What drawings do I need to regularise building work in London?

Opening up: what the drawings cannot show

Building control does not take the drawings on trust. Under regulation 18 the council may require the applicant to take reasonable steps, including laying open the unauthorised work for inspection, making tests and taking samples. Richmond's guide says the same in plainer words: it may mean opening up the works, carrying out tests or sampling materials.

This is where the drawings save money. A beam hidden in a ceiling, a cavity wall of unknown build-up or a floor of unknown joist size can each be checked through a small, well-placed opening instead of a ceiling stripped end to end. We mark those places on the plan before the officer visits, so your builder opens only what is needed and makes good only what was opened.

Removed walls are the commonest reason for opening up. What drawings a load-bearing wall removal needs explains what building control would have wanted to see had the work been approved first, which is the same evidence it will look for now.

The plan of additional work, judged by the rules of the time

The last plan shows what must be added for the work to comply. Regulation 18 measures that against the requirements in the building regulations that were applicable to that work when it was carried out. A loft built in 2012 is judged against the regulations in force in 2012, not against the latest edition of the Approved Documents. Dating the work properly is therefore part of the drawing, not paperwork around it.

After the officer's inspection the council tells the applicant one of three things: the work it considers is required, that it cannot determine what is required, or that no work is required. We draw the likely additions before that letter arrives, typically fire doors and a protected stair for a loft, smoke alarms, extract ventilation for a bathroom, or a fire-protected beam. You then see the probable scope while you are still choosing a builder.

Lofts carry the longest list. Our post on what drawings a loft conversion needs sets out the escape and structural drawings an approved loft would have had, which is the gap a regularisation plan has to close.

Structural calculations and drainage layouts

Where the unauthorised work changed the structure, a plan alone rarely satisfies building control. A removed wall, a new opening in a rear wall or a dormer cut into the roof needs calculations showing the beam or rafters are adequate. Our structural calculations and drawings start at £745, prepared by a structural engineer and drawn into the same set, so the beam on the plan is the one in the calculation.

Drains are the other common gap. A bathroom added in a loft or a kitchen moved into an extension usually means new pipework, and the officer will want to see where it runs and where it joins the existing drains. We show it on a drainage layout from what can be traced on site.

Selling a house with unapproved work

Many owners first hear the word regularisation during a sale. GOV.UK warns that without approval you will not have the certificates of compliance you may need when you want to sell your home. A buyer's solicitor who finds a loft or an extension with no sign-off will ask for a certificate or for another way to deal with the risk.

A regularisation certificate is evidence, but not conclusive evidence, that the requirements it lists have been met. It is not a warranty on the work. Leaving the work alone carries its own risk: under section 36 of the Building Act 1984 a notice to remove or alter contravening work cannot be given more than 10 years after the work was completed, and until then the council can still act against whoever owns the house.

Talk to your conveyancer before you apply, because the choice between a certificate and another remedy is theirs to advise on. If the work also went up without planning permission, that is a separate application to a separate team; regularisation answers the building regulations question only. Our post on what regularisation costs sets out our fee, the council's charge and the builder's costs side by side.

Which building control, and what it charges

Only the council can regularise. GOV.UK's guide on how to apply for building regulations approval says regularisation can be applied for from a local authority building control body only, so a private inspector is not an option for work already done. The application goes to the London borough the house is in.

Each council sets its own regularisation charge. Richmond, for example, asks for 120% of its current plan charge, so there the council's fee is higher than an ordinary application for the same work would have been. We tell you the figure for your borough before we apply.

If you are planning new work rather than regularising old, the cheaper route is to apply first. Our post on what building control needs for an extension lists the drawings for the ordinary route, and our building regulations regularisation service has the details of the regularisation route.