What Counts as Commencement Under Building Regulations?
Starting work on site does not automatically mean a building has legally reached the point of commencement under the Building Regulations. Regulation 46A sets specific construction thresholds, and for new buildings foundations alone will not normally be enough.
Request a Commencement ReviewWhat Does "Commenced" Actually Mean?
Under the current Building Regulations, commencement is more specific than simply breaking ground, excavating foundations or starting construction activity on the site.
Regulation 46A sets different physical construction thresholds depending on the type of building work being undertaken.
This is particularly important for developers relying on transitional arrangements, protecting a Building Control approval from lapsing or programming a multi-plot or multi-block development around an upcoming regulatory change.
The Three Main Regulation 46A Commencement Tests
The construction milestone that needs to be achieved depends on which category the building work falls into.
Complex Building
Work is regarded as commenced when the foundations supporting the building and the structure of the lowest floor level of that building have been completed.
Foundations + lowest floor structureNew Non-Complex Building or Horizontal Extension
The sub-surface structure must be completed, including all foundations, any basement level and the structure of the ground-floor level.
Ground-floor structure must be completeOther Building Work
For work that does not fall into the other categories, commencement is reached when 15% of the overall proposed building work has been completed.
15% of the overall workAre Foundations Enough to Commence a New Dwelling?
For a typical new dwelling falling within the new non-complex building category, foundations alone will normally be insufficient to satisfy Regulation 46A.
Foundations alone do not normally satisfy the current commencement definition for a new dwelling.
The Ground-Floor Structure Matters
For a new non-complex building, the required sub-surface construction includes all foundations, any basement and the structure of the ground-floor level.
A developer who excavates and pours foundations but stops before completing the required ground-floor structure should therefore not assume that the building has achieved the Regulation 46A commencement point.
This can become particularly important where the developer is relying on commencement before a regulatory transition date.
Planning Commencement vs Building Regulations Commencement
Planning permission and Building Regulations operate under different legal regimes. Commencement for one purpose should not automatically be assumed to satisfy the other.
Planning Commencement
- Concerns lawful implementation and preservation of the planning permission.
- Depends on planning law, the permission and relevant planning conditions.
- A qualifying material operation may be sufficient in planning terms.
- Does not automatically lock in the Building Regulations.
Building Regulations Commencement
- Concerns Building Control approval and regulatory commencement requirements.
- Uses the construction thresholds set by Regulation 46A.
- May need to be established for each individual building.
- Does not automatically preserve planning permission.
Does Starting One Building Protect the Whole Development?
Developers should be particularly careful on developments containing multiple houses or separate blocks. Commencement can need to be considered building by building.
Commenced
Required Regulation 46A construction stage achieved.
Foundations Only
May not yet meet the commencement threshold for a new non-complex building.
Excavated
Site activity alone should not be assumed to amount to statutory commencement.
Not Started
No physical commencement milestone has yet been reached.
Can Building Control Approval Lapse if Work Is Not Commenced?
The current building control regime includes provisions under which building control approval can lapse where the required commencement stage has not been reached within the applicable three-year period.
On developments involving more than one building, this is particularly important because the commencement position can be considered separately for each building.
Developers with approvals that may remain dormant for a significant period should therefore review their programme with their Building Control provider rather than assuming preliminary works elsewhere on the site preserve every approval indefinitely.
Starting Work and Commencement Are Different Stages
Developers should distinguish between notifying Building Control that work is about to start and confirming that the statutory commencement stage has actually been reached.
1. Building Control Application
The appropriate Building Control route is established and the project information is submitted.
2. Intention to Start Work
The required notice is given before work starts in accordance with the applicable Building Control procedure.
3. Construction Progresses
Work proceeds through foundations and the other physical construction stages applicable to the project.
4. Regulation 46A Commencement Is Reached
The relevant physical construction threshold for that building or work category has been achieved.
5. Commencement Position Is Recorded
The appropriate commencement notification and supporting project evidence should be dealt with through the relevant Building Control route.
Why Commencement Matters for the Future Homes Standard
Commencement becomes particularly important where a developer wishes to rely on transitional arrangements associated with a change to the Building Regulations.
The Future Homes Standard is a clear example. A timely Building Control submission may be one part of the transition, but qualifying projects must also reach the applicable commencement point within the relevant transitional period.
On a multi-plot or multi-block development, this can make the physical construction programme just as important as the date of the Building Control submission.
What Should Developers Check Before Relying on Commencement?
Where commencement has programme, cost or transitional consequences, the position should be reviewed before site works are programmed around an assumed milestone.
Check Building Control Status
Confirm the application route, approval status, submission date and any relevant regulatory deadline.
Identify Each Building
Break multi-plot and multi-block schemes down into individual buildings rather than treating the site as one commencement.
Identify the Correct Test
Establish whether the work is a complex building, new non-complex building, horizontal extension or other work.
Programme the Physical Works
Work backwards from the required deadline to the actual construction stage that must be completed.
Keep Evidence
Maintain inspection records, notices, photographs and supporting project information showing the stage reached.
Review the Wider Transition
Check that both the Building Control submission and physical commencement requirements of the relevant transition are met.
What Information Should I Send One Stop Consult?
If a regulatory deadline or Building Control lapse date is approaching, send us the following information where available.
- Site address
- Planning reference
- Building Control reference
- Building Control application date
- Approval or Initial Notice information
- Plot or block schedule
- Site layout
- Architectural drawings
- Current construction programme
- Current site progress
- Photographs of works completed
- Relevant regulatory or transition deadline
One Development, Building by Building
One Stop Consult can review the development programme, planning information and Building Control position and help map the relevant commencement milestone for each building.
Where a regulatory transition is involved, we can also coordinate connected services such as L1A SAP assessments , overheating assessments , design information and supporting compliance services.
Send Us Your Project →Common Questions About Building Regulations Commencement
Regulation 46A Commencement FAQs
What is Regulation 46A?
Regulation 46A of the Building Regulations sets out when building work is regarded as commenced for relevant Building Control purposes. Different construction thresholds apply depending on the type of work.
Are foundations enough to commence a new house?
Normally no. For a new non-complex building the sub-surface structure must be completed, including the foundations, any basement and the structure of the ground-floor level.
Does the 15% rule apply to every project?
No. The 15% test applies to the category of other building work. New buildings and horizontal extensions have specific physical construction tests instead.
Does starting foundations protect the whole housing site?
It should not be assumed to do so. Where work relates to multiple buildings, commencement may need to be established separately for each relevant building.
Is planning commencement the same as Building Regulations commencement?
No. They are separate legal concepts. Work sufficient to implement or preserve a planning permission does not automatically mean Regulation 46A commencement has been achieved.
Can Building Control approval lapse?
The current building control regime includes provisions for approval to lapse where the required commencement stage is not achieved within the applicable three-year period.
Why does commencement matter for transitional arrangements?
Some regulatory transitions require both a qualifying Building Control submission and sufficient commencement of the relevant building before a deadline. Missing the physical commencement requirement can therefore affect whether the older requirements can continue to be used.
Can One Stop Consult review our site programme?
One Stop Consult can review available planning, Building Control, design and programme information and help coordinate the relevant technical and Building Control requirements around the development.
Related Developer Guidance
Approaching a Regulatory or Commencement Deadline?
Send us your planning reference, Building Control status, plot or block schedule and construction programme. We can review the relevant dates, identify the commencement requirements for each building and coordinate the support required to keep the development moving.