As-Built Drawings for Tenant Improvements

A tenant improvement starts from a base plan, and the base plan the landlord hands over is usually the weakest document in the project: a CAD file or a PDF from the building’s original construction, marked up, or not, by every tenant who has built out the space since. Walls have moved, a restroom was added, the ceiling was dropped, ductwork was rerouted for a server room that is gone. The architect designs the new fit-out against that plan, the permit set is drawn on it, and every difference between the plan and the space turns up later as a correction or a change order. This guide explains what as-built drawings for a tenant improvement are, what they show, how they are made from a laser scan, and what they cost.

What an as-built set for a TI is

An as-built drawing shows the space as it stands today, with the dimensions and positions measured in the space rather than taken from an older design set. For a tenant improvement the set is usually a floor plan of the suite with the demising walls, the core, the columns on the building grid, the doors and the windows; a reflected ceiling plan with the ceiling heights and grid, the lights, the diffusers, the sprinkler heads and the soffits; the interior elevations the design needs; and a section or two through the floor-to-floor height and the ceiling cavity. The sheets are delivered in DWG and PDF, with each sheet saying which lines were measured and which were taken from other documents, and the registered point cloud they were traced from comes with them in E57, the ASTM exchange format for 3D imaging data, and in RCP/RCS for Revit. When the design is done in Revit, the same cloud becomes a model of the suite instead of the drawings or on top of them.

The drawings are a measured base for the architect and the engineers. The permit set, its code review and its stamps are the design team’s; what the building department in your jurisdiction asks for in the existing-conditions sheets is for the architect to confirm, and the as-built set is drawn to that list.

Why a TI base plan is usually wrong

A suite that has had three tenants has had three fit-outs, and the landlord’s file shows at most the first. Partitions are added and removed without the base plan being updated; a ceiling is lowered under new ductwork; a column is boxed out; a restroom or a kitchenette is added with its own plumbing. None of that is unusual, and none of it is visible in a PDF. A tape survey finds the walls but straightens what it cannot describe and leaves the ceiling to a sketch. A laser scan records every surface in its line of sight, the walls, the floor, the ceiling and the structure where it is exposed, so the plan is traced from what is there.

How the space is scanned

The scan is made with a terrestrial scanner of the Trimble X7 class, which by its datasheet measures up to 500,000 points a second with a 3D point accuracy of 2.4 mm at 10 m and 3.5 mm at 20 m (one standard deviation). The scanner stands on a tripod and is moved from room to room, each station taking a few minutes, and the stations are registered into one cloud in the field and checked before we leave, so a missed corner is rescanned the same day. An occupied suite can be scanned during business hours if the tenant prefers: the scanner is quiet and works around people, though furniture and stock hide floor and wall lines, and rooms that can be cleared are drawn more completely. A suite is usually scanned in a day.

Above the ceiling is where a TI base plan is usually emptiest, and it is where the new ductwork, sprinklers and lighting have to fit. Where the ceiling is a lay-in grid, tiles are lifted on an agreed pattern and the scanner is raised to look along the runs, so the ducts, the pipes, the sprinkler mains and the structure in the plenum are recorded where they are visible. What stays hidden behind a hard ceiling or inside a wall is not in the cloud; the drawings show it only where an existing drawing does, marked as unverified. The MEP BIM page describes how the systems above a ceiling are modeled when the engineers need them in Revit.

What it costs and how long it takes

Price follows the area, the number of sheets and how cluttered the space is. Typical ranges from recent projects: an office or a commercial floor, scanned and drawn, $3,000 to $9,000; interiors with the facades and the site, $2,500 to $5,000; large buildings from $12,000, quoted on their own. The registered point cloud alone, for a team that drafts in-house, starts at about $1,200. The exact price comes in a quote within one business day of your sending the address, the suite’s approximate area, the sheets the design needs and whether ceiling tiles may be lifted.

The scan is scheduled as soon as the project needs it, often within days of the order. The drawings usually follow in two to three weeks for a small suite and in four to eight weeks for a full commercial floor, depending on the sheet count; the registered cloud with its report usually comes within a few days of the scan, so the design team can start from it while the sheets are drawn. We scan in all 50 states.

What to send for a quote

The address and the suite number, the approximate area, the sheets the design needs (floor plan, reflected ceiling plan, elevations, sections), any existing drawings even if they are not trusted, and the access: who opens the space, which rooms are locked, whether the suite is occupied, whether ceiling tiles may be lifted and whether an escort is required. The site preparation checklist covers the rest. The as-built drawings page describes the sheet set, and the guide to as-built vs record drawings explains why a design is drawn on a measured set.

Sources

• Trimble X7 3D laser scanning system datasheet: scan speed and 3D point accuracy.
• USIBD Document C120, Level of Accuracy Specification Guide, version 2.0 (2016): the LOA levels as standard deviations at the 95 percent confidence level.
• ASTM E2807, Standard Specification for 3D Imaging Data Exchange: the E57 file format.