Slimline Double Glazing
Specially designed slimline double glazed units for heritage windows, improving thermal performance while retaining authentic appearance.
Heritage Thermal Upgrades
Traditional single-glazed sash windows are a significant source of heat loss in period properties. Slimline double glazing offers a solution that dramatically improves thermal performance without compromising the historic character of your windows or requiring planning consent in most cases.
Our slimline units are just 10-14mm thick, compared to 24-28mm for standard sealed units. This allows them to fit into the existing glazing rebates of traditional sash windows without requiring alterations to the sash profiles that would change the appearance of the window.
Key Benefits
- Dramatically improved thermal insulation (U-value improvement from 5.0 to 1.2 W/m2K)
- Significant reduction in heating costs
- Elimination of internal condensation
- Enhanced acoustic performance reducing external noise
- Preservation of original window profiles and proportions
- Increased security through toughened or laminated glass options
- UV protection for furniture and furnishings
Installation Process
Slimline double glazing is typically installed as part of a full sash window restoration. We remove the sashes from the frame, carefully extract the existing single glazing, make any necessary adjustments to the glazing rebates, and install the new slimline units using traditional glazing techniques. The process adds 1-2 days to a standard restoration project.
FINEO Vacuum Glazing
For listed buildings and conservation areas where planning requirements are strict, we offer FINEO vacuum glazing. At just 6.7mm thick, FINEO closely replicates the appearance of traditional single glazing while delivering exceptional thermal performance with U-values as low as 0.7 W/m2K.
FINEO achieves this performance through a vacuum sealed between two panes of glass, eliminating heat transfer through gas convection. The result is a glazing solution that satisfies even the most demanding conservation officers while providing 21st-century energy efficiency.
Glazing Options
- Standard Slimline (10-14mm): Cost-effective solution for most applications
- Heritage Slimline: With drawn glass for authentic period appearance
- FINEO Vacuum (6.7mm): Premium option for listed buildings
- Acoustic Slimline: Enhanced sound reduction for urban properties
- Security Slimline: Laminated options for ground floor windows
Common Questions
Slimline double glazing is a specially designed glazing unit that fits into the existing glazing rebates of traditional sash windows. At just 10-14mm thick compared to 24-28mm for standard double glazing, slimline units can be installed without altering the original window profiles. This allows you to achieve improved thermal and acoustic performance while maintaining the authentic appearance of your period sash windows.
Yes, slimline double glazing is often approved for listed buildings, particularly when using FINEO vacuum glazing which is just 6.7mm thick. FINEO closely replicates the appearance of single glazing while delivering excellent thermal performance. We work closely with conservation officers throughout Belfast and Northern Ireland to ensure our glazing upgrades meet listed building consent requirements.
Slimline double glazing costs vary depending on the size of the glazed areas and the type of unit specified. Standard slimline units are more affordable, while FINEO vacuum glazing carries a premium due to its superior performance and minimal thickness. We provide detailed quotations following our free survey, and the investment typically pays back through reduced heating costs over 5-10 years.
FINEO is a high-performance vacuum glazing system developed by AGC Glass Europe. At just 6.7mm thick, it achieves U-values as low as 0.7 W/m2K, comparable to triple glazing. The vacuum between the glass panes eliminates heat transfer through gas convection, making it exceptionally energy efficient. Its slim profile makes it ideal for heritage applications where traditional double glazing would be too thick.
Yes, slimline double glazing significantly reduces internal condensation. The improved insulation means the internal glass surface stays warmer, preventing the temperature dropping to the dew point where moisture condenses. Combined with our concealed draught proofing which reduces uncontrolled air infiltration, your windows will stay clear and your rooms more comfortable.
In most cases, yes. Slimline units can be fitted during a restoration where we remove the sashes to access the glazing rebates. The existing single glazing is carefully removed, the rebates may be adjusted slightly to accommodate the thicker units, and new slimline double glazed panes are fitted using traditional glazing techniques. The process typically adds 1-2 days to a standard restoration.
Book Your Survey
Book a free, no-obligation survey to discuss slimline double glazing options for your sash windows. We serve Belfast and all of Northern Ireland.
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