Sashless Windows

Why choose sashless windows?

Sashless windows, sometimes called frameless or counterbalanced windows, create a clean-lined aesthetic because the glazing panels slide past each other without the need for a surrounding sash. Designers specify them to:

• maximise daylight and views
• reduce visual bulk in heritage refurbishments where the original timber frame is too thick
• achieve a minimalist modern façade
• improve passive ventilation compared with fixed panes

Unlike standard double-hung units, the top and bottom panels can be set up to move independently, allowing warm air to escape near the ceiling while pulling cool air in at floor level. High-performance seals mean today’s systems can achieve similar weathertightness and acoustic ratings to traditional sash windows.

Key specification checklist

• Glazing: Most NZ suppliers offer 6 mm–12 mm toughened glass as standard. Upgrading to low-E double-glazing lifts R-values to around 0.36 m²K/W, in line with H1/AS1 requirements for most climate zones.
• Balancing hardware: Spring or counterweight systems should be sized for the pane weight so that anyone can operate the window safely. Specify stainless steel or powder-coated balance tubes for coastal sites.
• Frame options: Sashless windows sit inside a slim aluminium or timber perimeter. For maximum thermal performance look for thermally broken aluminium or FSC-certified timber.
• Size limits: Typical maximum panel size is 1,200 mm wide by 3,000 mm high, though custom-engineered solutions can go larger. Check wind zone ratings and glass thickness with your supplier.
• Security: Ask for key-locking latches or restrictor stays to comply with NZ Building Code F4 Safety from Falling when the sill is less than 760 mm above floor level.

Installation & compliance in New Zealand

Because sashless windows rely on precise tolerances, accurate set-out is critical. Most manufacturers pre-glaze and deliver units ready to slot into prepared openings, reducing on-site handling. Flashings, air seals and cavity closers follow the same principles as other window types covered in Acceptable Solution E2/AS1.

If the lowest opening is higher than two storeys, you may need safety screens or restrictor stays. For guidance refer to the Ministry of Business, Innovation and Employment’s Building Code Clause F4 – Safety from Falling (MBIE F4 guidance).

Always engage a Licensed Building Practitioner for installation. A producer statement (PS3) from the window fabricator can streamline council consent.

Cost expectations

• Single-glazed aluminium unit 900 × 1,200 mm: $1,200–$1,600 + GST
• Double-glazed thermally broken aluminium unit: $1,800–$2,400 + GST
• Oversize or specialist glass (acoustic, security): add 20–40%

Lead times are 4–6 weeks ex-factory, longer in peak season or for powder-coat colour matching.

Maintenance tips

Clean glass and tracks quarterly with a mild detergent. Lubricate springs or counterweights annually. Replace weather seals every 10–15 years, or sooner in high UV zones.

Related window styles

Still deciding? Compare other NZ window options:

• Skylights and roof windows bring top-light into dark spaces.
• Awning windows shed rain while open.
• Sliding windows suit wide horizontal openings.
• Casement windows seal tightly against high winds.
• Tilt and turn windows combine ventilation modes.
• Louvre windows offer fine airflow control.
• Bifold windows open entire walls to the deck.
• Security window grilles boost safety without blocking views.
• Window mouldings finish heritage facades.

For a full overview of all profiles and frame technologies, visit our Windows category.

Explore the curated range of sashless windows on ArchiPro, request samples, and connect with trusted local fabricators today.