The NHBC Standards set out how NHBC expects its registered builders to design and construct new homes covered by an NHBC warranty. Chapter 10.1 deals specifically with garages, covering integral garages built within the home, attached garages joined to it, and detached garages standing on their own, as well as prefabricated garages and carports.
The Standards are written as guidance for builders rather than for homeowners, and they explain how NHBC interprets its Technical Requirements. This article translates the 2026 edition of Chapter 10.1 into plain language so that buyers can understand what good practice looks like for the garage that comes with their new home. Each section below mirrors a clause in the chapter and keeps the original clause number so you can cross-reference it against the source document.
A note on snagging inspections appears at the end. In short, a snagging inspection is a visual assessment of finish, workmanship and the things that can be seen and operated on the day. Many of the items in this chapter, such as foundations, buried membranes and structural design, are concealed once the garage is built and fall outside what a snagging inspection can reasonably check.
10.1.1 Compliance
Garages must comply with the NHBC Technical Requirements. A garage built in line with the guidance in this chapter will generally be acceptable to NHBC. This applies whether the garage is integral, attached or detached.
10.1.2 Provision of information
Before work begins, the builder should produce clear designs and specifications and pass them to the people who need them, including site supervisors, specialist subcontractors and suppliers. That information should cover the location of the garage, relevant levels against an agreed reference point, the foundations, waterproofing, the roof structure and coverings, the walls, internal and external finishes, any services, and the type of garage being built.
10.1.3 Garage foundations
A garage’s foundations must carry all loads safely down to the ground without undue movement. In planning them, the builder should take account of hazardous ground, the type of foundation suited to the garage, any adjacent structures, underground services, and the need to allow for movement. Foundations should adequately support the loads imposed on them, taking the ground conditions into account.
10.1.3.1 Hazardous ground
Where the ground may be hazardous, the builder should examine and identify any existing fill on the garage site. If there is a potential health hazard or a risk of damage, appropriate precautions should be taken in line with NHBC’s chapters on land quality and substructures.
10.1.3.2 Foundations for integral and attached garages
Foundations for an integral or attached garage should normally be the same as those used for the home itself. They can differ only if proper thought has been given to each foundation and to the possibility of one moving differently from the other.
10.1.3.3 Foundations for detached garages and blocks of garages
Foundations for a detached garage, or a block of garages, should avoid damage from differential loads and uneven settlement. Where the ground is uniform and gives a satisfactory bearing, an unreinforced edge-thickened concrete slab may be used. Such a slab should be at least 100mm thick, sit on at least 100mm of properly compacted hardcore, and have a thickened edge running around the whole perimeter that is at least 300mm wide and extends at least 350mm below ground level. The slab should not exceed 6m in any direction, and movement joints should be provided where it does.
10.1.3.4 Adjacent structures
A garage’s foundations should not undermine the stability of the home or of any other nearby structure.
10.1.3.5 Underground services
Where foundations sit above or near services, they should be built so that the foundations do not settle excessively and the services are not damaged.
10.1.3.6 Provision for movement
Movement joints in the foundations should be provided between the home and an attached garage wherever the foundation type changes, and at 6m intervals where unreinforced concrete slab foundations are used.
10.1.4 Garage floors
A garage floor must carry all loads safely to either the foundations or the ground without undue movement. Points to consider include the bearing capacity of the ground, resistance to moisture and to hazardous gas, the thickness of the slab, drainage, any structural topping, and construction joints. A floor built to NHBC’s substructure or suspended floor chapters, or to the guidance in this chapter, will be acceptable.
10.1.4.1 Bearing capacity of the ground
Where the depth of fill is more than 600mm, the floor should be a suspended floor designed in line with NHBC’s suspended floor chapter and BS 8103-1. Where the slab needs protection from sulfates in the ground, groundwater or fill, an impervious isolating membrane should be placed between the concrete and the ground.
10.1.4.2 Resistance to moisture from the ground
A damp-proof membrane is generally unnecessary in a garage floor, unless one is needed to keep dampness out of the home or to protect the floor from chemical attack. Where no membrane is fitted, the floor may show signs of dampness. Where the floor sits below ground level, steps should be taken to keep groundwater out, and tanking may be required.
