Exterior painting: when to paint, what weather and what the painter does

Exterior paintwork is not just a matter of appearance. An intact paint layer keeps rainwater out of wooden window frames, windows, doors, fascia boards and bargeboards; as soon as that layer cracks open, the timber absorbs moisture and the process begins that ends in wood rot. If you leave the paintwork a few years too long, you pay for it later in carpentry instead of painting. This article is about the moment to paint: how you can tell it is needed, how often it has to be done, in what weather a painter can work and what a good painter does step by step. An overview of all the maintenance throughout the year can be found in the maintenance calendar for your home.

Signs that the paintwork is due

At least once a year, preferably in spring, walk around your home and look at the paintwork up close. Pay particular attention to the places where water stands or can get in: the bottom rails and sills of windows and doors, the corner joints of frames and the underside of fascia boards. The main signs:

• Flaking. Paint that comes away in flakes no longer adheres and lets water straight onto the timber. There is often moisture behind the paint layer.
• Bare patches. Where the timber is exposed, it turns grey within a short time and absorbs water.
• Chalking. If you run your finger over the paint and a powdery layer stays on your finger, the binder has been broken down by sunlight. The paint then protects less and less, even if it still looks reasonable.
• Cracks in the paint. Hairline cracks, especially along the grain of the timber and at joints, let in water that can no longer get out.
• Open joints and sealant seams. An open seam in a corner joint or between frame and glazing bead is a direct entry point for water.
• Wood rot. Prod the bottom rail and the corners with a screwdriver or an awl. If the tip sinks into the timber without effort, the timber is soft and there is wood rot. Flaking paint in one spot with dark or soft timber underneath is often the first visible sign.

If you only see paint that has become dull or slightly discoloured, a wash is often enough and a complete repaint is not yet needed. If you see flaking, bare patches or soft timber, it is time for a painter, and in the case of wood rot also for a carpenter.

How often do you need to paint the exterior?

Wooden window frames and other exterior woodwork are generally repainted completely every five to eight years, depending on the paint system, colour and orientation. In between, it is sensible to wash the paintwork annually and touch up damage before moisture gets behind the paint. Why the range is so wide:

• Orientation. The south and west facades get the most sun and the most wind-driven rain. That is where paint breaks down fastest and repaints are due sooner. On the north side paint stays good for longer, although green algae can form there because of the damper climate.
• Colour. Dark colours heat up much more in the sun than light ones. As a result the timber moves more, which encourages cracks in the paint and open joints.
• Paint system. A complete build-up of primer, undercoat and topcoat in sufficient film thickness lasts longer than one quick coat over old work. Some manufacturers offer systems with a longer maintenance cycle if the build-up has been carried out according to their specification.
• Timber species and detailing. Timber that drains well, such as a bottom rail with a slope, keeps the paint intact longer than a flat detail on which water stands.

If you wait too long, the repair is more drastic: flaked paint then has to be removed completely and wood rot has to be routed out or replaced. Painting on time is therefore almost always less work than painting too late. If you are considering replacing poor frames with uPVC or aluminium, read Replacing window frames: timber, uPVC or aluminium.

What weather is suitable for exterior painting?

Paint must be able to adhere, flow out and dry. That only works if the timber is dry and the weather cooperates. A skilled painter pays attention to four things.

• Temperature. Most exterior paints may only be applied when the air and surface temperatures are above a minimum, often around five degrees Celsius; for water-based paint that minimum is often higher, around seven to ten degrees. It is not only about the daytime temperature: if it cools down sharply at night, the paint dries poorly.
• Humidity and dew point. At high relative humidity, paint dries slowly and condensation can form on the surface. Paint manufacturers usually set a maximum relative humidity of eighty-five per cent, and the surface must be at least three degrees warmer than the dew point. In the early morning and late afternoon in autumn, dew often forms; a good painter stops then.
• No rain. The timber must be dry, not only on the surface. After a rainy period, timber needs time to dry out; when in doubt, painters measure the moisture content of the timber. Fresh paint that gets rained on within a few hours can stain and cure poorly.
• Not in full sun. In full sun, the paint dries too quickly on the surface, so it flows out poorly, lap marks become visible and blisters can form. Painters therefore follow the sun: the west facade in the morning, the east facade in the afternoon, and the south facade preferably early or late in the day.

