White Stains On Roof Trusses

The house is late victorian and the roof was re slated and felted etc about three years ago.

White stains on roof trusses.

White stains on roof surfaces may be from wash down of pigments in paint on surfaces above the roof such as a gable end or dormer wall. Indicates condensation increase ventilation add soffit or ridge vents apply mould cleaner treat with boracol 10rh. This growth will cease once the moisture content drops to 19 or less. This seems to have appeared only recently.

Therefore we already know something about your third remediator and his or her claim. Typical roof mould damp cold timber condensation mold growth. Fungus and mold will grow on the trusses if the lumber moisture content exceeds and remains above 20. Mould white blue or black spots on timber lining felt masonry.

White or less black roof surfaces may also be found below copper or aluminum flashing whose salts run down the roof surface in wet weather preventing algae or moss growth and leaving a white area on an otherwise stained roof surface. Trees plant debris stains stain patches under trees or nearby may be due to seeds berries leaves and other debris falling and decaying. The client will certainly expect an explanation for this white material on the roof rafters in the attic. If the wood used in trusses is kiln dried the moisture content is equal to or less than 19.

Several of the rafters running along the edge nearest to the felt have a white residue. It is quite moist and is easily wiped off leaving a black mark on the cleaning cloth. White stains on slate roofs efflorescence or salt stains from rain water sometimes appear on slate shingles. Frankly nobody who actually knows much about mycology and mold would from looking at the white growth on a surface by naked eye assert that it is a species of aspergillus.

That could indeed be and looks like a white fungus or mold growth on roof sheathing.