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What is a Window Sash?

window sash

The first glass windows were crafted in 100AD, but it took centuries for architects to design the first sash. The oldest surviving example dates back to the 17th century. Even then, sashes were more than mere frames for glass. Surviving examples have vertical sliders that operate with a system of pulleys and weights. The world was instantly smitten with the trend, even if ancient sashes were thick and unwieldy. The design evolved to include larger panes and slimmer sashes.

What is a window sash?

Window sashes hold your glass in place and are fitted into the frame. Not all sashes are mobile, but they all play a crucial role in reinforcing overall window construction. There are six broad sash styles:

  • Georgian sash windows evoke the elegance of the Georgian era. They have a characteristic six-panel grid on either side so that their bottom panels can slide open over a fixed upper sash.
  •  Victorian sash windows use a four-panel grid designed to let extra daylight through. Some designs implement the old Victorian sash horns to achieve a vintage aesthetic.
  • Queen Anne sash windows have a Baroque style with multiple panes, often with curved lines.
  • Edwardian sash windows have a two-panel sash that opens onto a six-panel sash.
  • Bay sash windows are another Edwardian favorite with fewer grid lines. One box bay window remains static while the other opens upward. This design is typically built into the bottom floor.
  • Oriel windows are often placed on the top floor or attic.
  • Coupled windows include two windows that sit side-by-side with a slim sash.
  • Venetian sash windows take their inspiration from Palladian architecture and feature one fixed arch with two flanking designs.

How do window sashes work?

A traditional or box sash window uses a counterbalance system to offset gravitational force. Two window sashes open smoothly, one in front of the other. The front panel is weighted by a cord and pulley that holds the window in place when open. This system hides the pulleys inside a discreet case, allowing for effortless movement. In recent years, spring balance systems have become increasingly popular. They rely on a spring covered by a PVC tube.

Which system is better? Box or spring sash windows?

Spring sash windows have become the most popular option in the sash universe, but box sash windows aren’t out of the race yet. Their authenticity is particularly valued in historic homes, but they are a high-maintenance option. They frequently need replacements due to their complex design. Spring-balanced sash windows have a simpler mechanism that’s cheaper and easier to maintain. If you live near the coast, however, the saltwater air will quickly corrode that spring. Still, they’re more affordable than box sashes

What’s the cost of a sash window installation?

If your existing sash windows are looking unkempt, restoring them could cost anywhere from $500 to $2,000. If you’re performing a new installation, you can expect to pay about $1,000 per window, but a few details can push that number up. A uPVC or vinyl product with double glazing could cost you around $1,000 per window. Timber products come in at an entry price of $1,500. Hard and exotic woods will come at a price premium, particularly if you’re customizing your design. Of course, size and weight will increase the quantity and price of your materials.

Glazing will also have an impact on price. Heavier glass is more expensive to process, so most homeowners choose a double-glazed design. It’s the cheapest option, but it’s not adequate for every home. If you’re exposed to weather extremes or require acoustic glass, your design will be more expensive to produce.

What are astragal and Georgian bars?

Astragal bars are the hardware that separates each pane of glass in a sash. Georgian bar windows are installed in a sealed unit between glazing layers. They’ll amplify your security, but you can mimic the Georgian aesthetic more affordably with vinyl or uPVC sash windows. While astragal bars give your home a vintage feel, they don’t require multiple panes since they’re applied to a single piece of glazing these days. Much like burglar bars, they’ll make your home harder to break into.  

What materials are best for sashes?

Wood, aluminum, and vinyl are the dominant trio of the sash world. Wood is natural and works beautifully in contemporary homes, but uPVC is stronger and more secure. Aluminum is easy to maintain and fully recyclable, but it can corrode.

Sash windows are constructed with sophisticated internal mechanisms and frames. That makes them superb insulators, especially if you install multi-chambered wood. This option is timeless and always in style. Choose well, and you’ll enjoy seamless corners and superb color bonding. Casement windows might be America’s favorite window style, but sashes deserve the space they’ve cleared for themselves in the industry.

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