Gas supplies to multi-storey timber framed
Safety notice: 1/2005 Issue date: June 2005
This notice is to highlight a recurring problem that
has been identified with gas supplies to multi-storey
timber framed buildings.
- The investigation of a gas release at a block of
flats in Bothwell, Scotland identified that a release of
gas had occurred following the fracture of a mallable
iron fitting on a steel gas service, the building was
evacuated. It was identified that shrinkage had occurred
in the timber frame relative to the external brick
shell- see diagram below.
- The identified mode of failure was due to the
imposition of excessive loads from the timber frame upon
the gas service, due to the cumulative effect of
shrinkage of the timber frame (this shrinkage usually
occurs within the first year of construction). The
effect is most notable in the upper stories - see
- Due to the mode of failure and the type of building
construction it is possible for large volumes of gas to
accumulate in the area between the external brick wall
and the internal timber frame structure.
- HSE have subsequently been made aware of a number of
similar failures at other similar sites
- The use of multi-storey timber frame construction
has developed over the last ten years and buildings of
up to five storeys are now more common.
- Duty holders should identify where gas services have
been installed in this situation and take action to
ensure that excessive forces are not exerted upon such
services. Duty holders should also ensure that measures
are in place to identify the type of construction being
used before installing gas services.
- Services passing through the external brick
structure and the timber frame should be designed to
accommodate the differential movement between the frame
and the external structure. It should be noted that this
should apply to all services (gas, water,
- Guidance for the installation of gas services in
multi storey dwellings is provided in the Institution of
Gas Engineers documents IGE/TD/4 (Gas Services) and
IGE/UP/15 (Gas Installations in Flats).
Relevant legal requirements
The relevant legal requirements are:
- The Health & Safety at Work etc. Act 1974,
Sections 2 & 3
- The Gas Safety (Management) Regulations 1996
- The Pipelines Safety Regulations 1996
Any queries relating to this notice should be
Health and Safety Executive
Hazardous Installations Directorate
Specialised Industries Division
Lord Cullen House
Fax: 01224 252587
Photograph 1 - Showing movement of timber frame (at
third floor) relative to external shell.
Diagram 1 - Showing relative movement.
This guidance is issued by the Health and Safety
Executive. Following the guidance is not compulsory and
you are free to take other action. But if you do follow
the guidance you will normally be doing enough to comply
with the law. Health and safety inspectors seek to secure
compliance with the law and may refer to this guidance as
illustrating good practice.