Poor design of guttering causing rot to roof framing, of a home in Westlake, South West of Brisbane.

Gutter design causing rot, identified by Peter Weddell owner/operator of Qld Home Buyers Inspection Service and Queensland Building Inspection Service, QBIS

Roof gutters without eaves are not good building practice.

Some examples of problems resulting from this bad design!

Gutter design causing rotting of roof frame

Badly designed roof gutter:

  • Front edge of the roof gutter being higher than the back edge, this is standard with the majority of gutters.
  • Small slots were positioned just below the front edge bead to allow excess water to escape, these will not allow water to escape quickly enough.
  • The down-pipes were insufficient in their size and numbers to cope in severe weather conditions.
  • Slots were far too small to be of any benefit.

Recommended rectification:

  • Fit larger slots to allow excess water to escape to front of the gutters where it will not cause any serious problems.

In normal weather conditions the downpipes will do their job, the enlarged relief slots will serve as a backup and help cope in adverse conditions.

This photo shows back of the metal fascia where water had been cascading over back of the gutter and metal fascia into the wall cavity.

In most cases this will not cause problems, but in this particular circumstance flashing incorporated within the wall (above a lower level window) was allowing water to enter a bedroom at a lower level.

Gutter design causing rot to roof truss

Here is an example showing consistent overflowing of water from back of the gutter causing rot to the tail end of the roof truss (top chord).

Gutter design causing overflowing and rot

Important points:

  • Always consider the practical advantages of including eaves when having your building designed.
  • Do not connect the stormwater to the surface drains, this will overload and cause backwash of water to occur.
  • Have large downpipes fitted.
  • Ensure the downpipes are connected to large enough stormwater pipes also number of them to carry the water away.
  • Check the stormwater system and make sure it is kept clear of debris so it can operate effectively.
  • Do not use gutter guards, they allow accumulation of debris to occur below them that will cause premature rusting of the gutters.

Roof’s must be checked and maintained on a regular basis to avoid serious problems from occuring.

For independent Building Inspections Brisbane in all suburbs, Qld Home Buyers Inspection Service. qbis.com.au