Who does what in a major renovation?
Published: 1 November 2026.
A major renovation brings several disciplines together. An extension, roof addition or complete renovation involves design, structure, permits, building services and construction. Who handles each task depends on the project and contract. A clear overview at the outset helps prevent essential work from falling between parties.
Start with the client’s role
As the client, you define what the new space should achieve: more living area, a different layout or a home that better suits you. Set your priorities, indicative budget and preferred timing. Available drawings, photos and details of earlier work help professionals understand the existing building.
You do not need every technical answer yourself. It does help to discuss decisions and changes promptly. A late change to a glazed door, kitchen layout or floor can affect the design, schedule and quotation.
Design: architect or building designer
A designer turns your wishes into a spatial plan. For an extension, this includes the connection to the existing home, daylight, circulation and the relationship with the garden. For a roof addition, the layout, stairs, façade and roof connection matter. Depending on the project, sketches, floor plans, elevations and technical details may be needed.
Agree in advance who designs the project and which drawings are included. A sketch to guide early choices is different from a full technical package for permits or construction. Also read which building drawings can help with a renovation.
Structural engineer: assessing what is technically possible
When load-bearing elements change, it must be clear how loads will be safely supported. A structural engineer assesses the existing building and, where needed, calculates new elements or alterations. Examples include an opening in a load-bearing wall, a new floor or extra weight on a roof. The required information and calculations depend on the plans.
Arrange a structural assessment in good time. An attractive design must also be feasible within the existing home’s limits. In our article about structural engineers you can see which questions to prepare.
Contractor: preparing and carrying out the work
The contractor discusses how the agreed plans can be built and organises the work covered by the contract. This can include preparation, material choices, scheduling, coordination between trades and communication during construction. The exact responsibilities follow from the agreement, so ask what is and is not included in the quotation.
A good proposal states which drawings and choices it is based on. Check whether preparatory work, services, finishes and handover are included. A quotation for structural work alone cannot be compared directly with a proposal that includes all finishes. Learn how to assess cost items and allowances.
Specialist trades
A building project may need specialists for electrical work, plumbing, roofing, plastering or painting. Sometimes they work as subcontractors under the main contractor; sometimes the client appoints them directly. This affects coordination. Agree who schedules the work, answers questions and checks how the different tasks fit together.
When several parties work alongside each other, small uncertainties can have major consequences. Consider where pipes run before closing a floor, or the dimensions of a window before building the façade. Clear drawings, an up-to-date schedule and documented choices help limit misunderstandings and remedial work.
Permits: agree who checks and applies
Whether a permit or notification is required depends on the location and specific design. Check this using the Omgevingsloket permit check and discuss any uncertainty with the municipality or a qualified adviser. Before work starts, agree who gathers information, supplies drawings and calculations, and submits any application. Do not assume the same division of responsibilities applies to every project. Read more about the permit check.
Safety and changes during construction
The parties carrying out the work must plan and perform it safely. The measures needed vary by site and activity. A roof addition, for example, may require extra attention to working at height, access and protection of the existing home. Discuss with the contractor how the site will be set up and how residents and neighbours will be informed about work that affects them.
Unexpected conditions can arise in an existing building. If a detail proves different from the drawings during construction, first discuss the solution and its effects on time and cost. Record a change before carrying out the revised work. This keeps everyone aligned on the scope.
Questions for an initial discussion
- Who will design the project, and which drawings are included?
- Is a structural assessment needed, and who will appoint the specialist?
- Who checks the rules and handles any permit application?
- Which work and finishes are included in the quotation?
- Who coordinates the various trades and deliveries?
- How will we discuss and confirm changes during the project?
At Ponto, we agree these responsibilities for each project. We clarify which work Ponto coordinates, which specialist carries out each part, and what has been agreed for design and construction. Explore how we work or tell us about your renovation.
