Pressure washing

What it covers, and when it is worth doing

Pressure washing cleans siding, decks, walkways and driveways of grime, mildew, algae and loose failing paint using pressurized water, sometimes preceded by a cleaning solution for stubborn mildew or algae that plain water alone will not lift. It is simple in concept and easy to get wrong in practice, since the right pressure and technique differ by surface, and what safely cleans a concrete driveway can easily damage wood siding or an aging deck.

It is worth doing when siding or a deck looks dull, streaked or has a greenish tinge, before painting, since a clean, sound surface holds paint far better than a dirty one, before selling, where it is one of the lowest cost ways to improve how the whole exterior reads in photos and in person, and as routine seasonal upkeep in any climate where mildew and algae build up quickly on shaded or damp surfaces that do not get much direct sun.

The case for this trade is how disproportionate its return is. Almost nothing else in this guide costs so little while doing so much to make every other exterior job, painting, selling, simply living with the place, look and perform better, which is exactly why it tends to come first on a list rather than as an afterthought once everything else is already done.

How often this is worth doing depends heavily on climate and surroundings. A shaded, humid yard under mature trees builds up mildew and algae far faster than an open, sunny lot, so a house in the first setting benefits from a more frequent routine than one in the second, and a local operator will usually have a realistic sense of what your specific property actually needs.

It is also a sensible once-over after a long, harsh winter, checking what salt, ice and grime left behind before the rest of the year's exterior work gets planned around what is actually found underneath it.

How to choose a good one, and where this goes wrong

Ask whether they adjust pressure and technique by surface. Wood siding, vinyl, a wood deck and a concrete driveway all call for different settings, and using driveway-strength pressure on old or soft siding is exactly how this goes wrong. A good operator will describe adjusting for the surface without being asked, rather than running one setting on everything from the walkway to the second story siding.

• Too much pressure on old or soft siding. It drives water up and behind the panels instead of simply cleaning the surface, which creates the exact moisture problem a siding contractor later gets called in to fix, sometimes within the same season.
• Treating a wash as a substitute for a repair. A pressure wash reveals problems, soft wood, failing caulk, damaged siding, far more often than it fixes them. Expect a real operator to point out what they find rather than simply quoting the wash and moving on to the next job.
• No insurance. Licensing bars here are minimal in most places, but a mishandled wand can genuinely gouge wood, crack a window seal, or strip paint it should not, so insurance still matters even for a job this size.

It is also worth asking how they handle plants and landscaping near the house, and where runoff actually goes, since a cleaning solution rinsed carelessly can stress grass and garden beds right along the foundation line.

For a roof or a painted surface, ask specifically whether they use a gentler, lower pressure approach sometimes called soft washing, which relies more on the cleaning solution and less on raw pressure. Using driveway-strength equipment on a roof or delicate paint is one of the more expensive mistakes in this whole trade, since it can strip granules or paint outright rather than simply clean them. It is also reasonable to ask for a smaller test patch in an inconspicuous spot before the whole surface is cleaned, especially on an older or delicate material, so you can see the result and the technique firsthand before committing to the full job.

What drives the price

Total surface area and how dirty or mildewed it actually is are the two real levers. A routine yearly wash costs less than a first cleaning on a surface that has gone untouched for a long stretch, since heavier buildup takes more time and sometimes a stronger cleaning solution to lift before rinsing. Using a cleaning solution before rinsing, often needed for algae and mildew rather than plain dirt, adds a modest amount on top of a simple water-only wash, and it usually pays for itself in how much less scrubbing or repeat passes the job needs.

Compared with almost anything else in this guide, this remains a small bill, which is exactly why it is worth doing before paying for paint, listing photos, or a larger exterior project. A clean surface makes every one of those jobs cheaper, faster or more effective, since a painter spends less time on prep and a listing photographer is working with a house that already looks cared for, so sequencing this first is one of the easiest wins available in exterior upkeep, for very little relative cost.

Bundling this with another exterior job, ahead of painting, before listing photos, alongside a deck refinish, often saves a separate site visit and setup, and many operators price a combined job a little more efficiently than two separate calls. Since the wash itself is quick relative to almost any other trade in this guide, the scheduling flexibility is usually on your side, not the operator's, so there is rarely a reason to rush it in isolation. A driveway or walkway alone is usually the smallest version of this job, while a full exterior, siding, deck, walks and drive together, costs more simply for the added area and time involved.

Access plays a small part too, a deck or a section of siding boxed in by tight landscaping or a fence takes longer to reach and clean carefully than an open, easy to walk around exterior, even at the same square footage. None of this changes the basic shape of the trade: it is one of the smallest bills in this guide for one of the more noticeable results.