Archiwa Sheet metal flashings

Measuring the eaves before ordering gutter aprons

Measuring the eaves should show not only their length but also the space between the covering and the gutter. Gutter aprons must fit this cross-section and direct water in the intended direction. When ordering, it is worth separating straight sections, corners and ends. An accurate sketch makes quoting easier and reduces the number of reworks. It is also needed when we plan to use a popular catalogue profile. Before measuring, the type of covering and the method of fixing the gutter must be established. Its position relative to the end of the roof slope is important. The gutter apron should correspond to the arrangement that will actually be installed. A measurement taken before changing the gutter may become outdated.

What determines rafter size and spacing?

The rafter cross-section is not selected from a single table that applies to every house. You need the span, spacing, timber class, loads and support scheme. Deflection and connections also matter. Ready-made advice such as "a rafter of this size is enough under metal roofing sheet" leaves out far too much information. Below we explain what influences the selection and when the design needs to be reassessed. The design span does not have to be the total length of the rafter. It depends on where the rafter is supported. A rafter supported only at the eaves and the ridge behaves differently from one supported by an additional purlin. On top of that come the overhangs beyond the walls. The designer must know where the forces are transferred into the structure of the storey below.