How to protect your exterior wooden doors from the summer’s assault

Sun damage to solid wood doors is inevitable but luckily treatable. As soon as you start seeing any damages to your door, it is time to address the matter.

Varnished or oiled doors are the most vulnerable and need regular care; even one coat of finish can minimise damage. 

Front doors are expensive to replace, and not something you want to do regularly. Follow these simple steps to protect your wooden door from the hot summer sun. A proper paint or varnish job is the key to long-term protection and beauty. 

• First, you want to lightly sand down the door and give it a good wipe down. Scrape to remove any loose or peeling paint or varnish.
• Next, apply a coat of varnish or primer that will seal the wood. In the case of a painted door, provide a good surface to caulk or putty to if necessary. In the case of varnish, the wood will have changed colour. If you should opt to putty or patch, you’ll be able to pick a colour that will be close to the finished door.
• In most cases, damaged wood will get darker when sealed. If you feel that stain might be needed, wet the wood with water or solvent before the first coat of varnish. Everything that turns dark with the wetting will get at least that dark when stained. Areas that don’t change colour or change very little will probably react the same way with the stain.
• One or two more coats of the finish enamel or varnish will finish the job. 
• Sand lightly between coats to remove any dust or debris that may have stuck to your door. 
• If the finish looks a little uneven or partly soaked in, then give the third coat. If it doesn’t change the appearance, then it’s probably a texture difference you see, and additional coats won’t change it much.

Varnished doors should be evaluated every year, especially if they get a lot of sun.

Choosing the Best Exterior Wood Door Protection

Your front door is exposed to sun, wind, and rain every day, which makes protective finishes a key component. Different finishes provide varying levels of durability, appearance, and UV resistance. Here’s a comparison of common options for the best exterior wood door protection:

Finish Type	Protection Level	UV Resistance	Appearance	Best Use
Spar Varnish (Marine)	Excellent	High	Glossy, warm tone	Front doors with direct sun exposure
Exterior Polyurethane	Very Good	Moderate–High	Clear, durable	Versatile, good for sheltered doors
Penetrating Oil (Tung/Teak)	Good	Moderate	Natural matte finish	Doors with rustic or natural style
Paint (Exterior Grade)	Excellent	High	Opaque, customizable	Maximum UV + moisture protection

According to Fine Woodworking, marine spar varnish is considered one of the best varnishes for wooden front doors, as it expands and contracts with temperature changes while providing excellent UV protection.

How to Seal Your Exterior Wood Door for a Long-Lasting Finish

Sealing your exterior door prevents cracks, fading, and warping. Here’s how to seal an exterior wood door effectively:

1. Sand the surface gently to remove old finish or imperfections.
2. Clean thoroughly with a tack cloth to eliminate dust.
3. Apply a wood conditioner or sealer if the wood is porous (like pine or cedar).
4. Use a UV-protective varnish or polyurethane, applying thin, even coats with a high-quality brush.
5. Allow proper drying and sanding between coats for a smooth finish.
6. Seal all edges (top, bottom, and sides) to prevent moisture infiltration.

By ensuring full coverage, you provide your door with the best exterior wood door protection against sun and seasonal weather.

UV Protection for Exterior Door Finishes: Varnishes, Polyurethane & Oils

UV rays are the leading cause of fading and surface degradation. Using finishes specifically designed for exterior door finish UV protection makes a major difference.

• Spar Varnish: Formulated for boats, it provides maximum UV resistance and flexibility.
• Polyurethane (exterior grade): Great balance of durability and clarity; many versions include UV absorbers.
• Penetrating Oils (like tung or teak oil): Offer natural UV resistance and bring out the grain, though they require more frequent reapplication.

Taking a combination approach, such as applying oil followed by a UV-resistant topcoat, can give you both depth of colour and long-term protection.

Pro Tips for Applying the Best Varnish for Wooden Front Door

• Always apply multiple thin coats instead of one thick layer.
• Use a natural-bristle brush for oil-based varnishes and a synthetic brush for water-based finishes.
• Work in a shaded area to prevent premature drying and brush marks.
• Don’t forget the edges and underside of the door, which are highly vulnerable to moisture.
• Recoat every 12–24 months, depending on sun exposure.

Following these steps ensures your finish maintains both its appearance and protective properties.

Seasonal Maintenance for Front Doors to Protect from Sun Damage

Even the best finish requires routine care. Here are seasonal tasks to extend the life of your wooden door:

• Spring: Inspect for cracks, reapply sealer to edges if needed.
• Summer: Clean monthly with a damp cloth to remove dust and pollen.
• Fall: Apply a protective wax or polish for added resistance.
• Winter: Ensure weatherstripping and seals are intact to keep moisture out.

Routine maintenance prevents small issues from becoming costly repairs and keeps your door beautiful year after year.

Damaged to the point of no repair, we can help 

Master Doors has hundreds of standard options to choose from in a variety of wood species, sizes, and glass options. We have everything from wood front doors, solid wood exterior doors and custom entry doors. Browse through our website for the latest elegant styles available for your picking.