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Garden Rooms and Offices Technical Specification

Garden Rooms and Offices Technical Specification

Our bespoke cedar Garden Rooms and Offices are hand built to order by skilled craftsmen in our factory in Worcestershire, using the finest quality materials. They are then delivered and installed by a team of experienced and skilled fitters.

The Western Red Cedar story

Western Red Cedar (Thuja Plicata) is a contemporary yet classic building material offering beauty, versatility and durability. No man-made material can match Cedar’s beauty and centuries of proven performance. Western Red Cedar is preferred where attractive appearance, superior performance and resistance to weather are paramount.

Western Red Cedar has superior thermal insulating properties and is far superior to brick, concrete and steel. This helps keep buildings cool in the summer and reduce heating costs in the winter. Cedar has a very low shrinkage factor and is therefore highly resistant to warping, twisting and shrinkage.

Western Red Cedar’s naturally occurring compounds called ‘thujaplicins’ act as natural preservatives making the wood incredibly durable. Properly finished and maintained, cedar will deliver decades of low maintenance timber.

Whilst Western Red Cedar offers unparalleled performance, it is also renowned for its distinctive beauty. Cedar provides natural charm and warmth that cannot be duplicated by plastic, steel or composite products.

Do not settle for anything less than the best. Western Red Cedar – specify it by name.

Wall construction

External tongue and grooved cladding and finishing strips are manufactured from Western Red Cedar as standard. The shiplap walls are then lined with a breather paper membrane. The walls are constructed using 44mm x 69mm Scandinavian redwood.

The cavity is then filled with 50mm foil backed insulation board. Internally, the walls are lined with 9mm painted MDF (see fig 1).


19mm deal tongue and groove boards are fixed to 44mm x 69mm pressure treated deal joists with a breathable paper membrane sandwiched between. The floors are sprayed with a high quality timber preservative. Techniboard insulation is laid on top of the internal floor.


Heavy duty bitumen roof tiles are laid onto 12mm deal tongue and groove matchboard (dipped with standard treatment). The roof tiles are available in black, green or red (excluding the flat and pent roof models). The flat and pent roof versions have a one piece heavy duty rubber roofing membrane cover. Pressure treated Western Red Cedar shingle tiles are available as an optional upgrade instead of the heavy duty tiles (apex and hipped only).

A breathable paper membrane is sandwiched between the roof boards and the 32mm x 70mm pressure treated redwood joists. The roof is then fully sprayed using a high quality timber preservative. 50mm foil backed insulation fills the cavity between the joists and 9mm painted MDF lining is placed on the inside (see fig 2).

UPVC guttering is fitted as standard to the rear of the pent and flat roof models, and is available as an option on the apex and hipped models. All models can be upgraded to a steel zinc coated guttering.

External finish

Buildings are treated with a Medium Oak Aquastain finish as standard. An optional comprehensive paint system to protect and decorate the exterior is also available. The paint system comprises of an initial undercoat and a top coat of your chosen colour. A wide selection of colours are available to suit.

Doors and windows

All windows and doors are made from Western Red Cedar and fitted with double glazed units using 4mm toughened glass with Planitherm heat loss coating as standard (see fig 3). All opening windows are fitted with lockable key catches. All doors are fitted with a 5 lever mortice lock and brass/chrome handles.

Different designs come with a specific number of doors and windows, however, extra can be added to suit different requirements. Positioning of doors and windows is determined by the customer.

Our 10 year guarantee

All Malvern Garden Rooms come with a 10 year timber guarantee against rot and decay. This guarantee is subject to all exterior paintwork being maintained in line with the manufacturer’s recommendations. We leave all of our customers with touch-up paint to help preserve their building.  All other workmanship and materials are guaranteed for a twelve month period from date of installation. This guarantee does not affect your statutory rights.

We would like to remind customers that timber is an organic product, subject to naturally occurring changes that may result from different environmental conditions i.e. changes in colour, surface splits and shrinkage.