What good looks like
Windows and external doors: what good looks like
Openings, cavity closers, fixings, sealing and thresholds — the junctions where air leakage and water ingress usually start.
An opening is a hole in three continuous lines at once: the weather line, the thermal line and the air barrier. A window can be perfectly installed and still fail if the closer leaves a thermal bypass or the perimeter seal is pointed rather than backed. Frames should be fixed with the specified mechanical fixings at the correct centres, packed at load points, and square within tolerance rather than adjusted with the seal. Cavity closers must be continuous and tight to the frame, with insulation continuity maintained at head, jamb and cill. Thresholds need their upstand and drainage detail, and accessible entrances need a level threshold formed to the design rather than improvised.
Basis in regulation
Part M, clause 1
Access to and use of buildings: entrances
Read the sourceChecked against the live source on 20 August 2026
Key requirements
Door, window, and glazing performance
All doors, windows, and glazing must be designed, specified, and installed to meet relevant technical requirements and ensure adequate in-service performance. This includes considering factors such as weather resistance, security, thermal efficiency, and durability.
All doors, windows, and glazing must be designed, specified, and installed to meet relevant technical requirements and ensure adequate in-service performance. This includes considering factors such as weather resistance, security, thermal efficiency, and durability.
Basis in regulation
Key requirements: windows and external doors
The checks worth making while the fixings are still reachable.
Frames mechanically fixed at the manufacturer's specified centres and packed at fixing points. Cavity closers continuous at head, jambs and cill with no gap to the frame. Perimeter joint backed with closed-cell rod and sealed, not filled with mastic alone. Cill projection and end caps correct, with the drip clear of the wall face. Trickle ventilation provided where the design requires it and left unblocked. Thresholds to accessible entrances formed level to the designed detail with the drainage in place.
Basis in regulation
Part F, clause 1
Ventilation: background ventilators
Read the sourceChecked against the live source on 20 August 2026
Window and Door Frame Installation
Window and door openings must be correctly sized and square, allowing for adequate tolerance and movement between the frame and masonry without causing frame distortion. Frames should be securely fixed using appropriate methods such as frame cramps, proprietary cavity closers, or plugs and fixings.
Window and door openings must be correctly sized and square, allowing for adequate tolerance and movement between the frame and masonry without causing frame distortion. Frames should be securely fixed using appropriate methods such as frame cramps, proprietary cavity closers, or plugs and fixings. Cavity closers must be fitted continuously or as per manufacturer's instructions for jointing, ensuring a full seal.
Basis in regulation
Adjustable hinges and frame fixings
External doors typically incorporate adjustable hinges to allow for fine-tuning of the door's alignment and operation after installation, which can accommodate minor building movements. Frame fixings, often self-drilling concrete screws, must be appropriately sized and installed in sufficient number
External doors typically incorporate adjustable hinges to allow for fine-tuning of the door's alignment and operation after installation, which can accommodate minor building movements. Frame fixings, often self-drilling concrete screws, must be appropriately sized and installed in sufficient numbers to secure the frame firmly to the structure.
Basis in regulation
BS 8213-4
Read the source
External door frame gap filling
Gaps between external door frames and the surrounding structural opening must be minimised and correctly filled to maintain thermal, acoustic, and weather performance. Excessive gaps should be mechanically packed with solid materials, not solely relying on expanding foam, to provide structural suppo
Gaps between external door frames and the surrounding structural opening must be minimised and correctly filled to maintain thermal, acoustic, and weather performance. Excessive gaps should be mechanically packed with solid materials, not solely relying on expanding foam, to provide structural support and prevent thermal bypass.
Basis in regulation
External door frame fixing to masonry
External door frames must be securely fixed to the surrounding masonry or structure using appropriate mechanical fixings to resist operational forces and wind loads. The method and type of fixing, including pilot drilling and screw selection, must be suitable for the substrate and frame material to
External door frames must be securely fixed to the surrounding masonry or structure using appropriate mechanical fixings to resist operational forces and wind loads. The method and type of fixing, including pilot drilling and screw selection, must be suitable for the substrate and frame material to ensure long-term stability.
Basis in regulation
BS 8213-4
Read the source
External door fixing methods
External door frames must be securely fixed to the surrounding structure using appropriate fixings and brackets specified by the manufacturer or structural drawings. Correct installation ensures the door's stability, weather tightness, and security. The method of fixing depends on the frame material
External door frames must be securely fixed to the surrounding structure using appropriate fixings and brackets specified by the manufacturer or structural drawings. Correct installation ensures the door's stability, weather tightness, and security. The method of fixing depends on the frame material and the wall construction.
Basis in regulation
BS 8213-4
Read the source
Garage doors and windows suitability
Garage doors and windows must be fit for purpose, considering their robustness and ease of operation. They should be selected and installed to withstand regular use and provide adequate security and weather protection.
Garage doors and windows must be fit for purpose, considering their robustness and ease of operation. They should be selected and installed to withstand regular use and provide adequate security and weather protection.
Basis in regulation
Garage door frame robustness
The robustness of a garage door frame is critical and must be carefully selected and fixed to support the specific type and weight of the garage door it will carry. Adequate fixings ensure stability and safe operation.
The robustness of a garage door frame is critical and must be carefully selected and fixed to support the specific type and weight of the garage door it will carry. Adequate fixings ensure stability and safe operation.
Basis in regulation
BS EN 12604
Read the source
Critical dimensions at this stage
Original editorial guidance based on publicly available Approved Documents. Not building control approval, a warranty determination, or a substitute for the full source document.