House roofing generally comprises the
combination of a number of materials and surfaces aimed at
maintaining a barrier between inside the house and the external
weather. The hardest weather element to control is water since
water is particularly invasive. Roof flashing is generally used as
the final barrier against water penetration.
Flashing comprises the intersections and terminations of roofing
systems and surfaces to prevent water penetration.
Roof flashing is generally installed around roof windows valleys,
chimneys, eaves, rakes, skylights, ridges, and at roof to wall
intersections. In all cases, effective flashing should resist all
three drivers of water penetration: gravity, surface tension and
wind pressure. As a result, flashing materials must be durable, low
maintenance, weather resistant, able to accommodate movement and
maintain compatibility with adjacent materials.
Roof flashing materials generally fall into one of two categories:
membrane or sheetmetal. Commonly used roof flashing materials
include aluminium, copper, lead-coated copper, lead, stainless
steel, galvanized steel, zinc, and Galvalume.
Roof Window Flashings
As mentioned, flashings are required
for roof windows. Roof window flashings come in grey aluminium as
standard to match the window profile, with the options of copper,
titanium zinc and coloured aluminium.
- What is the pitch of the roof, ie. the angle of the roof's
- What is the existing roof made of? Eg. is the roof made of tile
- How thick are the existing roof tiles?
The following table illsutrates which
flashings will be required depending on your style of roof:-