How to Use a Level Over Long Distances

Overview

A 2-ft. level works just fine on small projects like installing small sections of wall tile, building closet walls and installing single cabinets. But when you have to quickly and accurately set elevations over long distances for bigger jobs like building decks, digging trenches and setting concrete form boards, this trusty ol' level is out of its league. Any time you try to pencil a long level line by repositioning that 2-ft., or even 4-ft., level end to end, you'll build in an error that magnifies as you extend the line. There are several tools you can use indoors and out for improving your leveling results. We'll show you the best techniques and tools for short-, medium- and long-distance leveling.

Two levels for short distances (4 - 15 ft.)

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Photo 1: Extend the level

Mark exact elevations for mounting deck beams using a 2-ft. level atop a straight 2x4. Find the straightest 2x4 by sighting down the edges. Pencil the height of the wall ledger onto each deck post.

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Photo 2: Leveling trenches

Set drainage slopes by measuring from a level string line. Tap in a reference stake and then a series of measuring stakes 6 ft. apart along the trench. Check the trench depth for the proper drainage slope by tying off the string line level at each perimeter measuring stake and measuring the depth of that spot in the trench.

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Photo 3: Line level

Measure off the string line once the level reads true and stabilizes. The line level is true when the bubble settles between the hairlines.

Combining a straight board and a 2-ft. level is a good yet inexpensive way to level over shorter distances. For tasks like laying out deck beam heights (Photo 1), set your level on top of a perfectly straight 2x4 to accurately extend its reach. Two-by-six and 2x8 lumber is too heavy to hold steady. To make a lot of measurements quickly, strap the level to the 2x4 with duct tape or an elastic cord.

For jobs where absolute accuracy isn't essential, like digging slopes in trenches, use an inexpensive line level (Photo 2). Hook it directly onto a strong string, like nylon mason's line. For the level to work properly, use only one line level per string, draw the line very tight and make sure there's little wind to blow the level around.

Electronic water levels work well at medium distances (15 - 50 ft.)

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Photo 4: First calibrate

Calibrate an electronic water level by first attaching it plumb and level to a plywood scrap. Fill the tube with water and bleed air out of the line. Calibrate by loosening both tube clamps, turning on the electronic level and raising the working tube to the reference line. The unit's horn should sound as the water in the working tube touches the reference line.

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Photo 5: Listen for horn

Mark level lines anywhere in the room by placing the working tube against the side of a stud to be marked, loosening the working tube clip, and slowly raising or lowering the tube until the horn sounds. Draw a light mark on the stud, recheck the spot by sound and make a permanent mark.

The simple principle behind a water level is that the water columns inside two open ends of a single tube will be level with each other. Using crude water levels (like a section of garden hose) requires two people. For solo work, we recommend you buy an electronic water level (Photo 4). It's highly accurate, has a 25-ft. working radius and allows you to work alone and around corners because it “honks” when the water in the working tube is level with the reference line back at the unit. If you first establish a reference mark at the level and pencil many layout lines around a room (including around corners, Photo 5), you can connect the marks with chalk lines. Measure up (or down) from any line to accurately set acoustical ceiling track, install level wainscoting or add lumber wall blocking for hanging cabinets.

When filling the tube with water, add red, water-based food coloring for easier viewing. Clamp off both tube ends with the clips provided so that water doesn't suddenly spill out.

For best results, avoid water leaks from the water level by clipping the end of the working tube when not actually using it for a measurement. Take care not to step on the tube as you move around a room.

If water does leak out or air bubbles enter the tubing, you'll have to refill the tube and recalibrate the unit to maintain accuracy.

Laser levels: Best for establishing heights at long distances (50 - 100 ft.)

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Photo 6: Self-leveling laser level

Rent a rotating-head laser unit (with a self-leveling base) for long-distance work (50 to 100 ft.) outdoors or indoors. A basic kit should contain tools similar to those shown. Have the rental center check the unit's calibration and battery charge as well as instruct you on its operation.

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Photo 7: Find the laser line with the detector

To level the tops of all concrete form boards, set a rotary laser on its tripod in the middle of a building site, turn it on and wait a few minutes while the unit self-levels. Attach the laser detector (or target) to the elevation rod (it must always face the laser unit) and establish a reference height. Then rest the rod on top of each board and slowly raise the form board up and down until the laser target detects the laser beam and chirps.

We recommend that you use a rotary laser level (Photo 6) for tasks like setting concrete form boards, cutting fence post tops or building retaining walls. Like a lighthouse, the rotary laser shoots a level beam in a continuous circle. Rotary laser levels are the fastest tools for accurately establishing leveling marks (in direct view of the laser) anywhere on a building site. For big time savings, rent a rotary laser that is self-leveling.

Rotary lasers work in tandem with a “target” laser detector. The laser's continuous beam is too faint to be seen in daylight, so a sensor in the laser detector will chirp when it detects the beam. Mounted on an elevation rod (the kind surveyors use), the laser detector slides up and down the rod until it “finds” the laser beam to establish the proper elevation.

For the fastest results setting footing form boards, have one person use the elevation rod to find the laser beam and a second person set the form boards (Photo 7). Prepare a form board for placement by lifting it against a support stake and driving a couple of 3-in. deck screws through the board, ready to set into the stake. Once the laser detector chirps to signal “level,” drive the screws home.