Window and door specifications: what to include to avoid misunderstandings

Clear dimensions, requirements and responsibilities for an accurate quote and predictable installation.

An inaccurate or incomplete window and door specification is one of the most common reasons for additional coordination, cost changes and delays during a project. When the specification is clear from the outset, the quote can be prepared accurately and production and installation planned without surprises. This article is for architects, builders and developers and summarises what to include.

Why is the specification so important?

Windows and doors affect a building’s energy efficiency, appearance, security and comfort. They are also made to individual dimensions, so mistakes are costly: an incorrect size or unsuitable glazing cannot simply be exchanged for another item from stock. The more detailed the specification, the less room there is for uncertainty.

1. Dimensions and openings

• Opening dimensions. State whether the dimensions come from the design or on-site measurements. Actual dimensions can differ after construction work, so an on-site survey is recommended before ordering.
• Unit dimensions. Clearly distinguish the opening size from the size of the window or door unit.
• Heights and reveals. Specify sill height, reveal depth and wall thickness.

2. Material and profile

• Material: PVC or aluminium.
• Profile system and manufacturer (for example, PVC: Rehau, Deceuninck; aluminium: Reynaers, ProCular).
• Construction requirements: large glass areas, slim frames, non-standard shapes.

If the design includes specific requirements, such as frame width or profile design, include them in the initial specification.

3. Glazing

Glazing is one of the main factors that determines a window’s properties. The specification should state:

• The number of glazing cavities (two- or three-cavity glazing).
• Thermal insulation requirements (U-value).
• Sound insulation requirements if the building is in a noisy location.
• Safety or UV protection requirements, if applicable.
• Glass type: clear, frosted, patterned or coloured.

Glazing can often be differentiated by facade: for example, three-cavity glazing on the north side and two-cavity glazing on the south side.

4. Opening type and hardware

• Side-hung, tilt-and-turn, fixed or sliding window.
• Opening direction and hinge side.
• Handle type and colour.
• Security requirements: multi-point locking and locks.

The opening type affects both usability and safety, so it is worth agreeing on it during the design stage.

5. Colour and finish

• Exterior and interior colours (profiles can have different colours on each side).
• Finish type: smooth colour, wood effect or other textures.
• Colour coordination with facade materials, roof and other elements.

To avoid misunderstandings, specify colours using a precise code or sample.

6. Installation and finishing

The specification should clearly define what installation includes:

• Removal of old windows and doors, if required.
• Installation method and materials.
• Finishing the internal and external reveals.
• Removal of construction waste.
• Installation of sills and finishing trims.

If this part is not defined, it often becomes a source of disputes or extra costs at the end of the project.

7. Lead times and logistics

Allow for production lead times in the construction schedule: PVC windows 4-6 weeks, aluminium windows 6-8 weeks. For complex, non-standard units, confirm the lead time individually.

Plan window and door orders early enough for production to take place alongside the construction work.

8. Acceptance criteria

Agree in advance how the work will be accepted:

• Functional checks (opening, closing and locking).
• Visual checks (glass, frames and finishing).
• Documentation and warranty terms.
• After-sales care.

Summary checklist

• Item
• What to specify

Dimensions

Opening, unit, wall thickness

Material and profile

PVC or aluminium, system, manufacturer

Glazing

Cavities, U-value, sound, safety

Opening

Type, direction, hardware

Colour

Outside, inside, finish

Installation

Removal, materials, reveal finishing

Lead times

Production, delivery, installation

Acceptance

Checks, documentation, warranty

How do we work with architects and builders?

We offer a single point of contact for the entire window and door project: from the initial consultation and on-site measurement to delivery, installation and after-sales care. Our own team carries out the installation. After completion, we provide a 30-day comfort check and an inspection after 180 days.

Working on a project and want to agree on the window and door specification?

Contact us or send your project plans for an initial assessment. On-site measurement and consultation are free.

Discuss your project

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PVC window profile cross-section showing the frame and insulated glazing unit