As-built drawings for a renovation: record changes before walls close

As-built drawings should be prepared during the renovation, as each change is agreed and before pipes, cables or strengthening work disappear behind finishes. Leaving it until the end turns a control task into an uncertain search through photos, messages and memory. In a Lisbon flat, this record helps locate shut-off valves, junction boxes, risers and installed solutions; where works follow a planning procedure, it also provides the basis for checking whether a change needs notification, revised design information or final drawings.

Contents

1. What are as-built drawings, and when are they needed?
2. Which changes belong in the record?
3. How to build a record the site team will actually maintain
4. When does a change become more than a site decision?
5. Hold points before each irreversible stage
6. How to hand over a file that still works in five years

What are as-built drawings, and when are they needed?

As-built drawings and records are written and graphic documents showing the work as it was actually completed. They are not a polished copy of the original design: they identify what changed, where it changed and what solution was installed. Lisbon’s document list for use after prior planning control requires final drawings where project changes occurred, marked on the drawings and submitted in suitable digital formats. Check the Lisbon City Council document list for use after prior control before assuming that photographs alone are enough.

For an internal renovation exempt from licensing, an owner may not have to submit as-built drawings to the council. A simplified file is still worthwhile: an updated plan, dated photographs and an equipment index. It is useful for maintenance, sale, letting and future alterations.

This is different from a renovation interface map. An interface map confirms responsibilities before a wall is closed; as-built information records the finished result once that solution has been confirmed.

Which changes belong in the record?

Record anything that changes location, access, capacity or future maintenance. There is no need to document every paint touch-up. Moving a socket, changing a drainage route, lowering a ceiling, replacing a hinged door with a sliding one or relocating equipment should be recorded.

• Architecture: removed or new walls, openings, doors, niches, suspended ceilings, relevant levels and finishes different from those specified.
• Water and drainage: isolation valves, pipe routes, traps, pumps, access chambers and inspection openings.
• Electrical and communications: circuits, boxes, control points, consumer unit, dedicated outlets and routes for data or air conditioning.
• Equipment: brand, model, serial number, manual, warranty, filter location and maintenance requirements.
• Structure and safety: strengthening work, elements that must not be drilled and solutions approved by the competent professional.

Where pipework is concealed, photograph it against a fixed reference: a tape measure, a room corner or a door opening. A standalone photo of a pipe is of little use years later. To decide what must remain accessible, also read how to plan concealed pipes.

How to build a record the site team will actually maintain

The system must fit the site routine. For a home renovation, a shared folder, a short spreadsheet and marked-up PDF drawings are usually enough. Appoint one person to update the file, while allowing the contractor, designers and client to propose entries.

1. Create a base drawing for each discipline and give every room a reference: KIT-01, BTH-02, BED-03.
2. Number every change: CHG-001, CHG-002. Include date, request, decision, cost and programme effect, person responsible and affected drawing.
3. Keep three photographs for each change: overall view, detail and a location reference.
4. Replace the working drawing with a new revision. Never leave two versions carrying the same file name.
5. Before a wall is closed or a floor zone is covered, carry out a brief check and record sign-off.

The site log has a separate legal purpose for licensed works or works subject to prior communication: the works director must record relevant facts, stoppages, suspensions and changes to the design. The Lisbon City Council guidance on the site log explains that it must remain on site for inspection. An as-built folder does not replace it; it adds drawings, images and equipment records that are easier to use.

When does a change become more than a site decision?

Changing a cabinet alignment or selecting a different finish may be a straightforward contractual decision. Changing approved elements, extending the work, affecting the building footprint, structure, façade, common parts, fire safety or technical designs needs professional assessment before the work is done. Do not accept “we will sort it out at the end” where a change touches any of those issues.

In Lisbon, changes to an approved or submitted project involving an extension or a change to the building footprint are subject to an amended licence or prior communication procedure, depending on the case. Other on-site changes may, in certain circumstances, be communicated with the documents submitted before use. The applicable route depends on the work: check the municipal guidance on changes during construction and ask the project author or responsible professional for a written decision.

A technical change should also appear in the budget record. Note the omitted solution, the replacement, the cost difference, programme effect and authorising person. That prevents as-built drawings from becoming a way of concealing poorly approved extras.

Hold points before each irreversible stage

The best time to prepare as-built information is while correction is still possible. Set short hold points before suspended ceilings are closed, shower bases are tiled, floors cover services, technical walls are lined, and cabinets conceal isolation valves.

• Compare the revised drawing with visible work on site.
• Confirm heights of outlets, water connections, drainage points and equipment.
• Photograph routes and open boxes, including labels or references that will remain legible in the file.
• Test what can already be tested: drainage, water supply, circuits and maintenance access.
• Record snags with location, photograph and deadline instead of leaving them in scattered messages.

The process begins before the site is set up. In Lisbon, the start-of-works notice identifies the person responsible for execution and, where applicable, is made up to five days in advance. Use that preparation to agree who updates drawings and who signs off changes; see the municipal page on the start-of-works notice for the local framework.

How to hand over a file that still works in five years

At completion, hand over a digital folder organised by room and discipline rather than one oversized file. Include final PDF drawings, editable files where available, the change register, selected photographs, manuals, warranties, service contacts and a front sheet locating water, electricity and gas isolation points.

Use searchable file names: “BTH-02_basin-drain_CHG-014_2026-11-14.jpg” is far more useful than “IMG_4832”. Store a copy away from the phone and provide the same final version to the owner and the person managing the works. At handover, use the file to check that snags, installed materials and maintenance access match the agreed scope. The guide to renovation handover and snag closure helps close that stage without mixing documents up with outstanding work.

Good as-built information cannot fix a badly judged change. It does answer the question that will almost certainly arise later: “where does this run, and what was installed here?”

Key takeaways

• Start the change record on day one and update it before every wall, ceiling or floor closure.
• Keep the statutory site log, where applicable, separate from the practical file of revised drawings, photos and manuals.
• Obtain written technical approval before carrying out changes affecting design, structure, façade or technical systems.
• Hand over searchable files with location and date information so the record supports future maintenance.

Before your renovation starts, ask Obra Lisboa to include hold points, responsibilities and a final works file in the project plan. A straightforward method agreed at the outset prevents decisions getting lost between drawings, messages and walls that have already been closed.

Sources and further reading

• Lisbon City Council guidance on the site log
• changes during construction
• Lisbon City Council document list for use after prior control
• start-of-works notice

Editorial image; it does not depict an Obra Lisboa project.