New window frames change a home in two ways at once: from the outside, together with the brickwork, they determine the face of the facade; from the inside, they determine how warm, quiet and safe the house is. That makes replacing window frames a job that involves more than the choice between wood and uPVC. There is the question of whether you need a permit, there are technical building requirements that new frames must meet, there is the choice of glass, the finishing inside and outside and the way the tradesperson organises the work. This article goes through those topics in order. For the general framework around permits, read When do you need a permit for a renovation; for the choice of glass there is a separate article on HR++ or triple glazing.
When is replacing window frames permit-free?
Since 1 January 2024 the Omgevingswet (the Environment and Planning Act) has applied, and with it the permit question consists of two parts: the technical building activity (does the work comply with the building rules of the Besluit bouwwerken leefomgeving, the Bbl or Dutch Building Decree) and the environmental plan activity (does the work fit within the omgevingsplan, the environmental plan of your municipality, which among other things regulates the appearance of facades). For replacing window frames, the technical side is simple: a building activity on a window frame or frame infill is permit-free nationwide (Article 2.27(2)(c) Bbl), as is a facade panel on a building without a habitable area higher than 13 metres (under (d)), so you do not need to apply for a technical permit or submit a building notification. The rules of the Bbl still apply in full; the municipality simply does not check them in advance.
The planning side depends on exactly what you are doing. Three situations are the most common in practice.
- Ordinary maintenance. If you replace the frames with frames of the same dimensions, the same layout and the same detailing, profile and design, that is ordinary maintenance and permit-free nationwide, including at the front (Article 2.29(a) Bbl). Replacing a wooden frame like for like with a new wooden frame with the same glazing bar pattern and the same profiles falls under this. The type of material is not a criterion in Article 2.29, but in practice the profile of uPVC almost always differs from woodwork, and according to the Raad van State (the Council of State, the highest administrative court) replacement with frames with a different profile is not ordinary maintenance. For listed buildings and in a nationally protected townscape or village view, the colour and type of material may not change either (Article 2.30 Bbl).
- Facade alteration at the rear or on a side not facing a public area. If the new frame differs in layout, profile or material, or you change the size of the opening, that is a facade alteration. In the rear facade and in a side facade that does not face a publicly accessible area, such an alteration is permit-free nationwide for the environmental plan activity (Article 2.29(e) Bbl); this also applies to the facade of an extension or outbuilding in the rear garden area. A municipality cannot deviate from this, but it can take action against serious disfigurement, and the restrictions below apply to listed buildings and protected townscapes.
- Facade alteration at the front or on a side facing a public area. Here a different frame generally requires a permit for the environmental plan activity. The municipality assesses it against the environmental plan and, if your municipality uses them, against welstand criteria (aesthetic standards) or rules on spatial quality. Many municipalities have quick-check criteria for frames in the front facade: retaining the glazing bar pattern, a comparable sightline width, no uPVC with a smooth profile in a street with profiled woodwork. Before you order, ask for a preliminary consultation; a rejection afterwards means you have to start all over again.
Two exceptions take precedence over everything above. On a national, provincial or municipal listed building, replacing window frames in principle requires a permit, including at the rear and including for ordinary maintenance as soon as the type of material, colour, detailing, profile or design changes (for national monuments, Article 13.11 of the Besluit activiteiten leefomgeving, the Environmental Activities Decree; for municipal and provincial monuments, the environmental plan or the provincial environmental regulation). In a nationally protected townscape or village view, ordinary maintenance is only permit-free if the colour and type of material also stay the same, and the permit-free case for facade alterations only applies to a rear facade that does not face a public area; side facades and front facades there always require a permit (Article 2.30(3) Bbl). In all cases, do the permit check in the Omgevingsloket (the national environment and planning portal) and keep the result.
If you live in a flat, there is a third party involved. In most splitsingsreglementen (deeds of division regulations), the external window frames are a common part of the building, even though the window is in your home. You then need permission from the general meeting of owners, and the VvE (owners' association) often decides to replace frames collectively so that the facade remains a whole. For this, read Renovating in a VvE flat.