10.1.4.3 Resistance to hazardous gas
Where hazardous gas precautions are required and the home has an integral or attached garage, those precautions should run continuously into the garage and out to the perimeter of the property. This applies whether or not there is a connecting door, and whether or not there is living space above the garage. Membranes should be protected from damage and not left exposed. A detached garage may also need gas precautions following a site-specific risk assessment and specialist advice.
10.1.4.4 Thickness of floor slabs
A ground-bearing floor should be no less than 100mm thick, measured to include the float finish.
10.1.4.5 Floor drainage
Where practicable, the floor should be laid to falls so that water or spillage is directed out of the garage through the vehicle doorway.
10.1.4.6 Structural topping
Where the floor is built from suspended beams and infill blocks, the concrete topping should be reinforced with at least A142 mesh to resist a point load of at least 10kN. A reinforced screed used as a structural topping should instead be designed by an engineer in accordance with NHBC Technical Requirement R5.
10.1.4.7 Construction joints
Where the floor area is greater than 16m², the slab should either be reinforced or be divided by construction joints into bays of less than 16m² each.
10.1.5 Garage walls
A garage’s walls must carry all loads safely down to the foundations without undue movement. Points to consider include the stability of walls above ground, the stability of any walls retaining ground, the need to allow for movement, and resistance to rain and groundwater. Walls built to NHBC’s substructure or external masonry chapters, or to the guidance in this clause, will be acceptable, and integral garages within a timber-framed home should follow the external timber-framed walls chapter.
10.1.5.1 Stability of walls above ground
Walls to a detached garage, and the external walls of an attached garage, should be at least 90mm thick and have adequate lateral restraint against wind loading. Piers may be needed to give that restraint, for example in single-leaf walls up to 200mm thick, at corners that are not buttressed by a return of at least 390mm, on either side of a major opening such as the garage door, and at intermediate centres no more than 3m apart. Piers should be built off the foundation, run the full height of the wall, and be tied to the wall with stainless steel ties.
10.1.5.2 Stability of walls retaining ground
A garage wall that retains ground should be suitable for the ground conditions and structurally adequate. Where a wall acts as a retaining wall, it should be designed to NHBC’s substructure chapter or by an engineer in accordance with Technical Requirement R5.
10.1.5.3 Provision for movement
Movement joints should be provided in garage walls between the home and an attached garage, and wherever there are movement joints in the foundations, in line with BS EN 1996-2.
10.1.5.4 Resistance to rain and groundwater
To resist rising moisture, a damp-proof course should be set at least 150mm above the level of the adjacent ground. A single leaf of masonry around 100mm thick will not be fully weatherproof against wind-driven rain, so such walls can become damp, and absorbent linings such as gypsum boards should not be fixed in direct contact with them. In areas of severe exposure, single-leaf walls may need a high standard of workmanship and possibly a surface treatment. Where the garage is integral or attached, the design must make sure dampness cannot pass into the home, and any wall below ground level needs measures such as tanking, damp-proof courses and membranes, or drainage behind the wall.
10.1.6 Resistance to fire spread
A garage should be built so that fire cannot spread from the garage to the home. This means providing adequate fire separation between the two in line with the relevant Building Regulations.
10.1.7 Security
A garage should give reasonable security against unauthorised entry, which matters in particular where garages are linked together. Where linked garages are in different ownership, the dividing wall should prevent direct access from one to the other. Adequate security is generally provided by masonry walls, or by timber-frame walls with two layers of plasterboard each side, with ceilings of two layers of plasterboard. Where a wall does not need fire resistance, a timber frame faced with one layer of 6mm plywood or 9mm OSB on each side is acceptable.
10.1.8 Doors and windows
Garage doors and windows should be adequate for their purpose, with attention paid to robustness and ease of operation. They will be acceptable where they meet NHBC’s chapter on doors, windows and glazing.
10.1.8.1 Robustness
Frames should be chosen and fixed with the type and weight of the garage door in mind.
10.1.8.2 Ease of operation
Proprietary doors and door gear should be fitted in line with the manufacturer’s instructions, and care should be taken to ensure the door is in proper working order at handover.
10.1.9 Garage roofs
A garage roof must keep out rain and snow, support its own weight and any applied loads, and pass those loads safely to the walls without undue movement. Points to consider include holding down, bracing, restraint, detailing where the roof meets other structures, movement, and rainwater disposal. A roof built to NHBC’s flat roof or pitched roof chapters will be acceptable.
