Are Rotten Window Sills a Sign of Termite Damage?

Rotting Sills Vs. Termites

• Telling rotting wood and termite infestation apart may be difficult. Dry rot occurs when fungi attack wood, including windowsills and frames. Fungi make the wood hollow from the inside, sometimes moving water from a wet area to a dry one. Where dry rot appears as a dry block or dry brick, termite damage resembles tree branches, and termites often leave tiny holes where fecal pellets collect.

Signs of Termites

• Dry-wood termites live inside wood. They build round kick holes where fecal pellets may be present. The infested wood has a hollow, dull sound when tapped. The sill and frame's interior may contain chambers and nooks connected by tunnels. Probing the windowsill for the kick holes with a sharp instrument like a pencil may be necessary as they can be difficult to detect. Termite wings may also be present on the sill as females shed their wings while laying eggs in the wood.

Causes for Rotted Windowsills

• A variety of factors result in rotted windowsills and door frames. If a window doesn't sit perfectly level and square, water can penetrate through the frame, damaging the wood in the sill and frame. The wrong type of caulking or improper installation can also let moisture in. Most window manufacturers also require at least two coats of high-quality exterior paint on the outside to seal the wood frame. Fast-growth wood used for the window exterior also results in faster rotting.

Preventing and Treating Termite Infestation

• To prevent termite infestation, ensure sound design and construction in new homes and remodels. Remove stored lumber, firewood and dead trees to prevent outdoor infestation. Apply a fresh coat of paint to your exterior and interior frames and sills, sealing cracks, construction scars, joints and crevices with wood putty beforehand. Termite control includes removing infested wood and chemical treatment. If infestation is limited, treatment may involve removing and replacing damaged wood, usually with pressure-treated wood. Widespread infestation may require fumigation.