PVC is often the logical choice when thermal performance, low maintenance, value and a traditional or timber-style appearance are central. Recessed profiles suit many Dutch homes.

Aluminium is suitable when narrow sightlines, large glazed areas, high stability, a wide colour range or intensive use are important. Always compare the complete element: the material alone does not determine performance.

A recessed profile has greater visible depth and reflects traditional Dutch window proportions. The Intura Ideal 7000 NL block profile has a 120 mm frame depth and is available with or without a rebate.

Whether it suits the construction depends on the existing façade, reveal, cavity, internal finish and required position of the window.

Uf applies to the frame, Ug to the glazing and Uw to the complete window. Uw is the most useful value for the real element because it also includes the ratio between glass and frame and the edge connection.

A low Ug-value does not automatically produce an equally low Uw-value. Large, small and differently divided windows can have different Uw-values even when they use the same profile and glass.

Triple glazing reduces heat loss more than standard insulating double glazing but is thicker and heavier. The profile, hardware and installation must be suitable. In renovation, the ventilation strategy, thermal bridges and the rest of the building envelope should also be considered.

For large south- or west-facing glazed areas, summer comfort may be more important. Solar-control glass or external shading may then be required alongside strong insulation.

A fixed light provides the largest glazed area within the available frame. A tilt-and-turn window combines full opening with secure ventilation. An outward-opening window keeps internal space clear but requires consideration of wind load and access.

Also determine handing, operation, guarding, cleaning and insect screens. Record these choices for each room in the window schedule.

A lift-and-slide door suits large glass areas and smooth everyday operation. A tilt-and-slide door is more compact and provides a ventilation position but has lower maximum dimensions. Bi-fold doors create the largest clear opening but require more hinges and stacking space for the folded panels.

For every system, check threshold height, exposure to rainwater, accessibility, wind load and the required supporting structure.

A low threshold reduces the level difference between inside and outside and can improve accessibility. At the same time, the construction detail must control rainwater, splashback, floor build-up and airtightness.

A flush threshold is therefore not an isolated product feature. The internal floor, external paving, drainage, canopy and system detail must be designed together.

Record which dimension is being used: structural opening, clear opening, overall frame size or manufacturing size. Measure at several points and check squareness, plumb, level, reveals, rebates and sill.

For renovation, photographs and a section are essential. If there is any doubt, the opening should be surveyed by a competent person before production starts; custom-made windows cannot easily be altered afterwards.

Security depends on the combination of profile, reinforcement, hardware, locking points, cylinder and glazing. PVC systems can be specified with steel reinforcement and high-quality BUVA hardware. Aluminium elements are also built with project-specific window and door hardware.

Specify burglary resistance, safety glazing, guarding, escape functions and access control before quotation. The required solution varies by building and position.

Choose double doors where headroom is limited or a traditional two-leaf appearance is required. A residential sectional door opens vertically and saves space. An industrial sectional door is designed for larger openings and frequent operation.

Measure the opening, side room, headroom and clear depth. Also record frequency of use, operation, insulation, vision panels, personnel door, colour and track arrangement.

• Providing only width and height without identifying the type of dimension.
• Confusing the Ug-value of the glass with the Uw-value of the complete window.
• Defining handing, thresholds and floor levels too late.
• Selecting triple glazing without checking the profile, hardware and glass weight.
• Designing large sliding doors without assessing the support and transport route.
• Using a low threshold without resolving drainage and external levels.
• Failing to specify colour, texture and gloss level clearly.
• Treating ventilation, shading and safety as late additions.