MR. BARTON
P6- Describe the techniques used to construct and finish the component elements of a superstructure.
Domestic Dwellings
The two most common types of construction are:
Traditional block Cavity wall construction
And
Modern Timber Frame Construction
Traditional Block Cavity Wall
The fundamental principle of a cavity wall is to prevent moisture moving from outside to inside. A cavity wall consists of two separated walls or ‘leaves’ joined by rust proof wall ties. This allows the exclusion of dampness and the prevention of heat loss by incorporating insulation.
Moisture will penetrate masonry walls where hairline cracks exist between masonry unit and mortar. Water which runs down the exterior wall surface will be drawn towards the inner cavity due to wind pressure exerted on the exterior of the wall and the negative pressure present within the cavity.
Providing a clean air space will allow this moisture to flow unobstructed down the cavity face of the outer leaf. Flashing, installed at recommended locations will then divert this moisture back to the building's exterior through weepholes. Proper drainage of moisture will reduce the chance of efflorescence and freeze-thaw damage.
The thickness of cavity wall can vary. This is mainly due to the thickness of insulation used. When constructing cavity wall leave minimum 50mm for the residual cavity.
The steps of building a traditional block cavity wall domestic building:
1. Determine the overall cavity width by adding the thickness of insulation required to the residual cavity width (50 mm minimum).
2. All masonry walls will rest on a foundation or concrete slab. Prior to erecting a block or brick wall, the foundation must be clean so the mortar will adhere to it. It should also be relatively level.
3. Block work is built up to DPC level. This is usually located at 250mm above ground level.
4. Damp Proof Course laid on block work course and lapped