Preparing to Build Your Home: Setting Out the Project

The initial set-out of your housing project is critical. Follow these guidelines to ensure your plans are off to a good start.

The skill comes in transferring your two-dimensional diagram to the three-dimensional world of the building site so that the corners of the building can be pegged in the right places. For this reason many people, including professional builders, use the services of a surveyor to do a peg-out survey. They have the equipment and experience to do the set-out accurately.

If you are building in the middle of a huge property, this may seem unimportant, but consider if your site is on a slope that becomes steeper as you descend; a house built even a short distance further down the slope than originally planned may use many more building materials to reach floor level than a house on a gentle slope. Before you start building, place a marker at each corner of the site so that you can set up profiles from which you can run string lines. The lines show the location of walls, footings, excavations and so on.

Whether you use strip footings or a concrete slab some excavation will be required. Traditionally the work would have been done by labourers to set-outs supplied by the owner or builder. This can still be done, of course, but it is much quicker and cheaper with a small machine such as a backhoe. An advantage of excavating manually, if the job is not too large, is that you can skirt around vegetation or other features near the house site that you may wish to preserve. You also have total control over where the excavated soil will go. Machines tend to be more unforgiving.

In general it is not a good idea to build a house partly on rock and partly on soil. Rock may be excavated to such an extent that all the footings are on soil, or the whole excavation deepened so that they fall on rock. Where rock is not found, the structure can be supported on appropriately engineered footings that will span those areas.

There may be serious subsidence problems in areas that have been heavily mined, Normally, such places are identified by the local authorities, which sometimes recommend particular footings, ma­terials and con­struction methods to minimize potential problems. In some regions, house designs and construction methods for building in mined areas need to be separately approved by mining authorities. Building land sometimes becomes available where strip-mining companies have removed layers of rock strata and ore, then replaced the burden and reveg­etated the area. This type of land will need careful assessment before building is carried out, and en­gi­neering advice will be essential.

If there is a particularly handsome tree in the vicinity of your homesite you may be tempted to plan the building around it. If this is the case, beware of snuggling up too close to nature as you will probably be taking on a long-term problem. Trees trunks not only swell imperceptibly to the point of overfilling any space you may have left for them, they also die, decay and need to be removed. Removing a dead trunk from within a building structure is almost inevitably going to be an expensive and messy procedure.