I was watching an episode of Ask This Old House. They guy was dealing with a old, settling house. He determined that the main beam (layman’s term) in the basement was drooping in spots, causing the upstairs doors to scrape in their frames and not close properly.
He determined the location and severity of the droop spots using a stringline stretched from one end of the basement to the other. I see this same stringline arrangement used by bricklayers to help them keep their rows level.
But doesn’t the string sag, resulting in an inaccurate line?
(Or do they use some special anti-gravity string? [Grinny.])
Doesn’t matter how tight you pull it, it will sag into a catenary shape. But on a thin string, taut to the limit of it’s elasticity, the sag will be small enough as to be unnoticable, at least over short (less than 15-20 ft) distances. Even with longer distances, the catenary will only be an inch or so off plumb.
Use nylon and pull very hard before you tie it off. Works great when roughing in the plumbing on a job and trying to stay inside of a future 3 1/2" wall with a 2 1/2" (outside diameter) pipe, which doesn’t allow much room for error. I see it done all the time, even at close to 100’ distance.
They don`t use the string to keep the bricks/wall/fence level. --They use the string to keep the bricks/wall/fence straight.
Bricklayers/plumbers use the string as a vertical reference not a horizontal reference. If you look down on the string from the top, it will always be straight - always. Few in the trades use it by looking at the string from the side, where it can sag.
Bricklayers will use a level on the bricks as they work them and the string helps keep the wall straight (they will take measuresments from the string to the bricks) so the finished wall will be square at the corners and straight.
Occasionally we will have to snap a string line on a horizontal surface but the distance is relatively short, like less than thirty feet or so.
A good tradesman (as opposed to, say, a surveyor[sup]*[/sup]) will use a water-level to equate heights over long distances. It’s just a length of clear plastic hose filled with water. The water level at one end has to be at the same height as the water level at the other end.
It takes a bit of fiddling, because you set the water level at one end, then adjust the level at the other end, which alters the level at the first end, etc.
[sup]*[/sup]Not slagging surveyors, here. They’re the ones with laser levels.
whuckfistle, a string stretched between batterboards is indeed used for horizontal measurements. We tend to use a laser level to get vertical measurements for roughing in the plumbing. Without a string, how are you going to know exactly where to put the riser if it’s not anywhere close to the outside wall?
Plumb’s vertical, but I think you know that. I’m just what every job site needs: carpenter/word-Nazi.
I agree with the use for straight, as opposed to level. But we would sometimes use stringlines to get level. The Mark I Eyeball (straightest tool on the job) can detect sag pretty accurately. Combined with a rule of thumb of around 1/4" per 20’ sag can result in straight, low-tech lines. FWIW…
Chaulk lines are used all the time in roofing. Lay it across the roof, pull taught as Hell, snap for an easy to follow straight line. Trust me, if you don’t do this, the shingles will actually be the things that start to sag in the middle. Of course, since a roof is at an angle and not vertical, the amount the string sags is even less, and therefore negligible.
