Prepare for an inspection

Start of Works Inspection

At the start of your project, our Building Control Inspectors carry out a first visit to confirm that work has begun correctly and is ready to proceed safely. This guide outlines the key areas that may be checked. As every project is different, the exact checks will vary depending on the type and scale of work.

  • That work has started in line with the approved application, this includes checking that the correct design is being followed, key approvals (such as plans or structural details) are in place, and that work is not progressing without the necessary information.
  • General site and safety considerations, including how the site is set up and whether early works are being carried out safely.
  • Foundations and ground (substructure), where visible, checking excavation works such as trench depth, width and ground type. Nearby trees, drainage and existing structures that could affect the foundations may also be considered.
  • Structural elements above ground (superstructure), where work has started, checking that key structural elements are in line with the agreed design.
  • Drainage and below-ground services (if started), confirming layout, connections and access points, including any approvals needed where building near or over drains.

  • Early compliance requirements, checking that required information, documents and responsibilities are understood before work progresses further.

During this visit, Inspectors will also:

  • Provide guidance on upcoming inspection stages
  • Highlight any early issues or risks
  • Confirm what needs to be in place before the next inspection
  • Advise when work should be left visible for inspection before being covered
Commencement Inspection

This inspection usually takes place shortly after work has started on site. The Inspector can guide you on the most appropriate timing, depending on the type of project and how the work is progressing.

Building Regulations define “commencement” differently depending on the type of work. For some projects, this may be around 15% complete, but this does not determine when inspections should be carried out.

What does “commencement” mean?

“Commencement” is a legal stage in the Building Regulations. It is different from simply starting work on site.

What counts as commencement depends on the type of project:

  • New buildings and extensions: when foundations and the ground floor structure are completed
  • Other types of work (such as alterations or loft conversions): when around 15% of the work is completed

You must notify Building Control when work has reached this stage.

Important:

This definition is used for legal and administrative purposes. It does not set inspection stages or when you should book an inspection. Your Inspector will guide you on the right time for inspections based on your project.

Foundation Inspection

Inspectors will check:

  • Ground conditions are as expected for the design
  • Foundation depth and width are suitable
  • Nearby trees or structures have been considered
  • Any concerns identified are raised with the contractor or designer
Damp Proof Course (DPC) Inspection

This inspection checks that measures are in place to stop damp from rising up through the walls or floors of the building and takes place before the DPC or damp‑proof membrane is covered up by brickwork, plaster, flooring or concrete.

What the inspector checks

  • The DPC is installed at the correct height above ground level
  • The DPC is continuous, with no gaps or damage
  • The correct materials are being used
  • The DPC lines up properly with floor membranes so there is no route for damp
  • External ground levels will not bridge the DPC once finished

Why this inspection matters If a DPC is missing, bridged or incorrectly installed, it can allow damp into the building. This can cause long‑term problems such as mould, damage to walls and floors, and poor indoor conditions.

Important to know DPC inspections are carried out in person on site. The inspector will explain what they are looking for and raise any issues during the visit, followed by written notes or a site inspection record. The DPC must not be covered until it has been inspected and approved.

Oversight (Ground Floor) Inspection

Inspectors assess:

  • Correct hardcore material and compaction
  • Sand blinding thickness and condition
  • Proper placement and protection of the damp‑proof membrane

The Damp Proof Course inspection takes place before or alongside this stage to ensure damp protection is continuous between walls and floors.

Drainage Inspection

The inspector will check:

  • Installation of drainage systems
  • General alignment, support and condition
  • That work is suitable before and after backfilling
  • That no damage or movement has occurred
Structural Inspection – Steel Beams

The inspector will assess that structural steelwork is installed safely and in line with the approved structural design.

IMPORTANT – Structural elements must be inspected before they are covered up, so before plaster boarding or boxing‑in.

What is checked

  • Steel beam size, position and specification match the approved structural calculations
  • Adequate bearing at each end of the beam
  • Correct padstones or supporting masonry
  • Appropriate fire protection (for example, encasement or fire‑resistant board)
  • Proper connections to surrounding structure
Oversite (Ground Floor) Inspections

Inspectors assess:

  • Preparation of the ground floor build-up
  • Materials and general condition
  • That damp protection measures are in place
  • That the work is suitable before it is covered
Drainage Inspections

Before back filling, the following should be checked:

  • Correct pipe gradients achieved
  • Suitable bedding provided to support pipework
  • Watertight joints correctly formed and secure

Following backfilling, checks should confirm that:

  • Pipe runs remain correctly aligned and undamaged
  • Backfill material is suitable and properly compacted
  • No movement or displacement of pipework has occurred
Insulation Checks

This inspection is to assess that the building meets energy efficiency requirements before insulation is covered up.

IMPORTANT – These inspections are normally carried out before plasterboard or floor finishes are installed. Missing this stage may require work to be opened up later.

What is checked

  • Insulation type and thickness match approved details
  • Insulation is fully fitted with no gaps or compression
  • Correct insulation to walls, floors and roofs as required
  • Continuity of insulation at junctions to reduce cold bridging
  • Damp proof membranes and vapour control layers where required
Structural Inspection – Roof Construction

This inspection is to check the structural stability of the roof before it is fully loaded or covered.

IMPORTANT – This inspection happens before coverings or ceilings hide the structure.

What is checked

  • Roof structure type matches the approved design (trussed or traditional cut roof)
  • Roof timbers are the correct size, spacing and grade
  • Adequate support and restraint to prevent movement
  • Fixings, bracing and strapping are in place
  • Openings for rooflights or dormers are properly supported
Completion Inspection

Your Completion Certificate can only be issued when:

  • All required inspections have been completed
  • The work complies with the Building Regulations
  • No defective or uninspected work remains