FSD Installations
telephone 0845 643 6440
eMail info@fsdinstallations.co.uk

Box Sash Windows


For the traditional or natural look you can’t beat the feel and warmth that timber brings to any room. All our windows are expertly crafted and are laminated to give extra strength and to prevent warping.

Lamination involves splicing the timber into three pieces, and then gluing them back together under high pressure with the timber grains against each other, which prevents the frames from twisting out of shape.

The timber frames are factory finished prior to assembly which best protects the timber from moisture absorption.  They receive a base coat of timber preservative, then a primer coat, followed by two coats of micro-porous paint or stain with uv protection. In general one should expect our coatings to last from five to eight years without the need for re-treatment. Redecoration itself is a very simple task as no sanding down or preparation required. An average window should take about thirty minutes to re-decorate.

Our windows are double glazed with an enhanced thermally insulating glass to provide an extremely low U-value. We further improve the efficiency of the unit by filling the cavity with argon gas. The result is glazing unit U-value = 1.0 W/m2K (according to EN-674), which gives insulation up to 3 times better than traditional double glazing.

  • Available in Redwood, Meranti or European Oak
  • Laminated profiles to reduce expansion and warping
  • Factory sprayed with long life and low maintenance finishes
  • 4-12-4 low e argon filled double glazing fitted, as standard

Ideal Applications

Ideal for all locations, used extensively near coastal regions.

Technical Information

Standard Key Features

  • Constructed using European Oak, Meranti or treated Pine.
  • Multi-layered laminated sections (also known as ‘engineered sections’) help to eliminate seasonal movement and warping.
  • Fitted with either traditional weights and pulleys or spiral balances.
  • Traditional sash lifts and fitch catches are available in a range of finishes including brass and chrome.
  • 4-16-4 low e argon filled double glazing fitted, as standard, giving a centre pane value of 1.0 W/m2K.
Glazing Bars
  • Available with any configuration of bonded astragal glazing bars.
  • Fully finished with micro-porous high performance paint or translucent stain with UV protection.
  • Any choice of colour paint from the RAL colour system is available.
  • All finishes are tested under severe conditions to ensure extremely long outdoor resistance and low maintenance.
Weather Strip
  • Fitted with full window seals to avoid draughts and rattle.
  • Trickle ventilation supplied to comply with Part F of the building regulations, where required.

Non Standard Key Features

  • Toughened, laminated, obscured and self-cleaning glazing options available.
Glazing Bars
  • Available with any configuration of genuine glazing bars.
  • We offer the option of dual painting. e.g. different colours inside and out.
  • Traditional weights and pulleys available on request.
  • Sash lifts and fitch catches are also available in period ironwork, either wrought iron or pewter.


Box Thickness:
Weights & Pulleys - 168mm
Spiral Balanced - 156mm
Frame Thickness:
80mm (60mm option available)
Glass Units:
20mm argon filled units
Optional Glazing Treatments:
Toughened, laminated, obscured and self-cleaning glazing options available.
Standard Colour:
Any RAL colour or various natural stains
Optional Colours:
Dual Painting e.g. different colours inside and out.