Thatch Treatment: a Cape Town guide

Know what you are dealing with

Thatch jobs in the Western Cape tend to fall into a few patterns. The most serious is borer in the structural poles and laths, where powder post beetles go for the sapwood of hardwood poles and other wood borers can attack softwood battens. The thatch layer itself shelters cockroaches, spiders, crickets and fishmoths, which then drop into the rooms below. Rats and mice tunnel through the thatch and nest against the ridge, and birds pull out the reed to build nests, bringing bird mites with them. We also treat lapas, braai areas and game farm chalets in the Boland where the thatch is open underneath and easy to inspect.

Myths, mistakes and lesser-known facts

If you have a pool or pond next to a lapa, mention it. We plan treatments under thatch so nothing drifts into the water.

For holiday rentals and lodges, insects falling from an open thatch ceiling are the kind of thing guests photograph. An annual check before the busy season is cheap insurance.

Cables running through thatch should be in conduit. Rodent damage to a bare cable in a thatch roof is a fire risk that is easy to prevent.

Warning signs

1. Fine powder dropping from the poles or laths onto floors and furniture below.
2. Small round exit holes in the poles, especially in the paler sapwood.
3. Insects such as cockroaches or spiders falling from the ceiling.
4. Tunnels or loose patches in the thatch where rodents have been moving.
5. Droppings on beams or along the top of walls under the thatch.
6. Birds pulling reed out of the roof or nesting under the eaves.
7. Rustling or scratching in the roof at night.

Borer in the poles and laths weakens the timbers that carry the weight of the thatch, which is heavy, and serious damage can mean replacing structural members. Rodents nesting in thatch chew electrical cables, and in a thatch roof that is a fire risk to take seriously. Insects dropping from an open thatch ceiling are a nuisance in homes and a real problem in guest lodges and restaurants. Bird nests in thatch can bring mites into bedrooms below.

Can you do it yourself?

Spraying the underside of your own thatch with a garden insecticide does very little for borer, which lives inside the poles, and soaking thatch in products not meant for it can do more harm than good. We would leave borer and rodent work in thatch to someone who does it regularly. Keeping the roof clear of overhanging trees is the one thing every owner can do themselves.

Seasonal pattern

Adult borer beetles emerge mainly in the warmer months, so fresh powder and holes often appear from late spring into summer. Rodents move into thatch most during the wet Cape winters when it offers dry shelter. Treatment can be done at any time of year, though a dry day makes inspecting the roof easier.

Prevention checklist

• Ask your thatcher to check the poles and laths for borer whenever the roof is being repaired or re-combed.
• Keep trees and creepers trimmed back from the thatch so rodents cannot step straight onto the roof.
• Fit bird netting or wire at the eaves if birds keep pulling reed or nesting there.
• Have electrical wiring in the roof inspected regularly, especially if you have had rodents.
• Do not store firewood or boxes against the walls under the thatch, as they give insects and rodents cover.
• Have open thatch ceilings in lapas and lodges checked once a year, since problems are easy to see early.

What affects the price

The price depends on the size of the roof, how much of the structure is exposed and how many poles and laths show borer activity. A small lapa with an open underside is a very different job from a double-storey home with a closed ceiling. Rodent and bird work is added where needed, and timber that is too damaged to treat has to be replaced by a builder or thatcher.

Frequently asked questions

Areas we cover for thatch treatment