Cavity Brick or Double Brick Construction

What is cavity Brick?

Unlike brick veneer cavity brick is two brick walls standing side by side. Cavity brick still has the same 40mm to 50 mm gap between the walls to help stop water seeping in through to the inside of the house. It constructed by laying two brick walls side by side and tying them together with brick ties and cross cavity embedment. Cross cavity embedment is just that, at the correct spacing bricks will be laid into both walls from one to the other for strength. The floor can be ether timber or a concrete slab. The inside wall can be a feature brick and left clean or a cheaper common brick can be used and then rendered smooth and painted.

For internal walls such as bedroom partitions can be cavity brick or timber and plasterboard. If timber internal walls are used they must be dyna bolted to the brick outer walls and then lined. A timber top plate is added to the internal brick wall and bolted down to it every 600mm. Then the roof trusses are then fixed off to the top plate as per normal timber frame practise.

Stages of construction

1. Site prepared, reinforcing put in place, and then the footing are laid.

2. Bricks are laid up to the slab height. For a timber floor the bricks are laid up to the height of the bottom timber floor bearer.

3. The slab is then laid or the timber floor constructed in place.

4. The inner brick wall is laid in place with brick ties in place.

5. The internal partition walls are then constructed.

6. The roof trusses or roof framing constructed and then the roof added.

7. The internals such as door, wall linings and fix out can be completed. Also at the same time the brick layers can brick up the outer wall tying it to the inner wall.

Tips

Windows

Make sure your aluminium windows and glass have a protective coating on them to prevent cement staining. The protective coating can be sprayed on or be a thin peel off film. When ordering your windows ask your window supplier to provide a protective coat with the windows.

Damp Course

A damp proof course must be provided 150mm above the ground or any concrete or paving. Thus if you are planning to have an outside entertainment area make sure your damp course is in the right place. The paving or concrete floor of the entertainment area must be 150mm below the damp course.

Lintels

When the brick work has an opening for a window or door frame it must have a galvanised lintel above it to support the weight of the bricks. Each wall must have a lintel over the openings. The lintels are angles which have a long side and a shorter side. The long side extends up the wall and both ends must extend into the supporting walls a minimum of 110mm for opening up to 1800mm. For opening above 1800mm the lintels must extend a minimum of 225mm on both side of the opening.