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Where the surveyor believes that an element, or group of elements, has a
different residual life when assessed from each viewpoint the surveyor
should record the shorter residual life.
EXPECTED LIFE OF MATERIALS/ELEMENTS
It is most important that the surveyor=s assessment of the residual life of an element/material
should be derived from a review of its condition in conjunction with its expected life. Because
a softwood window is 30 years old does not automatically mean that it should be replaced.
The following list is derived from Life Expectancies of Building Components published by the
RICS in August 1992, and is provided as guidance on the expected life of materials/elements
when first installed. This list should only be used as an aid in the surveyor=s assessment of
residual life as many factors will contribute towards the life expectancy of a material/element.
QUESTION
MATERIAL/ELEMENT
EXPECTED LIFE (Years)
Q1
Principal roof structure
No assessment required
Q2
Principal roof covering
Pitched
Slate natural
Slate artificial
Stone
Tiles clay
Tiles concrete
Metal
80
40
100
60
43
25-30
Ridges
Mortar bedded tile
Dry systems
30
25
Flat
3-layer-felt
Single coat asphalt
Single coat elastomeric
14
25
15
Q3
Secondary roof structure
No assessment required
Q4
Secondary roof covering
As Q2
Q5
Chimney stacks
Q6
Flashings
Lead
Dry systems
GRP
Felt
Cement
Asbestos cement
Mortar
60
25
25
10
10
29
20
Q7
Roof gutters and downpipes
Cast iron
50
50
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