Standard Unit Eco Specification

For all Product Types except Stores

2024 Model Year, 1.0


A high performance product offering a combination of flexible configuration in 1, 2 and 3 storey arrangement in standalone and linked layouts with an innovative Eco specification producing substantial environmental benefits as well as reduced running costs and whole life cost savings. The range incorporates office, toilet, canteen, drying room, welfare unit, shower and sleeper specification products supported by a number of complementary ancillary items such as staircases, effluent tanks and linkways. Please note that store units and any derivatives which include store doors cannot be stacked on each other and cannot be used in any three storey configuration.

All units are available with either a profiled or flat panel external finish and in a range of standard sizes covering 8′, 9′, 10′ and 12′ widths with lengths from 4′ to 40′. The product layouts, specification and external colour schemes are entirely configurable and a wide range of alternative or additional options are available to suit your exact requirement. Please view our website at or contact our sales team directly on 01482 372525 for further information.

The entire product range and all ancillary items are fully supported by formal structural and thermal calculations.

The movement, installation, operation and maintenance of this product should take place in accordance with the relevant standard Alsim guidance documents.

Table of Contents

Product Development

Alsim is committed to the continuous improvement and development of our product range to the ultimate long term benefit of our customers and product specification is therefore subject to change.


The basic building frame is formed from heavy gauge mild steel sections, each fully welded to form a rigid framework into which the wall panels, doors and windows are fitted.

The base rail is a 3mm thick ‘z’ section, which is fully welded into the corner posts. The floor joists are welded inside the base rail at 406mm centres on all products up to 10’ in width to form the floor frame. On 12’ wide units the floor joists are fixed at 203mm centres. The corner posts support the 50mm x 10mm flat bar which runs around the top of the wall panels to form a rigid section onto which the roof panels are fitted. Reinforcing sections are welded inside the flat bar both across the unit width and also longitudinally to complete the framework. This section sits underneath the roof panels to provide additional support to help prevent roof damage and improve water drainage.

The frame is completed by 6mm top plates and 10mm base plates which are welded to each of the four corner posts. These are fitted with a basic hole and pin to provide a positive initial location when the units are stacked and matching connection slots to ensure the required long term stability.

Four high level lifting points are fitted along the side sections of the roof and four low level lifting points are fitted along the side sections of the floor to allow the simple lifting of the unit by a suitable crane. The floor is fitted with continuous fork tunnels across the width of the unit to allow lifting and movement of the unit by a suitable fork truck. The four low level lifting eyes also act as lashing points to allow the product to be easily secured to the delivery vehicle whilst in transit.


The floor structure is created using 100mm x 50mm heavy gauge joists at 406mm centres on units up to 10’ in width and at 203mm centres on 12’ wide units and is underdrawn with 1.6mm galvanised steel sheet. The system is insulated with both 100mm – 0.040W/mK and foil bubble insulation and fitted with an 18mm tongue and groove, moisture resistant, particle board floor deck fixed to the joists using self drilling screws.

The floor is finished with 2mm vinyl complete with white PVCu interior trims.


The profiled finish product uses 1.6mm thick corrugated mild steel panels which are fully seam welded to each other and the unit framework to form an extremely robust and rigid wall section.

The flat finish product uses 1.6mm thick mild steel panels which are welded to each other and the unit framework to form a robust wall section.

The internal wall lining is 12.5mm vinyl faced plasterboard complete with white PVCu interior trims. The lining sheets are mounted onto an internal framework of 70mm x 34mm timber at 406mm centres, which also encloses the 100mm – 0.040W/mK insulation.


1.6mm thick profiled self supporting roof panels are fully seam welded to each other and the framework.

The internal ceiling lining is 12.5mm vinyl faced plasterboard supported by 70mm x 34mm timber at 406mm centres which also supports 2 layers of 80mm – 0.040W/mK insulation. The void between the roof and ceiling is ventilated by vents on each gable end of the unit to reduce the build up of condensation.


The robust door is formed from a 2mm external steel skin welded to an internal 1.2mm skin and is insulated with 80mm – 0.040W/mK insulation. Anti-jemmy protection is provided down the closing edge, top and bottom of the door with welded escutcheon plates for additional security against drill attack.

Stainless steel lift-off hinges have been incorporated into the standard design in order to allow the door to be removed quickly and easily when required. The pioneering magnetic door retaining system is used for day time closing whilst a pair of suited 5 lever deadlocks have been fitted for secure locking. The deadlocks and anti-jemmy bolts close into the pre-formed 3mm mild steel door frame and combine to provide an advanced locking system. The door frame also incorporates a high performance rubber door seal for draught exclusion and additional protection against the weather.

The door is fitted externally with a round steel door handle, designed to reduce the possibility of use in an external attack on the locked door, and internally with a welded pressed steel handle.


The window shutter frame is formed from 6mm thick rolled steel angle with fully welded corners and is designed to house a 915mm x 915mm PVCu double glazed tilt and turn window system, complete with window locks.

3mm thick mild steel pressed shutter leaves are welded to the frame with full length continuous pre galvanised piano hinges complete with a stainless steel pin which allow the shutters to open and close freely. When closed two spring bolts fitted to each shutter leaf are used to secure the leaves at the top and bottom of the frame whilst the interlocking leaves are protected from jemmy attack by a central 5mm tee-bar. An additional fifth spring bolt locks the shutter leaves together for additional attack protection and to complete the creation of a highly secure locking mechanism.

Externally the shutter provides an aesthetically pleasing flush finish with innovatively designed security features to increase resistance to attack. When open each leaf of the shutter can be held in position using the anti-luce retainer.

Surface Treatment

All external wall surfaces are manually scraped down to remove welding spatter and then all surfaces are degreased thoroughly. An etch primer is applied to all areas followed by the addition of a high build primer to the welded seams and other relevant parts.

The internal and external surfaces are then given one coat of high build anti corrosive compliant paint to the specified finish colour except for the corner base plates. Internal faces of doors and window shutters are also painted to match the external colour. The whole system is applied using an air assisted airless system to provide an excellent surface finish.

The standard paint finish is a single colour of your choice from the BS 4800, BS 381C or RAL colour ranges.

‘U’ Values

The thermal performance ‘U’ values for this product are as follows:

  • External Wall – ‘U’ Value of 0.35 W/m2K
  • Roof – ‘U’ Value of 0.24 W/m2K
  • Floor – ‘U’ Value of 0.22 W/m2K
  • Door – ‘U’ Value of 0.82 W/m2K
  • Window – ‘U’ Value of 1.60 W/m2K

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