What requirements does the Bbl set for new window frames?
Permit-free does not mean rule-free. The Bbl has its own requirements for renovation, which are generally more lenient than for new builds but definitely apply, and the owner is responsible for ensuring the work complies with them. The most important topics for window frames are the following.
- Insulation. When replacing windows, doors and frames, a minimum thermal insulation applies, expressed as the U-value of the complete window (frame plus glass). The renovation requirement is a U-value of no more than 2.2 W/m²·K per window, door or frame, or the existing level if that is better (Article 5.20(2) Bbl); the average requirement of no more than 1.65 W/m²·K across all windows only applies to new builds (Article 4.153 Bbl), not to renovations. In practice, every new frame with HR++ glass easily meets these values; ask the supplier to state the U-value of the whole window in writing, not just that of the glass.
- Ventilation. Old frames with single glazing or draughty windows ventilated unnoticed. New frames close airtight, and a home without mechanical ventilation then needs trickle vents or top-hung vent windows to continue meeting the ventilation requirements: in a renovation, the ventilation level may not fall below the existing one (the legally obtained level, Article 5.4 Bbl), and for new builds the benchmark is 0.9 dm³/s per m² of habitable area with a minimum of 7 dm³/s (Article 4.122). Have the vents incorporated into the frame or above the glass; adding them afterwards is awkward and ugly.
- Fall protection. If you replace a window with frame on an upper floor (a height difference with the outside of more than 1 metre), there must be a fixed barrier at least 0.85 metres high under the window, for example a parapet, a fixed glass panel or a Juliet balcony railing (Articles 5.10a and 4.21 Bbl). This mainly applies to low tilt-and-turn windows on the first floor and floor-to-ceiling windows in bedrooms.
- Burglary resistance. For new-build homes, the Bbl requires accessible windows and doors to meet resistance class 2 according to NEN 5096 (Articles 4.99 and 4.100 Bbl). For renovations this is not mandatory, but it is unwise to forgo it with new frames. In practice, resistance class 2 translates into SKG stars on the hardware (hinges and locks): two stars corresponds to resistance class 2 and is the usual level for homes, three stars to class 3. If you want to obtain the Politiekeurmerk Veilig Wonen (the Police Secure Housing Label), you need approved hardware from the PKVW product list on all accessible windows, doors and roof domes, and some insurers give a discount on contents insurance with the certificate.
- Safety glass. In places where someone could fall against the glass, such as glass down to the floor or next to a door, laminated or toughened glass is sensible; the Bbl does not prescribe it for homes, but the standard NEN 3569 (safety glazing) is often declared applicable in specifications and guarantee schemes, and suppliers apply it as standard.
Wood, uPVC, aluminium or wood-aluminium
The material determines the appearance, the maintenance, the lifespan and in part the price. None of the four is the best in every respect; the choice depends on the home, the street and how much maintenance you want to do.
| Aspect | Wood | uPVC | Aluminium | Wood-aluminium |
|---|---|---|---|---|
| Appearance | Classic, slim and profiled details possible | Wider profiles, sleeker | Very slim, modern | Wood inside, sleek outside |
| Maintenance | Periodic painting | Cleaning, no painting | Cleaning, no painting | Cleaning outside, occasional inside |
| Insulation | Naturally good | Good thanks to multi-chamber profile | Only with a thermal break | Good |
| Repair | Easy to repair | Limited | Limited | Limited |
| Listed buildings and aesthetic standards (welstand) | Usually preferred | Often difficult in front facades | Depends on the criteria | Depends on the criteria |
Wood is the traditional material and in older streets often the only one the welstand (aesthetic standards) committee accepts. Choose wood with an FSC or PEFC label and preferably factory-primed and finished according to the KVT (Kwaliteit van Houten gevelelementen, quality of timber facade elements), the guideline of the joinery industry, preferably with a KOMO certificate (BRL 0801). Wooden frames require maintenance: the paintwork generally needs repainting every five to eight years, depending on the paint system, colour and orientation, and touching up in between in places where the paint is damaged. If you keep that up, you will have frames that last many decades and can be repaired locally if damaged. Dark colours on the sunny side age faster.
