Roof Construction on Modern Houses

With the changes and consolidations of building companies in the last decades, house building is more and more being undertaken by fewer very large house building companies.

These companies are the ones which contract in the modern way, to build perhaps 20 to 200 houses at a time.

Apart from individualising the exteriors, the houses are often constructed very very similarly to one another. The most important out of ground part of house construction is the roof.

In the days of individual builders building individual homes, roofs were “cut”, which means the more traditional method of cutting the timber on site and building up the roof, making individual rafters, purlins, the ridge board and joists, with each home having its roof crafted using available timber.

This “cut roof” method consists of rafters and joists, the joists prevent outward pressure movement from the rafters or the walls themselves. The joists are also to be used for hanging the ceiling from.

The wall plate is the timber length of normally 100x75mm embedded in the top of the supporting walls and usually cemented in.

The rafters have to have a small nick type V cut into them called a birds mouth which fits the rafter onto the side of the wall plate to which they are then nailed.

Where the rafters meet at the apex they are cut at an angle to be flush with the ridge board to which they are then nailed.

A truss roof which will be more commonly used, though not exclusively, in a larger number of units being built where uniformity allows for economy.

The trusses, or frames, are triangular units computer designed and factory made, each for their particular position in the roof structure. These are then lifted into position on site using construction equipment for speed, economy and efficiency.

The timbers are cut to predetermined lengths then butt joined and nailed together through metal joining plates.

Once the timber construction is in place, a layer of roof felt or breathable membrane is nailed, with either galvanised or stainless steel nails, to the rafters, and on top of this are nailed the batons, strips of wood which have been tanalised, (pressure treated with Tanalith preservative), upon which the tiles will be nailed.

Before the tiles are established the plastic soffit boards are nailed, with stainless steel plastic topped nails into the bottom of the rafter feet and silicone to the wall.

The facia boards are then attached by nailing them to the rafter ends, presenting a smart face under the eaves and covering the cut end of the soffit.

The guttering is attached to the facia so that the lowest tiles should just hang over the edge of the gutter allowing for easy channelling of rainwater.

The guttering is affixed at a slight angle allowing rainwater to flow to outlets from which downpipes deliver it into the drainage system or to an underground soakaway.