Caring for a Timber House in a Humid Climate

Timber houses are still common in Kalimantan, from old stilt houses along the rivers to new homes with plank walls. Wood has long been a building material here, especially for stilt houses on soft ground and wetland.

A timber house that is looked after can last a very long time. One that is neglected can rot from below without showing it from the outside.

This guide is for owners and buyers of timber houses, or houses with a lot of timber in them. It covers what to check each year, and the small habits that help wood last in a hot, humid climate.

The main threats to a timber house

• Damp. Wood that stays wet, or keeps going from wet to dry, is where rot fungi grow.
• Rot. Rotten wood turns soft and crumbly, changes colour and smells musty.
• Termites. Subterranean termites are the most common pest. They come up from the soil through mud tubes and eat the wood from the inside.
• Sun. Heat and sunlight make the surface dull and cracked and make paint peel quickly, especially on the west side.
• Fire. A timber house burns more easily, and fire can spread quickly to the house next door.

These threats feed each other. Damp wood rots more easily, and damp or rotting wood is what termites prefer. So most of looking after a timber house comes down to keeping the wood dry.

Ulin (Bornean ironwood) is very durable and termite resistant. But not every part of a house is ulin, so maintenance still matters. Signs of termites and how to check for them are covered in checking for termites and wood rot.

The yearly check

Set aside one day each year, ideally before the rainy season, to go round the house with a torch and a screwdriver. Probe the wood with the screwdriver. Sound wood feels hard, while rotten wood feels soft or lets the tip sink in.

What to look at:

• The roof and gutters, including slipped tiles or metal sheets and blocked gutters.
• The ceiling, for leak stains.
• The posts and their bases, especially the parts near the ground or water.
• The space under the floor, whether it is dry, airy and free of rubbish.
• Floor and wall boards, especially in the bathroom, the kitchen and below windows.
• Door and window frames, for gaps, rot or doors that have started to stick.
• Paint or varnish, noting where it has started to peel or go dull.
• Signs of termites, such as mud tubes, wood dust and shed wings.
• Wiring, especially cables fixed to timber and those above the ceiling.

Write down what you find and take photos. Year by year, the record shows which parts are getting worse.

A dry, airy underfloor

In a stilt house, the space beneath the floor lets the house breathe. Air moving under the floor carries away damp from the ground and from the timber.

• Don’t close the underfloor in completely with walls or piles of belongings. If it has to be enclosed, leave enough vents.
• Don’t store old timber, cardboard or damp items under the house. They attract termites.
• Clear weeds and rubbish under and around the house.
• Make sure water doesn’t pool under the house after rain.

Airflow inside the house is covered in a healthy home with good airflow.

Keep soil and splash away from the timber

Wood that touches the soil rots quickly and invites termites. The bottom of the walls also gets wet from rain splashing up off the ground.

• Leave a gap between soil and timber. Don’t bank up soil or build planting beds against plank walls.
• Lay gravel or a hard surface along the line where water drips off the roof, so it doesn’t splash soil onto the walls.
• Look after the gutters and downpipes. Point their outlets away from the posts and walls.
• Keep roof overhangs wide enough to shield the walls from rain and sun.

Refinishing with paint, varnish or oil

The protective coat is a timber house’s skin. There are three common choices:

• Paint, which gives the most protection from sun and rain because it covers the wood completely. The downside is that the grain disappears, and peeling paint has to be scraped off before repainting.
• Varnish, which shows the grain. On outside surfaces in direct sun it cracks and peels sooner.
• Oil or a penetrating finish, which soaks into the wood rather than forming a thick film. It is easy to reapply without scraping, but needs redoing more often.

Don’t wait for a fixed date. Recoat when the finish starts to crack or peel, or when the wood turns dull and soaks up water. A simple test: put a few drops of water on the surface. If they soak straight in, the finish is no longer protecting the wood.

Sides that take direct rain and sun usually need recoating before the inside does. Follow the instructions on the product for surface preparation and the number of coats.

Replacing damaged boards and treating new timber

Before replacing a rotten board, find out why it rotted. A new board will rot too if the leak, the splash or the termites haven’t been dealt with.

When you replace it:

• Use timber that is at least as durable, especially for parts near the ground and water.
• Treat less durable timber with a wood preservative before fitting it.
• Coat every side, including the cut ends, before it goes in. The end grain soaks up the most water.
• Use rust-resistant nails and bolts, so they don’t leave stains or weaken the joints.

A post that has rotted at its base is a job for an experienced builder, because the posts carry the weight of the house. Don’t just patch it with a board or cement. How stilt houses work and what their parts do is covered in Kalimantan’s traditional stilt houses.

Preventing fire

A timber house doesn’t have to be dangerous, but small mistakes cost more in one.

• Check the wiring. Old cables, joints wrapped only in tape and stacked plug adaptors need sorting out.
• Don’t overload one socket with several high-power appliances.
• Keep open flames, such as mosquito coils, candles and the stove, away from walls and curtains.
• Keep a fire extinguisher (APAR) in the kitchen, and make sure everyone in the house knows how to use it.
• Fit a smoke alarm near the bedrooms.
• Know your way out, and don’t block doors with belongings.
• Save the local fire brigade’s number on everyone’s phone.

Next steps

Put money aside for maintenance every year rather than waiting for major damage. Replacing one board and repainting one side of the house costs far less than replacing a rotten post or floor, especially if the material is ulin, which is expensive.

Start with one thorough check before the next rainy season. Note what you find, then deal with water and structural problems first.

If you are thinking of buying a timber house and have questions, you can reach the Vorneo team on WhatsApp.