right angle of a room how to check?

my contractor plastering my new home....my question is how could i check the exact right angle of rooms...

question no 2 is ...does it realy important for rooms to be exactly right angle in order to apply tiles on them?

Relevance
• chris
Lv 7
8 years ago

All walls are off a little. They are never perfect. But if you want to check. 3 foot on one wall and 4 foot on the other wall would be 5 foot diagonally from point to point.

• 8 years ago

Chris gave you an accurate answer; it's called the 6/8/10 rule in construction. A triangle with 6ft and 8ft sides that is 90 degrees will have a 10 ft hypotenuse or long side. The rule can be scaled down- divide each dimension in half and it 3/4/5. The bigger the size, the easier it is to be accurate.

You can make the check in multiple places around the house by making yourself a large triangle square using that rule. Just use something like 1x2 sticks that are straight, and join the corners. Be sure and round the 90 degree corner off a little so that it clears the slight radius of the plaster's inside corner, and see how it fits against walls.

• elhigh
Lv 7
8 years ago

You will rarely find a home that has perfectly square corners. And even when they start out square, after a few seasons they often drift a little off. Not much, but a little here and there.

My house is 80 years old this year and has a few square corners, but few of the door frames are perfectly plumb One door shuts itself very nicely, up against the other door that gently swings completely open. Oh well, win some, lose some.

Source(s): Handyman. Yes, I could fix both of these issues with no trouble, but frankly they are so minor I just don't care.
• Anonymous
8 years ago

waste of time.

What's more important, is that you don't mistakenly follow one crooked wall..

The reason ceiling tiles, and floor tiles installers find the center of both walls , and pop a chalk line,..then measure back from that line to stay center the room..

also taking into consideration the first, and last row might be cut tiles..