How long does Douglas fir cladding last?

With the right treatment and regular maintenance, Douglas fir cladding can last 25 to 40 years. Untreated or poorly maintained Douglas fir lasts considerably shorter, because moisture and UV radiation attack the wood from the inside. The lifespan also depends on the orientation of the facade: a north or east facade has less to endure than a facade that is in full sun all day.

Why does Douglas fir turn gray so quickly?

Douglas fir naturally contains few UV-blocking substances. As soon as the wood is exposed to sunlight, the lignins in the wood break down. Lignins are the binding substances that give wood its structure and color. This process causes the characteristic silver-gray color. Douglas fir turns gray faster than, for example, Accoya or bankirai, but that does not make it an inferior wood. Douglas fir simply needs more active protection.

Is graying harmful to Douglas fir?

Graying in itself is not directly harmful, but it is a sign that the wood is unprotected. Unprotected wood is more prone to absorbing moisture, mold growth and drying out. Over time, this can lead to cracks, splitting and rot. Graying is therefore a warning sign rather than a problem in itself.

What is the difference between Douglas fir and other wood species for cladding?

Douglas fir is relatively affordable, lightweight and easy to work with. Compared to alternatives such as hardwood (bankirai) or Accoya, Douglas fir is less durable by nature, but with the right treatment it performs excellently. Accoya, for example, is much more stable and grays more slowly, but it is also considerably more expensive. For anyone who wants a beautiful result at a reasonable price, Douglas fir remains an excellent choice. Just make sure you maintain it properly!

How do I know whether all the old paint or oil has been removed?

If the old paint, stain or oil layer is still intact, you will see that water cannot soak into the wood. If the old layer is weathered, you will see that it has absorbed dirt in the form of green or gray dirt or algae. If the wood is clean, it no longer has a green or gray color after drying and the Douglas fir has regained its own color.

Does the Verf Remover Gel also work on stubborn or thick layers of paint?

In principle it also works on thick layers of paint, but we recommend testing it properly first. The Verf Remover Gel is available in 0.5 liter, which is enough to clean approximately 4 to 6 m2.If this does not work, you can also use Osmo Verf Stripper; this product is better suited to stubborn layers. Do use protective equipment for your skin and airways with this product.

Is the Verf Remover Gel harmful to plants or the environment?

Cover plants before you start treating and prevent animals from coming into contact with the Verf Remover Gel. Rinse away any gel residue thoroughly after use, including from the ground. Always follow the safety instructions on the packaging.

What is the difference between Osmo and other brands?

Osmo has developed a colorless exterior product based on natural oils that offers high UV protection. That is unique on the market. Other products often still contain pigments or are pure oil. Other colorless oils often protect against UV radiation and rain for only a few months.

How long does it take for the UV-Beschermingsolie to dry?

The drying time is approximately 12 hours at a temperature of about 20°C and normal humidity. Full curing takes longer: allow 2 to 3 days before the facade is fully resistant to rain and other weather conditions. Preferably work in dry weather with temperatures between 18°C and 25°C.

What if I want as little color difference as possible?

Osmo UV-Beschermingsolie is available in transparent versions and in wood colors. The transparent version preserves the natural color of the wood and keeps the grain visible. The wood color versions give the wood as little color difference as possible; for example, the color Douglas comes close to the color of dry Douglas fir.

Does UV-Beschermingsolie prevent graying completely, or does it only slow it down?

UV-Beschermingsolie slows down the graying process considerably, but does not prevent it completely. Wood that is outdoors will always slowly react to sunlight and the weather. With regular maintenance coats, you keep the protection up to standard and graying remains minimal.

How often should I re-treat my wooden facade?

As a rule of thumb: inspect the facade every spring and treat it as soon as the protective layer visibly wears off or the wood starts to turn gray. In practice, this means a maintenance treatment every 2 to 4 years for most facades, depending on exposure to sun and rain. A south-facing facade in an open setting needs attention more often than a sheltered north-facing facade.

How do I know when it is time for a new maintenance treatment?

There are a few clear signs: the wood starts to turn gray, water soaks quickly into the surface instead of beading, or the color becomes matte and dull.

Can I carry out maintenance without fully sanding or stripping the facade?

Yes, for regular maintenance on a well-treated facade, stripping it completely is not necessary. Clean the surface with Osmo Power-Gel or Osmo Terrasreiniger, let it dry and then apply a new coat of UV-Beschermingsolie. Complete stripping is only necessary if the old layer has peeled off completely, the wood has grayed heavily or an incompatible product was used in the past.

What happens if I do not maintain my wooden facade for years?

Without maintenance, the wood weathers further and further. Moisture penetrates deep into the wood, which leads to mold growth, wood rot and structural weakening of the boards. At some point, the damage can no longer be repaired with a cleaning and a new coat of oil, and the cladding has to be replaced. Regular maintenance is therefore not only a matter of appearance, but also of keeping costs under control in the long term.Unlike other products, this treatment does not peel or crack. That is why you can still maintain it after 4 years without sanding!

Cleaning and treating your Douglas fir wooden facade yourself? Follow this step-by-step plan!

In this tutorial, we explain how to remove old layers of paint, or in this case an old linseed oil treatment, from a Douglas fir facade. Osmo Verf Remover Gel can remove old layers of paint, stain or oil, so that the wood can absorb a new treatment again. To protect this facade for a longer period this time, we use Osmo UV-Beschermingsolie. It is water-repellent and provides long-lasting protection against UV radiation up to factor 12!

Woman treating a Douglas fir wooden facade with a brush

What you need for this tutorial;

Douglas fir cladding: beautiful, but vulnerable to UV radiation

Douglas fir cladding is a popular choice for facades thanks to its natural look, durability and attractive purchase price. Most professionals treat Douglas fir with a colorless oil such as linseed oil. Unfortunately, UV radiation quickly breaks down this protection, causing the wood to absorb dirt and eventually turn gray.