As a result, the outdoor season runs roughly from April to October inclusive. Spring and late summer are often the most pleasant: not too hot, not too wet. In July and August it can be too warm on the sunny side, and from October the days get short and the mornings damp. Painters are busiest in spring and summer; if you request a quote in autumn or winter, you have the most choice in scheduling. Interior painting can be done all year round and painters like to schedule it in the winter months.

What the painter does step by step

The difference between paintwork that lasts three years and paintwork that lasts eight lies mainly in the preparation. A good painter works in this order:

1. Inspection. The painter checks all the parts to be painted, prods bottom rails and joints for wood rot and notes which parts need extra attention. A good quote is based on that inspection.
2. Cleaning and degreasing. Dirt, green algae and grease are removed with a degreasing cleaner and then rinsed off. No paint adheres well to a dirty surface.
3. Removing loose paint and sanding. Flaking paint is scraped or stripped off, edges are sanded so no raised edges remain, and the existing paint layer is lightly sanded so the new coat can adhere. If the old paint is in poor condition, it is removed completely.
4. Repairing wood rot. Small areas are routed out down to sound timber and filled with a two-component wood repair compound, which is sanded after curing and painted along with the rest. If the rot is too extensive, for example in an entire bottom rail or a frame jamb, a carpenter replaces the affected part with new timber, or in the worst case the entire frame. Discuss in advance who will do this; many painting companies carry out minor wood rot repairs themselves and bring in a carpenter for replacement.
5. Sealant work. Open seams between frame and brickwork and between glass and glazing beads are cleared of old, loose sealant and resealed, with a paintable sealant where needed.
6. Priming. Bare timber and repairs first get a primer, which provides adhesion and seals the timber.
7. Undercoating. An undercoat fills small irregularities and builds up film thickness. After drying, it is lightly sanded between coats.
8. Topcoating. The topcoat provides colour, gloss and the actual protection against weather and sun. On heavily exposed parts, such as bottom rails, painters sometimes apply an extra coat.

In all these steps, the film thickness is important. The manufacturer states for each product what dry film thickness is required; too thin a build-up wears through quickly, too thick a layer can crack or cure poorly. The drying time between coats must also be observed. Ask the painter which system they use and how many coats they apply.

Opaque or transparent, alkyd or water-based

For exterior timber there are two main types of finish. Opaque paint forms a closed, coloured layer and is usual for window frames, windows and doors. A stain is transparent or semi-opaque, shows the wood grain and forms a thinner layer that lets more moisture through. Stain flakes less, but wears faster and needs maintenance more often; it is mainly used on fences, timber cladding and garden woodwork. A transparent finish also offers less protection against UV light, so the timber underneath can turn grey.

There is also the choice between solvent-based paint, usually alkyd paint, and water-based paint. Alkyd paint flows out nicely, gives a high gloss and has long been the standard for exterior work. Water-based paint contains far fewer volatile organic compounds (VOCs), dries faster, yellows less and stays elastic for longer, but is more sensitive to application conditions. European rules (Directive 2004/42/EC) limit the VOC content of paint, and under the Arboregeling (the Dutch Working Conditions Regulation) professional painters may only use low-solvent paint indoors, in practice water-based paint. That working conditions rule does not apply to exterior work. For exterior work, both types are common. More important than the choice itself is that the new system is compatible with the existing paint layer; a good painter checks this during the inspection.

Lead in old paint

In older homes, the bottom layers of paint may contain lead, for example in white lead or in red lead primer. White lead has been banned in the Netherlands for interior painting since 1939, but for exterior painting only since 2009, and red lead since 1990. Precisely in old exterior paintwork, especially on homes built before 1990, the bottom layers may therefore contain lead. As long as the paint is intact, the risk is small. Sanding, burning off or scraping, however, releases lead-containing dust or fumes, which are harmful if inhaled or swallowed, especially for young children and pregnant women.

A painter working with lead-containing paint sands wet or by machine with dust extraction, does not burn the paint off with an open flame or an overly hot heat gun, covers the ground and disposes of the waste separately. If in doubt, ask the painter to test the paint before they start sanding; simple test kits are available for this.

