Sunbloc Ltd

Summer House Rear of 53 High Street

Tenterden, Kent

TN30 6BD

Tel: 01580 767700


Sunbloc Technical Information

Thermal Insulation

Thermal insulation for our purposes is expressed as a U value. The lower these figure the greater the thermal efficiency of the component.

Current building regulations require a U value of an external wall to be 0.28w/sqmK.

The Sunblocs provide the following U value:


  • Sunbloc = 0.20 w/sqmK                                            

Sunbloc components have tongues on the top and grooves on the bottom, arranged so that they will interlock in parallel or at right angles in a modular grid of 50mm.

This means the designer can realise any plan layout to dimensions which are a multiple of 50mm. Smaller site dimensions may be cut exactly to size within the thickness of polystyrene once the concrete is cured.


         Features of the Sunbloc:


  1. The tongues on the top and groves on the bottom of components are arranged to interlink and crosslink in a modular grid of 50mm.

  2. The tongues and grooves have a positive interlock so that the elements cannot be carried away by a gust of wind.

  3. The hollow core of the components is calculated to optimise economy of design and building processes.

  4. All faces have grooves 2.5mm deep and 17.5mm wide in a pattern repeated every 50mm to eliminate thermal bridging. These grooves have a dovetail profile to provide a mechanical key for the application of plaster.

  5. Location detail for horizontal reinforcement.

  6. End pieces are inserted above and below the bridges to make a closure when forming corners, reveals and wall ends.

  7. The bridges are tapered at the top and bottom to avoid trapping air during concreting.

  8. The firewall endpiece is used to form the closure where this does not coincide with the bridge.



Thermal Bridges


Walls with 2 different materials and a different thermal conductivity values leads to thermal bridges. Vapour condensing on the cooler of the materials can lead to mould fungus.

Typical places where this occurs are lintels and joists, where the ceiling abuts the wall. Sunblocs avoid thermal bridging.


The Sunbloc lintel is insulated on 3 sides (U-Profile) by Neopor and does not admit thermal bridges.


The Sunbloc floor/edge block has an exterior raised edge and therefore avoids thermal bridges on the joists, where the ceiling is placed on the walls.


Exterior finish


A Sunbloc house is a complete weatherproof and load bearing structure in its own right. Subject to planning control the exterior finish can be almost any material of your choice. This represents one of the fundamental advantages of the Sunbloc System, namely, that the structure is completed swiftly and independently of the exterior cosmetics. 

With Sunbloc you choose the face you want to put on, be it the most traditional Tudor building or the most modern designed house by the most skilful of architects.


Rendering and Waterproof Tanking

Exterior render is the easiest and most cost effective of all the exterior finishes.

Rendering on to the Neopor Sunblocs is a well established and proven practice.  There are several established methods involving the use of either a reinforcing mesh or base layer - usually both.



In recognition of the popularity of the traditional brick finished home wall ties can be inserted into Sunblocs prior to pouring the concrete. The embossed markings at regular intervals on the blocks make this a quick and simple task. Yet another saving! The use of flexible butterfly type wall ties is recommended to enable the bricklayer to follow the correct line should he run slightly out of course whilst laying. 

Bricks are set app. 10mm in front of the Sunbloc wall. This provides sufficient working depth for the trowel and any adjustments that need to be made.   In addition Sunbloc have a corbel block . This corbel block provides an extended concrete shelf from which brick cladding can be laid. This is especially useful in basement construction as it eliminates the need to take the brickwork down to basement slab level. 


Brick Slips 

Brick Slips are an alternative to building a complete brick wall. The Neopor walls of Sunbloc make the ideal surface for the application of slips or indeed any other similar material such as ceramic tiles. Unlike brick laying it does not take a skilled professional to place slips.

Tiles, Slates and Weatherboarding 

Tiles, slates and weatherboarding are fixed in the traditional manner to vertically placed treated timber battens, anchored through to the concrete core with conventional fixings.



Pump Grade Concrete









10mm aggregate size improves workability of the concrete, although aggregate size up to 20mm may be used providing additional care is taken to ensure the larger sized aggregate does not restrict the flow of concrete.


Design strength of the concrete may vary depending upon the structural design and performance required.  Specification of a pump grade mix serves to ensure that the formwork system will fill fully under the natural flow of the concrete and consequently vibration is not required to achieve adequate compaction.


Unless prohibited, a water reducing plasticiser may be added.


* According to the engineer's specification: 
             C25 is the standard specification. 
             C35 is usual for basement construction.

             For more details please see Technical guide.


Interior Finish


Interior walls can be treated the same as exterior walls, although in the main a dry lined plaster board applied in the conventional manner is the preferred option. Battens can also be used to dry line.

Sunbloc does not need to be dry lined with thermally insulated 30-40 mm EPS backed plasterboard as in conventional build. The 50 mm internal insulation is already in place as an integral part of the Sunbloc System. Yet Another Saving!

Technical notes for wet-plastering internal walls:

  • Wet finishes do not usually require a reinforcing mesh.

  • Thistle bondit is applied to the Sunblocs and left to dry overnight.

  • The following day, an 8-11mm thick coat of Thistlebond is then applied, followed by a 2mm skim of multi-finish.

For dry lining, simply fix plasterboard to wall with dabs of dry wall lining adhesive in the conventional manner.

Information supplied by British Gypsum.  Further information is available on British Gypsum's Website or by faxing their technical department on 08705 456 356.

* The Sunbloc surface can be roughened first with a wire brush or similar to provide additional key




The Concrete Pour


Before The Pour: 
Sunblocs are secured in position by means of the trestle support system. Ensure that any ducting or ties are installed prior to the pour. 

The concrete used is a uniform pump grade C25 mix, with a 10 mm aggregate size and a minimum 30 cement content - slump factor app.75 depending on the application (more details).

The placing hose should be fitted with a type 65 exit nozzle in order to reduce the pressure when pouring, making the placement of the concrete more difficult.  Alternatively use a swan-neck discharge nozzle when placing concrete from a boom pump as this will reduce the momentum of the concrete at discharge point and make placement much easier.


When Pouring:

When pouring the concrete the placement hose should be held so as to form almost an "S" bend. Generally it is not necessary to vibrate the concrete in order to eliminate air pockets. This is only carried out on walls heavily reinforced with steel. To confirm there are no voids simply tap the walls. You can pour up to 1 lift at a time, to a height of 2.5m.


After The Pour:

Check all walls are vertical and adjust where necessary before the concrete has had time to cure. By the following morning it will be too late! If you have used the trestle support system correctly, you will probably not need to make any such adjustments, but check anyway.


For More information go to the Sunbloc Technical Guide. or see BBA certificate.


Build Times


The area of Sunblocs that can be built at any one time may be as little or as much as practical.Whether it is the single course of a wall, or the complete storey height,construction of a building will depend upon project requirements and resources available.The maximum height of a wall that can be poured at any one time is 3 meteres.Wall Assembly 6 hours for this bungalow


Shorter building programs

The general simplicity of the build process leads to shorter building programs for construction of the weather-tight shell and for completion of the follow on trades. The Sunbloc system gives performance not only before and during construction but also in the finished building. With higher levels of occupant comfort and lower running costs, Sunbloc gives long-term performance for the life of the building. Sunbloc is the latest and best engineered ICF on the market today. An economic and environment friendly method of wall construction providing optimum insulation for living accommodation it surpasses the competition on many fronts.