Most flat roofs consist of a timber decking nailed to the roof joists covered with three
layers of roofing felt. They are often used on house extensions and garages. Using a layer
of proprietary chipping compound, such as limestone, gravel or granite on top of the layers
of felt, strengthens the surface further. The idea is for the surface to reflect rather
than absorb sunlight, thus helping to protect the felt.
Checking the condition of a felt roof
From inside
Check for water staining on the ceiling as this will indicate dampness getting through. Felt
covering can deteriorate with age and become porous. This can result in the surface becoming
uneven, buckling or cracking in areas. On a particularly wet day, check for drips of water
seeping through the surface. It is useful to inspect the ceiling after a long period of rain,
as the source of a leak is easier to trace. If stains are found, try tracing the source of
the stain as it is not always directly overhead. Water can penetrate the roof surface and
travel between the roof and ceiling level before finding its way through the ceiling.
Outside at ground level
Outside, check the roof by inspecting at ground level. Check the apron, which is the area
where the edge of the front of the roof does not meet a wall. Here strips of felt are secured
over facia boards, sealing the edges of the roof. If there is a change to the colour of a
section, it could be newly exposed and therefore unweathered. If the roof is too high to
allow you comfortable access by ladder for a closer inspection, use binoculars to scan the
surface as carefully as possible, from all angles - front, back and sides where applicable.
At the roof level
If you are using a ladder, always make sure it is set up correctly and long enough - at least
3 rungs above the gutter. Always work with someone standing near by when you are working at
a height. See our Ladder Users Guide for details on how to
use a ladder correctly and safely.
Once at the roof level, only access the surface of the roof if you are sure that the
structure is safe. If there are signs of dips in the roof or puddles, it could be due to
the deck or the structural joists having deteriorated or perished. If you have no
confidence in the strength of the roof taking your weight, use scaffold boards across the
roof in order to spread the load when you walk across it. Ladders and scaffold boards can
be hired see Hire Shops.
Should a felt roof be replaced?
If patch repairs are regularly necessary, it may be time for the roof to be re-covered. It
can be difficult for an amateur to decide whether to attempt a repair or replace the roof.
If you need advice about the soundness or safety of your roof, contact one or two builders
for their opinion see Builders.
Alternatively, pay a surveyor or architect for an unbiased report on its
condition. A contractor, who will guarantee the work completed, should undertake major roof
repairs or replacement of sections.