uPVC (PVC) is one of the most popular materials for replacement in the Netherlands. It never needs painting, is colourfast in the common colours and insulates well thanks to profiles with several air chambers and steel or composite reinforcement. Drawbacks are the wider sightline width of the profiles, which makes the glass opening smaller than with wood, and the limited scope for repair if damaged. Good uPVC frames contain a core of recycled material, old PVC that has been reprocessed, and can be recycled again at the end of their life; ask the supplier about the recycled content, because it is rarely stated on the product and Milieu Centraal (the Dutch independent information centre on energy and the environment) calls frames with a high recycled content the better choice. Wood-grain foil or a dark colour is possible, but dark foil gets hot in the sun and requires a reinforced profile.
Aluminium is strong and stiff, which means the profiles can be very slim and large glass areas, sliding doors and bi-fold doors become possible. However, aluminium conducts heat extremely well; a frame without a thermal break, a plastic spacer between the inner and outer profile, is a cold bridge that leads to condensation. Modern aluminium frames always have a thermal break and then insulate comparably to uPVC, although the insulation level of the best wooden and uPVC profiles is usually slightly higher. The material is powder-coated in any RAL colour and only needs cleaning.
Wood-aluminium combines a wooden inner frame with an aluminium outer shell. Inside, the warm look of wood; outside, no painting. It is the most expensive of the four to buy and requires a supplier who knows the system, but for anyone who wants wood without the ladder, it is a logical choice.
Glass, window types and finishing
The glass determines most of the insulation value of the window. HR++ glass is the standard for replacement; triple glazing insulates better, but is heavier and thicker, so the frame must be suitable for it and the hinges and hardware must be matched to the weight. When the step to triple glazing pays off and what to look out for when choosing is explained in HR++ or triple glazing. Also consider solar control glass on the south and west sides, acoustic glass on a busy road and safety glass where needed.
Broadly speaking, the window types are fixed glass, a tilt-and-turn window (opening inwards, with a tilt position for ventilation), an outward-opening casement window, a bottom-hung or top-hung window and a sliding window. A tilt-and-turn window is practical and easy to clean, but needs room inside to swing open and has a wider stile where the window closes onto the frame. On the garden side, many people choose sliding patio doors: a lift-and-slide door with one fixed and one sliding section, or a bi-fold door that can open fully. Sliding patio doors need a low threshold, good weatherproofing and a sturdy frame; they are made to measure, with the tradesperson assessing the dimensions and the structural consequences, such as a new lintel above a widened opening.
After fitting comes the finishing. Outside, this concerns the sills under the frame (aluminium, natural stone or concrete) that carry water away from the facade, the connection to the brickwork with a compression tape or sealant joint and, with wooden frames, the top coat. Inside, it concerns the window boards, the connection with the plasterwork or the trim and the sealant work. New frames often have a different depth from the old ones, so window boards cannot always be reused; agree in advance who does the interior finishing and to what level: just sealing, or plastering and painting as well.
Subsidy and energy label
Through the ISDE (Investeringssubsidie duurzame energie en energiebesparing, the investment subsidy for sustainable energy and energy saving) from RVO (the Netherlands Enterprise Agency), homeowners can get a subsidy for insulating glass and, in combination with it, for insulating frame panels and insulating doors; the frame itself is not subsidised, but with triple glazing the frames do have to be replaced to qualify for the higher glass rate. In outline, the conditions are: you are both the owner and the occupant of a home built in 2018 or earlier, the glass is on the reporting code list and achieves a maximum U-value (1.2 W/m²·K for HR++, 0.7 for triple or vacuum glass), you replace at least 3 m² of glass (measured including the frame, up to 45 m²), a construction or installation company carries out the work and you apply for the subsidy within 24 months of completion with the invoice, proof of payment, a photo of the work and a glass or frame schedule. The subsidy amount is higher when you combine two or more insulation measures than for a single measure on its own. Which insulation measures contribute most to a better label is explained in Improving your energy label.
