August 14, 2012
Due to the variation in window styles, listed building requirements and planning authority interpretation, we have created a very wide range of options to ensure that we can meet the optimal requirements for any project.
To specify the optimum design, we have produced a flowchart. This starts with the best performance the lowest cost (a solution that works for about 75% of projects we have been involved with), with the cost/performance then affected as more strict aesthetics are specified further down the chart. We are able to quote for multiple options to provide you with more precise details. The flowchart below gives more details on the glazing method, performance and cost of our options.
System 1: Internal Bead with Astragal bar
Narrow sash and frame profiles and all of our historic features but using a modern internally glazed design for optimal performance.
Glazing Method: Internally beaded using advanced system from traditional range.
Glazing Bar: 21mm astragal bar (with interbar as option)
Performance: *****
Cost: ££
Options: Sash Bead Profile, Astragal Bar Profile, Standard Glass.
System 2: External Bead with Astragal Bar
Changing to an externally glazed system more accurately replicates the original designs, but loses many of the performance advantages of modern internally beaded design.
Glazing Method: Externally beaded
Glazing Bar: 21mm astragal bar matching historic sash profiles
Performance: ***
Cost: £££
Options: Historic Sash Profile, Historic Astragal Bar, Historic Glass
System 3: External Bead with Structural Glazing Bar
As System 2 but with a traditional structural glazing bar. As this requires separate glazing panels rather than a single unit, there are more thermal shortcuts and it requires more time to glaze the window.
Glazing Method: Externally beaded
Glazing Bar: 21mm (single glazing) / 24mm (double glazing) solid glazing bar
Performance: **
Cost: ££££
Options: Historic Sash Profile, Historic Glazing Bar, Historic Glass
System 4: External Putty with Structural Glazing Bar
As System 3 but glass is installed with putty rather than a bead. This replicates the aesthetics and the production methods of the original product but is the highest cost option with reduced performance and guarantees.
Glazing Method: Externally face puttied
Glazing Bar: 21mm (single glazed) / 24mm (double glazed) solid glazing bar
Performance: *
Cost: £££££
Options: Historic Sash Profile, Historic Glazing Bar, Historic Glass
View our Historic Range.
