusion and casting for non-standard cross-sections, custom rectangular profiles and unusual weight specifications matched to your sash box.
Bespoke Lead Manufacturing for Window & Joinery
We manufacture lead and steel sash weights for window and joinery applications to meet specific project requirements — whether you’re producing a production run of new timber sash windows, restoring a Georgian terrace, replacing weights in a Victorian sash window, or sourcing a single counterweight for a heritage property.
Our production capabilities allow us to supply lead sash weights, steel sash weights and bespoke window counterweights in dimensions, weights and lengths matched to your project. For complex specifications we can review drawings, recommend appropriate weight and material specifications, and suggest manufacturing approaches that reduce lead time or cost.
Find out more about our wider construction lead products including lead sheet, lead came and bespoke architectural components.
Sash Weights Frequently Asked Questions
What lead sash weight sizes do you supply?
We manufacture lead sash weights in three cross-sections — square (10 sizes from 25mm to 63mm), round (7 sizes from 25mm to 76mm) and rectangular (multiple combinations from 50mm × 25mm to 75mm × 50mm and beyond). Standard lengths are 600mm and 1200mm with special lengths on request. All lead sash weights have a 12mm central hole for sash cord fitting.
What's the minimum order quantity for sash weights?
There is no minimum or maximum order quantity for either lead sash weights or steel sash weights. Whether you need a single replacement weight for a restoration project or thousands of weights for a production run of timber sash windows, we can quote and supply.
Are steel sash weights a direct replacement for cast iron?
Yes. Steel sash weights are the modern alternative to traditional cast iron sash weights and are dimensionally compatible with standard sash box configurations. Available in 40mm, 45mm and 50mm square cross-sections in weights from 6lb (2.7kg) to 35lb (15.8kg) and beyond — any weight produced to order.
How do I work out what weight I need for a sash window?
The counterweight required is determined by the weight of the sash being balanced. The combined weight of both counterweights for a sash should equal the sash weight, allowing the window to remain in any position. For exact specifications, send us the sash dimensions, glass thickness and pane configuration and we can recommend appropriate weight specifications.
What sash cord size fits the central hole?
All our lead sash weights are supplied with a 12mm central hole, which accommodates standard sash cord sizes used in UK joinery. Steel sash weights are also configured with appropriate fixing arrangements to suit standard sash cord and chain mechanisms.
Can you supply weights for non-standard sash boxes?
Yes. Bespoke sash weights are a routine part of our manufacturing — non-standard cross-sections, unusual lengths, oversized weights for commercial sashes, or specialist profiles for heritage restoration. Send your sash box internal dimensions and required weight and we'll quote bespoke specifications.
How do I request a quote?
Visit our lead sash weights or steel sash weights product pages, email us with your specification, or call our sales office on +44 (0)1709 837669. Our team responds within one working day with availability, pricing and lead time.
Industries We Supply
Lead and lead alloy products supporting the UK nuclear sector
Lead solders, lead wire and bespoke lead components for automotive restoration and specialist engineering applications.
