Before a takeoff, record trench bottom width and depth, control reach and clear floor space, and edge protection where people work at height.
Key takeaways
- Record bottom widths and depths at matching stations.
- Measure each operable control from the available clear floor space.
- Keep permanent and temporary edge protection apart.
- Mark missing readings and match photos to notes.
You pace a bay, tape a wall, check the drop at an opening, and those figures become quantities for excavation, formwork, backfill, railing, and finishes. When a takeoff goes wrong, the arithmetic is often fine. The usual problem is that a dimension was taken at the wrong point, at the wrong height, or on the wrong side of an obstruction.
This post covers the three measures in the order you are most likely to reach them. Start at the ground, where any open cut is. Move to the floors and rooms, where people move and reach. Finish at the edges and openings where people work above the ground.
The rules quoted here come from three different sources: a California regulation, US federal accessibility guidance, and a regulation made under the law of another country. They show how a measure gets defined. They are not a checklist you can carry from one project to another. Use them as examples of the questions to ask on site, then confirm with the project team which rules apply to your job before you price from them.
A short note on names. A rail, a guard, and a parapet are not interchangeable on a drawing, and the takeoff prices each one differently. Use the drawing's word for each item. If the drawing is silent, write the word you saw on site and say so.
One habit helps with all three measures. Write the measurement, the point it was taken from, and what it is measured to. A width at the top of a cut and a width at the bottom are both "width" in a rushed field note, but they lead to different quantities. Photograph the spot and give the photo the same station number as the note, so the person checking your takeoff can see what you saw.
Step 1: Record the trench width at the bottom and the depth
Start at the ground. Any open cut can affect excavation and backfill quantities, so the first job on the walk is to decide what kind of cut you are looking at. The California excavation rules apply to open cuts, and the section says so directly: "This article applies to all open excavations made in the earth's surface." ( California Code of Regulations, Title 8, Section 1540) If the cut you are measuring is in the ground, check whether that section, or the equivalent rules where your project sits, covers it.
The same section separates a trench from other excavations by shape. It says that "In general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet." The words "in general" mean depth-over-width is the usual pattern, not a test every cut passes. The width limit is the part you can measure on the walk, and it is measured at the bottom of the cut, not at the top edge.
That detail is easy to miss. A cut with sloped sides can be much wider at the top than at the bottom. If you tape the top edge and record it as the width, the takeoff will carry that error forward. Get the width at the bottom. If you cannot reach the bottom safely, do not estimate it from the top. Write "bottom width not measured" and note the reason. Whether anyone can go down into a cut is a site safety question, so ask the site supervisor first. The takeoff question comes second.
Walk the full length of the cut once without the tape. Note where the sides change, where the bottom drops or steps, and where any ramp, ladder, or access point sits. Those changes decide where your readings belong. A reading taken at a change tells you more than one taken at a convenient spot.
Take the bottom width near each end and near the middle. Bottoms are rarely flat, and one reading can hide a narrow or wide section that changes your average. Record each reading with its station number, then take the depth at the same points. Because the rule compares depth with width, a single depth reading tells you little. Two cuts can share a depth at one point and have very different shapes along their length, and the shape is what the takeoff needs.
The same section also covers forms and other structures placed in the cut. It says that if forms or other structures are installed or constructed in an excavation so as to reduce the dimension measured from the forms or structure to the side of the excavation to 15 feet or less, (measured at the bottom of the excavation), the excavation is also considered to be a trench. This matters where footings or a wall go into the cut before excavation is complete. Record the bottom gap from the form to the cut's edge at the same stations as the bottom width, so the readings can be read together.
Note any feature that changes the shape of the cut, such as a step in the floor, a pipe run along the bottom, a sump, or a pit at one end. Sketch it on the field sheet with dimensions from a fixed point such as a column line, a wall face, or a survey stake. A sketch with three clear dimensions is worth more than a page of readings with no reference.
Back at the desk, check the field readings against the drawings. If the drawing shows one width and the bottom readings show a clearly different one, raise it with the design team rather than averaging the two. An average hides the question, and the question is what was built. The same goes for depth. If the drawing assumes a flat bottom and the site has a step, the difference belongs on the list of questions, not in a blended number.
Keep the trench record simple. For each cut, note the station, the bottom width and depth at each reading, the bottom gap from any form to the cut's edge, a sketch of features in the bottom, and the photo reference. Add a note if water, spoil, or loose material made a reading hard to take. A reading you could not take is still useful information, because it tells the estimator where the risk sits. For related pricing checks, see trench takeoff measures.
Step 2: Measure clear floor space and reach for each control
Once the cut is recorded, move to the parts of the building people use. This is where the second measure comes in: the space a person needs in front of a control, and how far they must reach to operate it. The United States Access Board's guide to operable parts sets out the reach ranges and clear floor space it describes. Use it to decide what to measure and where. ( U.S. Access Board guide)
Build the control list before you measure. Drawings show switches, handles, and panels, but rarely show where the site ended up putting them. Walk the room once with the list and mark each control as found, moved, or missing. Then take the readings.
Start with the reach range. The guide says, "The range for side reach, like forward reach is 15″ to 48″ if unobstructed." Record the height of each operable control above the floor and check whether it falls in that band. A light switch, a door handle, a thermostat, or a call button are the kinds of parts you are looking for.