Scaffolding, aerial work platform and safety

The ground floor can be done from the ground or a stepladder, but the upper floors, the dormer and the fascia boards require working at height. For professionals, the rules of the Arbobesluit (the Dutch Working Conditions Decree) apply: where there is a risk of falling, in any case from a height of 2.5 metres, measures against falling must be taken, and a ladder may only serve as a workplace at height if the risk is low and the work is brief or the location does not allow a safer means. A painter therefore works on the higher parts from a mobile scaffold tower, fixed scaffolding or an aerial work platform. If the scaffolding is placed on the pavement or the street, the municipality's rules apply: a permit or notification is often required, sometimes complying with municipal rules is enough; usually the scaffolding company or the painter arranges this.

As a private individual you do not fall under the Arbobesluit, but the risks are the same. According to the RIVM (National Institute for Public Health and the Environment), about five per cent of people who end up in A&E after an accident with a consumer product fall from a stepladder or ladder; that amounts to several thousand a year. Only paint yourself what you can reach safely from the ground or from a stable, well-positioned ladder, and leave the upper floors to a tradesperson. What else you can and cannot do yourself is covered in What you can do yourself during a renovation. Scaffolding that is up anyway can also be used for other jobs at height, such as gutters, pointing or roof edge finishing; that saves doing the work twice.

VvE, rented home and maintenance contract

If you live in a flat, the exterior paintwork is generally a matter for the vereniging van eigenaren (VvE, owners’ association). According to the notaries' model regulations (2006 and 2017), the window frames in the facades are common property, but your own splitsingsakte (deed of division) and regulations may differ from this. The exterior paintwork is then included in the VvE's meerjarenonderhoudsplan (MJOP, long-term maintenance plan), which sets out when which maintenance is carried out and how much is set aside for it. Check your deed of division and regulations to see exactly what is yours and what is the VvE's before you hire a painter yourself.

If you rent, exterior painting is major maintenance and therefore at the landlord's expense; minor repairs, such as painting interior woodwork, are the tenant's responsibility under the Besluit kleine herstellingen (Minor Repairs Decree). So report flaking paint or wood rot to your landlord.

For owners of a single-family home, many painting companies offer a maintenance contract. In it you agree a cycle, for example a full repaint plus interim inspections and touch-ups, so the paintwork never falls behind. Painters often link a guarantee on the paintwork to this, because they have the maintenance in their own hands. Read the terms carefully: guarantees usually do not apply to wood rot that was already present or to damage from other causes. Painting companies that are members of the trade organisation OnderhoudNL and have completed its quality programme may carry the Vakwerk Plusgarantie quality mark (formerly OnderhoudNL Garantie); they work with their own consumer terms and conditions with a dispute resolution scheme and a performance guarantee via the Geschillencommissie (the Dutch Disputes Committee).

What belongs in the quote?

Painting quotes are hard to compare if they contain different things. Request at least two or three quotes and check that they mention the same items:

• Which parts and surfaces will be painted: window frames, windows, doors, fascia boards, bargeboards, dormer, timber cladding, and on which facades.
• Preparation: cleaning, sanding, removing old paint, sealant work.
• Number of coats and the build-up: primer, undercoat, topcoat.
• Brand and paint system, including colour and gloss level.
• Wood rot repair specified separately: how much repair is included and how additional work is charged if more rot turns up during sanding.
• Scaffolding, scaffold tower or aerial work platform: included or not, and who arranges any permit for placement on the public road.
• Guarantee: how long, on which parts and under what conditions.
• Schedule: in which period, and what happens in bad weather.

How to compare quotes side by side and where the differences usually lie is explained in Comparing quotes: how to read a building quote.

Paint it yourself or hire a painter?

Exterior painting on the ground floor, such as a front door or a garden-facing window frame, is quite doable for a handy homeowner, provided you take the preparation seriously: cleaning, sanding, priming and waiting for the right weather conditions. The difference from a tradesperson lies mainly in the preparation and the coat build-up, not in the brushwork itself. A painter also has the means to work safely at height, recognises wood rot and lead-containing paint, and knows the paint systems. For the upper floors, extensive wood rot repair, and homes with possibly lead-containing paint, a tradesperson is the sensible choice.

In short: look at the paintwork every spring, repaint completely every five to eight years and sooner on the sunny side, have the work done in dry weather that is not too cold and not too damp, and choose a painter who sets out the preparation, the wood rot repair and the coat build-up in their quote. On VerbouwPro you post your painting job free of charge and painters and carpenters from your region respond.