Fighting 'Bolor': A Homeowner's Guide to Preventing Damp and Mould in the Algarve
November 6, 2025
Fighting 'Bolor': A Homeowner's Guide to Preventing Damp and Mould in the Algarve
There’s an unwelcome guest that many Algarve property owners dread, and it doesn't arrive with the summer tourists. It’s the musty smell that greets you when you open your holiday home for the first time after winter.
It’s the dark, fuzzy spots in the corner of a bedroom or inside a wardrobe.
It’s bolor—the Portuguese word for mould and mildew.
For a region famous for its 300+ days of sun, it’s ironic that one of the biggest challenges for property owners is damp. But the truth is, the Algarve’s mild, humid winters are the perfect breeding ground for mould, especially in a house that’s been locked up.
Fighting bolor isn't just about cleanliness; it's about protecting your health, your furnishings, and your property's value. Here is our expert guide to preventing and managing damp in your Algarve home.
Why is Damp So Common in the Algarve?
Understanding the enemy is the first step to defeating it. Damp in the Algarve is rarely caused by the same issues as in Northern Europe (like rising damp). It's almost always a problem of humidade (humidity) and condensation.
The Climate: The Algarve winter is mild (10-17°C) but humid. The air is often saturated with moisture from the Atlantic.
The Buildings: Most properties, especially older ones, are built to stay cool in summer. This often means single-skin brick walls with no cavity insulation.
The "Locked-Up" Problem: When you leave, you (rightly) shut all your windows and doors. This seals the property, trapping the humid air inside.
Condensation: As temperatures drop slightly at night, that trapped, moist air hits cooler surfaces—windows, mirrors, and, most commonly, north-facing walls. The moisture condenses into water, creating the perfect damp environment for mould spores to thrive.
In short: a sealed house plus humid air plus cool surfaces equals a bolor problem.
Part 1: The 'Before You Leave' Prevention Checklist
For holiday homeowners, the battle is won or lost in the preparations you make before you "lock-up-and-leave."
✅ 1. Ventilation is Your #1 Priority
Mould hates circulating fresh air.
Open All Interior Doors: Leave every single internal door wide open, including bathrooms and kitchens.
Open Wardrobes & Cupboards: This is essential. Leave all wardrobe doors, kitchen cupboards, and vanity units slightly ajar. Air needs to get inside these dark spaces.
Pull Furniture from Walls: If you can, pull sofas, bed heads, and chests of drawers about 10-15cm (4-6 inches) away from the walls, especially external walls. This creates a crucial air gap.
✅ 2. Banish All Moisture
Don't give mould a head start.
Wash and Thoroughly Dry Everything: Do a final wash of all bed linens, towels, and tea towels. Ensure they are 100% bone dry before putting them away. One damp towel in a laundry basket can create a huge mould problem.
Clean and Prop Open Appliances:
Fridge/Freezer: Empty, clean, and dry it completely. Leave the doors wedged open.
Washing Machine: Run a hot service wash. Wipe the rubber door seal dry and leave the door and detergent drawer open.
Stand Mattresses Up: If you are leaving for several months, we strongly recommend propping your mattresses up on their side. This allows air to circulate around the mattress and the bed base, a prime spot for mildew.
✅ 3. Deploy Dehumidifiers
You need to actively remove moisture from the air.
Passive Moisture Traps: For small, enclosed spaces (like wardrobes, under-sink cupboards, and small despensas), use the disposable salt-crystal moisture traps. They are cheap and effective for localised areas.
Electric Dehumidifiers: For the whole property, an electric dehumidifier is the best investment. Place one in a central hallway.
Pro-Tip: Don't just leave it running 24/7. Either use a model with a "humidistat" (which turns on when humidity hits a certain level) or attach it to a simple plug-in timer set to run for 3-4 hours in the middle of the day.
Warning: Ensure it has a continuous drain hose running to a sink or shower drain. The collection bucket will fill in 1-2 days and then switch off, useless for the rest of the winter.
Part 2: Maintenance – Stopping Water from Getting In
Prevention also means checking the building's exterior. A small, unchecked problem can lead to catastrophic water ingress.
Check Your Gutters: This is a major culprit. Gutters blocked with pine needles and leaves will overflow, sending water cascading down your exterior walls. This penetrating damp will quickly turn into bolor inside.
Inspect the Roof: Get a quick visual check (or ask your property manager) for any cracked or slipped tiles.
Check Window & Door Seals: The rubber seals around windows and patio doors degrade in the strong Algarve sun. Check for cracks or gaps where wind-driven rain could get in.
Part 3: What to Do If You Find Bolor
If you've returned to your property in Vilamoura or Loulé and found a patch of mould, don't panic.
Safety First: Wear rubber gloves and a mask. Mould spores can be harmful.
Clean the Surface:
The Best Solution: For most surfaces (painted walls, tiles), a solution of 1-part white vinegar to 1-part water in a spray bottle is highly effective. Vinegar kills the mould spores.
The Strong Solution: For stubborn patches in bathrooms, you can use a bleach (lixívia) based mould-remover spray.
Important: Never mix vinegar and bleach.
Wipe, Don't Scrub: Spray the solution on, leave it for 15-30 minutes, and then wipe it away with a damp cloth. Scrubbing a dry mould patch can release spores into the air.
Dry Thoroughly: Use a fan or a dehumidifier to dry the area completely.
Find the Source: Was it just condensation? Or is it a leak? If the patch returns, you have an underlying problem that needs professional investigation.
The Ultimate Solution: You Can't 'Arejar' from Abroad
You can set up all the timers and traps you want, but nothing beats the human touch. The traditional Portuguese solution is to arejar a casa—to physically open the windows and doors on a dry, breezy day to flush out the stale, humid air and let in the fresh.
You can't do this from thousands of miles away.
This is the real value of a professional property management service. A keyholder isn't just for emergencies. At Solid Key Management, our regular property inspections include:
Airing the property during dry spells.
Checking for any signs of damp or mould, catching it before it becomes a problem.
Emptying dehumidifier traps and ensuring systems are working.
Flushing all toilets and running taps to keep drains clear.
Inspecting the exterior after major storms.
Don't let the fear of bolor spoil the joy of owning your Algarve home. A little preparation and a trustworthy team on the ground are all you need for true peace of mind.
Contact Solid Key Management for a free consultatio
Is your Algarve hedge turning brown? It's a common issue, often Cypress Canker or aphids. Our guide helps you diagnose the problem and save your cypress plants.
Boost your home's kerb appeal in the Algarve. Discover how proactive property maintenance, from a perfect garden to a clean facade, creates a stunning first impression.