1 Subterranean development works

(1) This Act applies to any subterranean development works as defined in this
section.

(2) Subterranean development works are those of excavation for and construction
5of building or engineering works to form new or additional accommodation
for any purpose below ground level.

(3) This Act shall not apply to works exclusively for the purpose of repairing,
strengthening or supporting an existing building or structure.

2 Application

10Any owner of a property intending to undertake subterranean development
works shall—

(a) submit a Subterranean Development Application (“SD Application”) to
the relevant local planning authority;

(b) provide in the SD Application all relevant information required by the
15code of practice established under Schedule 1; and

(c) serve notice for any subterranean development in the manner set out in
section 6(5) (adjacent excavation and construction) of the 1996 Act as if
the distance of six metres is replaced by a distance of nine metres.

3 Approval

(1) The accommodation to be provided through any proposed subterranean
development shall be considered for approval under the following
categories—

(a) 5new or additional accommodation comprising a downward extension
not exceeding four metres in total depth within the existing building
footprint;

(b) new or additional accommodation which incorporates any area of the
site outside the existing building footprint; and

(c) 10new or additional accommodation which extends more than four
metres in total depth below the ground floor of an existing building.

(2) Before granting any approval, the local planning authority shall send notice to
all properties within a radius of fifty metres of any part of the proposed
subterranean development.

(3) 15For applications under subsection (1)(c) the local planning authority must also
consult the Secretary of State before granting any approval.

(4) Upon approval of an SD Application, the local planning authority shall—

(a) impose a condition that the Subterranean Development shall be
commenced in the same timescale as applies to planning approvals
20generally; and

(b) instruct, at the cost of the building owner, Her Majesty’s Revenue &
Customs Valuation Service to determine the present day value of the
property to be increased in size through the proposed subterranean
development.

(5) 25The local planning authority shall determine SD Applications in the same
timescale as it determines planning applications in general.

4 Notice to adjoining owners and disputes

(1) Not less than one month before commencing any works, the building owner
shall serve on any adjoining owner notice (a “Subterranean Development
30Notice”) of his or her intention to excavate stating—

(a) the name and correspondence address of the building owner;

(b) the nature and particulars of the proposed work including its address,
description and purpose together with location plans and sections
showing the relationship between the works and the structures of any
35adjoining owners and the position and depth of the proposed
excavation;

(c) the date on which the works will begin;

(d) the planned duration of the works;

(e) the measures proposed to be taken to avoid unreasonable disturbance
40and loss of amenity to adjoining owners; and

(f) whether the building owner proposes at his or her own expense to
underpin or otherwise strengthen or safeguard the building or
structure of the adjoining owner so far as may be necessary.

(2) Where an adjoining owner does not notify the building owner in writing
45within 14 days that the works notified under this section are agreed, or agreed
subject to conditions that are acceptable to the building owner, a dispute is

deemed to have arisen and is to be settled in accordance with subsection (3)
and section 10 of the 1996 Act (resolution of disputes).

(3) Where for the purposes of this Act any surveyor is appointed in accordance
with section 10 of the 1996 Act (resolution of disputes) the surveyor shall—

(a) 5be an independent person not being a party to the matter in dispute;

(b) be qualified by examination and experience in building surveying or
construction matters;

(c) be a member of a recognised professional body associated with
construction and regulating the surveyors’ professional standards and
10conduct; and

(d) hold a current and adequate policy of professional indemnity
insurance.

(4) If a building owner fails to serve notice before commencing subterranean
development works, he or she shall be guilty of an offence and liable on
15summary conviction to a fine not exceeding level 5 on the standard scale or 10
per cent of the contract value reasonably to be expected in relation to the
notifiable works, whichever shall be the greater and which, in the absence of
agreement, shall be determined by surveyors appointed in accordance with
subsection (3) or as otherwise directed by the Court.

5 20Suspension of works and access

(1) Where a building owner commences work on a subterranean development and
the work is suspended for a period of six months or more, an adjoining owner
may by a notice in writing require the building owner to—

(a) replace any temporary weatherings protecting exposed party
25structures or other parts of the adjoining owner’s property with
permanent durable weather proofing construction;

(b) complete any works of underpinning of an adjoining owner’s building
or of any party structure; and

(c) replace any temporary propping or shoring safeguarding an adjoining
30owner’s building with permanent durable construction.

(2) If a building owner does not consent to such a notice within 14 days of receipt,
he or she shall be deemed to have dissented from the notice and a dispute shall
be deemed to have arisen between the parties.

(3) Where a dispute has arisen under this section it shall be settled in accordance
35with section 4(2).

(4) Where for the purposes of this section a dispute is settled by the appointment
of surveyors in accordance with section 4(2), the surveyors may award a right
of access to the building owner’s premises for the purpose of implementing
any works they deem are required in pursuance of this section; in every such
40case the provisions of section 8 of the 1996 Act (rights of entry) shall apply as if
“building owner” in that section is substituted by “adjoining owner”.

6 Security for expenses

In any case where the security for expenses is determined in accordance with
4(2) by the appointment of surveyors, the sum held as security for expenses
45shall—

(a) reasonably reflect the risk of damage to the adjoining owner’s building
likely to occur in consequence of the works for which the building
owner has given notice, or as the case may be are the subject of an
award made by the appointed surveyors;

(b) 5reasonably reflect the likely cost of completing the works for which the
building owner has given notice, or as the case may be are the subject
of an award by the appointed surveyors, sufficiently to safeguard the
adjoining owner’s building and to leave it weathertight if those works
are suspended leaving them incomplete; and

(c) 10be held in a manner to be determined by the appointed surveyors and
be administered by them.