10.1.9.1 Holding down
To prevent wind uplift, holding-down straps should be fitted at no more than 2m centres where the roof bears on the supporting wall. They are needed where the roof pitch is below 15 degrees, where the covering is lightweight at less than 50kg/m², or where local experience points to a risk from wind gusts. Straps should be at least 30mm by 2.5mm in cross-section, at least 1m long, and either fixed to the wall in three places or turned into a bed joint.
10.1.9.2 Bracing
The building designer should specify all bracing. Trussed rafter roofs should be braced to NHBC’s pitched roofs chapter, unless designed and braced to PD 6693-1. Timber bracing should be at least 100mm by 25mm and nailed twice to each trussed rafter.
10.1.9.3 Restraint
On a masonry garage, the gable should be restrained at rafter level with restraint straps, provided either by straps or by a gable ladder. Restraint should also be added at ceiling level where the wall height exceeds 16 times the wall thickness for a single-leaf wall, or 16 times the combined leaf thickness plus 10mm for a cavity wall. The number and spacing of straps depends on the type of masonry, with more straps required for perforated or aerated blockwork than for solid brick.
10.1.9.4 Detailing at abutments
Where a garage roof meets the main building, or where stepped garages meet, the junction needs care. This includes flashings and weatherproofing that allow for differential movement, cover flashings in metal or another approved material, and cavity trays that direct water out of the cavity to the external surface.
10.1.9.5 Movement
Any movement joints in the foundations and structure should be carried through the roof coverings and given appropriate weather protection.
10.1.9.6 Disposal of rainwater
Rainwater disposal should follow the relevant Building Regulations. A roof, or a combination of roofs that drain from one to another, with a total area greater than 6m² should have a rainwater drainage system. Where rainwater from a larger roof discharges onto the garage roof, steps should be taken to prevent the lower surface eroding, and rainwater should not discharge straight onto a drive or path.
10.1.10 Permanent prefabricated garages and carports
A permanent prefabricated garage or carport should be suitable for its intended purpose. That means having appropriate foundations, being structurally adequate, being weathertight, and giving adequate separation between linked garages in different ownership. These structures should be put up in line with the manufacturer’s instructions, with particular care taken to hold carports and other light structures down against the wind.
10.1.11 Services
Any service or appliance fitted in a garage should meet the relevant regulations, with attention paid to frost protection of water services, the provision of electricity, and the risk of fire or explosion. Where services are provided, they should also follow NHBC’s chapters on below-ground drainage and internal services.
10.1.11.1 Protection of water services against frost
A rising main should not be routed inside a garage. Any water supply or outlet in a garage should have provision for isolating and draining it down, and pipes should be insulated and positioned to reduce the risk of freezing.
10.1.11.2 Provision of electricity
Whether to fit lighting and socket outlets in a garage is left to the builder. Any electrical installation should comply with BS 7671, and where rain might penetrate the walls, the wiring and equipment should be suitable for those conditions.
10.1.11.3 Risk of fire or explosion
An oil or gas burning boiler or heating appliance installed in a garage should meet any relevant statutory regulations. Where a garage is to hold solar storage batteries, NHBC’s guidance on that subject applies.
How this relates to a snagging inspection
A snagging inspection is a detailed visual check of a finished new home, including the garage, carried out to record defects in finish, workmanship and the components that can be seen and operated. For a garage, that can include things such as the condition of the door and its operation, the finish of walls and floor, visible damp, drainage falls at the doorway, and the way the roof and rainwater goods present on the day.
It is important to be clear about the limits. A snagging inspection is not a full structural survey and is not a substitute for building control or the builder’s own quality processes. Many of the requirements in this chapter relate to elements that are buried or hidden once construction is complete, such as foundations, hardcore, damp-proof membranes, gas membranes, slab reinforcement, wall ties and concealed restraint straps. These cannot be assessed by looking at the finished garage, and matters of structural design are outside the scope of a snagging inspection.
In practice, a snagging inspection is most useful for identifying visible and operational issues so they can be raised with the developer for resolution. Where you have concerns about structural or concealed elements, those are best directed to the developer, the warranty provider or a suitably qualified structural professional.
This article is a plain-language summary of NHBC Standards 2026, Chapter 10.1 Garages, provided for general information. The NHBC Standards themselves are produced by NHBC as guidance for its registered builders and should be referred to as the authoritative source. They do not constitute advice to be relied upon by third parties.