The range applies only to operable portions of an element. So a long counter, a full wall, or a large panel is not measured as one thing. Take the height of the operable part itself. A panel with controls at several heights needs a reading for each control. Measuring an installation's overall dimensions is the wrong measure for this job.
Next, the depth of the reach. The guide says, "The maximum reach depth for this range is 10″ measured from the available clear floor space." Measure from the edge of the available clear floor space to the operable part, not from the wall. A built wall, cabinet, or trim can project further than the drawing shows, so take the depth with a tape at the control on site.
Then look at the floor space in front of the control. The guide notes, "If clear floor space is obstructed on both sides more than half the minimum required depth, a wider clearance (36″ minimum) is required for maneuvering and sway." On the walk, check what stands on each side of the space in front of a control. A wall, a cabinet run, a column, a door swing, or a tall unit can change the clearance you must provide. Record the obstruction on each side, how far it projects, and the open width in front of the control.
Floor space also depends on what sits on the floor. Check whether the clear space in front of each control holds stored items, mats, temporary fencing, or site material. Record what it is and whether it is part of the finished layout or a temporary item. Those two answers lead to different takeoff lines, and a temporary item that blocks a control on the walk can become a permanent fix on the drawings if nobody asks.
The point for the walk is to record the figures the test uses: the depth of the space, the obstruction on each side, and the height and depth of the operable part. With those readings, anyone can run the test again without returning to the site.
Why does this change a takeoff? A control moved to another height changes the blocking, the box, the wiring run, and the finish. A wall that must move for a wider clearance changes the framing, drywall, and paint. A counter or cabinet that must shift changes the cabinetry and its installation. Note which controls fall outside the ranges so the takeoff can show the change. If the layout is not final, ask for a revised drawing before quantities are locked.
Record each control with its room or station, control type, height, depth from the clear floor space, obstruction on each side, open width in front, and a photo. If you could not measure a control because furniture or stored material blocked it, mark it. That mark becomes a question for the project team.
Step 3: Record edges, rails, and parapets where people work at height
The third measure comes last because it needs a view from the right position. Look at the edges of every floor, roof, platform, opening, and mezzanine where a person could fall. These edges decide how much railing, parapet, guard, and related work the drawings show. They also shape how the site protects people while the work is done, and that part often gets less attention in the takeoff than it should.
The Work at Height Regulations 2005, which come from outside California and the US, put a checking duty on employers. Regulation 13 says, "Every employer shall so far as is reasonably practicable ensure that the surface and every parapet, permanent rail or other such fall protection measure of every place of work at height are checked on each occasion before the place is used." ( legislation.gov.uk, The Work at Height Regulations 2005, regulation 13) That regulation may not match the rules on your project.
The duty is measured against what can reasonably be done, so the check and the protection need planning rather than luck. For the estimate, that planning shows up as labor, equipment, and material. Your walk notes give the planning team a starting list based on what is actually there, and they show where a crew will have to stop and set something up before work can go ahead.
Record each edge as its own item. For each one, note the surface type and condition, the length of the run, and whether a parapet, permanent rail, or other fall protection is in place. Mark any edge with no protection shown on the drawings or in the field. Do not guess a height for a rail or parapet you cannot measure. Write the reason and move on, because a wrong height puts the wrong material on the list.
Keep permanent and temporary items apart. A permanent rail is a permanent quantity that stays in the building. A temporary barrier is a site cost that may belong in general conditions and may be removed before handover. If the drawings show a permanent rail but the site has only a temporary barrier at that edge, record both and note which one the takeoff is pricing. Use the related fall-protection takeoff guide when reviewing the plans.
Ask the site team who will carry out the checks, how often the place will be used, and whether that time belongs in your labor allowance or a separate line. A line that says "checks included" with no owner gets missed.
Think about how each edge is used. A ledge a crew uses for hoisting, a platform a finishing team crosses daily, and a roof edge visited once a week carry different traffic. If the schedule shows which edges are used and when, note it beside the edge, since frequency of use changes how much checking time the estimate should carry.
Also record openings and surface condition. Note any floor or roof opening a person could walk into, the surface around it, and any standing water, debris, loose material, or uneven ground. The regulation names the surface itself, so the surface belongs on the sheet with the edges. A clean edge on a damaged surface is still a question for the team.
For each edge, record an edge ID, location, surface type and condition, run length, whether protection is present (yes, no, or unclear), protection type, photo reference, and a question if anything is unclear.
For photos at edges, put a tape or a known object in the frame so the scale is clear. Take one photo of the full run and one close photo of the installed protection, and give both the same edge ID so they can be matched later.
Illustrative example: separate top and bottom widths
Take the depth at the same station. Do not substitute the top reading if the bottom cannot be measured safely.
Next step: review your walk notes today
Today, go back through your walk notes in order. The ground cut, the reaches and clearances, and the edges should each have a station number, a reading, a note of its source, and a photo. If a reading is missing, mark it as missing. A takeoff that says "not measured" is more useful than one with a guessed number, because the gap can be filled before pricing closes. Keep the three records as separate sections in the takeoff, each with its own source notes, so a change in one set of readings can be traced without reopening the other two.
Related guides: Buried utility takeoff: three limits before bids · Power tool safety: check 8 rules before site work.
Questions before pricing
What if a reading differs from the drawing?
Raise the difference with the design team rather than averaging the readings. Keep the field measurement and drawing dimension separate until the question is answered.
Can these rules be used on every project?
Confirm which rules apply with the project team before pricing. The examples here come from different jurisdictions.