Good paving design is all about protecting the exterior walls of your house from damp related issues. Keeping consistent moisture content in the soils will go a long way to addressing all three issues noted in our last blog post.

Providing paving round the perimeter of the house is considered by all the experts to be an essential part of managing a property. Paving around the perimeter of a house, if constructed correctly will provide protection against all three of the issues raised in our blog post. Reliable Building Inspectors will therefore check for this in their inspection of a house.

Enter the need for good paving design. Good paving design must recognise certain goals.

It must be laid at a height that prevents ground water from entering the house. The first two principles of good paving design therefore is to locate it below the floor and below the damp proof barrier located at the base of the all.

The Building Code of Australia requires per clause 3.1.2.3 (b) (ii) that in areas of low rainfall intensity that the finished floor level should be at least 50mm above any external impermeable surface.

How far below the damp proof barrier is good paving design is usually left to the project consulting engineer, who can assess what height is appropriate given the type of soil on the site and the time of year the paving is laid. This will allow for the likely swelling ad shrinkage that will occur on the given site.

A 75mm gap is a good place to start in the absence of this advice. 75mm provides a clear line of site to allow Pest Control Inspectors to examine for the presence of termites.

Finally we need to ensure that any surface water runs away from the base of the walls, rather than toward it or pooling adjacent to it. Providing an effective fall in the paving away from the house therefore is the final piece of the puzzle of good paving design.

Once again I turn to the Building Code of Australia which requires per clause 3.1.2.3 (a) (i) that in areas of low rainfall intensity that the paving should fall 25mm over the first 1.0m in width of the paving. Clause (ii) indicates a fall of 50mm is required in all other cases.

If your property has achieved all these initiatives then chances are you will not be impacted by damp related issues in your home.