Standard Modular Specification

For all Ground Floor Product Types

2024 Model Year, 1.0


A revolutionary modular system offering flexible secure accommodation solutions in 1, 2 and 3 storey arrangement.

The Ground Floor product type outlined in this specification document is only for use in a single storey configuration or as the ground floor only in a multi-storey configuration. The complimentary Universal product type outlined in a separate specification document is designed for use in single or multi-storey configuration in any position.

The high performance range is available in 24’ x 10’, 32’ x 10’ and 40’ x 10’ modular sections which can be configured in a variety of formats using both side by side and end to end connections to produce a complex of unlimited size and virtually any shape to meet a wide variety of accommodation requirements.

The modular sections are provided in an attractive flat panel external finish which can be finished in an external colour scheme of your choice and successfully combine security with appearance to complete this market leading product range.

The product is supported by a range of internal and external staircases to suit all applications.

The system can also be connected to products from the Alsim unit range using our standard close coupled linking assemblies in order to maximise configuration options and offer enhanced flexibility.

The internal layout and specification can be designed to meet the needs of a multitude of applications including office, meeting room, storage, toilet, kitchen, canteen, drying room, changing area, shower and sleeper facilities in addition to providing the option of entirely flexible clear open plan areas without the drawbacks or restrictions of internal columns except on the largest product in the range – the 40’ x 10’ section.

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 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 each other in order to form a rigid framework into which the floor, wall and roof panels, doors and windows are fitted.

The side and end base structure is formed from 300mm x 90mm x 4mm thick rolled steel channel sections, which are fully welded into the 100mm x 100mm x 6mm corner posts. The 100mm x 50mm x 3mm floor joists are welded inside the base structure at 406mm centres to form the floor frame. 100mm x 50mm x 3mm rectangular hollow section transport beams are fitted to the underside of the floor structure in order to offer increased flexibility when the product is in transit. The corner posts support the side and end top structure which is formed from 180mm x 75mm x 6mm thick parallel flange channel sections. The 100mm x 50mm x 1.6mm roof joists are welded inside the top structure at 625mm centres to complete the roof frame. The wall and roof panels are fitted into this fully welded structure to complete the external skin.

The four corner posts are fitted with lifting points at the top to allow the simple lifting of the section by a suitable crane. The lifting points also act as locating devices to the four corners of the stacked section in the floor above in multi-storey configurations. The floor side beam is fitted with fork pockets to allow lifting and movement of the section by a suitable fork truck and combined lashing and lifting points which act as anchor points when the section is being transported and as alternative low level lifting points for the crane.

The structure has an overall external height excluding the lifting points of 3.030m and an internal ceiling height of 2.400m.


The floor structure is created using 100mm x 50mm heavy gauge 3mm joists at 406mm centres and is underdrawn with 1.6mm galvanised steel sheet. The system is insulated with 80mm – 0.040 W/mK 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.


305mm wide flat steel panel trays from 1.6mm mild steel are welded to each other and the unit framework to form a robust wall section offering an attractive flat steel external appearance.

The internal wall lining is cream 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 80mm – 0.040 W/mK insulation.


The roof structure is created using 100mm x 50mm x 1.6mm joists at 625mm centres and finished with 1.6mm thick flat steel roof panels which are fully seam welded to each other and the framework.

The internal ceiling is white 12.5mm vinyl faced plasterboard complete with white PVCu interior trims supported by 70mm x 34mm timber at 406mm centres. This also supports the 80mm – 0.040 W/mK insulation. The void between the roof and the ceiling is ventilated on the gable ends of the section 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. 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 1115mm x 915mm PVCu framed double glazed tilt/turn window as standard.

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 0.45 W/m2K
  • Roof – ‘U’ Value of 0.44 W/m2K
  • Floor – ‘U’ Value of 3.03 W/m2K
  • Door – ‘U’ Value of 3.2 W/m2K
  • Window – ‘U’ Value of 5.8 W/m2K

Enhanced thermal values are available with our Eco Options.

Question or Enquiry?

Get In Touch

Maximum file size: 50MB

Submit Your CV

Submit Your CV

Maximum file size: 50MB