That graying is not just unsightly: poorly protected Douglas fir dries out, starts to move and can crack over time. As a result, moisture penetrates deeper into the wood, which considerably shortens the lifespan of the cladding. By using the right products, you extend the maintenance interval and Douglas fir cladding can last for decades.

Grayed Douglas fir facade, treated with linseed oil

Removing old paint layers or linseed oil: how do you go about it?

Many wooden facades have been treated with paint, stain or linseed oil in the past. Before you can apply a new protective layer, those old layers must be removed completely. A new coat of oil or stain does not adhere well to a surface that is already saturated with an older product.

Option 1: Sanding or burning

Sanding or burning and scraping are well-known methods for removing old layers of paint or stain, but they have an important drawback: sanding an entire facade is a labor-intensive and time-consuming job.

Option 2: Osmo Verf Remover Gel (recommended)

A more effective and sustainable alternative is Osmo Verf Remover Gel. This gel has been specially developed to remove old layers of paint, stain and oil from wood, including stubborn linseed oil. You apply the gel thickly to the surface, the gel soaks into the old layer and loosens it without damaging the wood. This way you remove old paint layers without sanding.

This makes the Verf Remover Gel the most efficient method for cleaning a wooden facade with older treatments.

Before and after of the wooden facade

These are the photos of the facade before and after cleaning and treatment.

Before cleaning and treating the Douglas fir facade

The facade BEFORE cleaning and treatment

The grayed Douglas fir facade

The facade AFTER cleaning and treatment

After cleaning and treating the Douglas fir facade

Supplies for cleaning and treating your facade

Videos about cleaning and protecting a wooden facade

Houten gevel reinigen zonder schuren: zo pak je lijnzaadolie aan

Zo bescherm je een Douglas houten gevel tegen UV (deel 2/2)

Cleaning and treating a wooden facade

Follow this step-by-step plan for cleaning and treating wooden cladding.

Cleaning off green deposits and old treatments

Start by removing coarse dirt with a hand brush or soft broom. Then make sure you remove green deposits, so that the Verf Remover Gel can soak properly into the old layer of paint or oil.

30 minutes

Apply the Verf Remover Gel generously to the surface with a (block) brush

Make sure the facade is dry and free of loose dirt. Apply the Verf Remover Gel generously to the wood with a brush or roller. Then let the gel work for 60 minutes according to the instructions on the packaging.

Applying Verf Remover Gel with a block brush

Keep the Osmo Verf Remover Gel moist in the meantime

In the meantime, lightly spray the surface treated with Verf Remover Gel with water. You keep it moist by setting the garden hose to a 'mist' or 'spray' setting. NOTE: Do not spray the gel off.

60 minutes

Brush the Verf Remover Gel off the surface

After 60 minutes, scrub the gel off the wood with a stiff brush and plenty of water. You will see the old treatment come loose. Make sure the gel is really completely removed.

After brushing and rinsing, let the surface dry for 24 hours.

Brush the Verf Remover Gel off the surface

Zelf toevoegen:

Garden hose

24 hours drying

Neutralize the surface with Osmo Power-Gel

Before you can apply a new treatment to the wooden facade, you must make sure the Verf Remover Gel has been neutralized. If you do not do this, a new treatment may not adhere. In addition, the Power-Gel draws stains and graying out of the wood, so you start on a clean surface.

Use Osmo Power-Gel for this. Just like the Verf Remover Gel, apply it generously with a block brush. Wait 20 minutes before you brush it off.

30 minutes waiting

Brush off the Power-Gel with plenty of water

Make sure you remove the Power-Gel thoroughly with the garden hose and a stiff brush.

Rinse the Power-Gel off thoroughly

Then let the surface dry thoroughly for a day

Zelf toevoegen:

Garden hose

24 hours drying

Apply the UV-Beschermingsolie after drying

When the wood is thoroughly dry after at least 48 hours (this depends on the weather in the previous days), you can apply the UV-Beschermingsolie. After 2 coats, the wood is fully saturated, the surface is water-repellent and it is protected against UV radiation up to UV factor 12.

After applying the first coat, you must wait 12 hours before you can apply the second coat. You cannot work wet-on-wet with Osmo.

First coat of UV-Beschermingsolie applied with a roller

Roll or brush in the direction of the wood grain

This way you will not see any streaks or unevenness.

12 hours

Apply the 2nd coat after drying

You can roll and/or brush a maximum of 2 coats before the wood is saturated. After that, it no longer absorbs and the wood will dry less well.

With the 2nd coat, you will notice that the wood absorbs less than the first time. So make sure you distribute the oil well and apply a thin coat. The oil then dries to a silky matte finish within 12 hours!

24 hours

Maintenance: how to keep your wooden facade looking good for years

After the treatment, you will need to maintain the protection periodically, because everything outdoors weathers. The interval depends on the orientation of the facade (sun, rain, wind) and the age of the wood. Douglas fir is more vulnerable than hardwood species or thermally modified wooden cladding.

So check your facade every year for dull areas. Compared to other brands, maintaining Osmo treatments is very simple.

For regular maintenance:

Clean the surface with Osmo Terrasreiniger to remove green deposits.
Has the wood turned gray? Remove the graying from the wood with Osmo Power-Gel. If you do not do this, a new coat of oil cannot soak in.
Rinse thoroughly with water and let the wood dry.
Then apply a new coat of Osmo UV-Beschermingsolie.

So you do not need to sand or degrease.

Frequently asked questions

Douglas fir cladding

Removing old layers

Protecting wooden cladding

Maintenance

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