How does the window frame specialist or carpenter work?
For window frames you can turn to a specialist window frame company, which usually works with its own products or with regular suppliers of uPVC, aluminium or wood, or to a carpenter, who mainly makes or commissions made-to-measure wooden frames and is strong in repairs, partial replacement and non-standard sizes. The process for both goes roughly like this:
- Survey and advice. The tradesperson looks at the existing frames, the condition of the brickwork and the lintels, the ventilation and your wishes for layout and glass. A good adviser will also ask about the permit situation and the VvE.
- Measuring. Once the order is placed, all openings are measured precisely, because frames are made to measure and a measuring error cannot be put right. For uPVC and aluminium this is done by the manufacturer or the dealer; for wood by the carpenter or the joinery factory.
- Delivery time. Between measuring and fitting there is the production time, which can range from a few weeks to a few months depending on material, colour and season. Delivery times are longest in spring and summer.
- Fitting. A team of two tradespeople usually replaces several frames per day; an average terraced house is done in one to three days. The old frames come out, the rebate is cleaned, the new frame is positioned, anchored and sealed all round with expanding foam or insulation material, and on the outside with a compression tape or sealant. Airtightness on the inside and watertightness on the outside are two different things that must both be right.
- Finishing and sealing. Inside and outside, the joints are sealed, sills and window boards are fitted and the hardware is adjusted. Go over the frames together: do all windows close smoothly, is the sealant work neat and complete, can the vents be operated?
Checklist for the quote
- For each frame, the dimensions, the material, the colour inside and outside, the layout and the type (fixed, tilt-and-turn, sliding patio door).
- The glass: HR++ or triple, any solar control, acoustic or safety glass, and the U-value of the complete window.
- Hardware with the number of SKG stars and whether the frames meet resistance class 2 and the Politiekeurmerk (Police Secure Housing Label).
- Trickle vents: which ones, where and with what capacity.
- Who does the permit check or the application and who is in contact with the VvE.
- Measuring, delivery time and the expected fitting time.
- Removal and disposal of the old frames and the glass.
- The finishing: sills, window boards, sealant work, plastering and painting, and what is not included.
- Guarantee on the frame, the glass (especially on leaking insulated glass units) and the hardware, and who provides the guarantee: manufacturer or installer.
- Quality marks and certificates: FSC or PEFC for wood, KOMO or similar for the frame and glazing, and the information you need for a subsidy application.
What determines the price is mainly the number and size of the frames, the material, the choice of glass, the number of opening sections (these are more expensive than fixed glass), special shapes and colours, the finishing inside and outside and the accessibility of the facade. How to compare quotes side by side is explained in Comparing quotes.
Maintenance after fitting
All window frames need maintenance; only the amount differs. Wooden frames require you to keep the paintwork intact and touch up small damage quickly, with extra attention to the bottom rails and the horizontal parts where water stands. Clean uPVC and aluminium frames a few times a year with a mild cleaning product; no abrasives or solvents. For all materials: keep the drainage holes at the bottom of the frame open, lubricate the hardware every year, replace draught strips that have become porous, check the sealant for cracks and clean the trickle vents. Insulated glass that mists up on the inside is leaking and is usually covered by the guarantee, provided you keep an eye on the guarantee period.
In short: like-for-like replacement is usually permit-free, deviating at the front usually is not, and with listed buildings, protected townscapes and flats, others have a say too. New frames must meet the insulation, ventilation and safety requirements of the Bbl, regardless of whether anyone checks this in advance. Choose the material based on the street, the maintenance you want to do and the lifespan, and choose the glass with the article on HR++ and triple glazing to hand. On VerbouwPro you post your window frame job free of charge, and window frame companies and carpenters from your area respond.