MMC techniques

The application of thin bed mortar techniques is still very popular, albeit the skills required to apply the mortar are different from traditional brick laying skills. Another form of construction is insulated concrete formwork. There are many manufacturers but the principle remains the same. Hollow polystyrene blocks are fitted together with male/female connectors, and built up in stages before reinforcement is added and concrete pumped and tamped into the void. There are no lintels over openings, and the insulation remains in place to dry line or to render externally. It is quick, lightweight and simple to use.

Figure 1: Insulation and brick tie system

© Figure 1 is reproduced with permission from Metek Building Systems - part of the MMP Group.

Figure 2: External walls being assembled

Figure 3: External walls - note internal spacer bars and position of reinforcement

Figure 4: The concrete is levelled off in a traditional manner

Figure 5: Door opening former in position

Figure 6: Note how the insulating block is easily positioned over the opening

Figure 7: Traditional timber joists form floors

Figure 8: Precast concrete floors being installed

Figure 9: External stone cladding held with flexible wall ties

© Figures 2-9 are reproduced with permission from the Insulating Concrete Formwork Association

Brick slips

Brick slips are also popular and in general are applied in one of 3 ways:

• bonded to a concrete panel and then pointed;
• mechanically clipped and then pointed; or
• glued onto an insulated backing panel and then pointed.

The insulation can be premoulded to incorporate neat setting out lines and L-shaped slips are available for returns. Note that warranty providers may not allow bricks slips or other cladding forms to be directly bonded onto the frame itself, and will wish to see a drained cavity incorporated into the design. They may also require third party certification of the system. In the absence of a cavity, there are therefore no DPC or trays or weep holes.

Historically, much attention has been given to thermal movement and frost action which can 'pop' the slips, but today's manufacturing processes rely on flexible adhesives that give the bond an element of elasticity. The mortar can be applied in the factory or on site in a process similar to cake icing, with a premixed workable mortar.

Figures 10-11: Brick slips

© Figures 10-11 are reproduced with permission from Hanson Building Products