Historic Tax Credit Documentation: The Scan Before and After

Luiza PlievaSep 2, 2026

The federal historic preservation tax credit rewards a rehabilitation that keeps what makes a building historic, and the application that earns it is a record: of the building as it stands, of the work proposed, and of the work as completed. This guide explains what that application consists of, as the National Park Service describes it, where a 3D laser scan fits in historic tax credit documentation, and what the scan gives the owner and the architect beyond the application itself. It is not tax advice; how the credit is claimed and what it applies to are questions for the project’s tax adviser.

What the application is

The National Park Service, which decides the applications after the State Historic Preservation Office has reviewed them, describes the application: “A three-part application is required to qualify for the 20% tax credit.” In its words, “Part 1 presents information about the significance and appearance of the building. Part 2 describes the condition of the building and the planned rehabilitation work. The proposed work will be evaluated based upon the Secretary of the Interior’s Standards for Rehabilitation”, which the page calls “a set of 10 rules of practice”. “Part 3 of the application is submitted after the project is complete and documents that the work was completed as proposed.” Approval of Part 3 “certifies that the project meets the Standards and is a ‘certified rehabilitation.’”

Part 2 and Part 3 each describe the building at a point in time, before the work and after it, and the work between them is judged against the Standards. The condition of the building before the work and the work as completed are therefore what the record has to show.

Where a scan fits

The application’s own documentation requirements are the Park Service’s to set, and the scan does not replace them. What the scan adds is a measured record of the building at each stage, from which the drawings an architect prepares for Part 2 are traced and against which the completed work can be checked. A terrestrial scanner of the Trimble X7 class, 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), and a scan of the building before the work records every surface in its line of sight as it stood: the facades with their openings and ornament, the interiors with their moldings, the floors with their sag, the condition of each of them on that day. The panoramic images from every scan position, delivered with the point cloud, are themselves a dated photographic record of the building’s appearance, room by room.

A second scan after the work records the building as completed. When the two clouds are registered to the same coordinates, on survey control or on surfaces that did not change, the geometry shows what moved, what was removed and what was added, and that an opening kept its size. It does not show whether a cornice was repaired or replaced to the same profile, since both read the same within the scanner’s accuracy; that is the kind of thing the application’s own photographs and descriptions carry. The two scans are the owner’s measured record of the building at both dates, and for the architect preparing Part 2 the first scan is the base the existing-conditions drawings and the proposed work are drawn on.

What is drawn from the scan

The existing-conditions drawings are traced from the registered point cloud: plans, elevations, sections and the details of the profiles and ornament, in DWG and PDF, with the sheet saying which lines were measured and which were taken from older documents. The accuracy of the line work is stated in the U.S. Institute of Building Documentation’s Level of Accuracy terms, as a standard deviation at the 95 percent confidence level; a typical set is drawn to LOA30, between 15 mm and 5 mm, and a tighter level can be specified for the profiles that a replacement has to match, measured at short range. A Revit model of the building is built from the same cloud when the design is done in Revit. The guide to 3D scanning for historic preservation describes how a historic building is scanned and how the scan relates to the Park Service’s documentation standards more generally.

The scan also records things the application does not call for: the ornament at a resolution a replacement can be made from, and the movement of the structure that a repair has to allow for. Hidden conditions found when a finish is opened can be scanned again at that stage and marked in the record.

What the owner keeps

The point cloud in E57, the ASTM exchange format for 3D imaging data, and in RCP/RCS for Revit, with its registration report and station images, is the building’s measured archive, and it serves the next project and the next owner long after the credit is claimed. The 3D laser scanning page describes the scan and its deliverables, and the as-built drawings page the sheet set.

Price and time

A historic building is priced on its area, its stations and what is built on the cloud. Typical ranges from recent projects: a house or an apartment with drawings or a model, $2,000 to $4,500; interiors with the facades and the site, $2,500 to $5,000; an office or a commercial floor, $3,000 to $9,000; large buildings run from $12,000 and are quoted on their own; the point cloud alone starts at about $1,200. A second scan after the work is quoted as its own scope. The exact price comes in a quote within one business day of your sending the address, photographs and the deliverables the project needs. The scan is scheduled as soon as the project needs it, often within days of the order, which matters when the work is about to start. We scan in all 50 states.

FAQ

Does the tax credit application require a laser scan?

No. The application’s documentation requirements are the National Park Service’s to set, and the scan does not replace them. The scan is the measured record from which the drawings are traced and against which the completed work can be checked.

What is the three-part application?

As the Park Service describes it, Part 1 presents the significance and appearance of the building, Part 2 describes its condition and the planned rehabilitation, evaluated against the Secretary of the Interior’s Standards for Rehabilitation, and Part 3 is submitted after completion and documents that the work was completed as proposed.

What does a before-and-after scan show?

Two point clouds registered to the same coordinates show what moved, what was removed and what was added, and that an opening kept its size. They do not tell a repair from a replacement to the same profile; the application’s own photographs and descriptions carry that.

What accuracy are the drawings stated to?

The scanner is rated at a 3D point accuracy of 2.4 mm at 10 m (one standard deviation) by its datasheet. The line work is stated in USIBD Level of Accuracy terms in the quote, typically LOA30, with a tighter level for profiles measured at short range.

How much does the scan cost?

The point cloud alone starts at about $1,200; a house with drawings or a model usually runs $2,000 to $4,500. A second scan after the work is quoted as its own scope. The quote arrives within one business day.