Don’t Pressure Wash Windows! But if you do, here’s how

There are some things that we get advised against doing, and sometimes that advice is right. But not always, pressure washing windows is one of those things. Experts all agree that using a pressure washer to pressure wash windows is unwise. 

They say the power from a pressure washer will break the glass, damage seals, or cause any number of problems. This might be true, especially if you don’t know how to operate a pressure washer correctly or you can’t identify dodgy windows. If the windows are sound, and you know what you’re doing, it’s perfectly safe to pressure wash windows and it’ll save time too.

Why Do The Pros Say No To Pressure Washing Windows?

Washing Windows

Professional window cleaners don’t use pressure washers to wash windows, they advertise a hand window cleaning service. When asked why they say that they’ve seen too many windows broken by having been pressure washed. They claim that pressure washers:

  • Break glass
    If the PSi is too high, it is very easy to break glass, also if the jet stream is concentrated on one area it will break the glass.
  • Loosen putty
    If the putty that’s holding the glass in is old, dry or damaged, the pressurised water can dislodge it and cause the glass to fall out and break.
  • Damage wooden window frames
    Old wooden frames are liable to get water damage if exposed to high-pressured water. Also, softwood is easily damaged by high PSi from a pressure washer.
  • Damage rubber seals
    Inferior quality rubber seals on cheaply made or ill fitting double glazed windows can get damaged by high-pressured water. This can cause water seepage into the house.
  • Cause interiors to get wet
    Any loose, or ill fitting window or seal can allow water to enter the building, especially under high pressure.

How To Safely Pressure Wash Windows

If you do decide to pressure wash your windows there are a few safety aspects to consider first. The very first thing to do is inspect the windows for any damage, cracks, or any problems with the frame, seals, putty or wood. If it all seems good then you’re okay to start. There are a couple more safety issues to consider let’s list them to be sure you are aware of them all before you start.

  • Be aware of how much damage a pressure washer can do
    With just 928 PSi you can cut through rubber, 1,160 PSi you can cut through human skin, 1,914 PSi will cut through glass and 2,321 PSi will cut through softwood like pine.
  • Cover up with PPE
    Now you know just how much power you’re dealing with, it’s wise to take precautions. Wear a long sleeved shirt, long trousers and boots or at least covered in shoes. Wear gloves, goggles, and a face mask.
  • Keep off the ladder
    Some of the worst pressure washer accidents have happened because of ladders. It’s difficult enough to keep your balance with your feet firmly on the ground whilst operating a pressure washer, let alone while holding onto a ladder with one hand.
  • Be aware of where you are working
    Check for anything you might trip over, like tools, furniture, toys, pot plants, children, pets, etc.
  • Protect electric equipment
    Cover any fuse boxes, outdoor lights, A/C units, vents etc in plastic sheeting secured with masking tape.
  • Cover any plants that cannot be moved
    To protect them from the worst of the detergent, cover any plants with plastic sheeting or old blankets etc.
  • Give soil a good soaking
    To minimise the effect of any soaps, water around any plants thoroughly and make sure they are fully hydrated.
  • Look out for children and pets
    Children and pets like to be outside when dad is, especially with the added spectacle of a pressure washer, but they can get seriously injured with the high water pressure. Never point the water at any person animal or plant, no matter how funny you might think it will be. We have seen grown men hospitalised because they tried to spray a mosquito from their arm. They succeeded, but they also removed 7 layers of skin.
  • Use the lowest pressure possible
    This is true of every surface, but even more so with windows.

What Pressure Nozzle Is Safe For Windows?

Firstly, there’s no such thing as a safe nozzle, but the least dangerous nozzle for window cleaning is the black or 65 degree (detergent) nozzle. this should be used at a slanting angle, never straight at the glass. And you need to keep the tip moving so the water is never concentrated at one point at all.

The most powerful nozzle to use on windows is the white or 40-degree nozzle but start with the black detergent nozzle.

4 Step Guide To Safely Pressure Wash Windows

Gas Pressure Washer

To safely clean windows using a pressure washer follow all of the safety advice above and the following steps.

  1. Connect the garden hose to the inlet valve on your pressure washer
    Before turning the pressure washer on, attach the black nozzle, using the lowest pressure possible, turn on the machine, and aim at a garage or cellar window, if you feel you need to increase the pressure, move slightly closer to the window, too powerful? Move back slightly.
  2. Fill the detergent tank with the correct detergent (one that’s compatible with your machine)
    Keeping the sprayer tip a safe distance from the window, aim at an angle of no more than 30 degrees and keep the tip moving at all times.
  3. Spray from the edge of the window into the centre
    Remember not to touch the putty, joints, seals or frame or try to minimise contact with those areas.
  4. Rinse all of the suds away
    Once the whole window is covered in suds disengage the detergent conector and using the same nozzle, rinse from the top of the window down. Keeping the spray at an angle and moving constantly. Don’t allow any soap to dry on the glass.

If your pressure washer doesn’t have a detergent tank, consider washing the windows with a sponge and soap, and rinsing with the pressure washer. We advise using no more than 1300 PSi to be safe.

Frequently Asked Questions

Can pressure washing damage windows?

Pressure washing can damage windows a PSi of 1,914 is enough to cut through or break glass.

Can you wash windows with a power washer?

You can wash windows with a pressure washer as long as the windows are in good repair, you are careful and you don’t use a high-pressure nozzle.

Should you wear a mask while pressure washing?

You should wear a mask while pressure washing to keep safe and free from injury.

Can a pressure washer cut your finger off?

A pressure washer can cut your finger off if you are not careful.

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