How to check if a wall is squared

[adelast]

Hi team,

This might be a very very stupid question, and it also might be difficult for me to explain since I am not a native English speaker, but I'll try my best!

I have used spirt levels to test if something like a counter or a shelf is levelled or to check if a surface is vertically levelled. However, how do I check if a surface (let's say a wall) is levelled horizontally?

To better explain my question I am attaching an image, let's pretend that this is an image of a room and you are looking it from the roof (so what you see at the center is actually the floor), as you can see the wall at the right is slightly shorter in length and is causing the wall at the bottom to not being straight.
Is it possible to use a spirit level to check that?

I mean, if you are facing that wall and put the spirit level against that vertically, yes you can check if this wall it's going inwards or outwards, but what if it's going outwards at the right or at the left?

I apologise for the stupid question

[ayjay]

A spirit level can only check for horizontal or vertical accuracy.

You could just use a tape measure to check the difference in length of the walls, and Pythagoras theorem if you're setting out new walls and want them to be at 90° to each other,(i.e. Square).

You're English is perfectly acceptable, although we would call a diagram that looks down on something:- " a plan view"

https://en.wikipedia.org/wiki/Pythagorean_theorem

[Dave54]

Or measure the diagonals. If they're equal then whatever you've measured is square.
https://www.engineeringtoolbox.com/squa ... _1714.html

You can use "pinch rods" for some jobs. Just two pieces of wood that you "pinch" together to compare the measurements.

[adelast]

Thank you very much!

[Grendel]

I'd agree with the comments about how to check the walls . If anything going by the number of buildings i've worked in in my time there's probably more chance of walls being out if only just slightly. Try working on a four hundred year old timber framed building and the out of squareness , out of level out of plumb is often quite pronounced. May we ask what you are intending to do and why it's so important for everything to be square? In restoration we used to say the eye is more important than the spirit level. If something looks right it is right even if the spirit level says otherwise. And vice versa , putting something in to the level can also look wrong.

[Dave54]

Yes. I've seen a few times with old buildings, attempts to get things "level and square" can actually look way out when everything else is anything but.
Some of the cob and stone places down here, were literally built by eye. I don't suppose anybody gave a thought back then to more than that.

[Job and Knock]

To check if a wall is basically square at a corner use a folding builders square (e.g Stanley) or make up a 3-4-5 square from 2 x 1in (50 x 25mm) softwood roofing laths. If you need to check longer distances then a 3-axis green laser is a great help. Set up one axis parallel to one of the walls, in the corner, but set off by, say, 50mm. Then you can see directly if the adjacent wall.is square and straight. Very handy for setting out in listed buildings which are seemingly never square (or straight, plumb, level, etc).

On a more basic level you could mark lines parallel to the walls on the floor (mark points at each end of the wall and you can pick up bowing as well) at 100mm off the walls, using a chalk line. Setting a large builders square or home made 3-4-5 square to one wall in a corner would then allow you to see if you were within a reasonable approximation of square

Personally, I wouldn't bother checking diagonals because buildings are often substantially out in more than one direction

Note: Builders squares are at least 1 netre long. Home made 3-4-5 squares should be something like 600-800-1000mm (or better 900-1000-1500mm) to get the required accuracy. A 6in/150mm try square simply isn't big enough to give you anything sensible

[Grendel]

Or put up some patterned wallpaper. That'll show if the wall is out

[Job and Knock]

Not if it's a bare stone wall

[Grendel]

True , and stuff like panelling can be fettled to a degree to be more accomodating to out of squareness , and plain walls can go unnoticed altogether. Then there's the question of if one knows the walls are slightly out how to remedy and if it's even worth the effort. We still don't know why square walls are so important to the OP.