When you purchase a new build home, the internal services, including your water supply, gas, electrics, and drainage, should all meet the standards set out by the NHBC. Chapter 8.1 of the NHBC Standards 2026 covers the technical requirements for these internal services in detail. Understanding what these standards require can help you identify potential issues during your snagging inspection and ensure your new home has been built to the expected standard.
Below, we walk through each section of Chapter 8.1 and explain what it means for you as a homeowner.
8.1.1 Compliance
All incoming utilities in your new build home must comply with the NHBC’s Technical Requirements. This means the builder needs to account for how services enter the property, any ground hazards in the area, and the risk of chemical attack on pipework and fittings. Where applicable, precautions should also be taken against radon gas or contamination from nearby landfill sites. If your home is built on land with known ground conditions, the developer should have addressed these during the design and construction phases.
8.1.2 Provision of Information
The NHBC requires that all designs and specifications for internal services are produced in a clear, understandable format and shared with the relevant tradespeople on site. This includes drawings, fixing schedules, commissioning certificates, manufacturers’ specifications, and details of which contractor is responsible for each system. Proper documentation is essential because it ensures the work is carried out correctly and allows for energy-efficient use of the building. If something goes wrong after you move in, these documents can be invaluable in tracing the cause.
8.1.3 Water Services and Supply
Your home’s water services must be designed around the pressures and flow rates available from the incoming mains supply. The NHBC sets out several key requirements here.
The water supply should be based on a minimum dynamic pressure of 1.5 bar at the internal stop valve, with a flow rate of at least 20 litres per minute. Drinking water must be provided directly at the kitchen sink from the mains supply, or, where that is not practicable, from a storage cistern with an adequate supply of wholesome water.
All pipework materials should be corrosion-resistant and compatible with the local water supply. The system must also be capable of being fully drained, with hot and cold services draining separately. Service pipes should be buried at least 750mm below ground level, and where that is not possible, they need adequate frost protection.
Protection from freezing is a significant concern. Where pipes run through unheated spaces such as loft areas, they must be properly insulated. The NHBC standards reference specific insulation thicknesses depending on the pipe diameter and the thermal conductivity of the insulating material used. Pipes above the loft insulation, near eaves, or passing through ventilated voids beneath suspended floors are particularly vulnerable and require careful attention.
Water efficiency must also be considered in the design, either through a fittings-based approach or a water efficiency calculator.
During a snagging inspection, our inspectors will check that pipework is properly clipped and supported, that visible pipe runs are insulated where required, and that the stop valve is accessible and functioning correctly. However, it is worth noting that a snagging inspection is not a plumbing pressure test or a full assessment of concealed pipework behind walls or beneath floors.
8.1.4 Cold Water Storage
Where a cold water storage system is installed, such as a header tank feeding a vented hot water system, it must meet several requirements. Cisterns should be accessible for inspection and maintenance, protected by a rigid, close-fitting cover that keeps out light and insects, and properly supported on suitable boarding or sheet material.
Warning and overflow pipes must be provided at each cistern, with a minimum internal diameter of 19mm, and should discharge to a visible external location. They need to be positioned at least 25mm above the shut-off water level in the cistern.
Access to the roof space or any void containing cisterns and tanks must also be provided, making future maintenance possible.
8.1.5 Gas Services
Gas installations must comply with gas safety regulations and be carried out in accordance with the relevant standards published by bodies such as the Institution of Gas Engineers and Managers (IGEM), the British Standards Institution (BSI), and the Gas Safe Register. Service pipework up to and including the emergency control valve and meter must meet the requirements of the gas transporter, gas supplier, and meter owner.
Where a gas supply is provided to the home, a gas point must be fitted at the designated cooker space, unless an electric hob has been specified instead. Gas pipework must not impair the structural stability, fire resistance, damp proof course, radon barrier, or thermal and sound insulation of the building. Pipes should not be over-bent, stressed, or installed in locations where they could suffer mechanical damage.