7 Liability

Any liability arising from works shall remain with the owner of the land or
buildings being the address of the premises for which notice under section 4
15was served, or if more than one such owner then any one of them, and may be
registered as a charge against the property for the purposes of the Land
Registration Act 2002.

8 Code of practice for subterranean development works

(1) The Secretary of State shall approve from time to time a code of practice
20(hereinafter referred to as ‘the code’) in accordance with the provisions of
Schedule 1.

(2) The Secretary of State may from time to time amend the code for the purposes
of this Act, subject to annulment in pursuance of a resolution of either House
of Parliament.

(3) 25In discharging any development control duties required by statute, a local
planning authority in whose area the works are proposed shall ensure that
consents are made subject to the code.

(4) A building owner desiring to carry out works shall comply with the provisions
of the code.

9 30Building owner responsibilities

In addition to other provisions of this Act, building owners shall comply with
the requirements in Schedule 2.

10 Council Tax valuation

Upon completion of the subterranean development, Her Majesty’s Revenue &
35Customs Valuation Service shall determine the added value created in order
that a suitable adjustment may be made to Council Tax banding of the
property.

11 Application of Party Wall etc. Act 1996

Unless addressed elsewhere in this Act, the following provisions of the 1996
40Act apply to Subterranean Development works—

(a) section 7(1), (2) and (5) (compensation etc);

(b) section 11(1), (2) and (8) (expenses);

(c) section 12(1) (security for expenses);

(d) section 13 (account for work carried out); and

(e) section 15 (service of notices etc).

12 Definitions

5In this Act—

• “the 1996 Act” means the Party Wall etc. Act 1996; and

• “owner”, “adjoining owner” and “building owner” shall have the
  meanings ascribed to them under the 1996 Act.

13 Commencement and short title

(1) 10This Act shall come into force on the day on which it is passed.

(2) This Act may be cited as the Subterranean Development Act 2011.

SCHEDULES

Section 8

SCHEDULE 1 Code of practice

1 The code of practice for subterranean development shall include
5consideration of the—

(a) stability of structures and avoidance of unncessary risk to their
subsoil support;

(b) proper investigation of relevant factors and preparation of impact
studies prior to the commencement of works;

(c) 10adequacy of technical skills for investigation of subsoil conditions
and design of the works;

(d) adoption of best practice in the execution of the works in terms of
construction and supervision standards and the avoidance of
unreasonable inconvenience to adjoining owners;

(e) 15provision of adequate information to adjoining owners before,
during and after the works;

(f) protection of adjoining owners from the risks associated with
defective investigation or design and the interruption of the contract
of works once commenced;

(g) 20limitation of the effects of ground movements on third party
property to damage capable of repair by decoration and the repair of
minor cracking;

(h) protection of the subsoil environment including hydrological and
hydrogeological conditions;

(i) 25provision of such security for expenses, warranties and guarantees
as are necessary to protect third parties in the event of damage or
loss;

(j) adequacy of a contractor’s third party liability insurance; and

(k) adequacy of standards of post-construction monitoring.

2 30A building owner wishing to carry out works shall ensure that the proposals
for, and execution of, the works accord with this Schedule and that the
contractor appointed to undertake the works is a member of a considerate
contractors scheme and shall observe any relevant code of considerate
practice.

Section 9

SCHEDULE 2 Building owner responsibilities

1 Prior to commencement of subterranean development works, the building
owner shall—

(a) 5ensure that suitable studies and, if necessary, intrusive investigation
are carried out to examine factors related to the works which may
affect the ground around the proposed subterranean development
and structures and services supported on it or in it.

(b) studies carried out further to paragraph (a) shall include the—

(i) 10layout and geometry of the existing buildings and surface
and buried services,

(ii) ground conditions, including parameters to define earth
pressures, strengths and stiffness,

(iii) water conditions below ground and how these may vary
15with time,

(iv) surface water conditions,

(v) method of ground support of existing structures, and

(vi) condition of the existing buildings and services and their
sensitivity to any disturbance;

(c) 20identify how the proposed development will affect the local
environment, including whether the modified structure—

(i) will affect the long term stability of the ground, or

(ii) have a significant effect on the flow of ground water or
surface water within the general area;

(d) 25provide a specification of the proposed works taking account of
the—

(i) safety requirements,

(ii) potential adverse effects upon the surroundings,

(iii) difficulties of working on a congested site with limited
30access,

(iv) need to control the environment in terms of noise, dust and
vibration,

(v) need to maintain an acceptable working environment,

(vi) likely effect of each construction operation on the ground and
35ways of controlling that effect, and

(vii) need to provide adequate support to the ground and
structures at all times;

(e) provide where necessary—

(i) a detailed method statement identifying how the work will
40be undertaken,

(ii) designs of structural elements of the new structure to
demonstrate that they are adequate,

(iii) a design of the internal structure with regard to the
requirements to maintain an acceptable environment for the
45proposed usage,

(iv) documentary evidence of the adequacy of temporary works,
and

(v) an estimate of the amount of ground movement that may
occur as a result of the proposed construction and the likely
effect on the structures and services; and

(f) establish a monitoring regime before work is commenced.