Soft wash, pressure wash, and what is safe.

Pressure washing uses high force, well beyond the pressure of a garden hose, to blast a surface. Soft washing uses low pressure, closer to a garden hose, paired with a cleaning solution that kills algae and mould at the root. For house exteriors and roofs, soft washing is safer and lasts longer because it treats the growth instead of just knocking it off. High pressure is appropriate for hard flatwork like concrete driveways; it is the wrong tool for siding, stucco, or shingles.

No. High pressure can strip the protective granules off asphalt shingles and risk voiding the warranty. Shingle manufacturers such as IKO caution strongly against pressure washing shingles and recommend manual removal or a professional roofer's assessment instead; soft washing, low pressure with a cleaning solution, is the safer approach. If a quote mentions power-washing a shingle roof, treat it as a warning sign.

It can. Too much pressure forces water behind vinyl and into wall cavities, etches brick, and pits stucco. The safe pressure is manufacturer- and product-specific, so check your own siding manufacturer's guidance rather than assume a single number is safe. That is why exteriors should be soft washed: the clean is deeper and the surface stays intact. Older homes built before modern moisture-barrier standards are the most at risk.

No verified Niagara or Ontario figure for what this costs exists in any authoritative source, so this guide does not give one. Ask for a written, itemized quote from a local contractor, and a second one itemized the same way, so the two can be compared line by line.

Most St. Catharines homes need a soft wash every one to three years, sooner on shaded north sides near the lake. The best window is a dry, mild stretch from May through September. Early summer is ideal, before the deep-summer booking rush.