The standards include specific guidance on how gas pipes should be installed within different wall types, including masonry walls (where chase depths are limited), dry-lined walls on battens or dabs, and timber frame or light steel frame constructions. In timber frame buildings, steel plates and sealed joints are typically required to prevent gas tracking.
Where Corrugated Stainless Steel Tube (CSST) is used for gas pipework, it must conform to the CSST benchmark scheme, be certified by an accredited technical approval authority, and not be mixed with fittings from other brands. CSST should not be buried in concrete floors unless the manufacturer confirms it is suitable for that purpose.
8.1.6 Electrical Services
The electrical installation in your new home must comply with BS 7671 (the IET Wiring Regulations) and relevant Building Regulations. This section of the NHBC standards covers a wide range of electrical matters.
Sockets and outlets: The NHBC specifies minimum numbers of 13A socket outlets for each room. Kitchens and living or family rooms should each have at least eight outlets. The main bedroom requires a minimum of six, with other bedrooms needing at least four. Dining rooms should have four, and the hall and landing two each. Where appliances are provided in a kitchen, at least three outlets should remain free for general use.
Cable positions: Cables without special protection (such as earthed metal conduit) must be routed vertically or horizontally from the outlet or switch they serve, within defined safe zones. This is important if you ever plan to drill into walls or hang pictures, as cables outside these zones could be at risk of being struck.
Consumer units: These must be manufactured from, or enclosed in, non-combustible material such as steel. Each circuit should be clearly labelled so that it can be easily identified. Where RCDs (Residual Current Devices) are fitted, a notice should be provided advising occupants to test them every six months.
Cooking spaces: A minimum 30A switched and terminated supply is required for electric cooking. There must be at least 100mm of horizontal clearance between any electrical accessory and the edge of a freestanding cooker or hob. In non-bathroom locations, electrical items must be positioned at least 300mm horizontally from the edge of a sink or wash basin.
Smoke and heat alarms: These must be provided in accordance with Building Regulations and should be mains-powered. Interconnected alarms should all be on a single circuit, and appropriate labels must be fitted to isolators to prevent them being inadvertently switched off.
Electric vehicle charging points: Where these are installed, consideration should be given to product certification, the competency of the installer, the manufacturer’s instructions, and the suitability of the location.
TV provision: While aerials are not required, the developer must provide either a concealed coaxial cable from the roof void to a terminal outlet in the main living room, or a conduit with a draw wire.
During a snagging inspection, we can check that sockets and switches are level, properly secured, and functioning, that the consumer unit is labelled, and that visible electrical work appears to be in good order. A snagging inspection does not, however, include electrical testing or certification, which is the responsibility of the electrical contractor.
8.1.7 Meter Boxes
The openings in external walls for meter boxes must be structurally sound and must not allow dampness to enter the home. Meter boxes can be either built into the outer leaf of the wall or surface-mounted externally.
Where meter boxes are set into external walls, proper DPCs (damp proof courses) and cavity trays must be installed above them to prevent moisture bridging across the cavity. Insulation should be carried past the meter box to avoid cold bridging, and weepholes must be correctly positioned. The installation should also comply with the requirements of the relevant Gas Distribution Network Operator (GDNO) or Distribution Network Operator (DNO).
8.1.8 Hot Water Services
Your new home’s hot water system must be adequate for the anticipated demand and consumption. The NHBC standards set out specific design flow rates and temperatures for each type of outlet. For example, a bath fed from a storage system should deliver a design flow rate of 0.30 litres per second at 48°C, while a wash basin should provide 0.15 litres per second at 40°C. In accordance with BS 8558, water temperature at an outlet or thermostatic mixing valve should reach at least 50°C within one minute of running.
The standards also define minimum hot water storage volumes depending on the size of the dwelling, the number of bathrooms and shower rooms, and the heat input available. For a home with one bath and a separate shower fed by a 10kW heat source, a cylinder with stratification should be at least 130 litres.
