We are building, and just now after the windows have been installed is that I realised they are really high up.

The window is made of tempered glass 8mm thick, 3.5 m wide, 2.5 m high and starts at 3.5 meters above the ground, so it is 6 m at its highest point.

I was thinking about putting a ladder against the window when I was going to clean it, but I'm not sure if tempered glass can withstand the pressure of ladder and someone climbing it for cleaning.

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    Kaspang! Tempered glass is tough except for that one little scratch, at which point it explodes. – Fiasco Labs Jan 6 '15 at 23:06
  • You can reasonably access the window by placing the top of the ladder alternately below it and then above it. You will need a roughly 28-foot extension ladder, which is a bit unwieldy, but it's doable so long as the ground is reasonably flat and there are no obstacles within about 10 feet of the wall. – Hot Licks Jan 7 '15 at 0:37
  • (I suspect that there is a way to do it reasonably safely (and it probably is being done), with a properly-arranged padded bumper attached to the top of the ladder. But it's something that would require a bit of engineering analysis, plus some testing, to make safe.) – Hot Licks Jan 7 '15 at 0:40

Even if the windows were super thick, it wouldn't be strong enough to handle the pressure exerted by a properly positioned ladder.

A ladder is supposed to be sloped 25%, like this:

from Wikipedia en.wikipedia.org/wiki/Ladder#Safety

With someone standing near the top of the ladder, that means roughly 20% of his weight is directed as lateral force, directly into the wall or window, conveyed by the points of the corners. That could easily be hundreds of PSI, enough to crack almost any glass. That force is temporarily multiplied as each step is taken with something like acceleration and deceleration (this is the basics of physics kinematics, F = ma).

Wrapping the corners of the ladder with something soft (like a thick towel) would greatly reduce the pressure by spreading its force over a much larger contact area. However, the same total force is still applied, and that could well exceed the loading limit of the glass or its frame.

Leaning against glass is a high risk, low benefit undertaking. If the window breaks and the ladder moves, will that make you fall off? Will sharp, heavy pieces of glass fall onto you or be blasted into your face and eyes? Will you fall onto a window shard still held vertical in the frame?

There are many solutions which are easy, painless, and relatively inexpensive:

  • Lean the ladder beside the window
  • Get a longer ladder which can rest on the wall above the window
  • With climbing gear, belay yourself from above
  • Rent scaffolding, a cherry picker, or a self-supporting ladder like an A-frame or orchard ladder.
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    One minor quibble. Tempered glass shatters into very small pieces when it fails. Large stabby fragments come from weak glass; because the initial failure occurs before there's enough energy from the stress applied to it to produce more than a few fractures. Leaning a ladder against the window is still an extremely bad idea; but life threatening cuts/puncture wounds are not a major risk. Enough surface cuts to make your skin look like a bloody jigsaw puzzle OTOH... – Dan Neely Jan 7 '15 at 15:17
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    @DanNeely: Yes, it usually does. However, I once saw a spontaneously shattered oven window resolve into curved needle-like shards mostly 3 to 4 inches long and 1/4 inch wide, like in this photo. The literature says resulting small pieces is only a tendency due to variations in manufacturing and the history of the glass. – wallyk Jan 7 '15 at 17:40
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    Nice answer, but missing an obvious suggestion - get a long (extension) handled window-cleaning squeegee ... – rolfl Jan 8 '15 at 13:01
  • @rolfl: Yes, good suggestion. I seemed to have been in the limited mindset of getting a body up to the window rather than thinking about why he was wanting to get up there. – wallyk Jan 8 '15 at 14:23
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    Although it breaks into relatively small shards, the shards can stay together loosely bound. If you fall onto one end with a lateral force (ie parallel to the old pane), the shape can be retained (at least temporarily) long enough to do some serious damage. Add in the chance of it causing a fall and it's still un-necessarily dangerous – Jon Story Jan 8 '15 at 15:22

Don't do it. Put the ladder above the window, then clean by putting your arms through the rungs.

Shouldn't the windows have a way to tilt them inward and clean from inside the house? Most every modern window I've seen has a way to do that.

You may want to get a ladder stabilizer: enter image description here

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    They are fixed pane windows. They are high above and decorative. Haven't you noticed the sizes? They are very big. – Luiz Borges Jan 6 '15 at 23:17
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    I did notice the sizes. Is it one enormous sheet of glass? Or several windows side by side? You put the stabilizer on the frame in between panes if there is one. If not, you can use the stabilizer above the window, not to the sides of it like in the picture. It gives you a bit of offset that will make it easier to work on the window. – Ariel Jan 7 '15 at 1:01
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    @DMoore I would assume Luiz Borges would buy the stabilizer. I'm not really sure what you are asking. Did you post in the wrong place? – Ariel Jan 7 '15 at 6:40
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    Painting a window without paint on the brush. lol'd a little. – Sempie Jan 8 '15 at 10:59
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    @DMoore You are misunderstanding the use of this. It's not intended to span windows (even though it can). It does two thing: Stabilize the ladder! That's its main job. And secondly it pushes you a bit away from the house, making it easier to work at the very top of the ladder. The companies that make it are the ladder companies - they are ladder specific, it's not a 3rd party aftermarket product. – Ariel Jan 8 '15 at 17:01

Either use a A frame ladder or a squeegee on a pole. I personally wouldn't trust my health on the structural strength of glass.

  • +1 for squeegee on a pole. I use mine from an A frame ladder. – TomG Jan 7 '15 at 17:02

Get a combo sponge / squeegee on an extendable pole. They work very well.

It is also possible to get these window washing soap bottles that have an integrated sprayer mechanism. You attach these to a garden hose for water. They easily can spray a nice and vigorous soapy stream or water at the windows over 20 feet (like 6 meters) high. Normally the surfactants that are in the cleaning soap allow the water to run off the window and leave it clear when you switch the sprayer to rinse mode.

I use these spray cleaners to clean 2nd floor windows and then if there are particularly difficult spots I'll work with the sponge on the pole. Then re-spray the window with the spray. The squeegee can come into play if there is stray water remaining.


I know that this does not exactly answer you question, but here is an alternate option to your probable problem: I would get a water fed window cleaning pole squeegee.


  • It seems to me that it is safer, since you stay on the ground.
  • You wont need to go up and down the ladder.
  • the chance that the window breaks and that you possibly hurt yourself AND need to buy a new window is way smaller.
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    I will probably go to that route, but since the question was about ladders and glass, I already picked a more apropriate answer. – Luiz Borges Jan 7 '15 at 19:08

I wouldn't do it, you're just asking for trouble especially with such a larger window that will likely flex with the pressure.

In any event, how would you clean the entire window if a ladder is leaning against them?

  • I thought that IF I could stand a ladder, it would just be a matter of cleaning one area, move the ladder and then another, etc. But I need to find some way to clean this... – Luiz Borges Jan 6 '15 at 22:12
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    That's a long way up and down a ladder over and over. Might be worth it to just rent a scissor lift or similar. – whatsisname Jan 6 '15 at 23:22

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