Cedar & Wood Siding Cleaning
The most delicate siding in our service area and the least forgiving of a mistake. Pressure damage to wood does not wash out, it has to be sanded out.
Wood Does Not Forgive Pressure
Cedar siding is built from alternating bands of soft spring growth and harder summer growth. Pressure strips the soft bands out from between the hard ones, and what is left is a furred, raised surface. That is not a cosmetic complaint. A furred surface holds considerably more moisture and collects considerably more dirt, so wood that has been pressure washed gets dirty faster and dries slower than it did beforehand.
The damage is also not reversible by cleaning. Once the grain is raised, the only route back is sanding, which on a full elevation of siding is a different job at a different price.
What cedar actually needs is gentle. Low pressure, a cleaner matched to wood, and then the step most people have never heard of: a brightener. That is a mild acid that neutralises the cleaner and pulls much of the original warm tone back out of a grey surface. Cleaning alone gets you clean grey wood. Cleaning and brightening is what makes cedar look like cedar again.
The brightening step here is the same one used in wood restoration on decks and fences, and the growth being removed is normally moss in the grain plus algae on the shaded elevations.
How We Clean Cedar and Wood
Three stages rather than one, because the greying and the growth are two different problems and only one of them is dirt.
Assess the Wood First
Age, previous finish, how much is sound and how much has gone soft. Siding with failing boards or open joints needs to be known about before water goes anywhere near it.
Pre-Wet the Surroundings
Plantings and beds below are wetted down so anything that carries over is diluted on contact.
Apply a Wood-Appropriate Cleaner
A cleaner suited to wood, at very low pressure, left to do the work. Growth, mildew and surface dirt come off chemically rather than mechanically.
Brighten and Neutralise
A wood brightener neutralises the cleaner and restores much of the original tone, and it is what addresses tannin bleed around fasteners. This is the step that separates restored wood from merely washed wood.
Rinse and Let It Dry Properly
Everything is rinsed down. If a stain or seal is planned, the wood has to dry thoroughly first, and we will tell you how long rather than rushing you into a finish that fails.
What We Address on Wood
Cedar and redwood siding in this climate collect a specific set of problems.
UV Greying
Surface fibre damage from sunlight. Cleaning removes the dirt; brightening is what brings the tone back.
Tannin Bleed
Dark streaking below fasteners and in the areas that stay wet longest, drawn out of the wood itself.
Moss & Mildew
In the grain and in the shadow lines between boards, holding moisture against wood that needs to dry.
Mill Glaze & Old Finish
Surface residue and failing finish that stop a new stain bonding, addressed as part of prepping for refinishing.
Black Spotting
Small dark colonies common on shaded north elevations, which need chemistry rather than scrubbing.
Fastener Staining
Rust-coloured runs below nails and screws, which may indicate corroding fasteners worth a closer look.
Frequently Asked Questions
What does pressure actually do to cedar?
Wood is made of soft spring growth and harder summer growth in alternating bands. Pressure tears the soft bands out from between the hard ones, which leaves the surface furred and raised rather than smooth. That matters beyond appearance: a furred surface has far more area holding moisture and far more texture collecting dirt, so wood that has been pressure washed gets dirty faster and stays wet longer than it did before.
Why has my cedar gone grey, and will washing bring the colour back?
Grey is UV damage to the surface fibres, and washing alone does not reverse it. What does is a two-stage process: a cleaner to remove the growth and dirt, then a wood brightener, which is a mild acid that neutralises the cleaner and restores much of the original tone. That is standard in a proper wood restoration and is why restored cedar looks warm rather than merely clean.
What are the dark streaks running below the nail heads?
Tannin bleed. Cedar and redwood contain natural tannins, and water moving through the wood carries them to the surface, where they show as brown or black staining, concentrated around fasteners and in the areas that stay wet longest. It responds to the same brightening step rather than to more scrubbing.
Can you wash it if I am planning to stain afterwards?
That is the ideal time to do it, and the order matters. Cleaning and brightening opens the surface and removes the growth, grey and mill residue that stop a finish bonding, and the wood then has to dry thoroughly before anything is applied. Staining over wood that is still carrying moisture is the most common reason a finish fails in its first year here.
Have a question we didn't answer? Call (425) 298-7041or submit a quote request — we respond within 24 hours.
Soft Washing Across Seattle & the Eastside
Cedar tracks the age of the housing stock. Older Seattle, Snohomish, Bothell and Kenmore neighbourhoods have the most original cedar siding still in place, much of it decades old and much of it coated and recoated over the years. Medina, Mercer Island and parts of Woodinville carry cedar on larger, heavily shaded properties, where growth is the dominant problem rather than sun damage. Newer construction across Sammamish and Mill Creek is far more likely to be fiber cement wearing a wood look.
Pick your city for what we usually find locally.
Don't see your city? We work across the greater Seattle area, roughly an hour out from Kenmore. See the full service area, or call (425) 298-7041 and we'll tell you straight away whether you're in range.
Related Pages
Wood work on the house usually travels with wood work elsewhere:
Cedar Gone Grey?
Cleaning gets it clean. Cleaning and brightening gets the colour back. Free assessment across Seattle, Bellevue, Kirkland, Redmond, Sammamish, Bothell, Kenmore, Woodinville and the wider Eastside.
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