If it's level and plumb, it must be square, right?

[SteveB]

A square doesn't have any degree of error. With a level, you can get the bubble close, but to get it perfect and end up with a perfect 90 is not common. In any engineering problem, take it to the extreme. What if you were to lay our four lines, two one hundred feet long, and two two hundred feet long, using only level and plumb. I bet it would be inches off at the diagonal. And even if you do use a square, the diagonal is going to be the only mathematically exact correct thing. Your square can be bent, but not visibly.

Unless, you use a welder's square, then all bets are off.

Steve

[Oren]

I was thinking a non-fancy method.

Will your "spacer" work for framing mistakes in the transom ROs?

Me! A ladder and a level, measuring tape and set the first window. Then move on.

Note in the pic the first window set was on the right.

[RicodJour]

A water level also works well.

Sure, why not? The RO is larger than the window so there is some play.

With a rotating laser you can mark level on the wall before you install the window. Wouldn't matter the order the windows were set.

A water level works around corners.

R

[Larry Fishel]

I was going to say "because a $10 square is probably more accurate than a $100 level"...

[Oren]

I follow what you say. On some occasions I sat the window back on the ground.

What's wrong?!! The dang RO is to small.

Bring back the framer :-)

[Oren]

What happens, if we say a carpenter's square is not square? (can be fixed, btw)

There is a way to check levels for level.

I forget....

[DerbyDad03]

re: "Consider that two opposing sides have been shimmed too much and they are not straight. Consider that the bow toward the rough opening."

How could shimming the 2 opposing sides cause them to bow outward toward the rough opening? I'm not arguing, I'm asking.

re "This situation fulfills your parameters but the window would not be a square (or rectangle) because two of the sides would be curved."

If you ran into this situation, don't you think that you would notice the gap between the frame and the level? I'm not arguing, I'm asking.

[Wayne Whitney]

If you shim too much at the corners, you could cause that. Or perhaps the window frame was bowed to begin with.

Yes, although you have to know to check that.

The main point is that a tape measure is alot more accurate than a bubble level. If the two diagonals are off by 1/8", I don't think that could be detected with a bubble level (depending on the size of the window).

Wayne

[RicodJour]

Which is one of the reasons I like electronic levels. They're easy to recalibrate, have readings to 1/10 of a degree, have various reading units for different applications, you don't have to worry about your line of sight, there is a hold button so you can take a reading and then move the level to where you can see the reading, etc.

R

[DD_BobK]

Per Wayne's comment a 36" x 36" window where one of the diagonal is off by 1/8" the corner angle would be off by .3 deg (as I guess would the top or side as well).

Can .3 deg be resolved with a bubble level? I know my Smart level displays to .1 deg but how accurately I dont know.

A framing square would catch this small error.

cheers Bob

[DerbyDad03]

OK, so if the window is checked square by a tape measure, why would I need to check it for level and plumb? ;-)

[HeyBub]

If the sides are not consistent with the wall, that is, one side is indented in the hole, the windows may measure square but not BE "square" as we normally think of the definition. Taking it to the extreme: suppose the window was rotated on its long axis by 90° - it would still be plumb by every measurement, but wouldn't be "square".

[DD_BobK]

A set of cross corner measurements will tell you if the factory window is square prior to install or after install but it wont give you the relationship of the window to the "house"

After installation the window could have been knocked out of square so a corner to corner re-check would be advisable

OR

it could have been installed "clocked" slightly off but still be square to itself. So a plumb or level mesaurement would catch that.

I think its a case of multiple views, measures, techniques to get to the same result...... a true, square properly installed window. Bouncing from one technique or tool to another is gives multiple checks.......when my buddy & I do door or window installs we do mulitple checks until we're satisfied and get to "good enough / shoot in it".

Performing multiple checks gives a chance to find a possible error.

I suppose one could determine the minimum number & type of checks to do but at least for me its......measure twice (3 times?) cut once.

cheers Bob

[Bill]

Install a few sliding glass doors or a few french doors and you will be checking for square all over the place!

Or installing new tiles on a floor and getting to the corners. Where two walls meet in the corner can be interesting if the walls are not square!

As for the window, if it is not installed square, you could have problems with the window opening/closing properly...

[SteveB]

OK, so if the window is checked square by a tape measure, why would I need to check it for level and plumb? ;-)

[DerbyDad03]

I'm wasn't asking about problems that could occur with a window that is not square.

I was asking how a window that is plumb on both sides and level top and bottom would *not* be square.

The same goes for a french or sliding door.

I've done windows, I've done sliding doors. The thing is, after I'm made sure they were plumb and level, I'd check them for square and they always were.

As others have said, that extra check certainly can't hurt anything.

[aemeijers]

Because if it is cockeyed in the wall, the siding will look wrong, and people that look out the window will get seasick?

-- aem sends....