MEP Spacing Rules Introduction
This is the introduction to a series of articles providing guidance on MEP spacing rules to meet safe installation, access and maintenance requirements.
In Development
This page is under construction
Legal Obligation
The Construction (Design and Management) Regulations (known as the CDM Regulations) place an obligation on designers to consider the risks to construction and future maintenance consequences of design decisions.
Sufficient space must be allowed for maintenance access and due consideration of the replacement of all parts must be demonstrated. The design of all systems must demonstrate that all plant and equipment incorporated into the Works can be safely and easily maintained in full compliance with Health and Safety legislation, CDM Regulations, British Standards and Health Technical Memoranda (where applicable).
Mechanical, electrical and public health (MEP) services installations in buildings should be fully coordinated with all elements of construction to ensure adequate safe space is provided for installation, access and maintenance. Spatially coordinating plant and equipment, together with main vertical and horizontal distribution routes, including correct installation invert levels, should be considered a each stage of the design and installation process.
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Spacing Considerations
Care is required in the design of building services to ensure adequate space for the safe and efficient maintenance of installations. If sufficient space is not allowed in the initial concept it can be extremely difficult to achieve a satisfactory solution in the completed project.
Economic Consideration
The cost of providing space for plant and building services distribution comes at a premium but pressure to reduce the spatial requirements for services will only be detriment to future maintenance and repair. Note there is a specific obligation under the CDM Regulations to ensure that a design can be safely installed and maintained.
Regularly maintaining or replacing plant and equipment will incur excessive cost if suitable access is not provided for the safe and efficient maintenance of installations. Maintenance tasks may take longer or be omitted due to adverse conditions resulting in a higher risk of equipment failure. Dismantling of large sections of an installation or building fabric to provide access and facilitate removal should be considered a poor compromise and will add significant additional operating cost on maintenance.
The key considerations for designing safe space for compliant installation, access and maintenance is covered below.
Coordination and Spatial Provision
MEP/HVAC services should be fully coordinated and integrated at all stages of design development. The MEP design layout should facilitate testing and commissioning of all the completed installations.
See guide on MEP space allowances »
Space requirements for building services distribution systems shall be compliant with BSRIA TN 10/92 Space Allowances For Building Services Distribution Systems.
Plant Location and Access
All new plant and equipment should be designed to provide the required safe access for maintenance, operation and repair in accordance with industry recognized guidelines and manufacturers recommendations. The CDM Regulations (2015) requires designs to be safe to install and maintain.
Supports and Fixings
The principles for the supports and fixings products and systems should be determined at Concept Design [RIBA 2] stage in collaboration with structural engineers and fixings manufacturers.
Refer to BESA's Guide to Good Practice for: Supports and Fixings TR 50 which provides best practice guidance for design, specification, installation and testing of supports and fixings for MEP services systems in buildings.
Fire-stopping
Approved Document B Fire Safety (here) provides guidance on achieving the functional requirements of the Building Regulations which includes inhibiting the spread of fire and providing fire separation or compartmentation. Requirements for the fire compartmentation and any passive fire protection should be detailed in the project fire strategy.
In service riser and voids, fire compartmentation which prevents the spread of fire, smoke and toxic gases is provided by cavity barriers, fire stopping and fire/smoke dampers in ventilations ducts.
Refer to the Finishes and Interiors Sector Limited (FIS) document Firestopping Of Service Penetrations Best Practice In Design And Installation (available here ) for guidance on the design, specification and installation of building services penetrations through fire compartment walls and floors. This includes the nine Golden Rules for firestopping design, installation and inspection.
Also see Association for Specialist Fire Protection (ASFP) On-site guide to installing fire-stopping (here).
Design for Commissioning
The design should make allowance for the commissionability of the MEP services.
Suggested Reading
BSRIA Space allowances for building services distribution systems (TN 10/92)
HTM 2023 Access and Accommodation for Engineering Services
The Defence Works Functional Standard Design and Maintenance Guide 08 (DMG 8) Space requirements for plant access, operation and maintenance
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Planning for DfMA
There is a requirement to notify the authorities including the police and highway authorities about the movement of abnormally wide or heavy loads. In the UK a vehicle has an 'abnormal load' if: the weight is over 44,000 kg; the width is more than 2.9 m; or the rigid length is greater than 18.65 m. See UK Government advice on Transporting abnormal loads.
Off-site assembled module dimensions typically vary between (L x W x H in metres) 5 x 2.9 x 3 up to 12 x 3.5 x 3.5 per section with dry weight from 8,400 kg to 13,700 kg.
MEP Spacing Rules id: hvac-10