Where homes have one bathroom or shower room, the system should be capable of providing hot water for tasks such as washing immediately after the bath has been filled, and should be able to supply a second bath after 30 minutes. Homes with two or more bathrooms should have enough capacity for hot water immediately after each bath has been filled.
Combination boilers, which produce hot water on demand, are generally only suitable where simultaneous hot water demand is limited. Hot water storage vessels should be installed vertically (unless designed otherwise), supported according to the manufacturer’s recommendations, and accessible for maintenance and replacement. Immersion heaters, where fitted, must have thermostatic controls and an energy cut-out to prevent overheating.
8.1.9 Unvented Storage Systems
Unvented hot water storage systems, which are pressurised and do not rely on a cold water header tank, must be installed by competent persons and be the subject of third-party certification. The discharge pipework for these systems, which acts as a safety measure in case of overheating or excess pressure, has specific requirements.
The tundish (a visible air gap in the discharge pipe) should be fitted as close to the storage system as possible, in a position where it can be seen. Discharge pipework must not be connected to other waste pipes and must not terminate inside a garage.
For low-level discharge, the pipe should either terminate into a trapped gully (below the grating but above the water level) or discharge downwards onto the ground at a maximum of 100mm above ground level, with a protective cage fitted over the pipe end. High-level discharge is only acceptable where it terminates onto a roof capable of withstanding high-temperature water, at least 3 metres away from plastic guttering, or into a metal hopper head and downpipe.
The standard material for discharge pipework is metal. Where thermoplastic pipes are used, they require a satisfactory assessment by an independent technical approvals authority.
8.1.10 Internal Soil and Waste Systems
The soil and waste systems in your home must comply with Building Regulations and be installed so that effluent is removed without affecting health or creating unnecessary noise and smell. These systems should be adequately ventilated at the head of underground drains and at each branch, and must be arranged so that foul air from the drainage system cannot enter the home.
Air admittance valves, which allow air into the drainage system to prevent trap siphonage, must comply with BS EN 12380 and should not be positioned in areas liable to freezing. They need free air movement around them, typically achieved through ventilation grilles or gaps in any boxing.
Sound insulation is an important consideration for soil and vent pipes. All sections of soil pipe, including those running through bathrooms or as ground floor stub stacks, should be soundproofed. This is achieved by enclosing the pipe in boxing made from material with a mass of at least 15 kg/m² and wrapping the pipe with a minimum of 25mm of unfaced mineral wool. Where pipes run horizontally through floor voids above or below habitable rooms, they should also be wrapped in mineral wool and supported so they do not contact the floor decking or ceiling.
Sanitary fittings should be installed with all accessories (such as chains and plugs), secured with non-ferrous or stainless steel fixings appropriate to the weight of the item, and fitted to ensure that WC lids and seats are stable when open. Waste disposal units should be adequately supported and fitted with a tubular trap rather than a bottle or resealing trap.
The junctions between wall tiling and baths or showers must be sealed with a flexible sealant to accommodate movement, following the manufacturer’s instructions.
8.1.11 Further Information
The NHBC references several further standards for detailed guidance, including BS 6400 (covering the installation, exchange, relocation, maintenance, and removal of gas meters) and BS 6891 (covering the installation and maintenance of low-pressure gas installation pipework up to 35mm).
How a Snagging Inspection Can Help
While a snagging inspection is not a substitute for specialist testing of gas, electrical, or plumbing systems, it can identify many visible issues relating to internal services. Our inspectors routinely check for items such as poorly fitted sanitary ware, unsealed junctions around baths and showers, missing or incorrectly positioned socket outlets, unlabelled consumer units, uninsulated pipework in accessible areas, and improperly terminated discharge pipes.
If our inspection raises concerns about any aspect of the internal services that may require further specialist investigation, we will note this clearly in your report and advise you on the appropriate next steps. Understanding the NHBC standards that apply to your home puts you in a stronger position when discussing any issues with your developer.
For more information about our snagging inspections, or to book an inspection for your new build home, please get in touch with our team.
