Measure 5-10 meters accurately?

[Arne999]

When building deck frames, etc., you should measure diagonals to get right angles.

I never seem to get this 100% correct. How do you measure 6-7m so that it becomes exact? If you stretch a string, it stretches when you pull it tight, and a tape measure bends and is hard to get completely straight

(Unless you have a good laser, but aside from this luxury...)

 

[hempularen]

Use e.g. two thin planks or slats. Mark where they meet in the middle, move them to the other diagonal.

Should work quite well with wire too, it doesn't stretch, but can sag a little.

 

[hempularen]

Otherwise, there are quite good laser distance meters for about 300 SEK nowadays.

 

[mexitegel]

String is indeed the simplest, blind string stretches minimally. For a patio, this precision is fully sufficient.

 

[Finndjävel]

What happens if the diagonals on the patio are off by a centimeter?

 

[Arne999]

intending to add a conservatory with exact measurements, so I would really like to get it within +/- a few cm if possible

 

[mexitegel]

With a string that does not stretch, the margin of error is a few mm.

 

[ribbones]

If you are building against a straight house wall, it is sufficient to measure the distance to the wall from the outermost beam correctly.

 

[Tiger79]

If you build against a straight house wall, it is enough to measure the distance to the wall from the outermost beam correctly.

It doesn't have to be perpendicular then.

 

[ribbones]

Well, if you have a 2m rule and only when it is 2m from the wall is it at 90 degrees to the wall.

Edit:

You then measure e.g. from the wall that is directly opposite the bearer above the rule. And, of course, you must measure 90 against the wall.

 

[Finndjävel]

Yes, if you have a 2m rule and only when it is 2m from the wall it is at 90 degrees to the wall.

That doesn't work.

 

[ribbones]

That doesn't work.

See above.

If you have 3 rulers connected at the ends at about 90, only when the middle ruler has the other rulers' length against the wall, it is 90 degrees.

Take 3 matches and test if you don't get it. But if you only have a string, you don't know at what angle you're measuring.

 

[Finndjävel]

See above.

If you have 3 rules connected at the ends at about 90, only when the middle rule has the other rules' length toward the wall, it is 90 degrees.

Take 3 matches and try if you don't get it. But if you only have a string, you don't know at what angle you're measuring.

That doesn't work because: a) studs have a given width that will affect it, b) wood is never straight. You can try.

 

[Nils82]

See above.

If you have 3 rulers connected at the ends at about 90, only when the middle ruler has the other rulers' length against the wall is it 90 degrees.

Take 3 matches and try if you don't get it. But if you only have a string, you don't know at what angle you're measuring.

Develop

 

[larsbj]

With a standard 8 m measuring tape, you stay within 1-2 mm accuracy; I think it's difficult to achieve with string, in which case two battens are better.
Buy an 8m Hultafors, and there will be no problem.