The Kensington Traditional Box Sash

The Kensington Traditional Box Sash

The KENSINGTON is a traditional box sash window in design and operation, specifically targeted to satisfy the requirements of Planners, Conservation Officers and Architects alike. KENSINGTON windows can be tailor-made to suit any configuration, either single or double glazed and designed to be flexible enough to meet most planning constraints.


Sashes are operated using either cords or chains (depending on load) over a high quality pulley wheel with counterbalancing lead weights. Weights can be either factory fitted or supplied loose for assembly once the frame is in position.

KENSINGTON box sash windowsMaterial and Construction

Windows are manufactured in quality European Redwood, from PEFC certified forests or from environmentally sourced species of hardwood. Joints are formed using advanced machining methods and purpose designed tooling.
The Kensington window has been tested to meet the most stringent British Standard BS6375 Part 1, 2 and 3, Severe Weather Resistance ratings and Mechanical Strength .

Tailor-made Styles & Mouldings

Each window in the range is tailor made to order based around our proven sections. Lambs tongue and ovolo mouldings are available to suit single glazing. Ovolo mouldings are used on the double-glazed ranges.
Any size, style and shape can be produced within practical limitations to give specifiers reasonable freedom of choice and proportion. Coupled with our in-house design service, sections can be adapted to meet aesthetic requirements of listed buildings and properties within conservation areas where attention to existing detail is paramount .


Kensington windows are supplied factory glazed in accordance with BS 6262. Variations including toughened, laminated, obscure glazing and gas filling are available upon request. Either single or double glazing can be supplied. Single glazed sashes are designed to accept 4mm or 6mm glass and can incorporate either a hardwood putty profile bead or left open to accept putty by others. Double-glazed sashes are designed to accept a 22mm sealed unit, fixed with security tape and pinned bead system.

Acoustic Glazing

MH Joinery has extensive experience in the field of sound attenuation. Further details are available upon request.

Fire exit and retardant designed frames

Fire resistant framing and minimum sized egress information is available on request.

Health and Safety

Frames calculated to exceed CDM recommended limits can be supplied de-sashed if required for ease of handling and fitting. Kensington windows incorporate a removable push-fit timber staff bead, allowing effortless sash fitting or removal without the need for re-decoration. Lead weights can be fitted once frames are in position via a slide-way secret pocket and designed for easy attachment. A site commissioning service by our skilled remedial team is available. Please ask for further details.


Sections within the entire MH Joinery range have externally beaded profiles in line with good joinery practice. Factory glazing incorporates a proven security tape and pinned glazing beads.
The Kensington window has been tested to PAS24.

Building Regulation Part ‘L’

Thermal simulation testing has been carried out as described in ISO 15099. All products passed with thermal conductivity readings in line with or exceeding Document Part ‘L’ and meet the latest regulation standards (October 2010).

Window Energy Rating

MH Joinery manufacture a range of BSI A - C rated windows (WER). Our products meet or exceed the current Building Regulation requirements. Energy rating details are available upon request.

Applied glazing bars

To meet the visual requirements of clients and planning authorities, MH Joinery has adopted the applied glazing bar system to replicate slim sectional bars of single glazed windows.
A 22mm bar is standard with a 19mm option. The internal bar is tenon-jointed into the sash and external bars applied to the glass in a controlled environment as a matrix in a putty-check design. Bars applied this way are extremely unlikely to delaminate away from the glass over time. The air space between the sealed unit is filled with a back-to-back spacer to visually replicate individual panes


To avoid distracting from the aesthetic lines of the window, discreet trickle ventilation is hidden and operated via the head of the frame as standard.

Timber preservative treatment

All softwood timber frames are preservative treated before assembly by the double vacuum impregnation process using inert water based materials.


Windows are supplied as standard in a semi-finished condition of one basecoat of stain or primer/undercoat plus one top-coat of water based stain/micro-porous paint. Full factory finishing incorporating a third top-coat is available as an option. When site decorating, it´s important care is taken to avoid contact with operational and moving parts of the window. Paint applied to weather stripping and ironmongery will impair overall performance.


High quality Kensington ironmongery includes one Fitch type fastener (two to sashes over 900mm wide), two sash lifts and two matching finish pulley wheels. Opening restrictors and trickle vents are optional, all supplied factory fitted if specified.
Standard ironmongery finishes include traditional brass, polished bright chrome and satin plate chrome.

Ironmongery extras

Sash pulls ('D' handles)
Security/restrictor locks

Security/Safety/Design options

The following optional extras are available to clients own specification.

Sash horns to match existing or clients own profile to inner and outer sashes
Cill horns and extensions
Hardwood cills
Full grooving for water-bar underside of cill
Full factory paint or stain finish in selective RAL shades
Sash commissioning service - Frames supplied initially, sashes fitted and balanced by MH Joinery site remedial operatives

Complete joinery package

To complement the Kensington window, a complete range of compatible joinery to a customer´s own specification, including doors, door frames and French casements is available, ensuring continuity throughout a project. In addition, we offer a full design service and comprehensive technical support.


U-value Calculation Certificate - Kensington - Sliding Sash Window - Weights & Pulley s 4/12/4
U-value Calculation Certificate - Kensington - Kensington - Sliding Sash Window - Weights & Pulley s 6/10/4
Kensington Window BS 7950 & 6375 Part 1
Kensington Window BS 6375 Part 2&3

CE Marking

MH Joinery Products Ltd - Unit 11 Parrett Way - Colley Lane Industrial Estate - Bridgwater - Somerset - TA6 5LB
Tel: 01278 421718 - Fax: 01278 444792 - Email:

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