Pounds per square inch. A measurement of the pressure exerted on 1 square inch of an object’s surface. In terms of pressure washer lingo, it means the strength of the spray coming out of the nozzle as it hits your cement driveway, or vinyl siding.

Your average garden hose releases water at a pressure of about 40 PSI, a light duty/entry level electric pressure washer runs roughly between 1,000–1,200 PSI and a heavier duty gas powered pressure washer will typically operates spray at roughly 2,800–3,500 PSI. Industrial strength power washers can spray at upwards of 5,000+ PSI, which gives you an idea of what bucket your project might fit in.

GPM stands for Gallons per Minute. It’s also referred to as ‘water flow rate’, and is the measure of volume – in the case of a pressure washer this is of water – going through the system and out the nozzle.

GPM is super important in the equation that determines a pressure washer’s power. A rate of 3 or more is a good GPM rate, though anything above a 2 is fully adequate for most residential and home use.

Depending on the size and square footage of your house or building, pressure washing times will vary.

A typical residential property might take about day to clean all walls, grounds and patios, but in some areas of the Country, that average can go up to two days, and if you need a large house and pool pressure washed, plus a deep wash of the surrounding cement, garage, etc… you can expect the power washing company to be around for a few days.

Most pressure washing companies are pretty flexible here, but if you don’t want to get charged extra and in order to get the job done as quickly as possible, my recommendations are to go over the following:

• Usually access to electricity is not needed, but if you have an extension cord, don’t give them excuses and leave the cords out for them
• Leave all water taps turned on. I know some of you cheap bastards turn your taps off when you’re not using them. Make sure you don’t shoot yourself in the foot by not giving them access to water
• Close and lock all windows and doors to avoid water – or soap – getting in anywhere
• Unlock gates or any entrances that might prevent access to the property. Try to give your power washing company all the access they need to properly clean and work on your project
• If the pressure washing company will be cleaning an area directly beside a door at your place, it’s a good idea to place a towel under door frames
• For pete’s sake, report any and all leaks and concerns at the time of estimation; don’t wait until your house is flooded up to your knees to warn them about a weak spot/or leak

A lot of the time a power washing company will expect to use soaps to get your areas super clean. If you have children, pets, or gardens you’d like to keep safe, bring that up during your estimate and the power washer will make note of it.

A hot water pressure cleaner is a great substitute for soaps and algaecides, and in many cases does the same quality job.

To extend the life of your deck or fence I recommend cleaning and sealing it every 3–5 years. This will save you a grand or more in the long run, by not having to tear the deck up and start over as often.

Look for typical signs of damage:

• A grayed surface means Sun or U.V. damage
• A warped or cracked deck means water damage
• Loose nails are a sign of swelling & shrinking

Moss and other crap should be removed first. A preventative spray can be applied to slow future growth, and there are probably green versions to do the same job. Zinc flashing or stripping can be installed to keep moss away.

If the area growing moss is in the shade and/or damp or moist for most of the year, regular visits or a scheduled maintenance program is a great idea, but let’s be honest you’ll never do that. It would prevent any permanent damage before it happens.

A proactive approach to home maintenance is highly recommended. The more frequent the cleaning, the less pressure needed during cleaning, and the longer your driveway, garage, fence, and deck will last.

Preventative cleaning takes less time and is more gentile on surfaces which also prolongs the life of whatever’s being washed.

Not always. Blasting the surface with high-pressure might remove more dirt, but can also weather the surface and damage it over the long term. The proper technique is to use low pressure, the correct cleaning agents, and a lot of water.

Overall, a higher GPM (gallons per minute) is more important than the PSI (pounds per square inch).

The best way to avoid streaks and/or ‘wand marks’ is to use a flat surface cleaner, which will provide a gentle, even clean. Flat surface cleaners are also less likely to lift edges around tiles, which causes flaking and other bad stuff to happen.