Building Regulations (Northern Ireland) 2000

PART C Preparation of site and resistance to moisture

Application and interpretation

C1—(1) Regulation C2(2) shall not apply in relation to an existing dwelling or part of an existing dwelling—

(a) which is altered; or

(b) which is extended by less than 30 m²,

if measures to prevent or limit the ingress of radon are not already incorporated in that dwelling.

(2) Regulation C4 in respect of resistance to ground moisture of floors and walls, and weather resistance of walls shall not apply where the building is intended to be used wholly for—

(a) storing goods, provided that any person who is habitually employed in the building is engaged only in storing, caring for or removing the goods; or

(b) a purpose such that compliance with regulation C4 would not serve to increase protection to the health or safety of any person habitually employed in the building.

(3) Regulation C5 applies only to a dwelling.

(4) In this Part—

• dangerous and harmful substances includes any substance which is or could become corrosive, explosive, inflammable, radioactive or toxic and includes deposits of faecal or animal matter;

• floor includes any base or structure between the surface of the ground, or the surface of any hardcore laid upon the ground, and the upper surface of the floor;

• moisture includes water vapour as well as liquid water; and

• wall includes piers, chimneys, columns and parapets which form part of the wall.

Preparation of site and resistance to dangerous and harmful substances

C2—(1) The site of a building and the ground adjacent to it shall be prepared and treated, and measures shall be taken, so as to prevent, as far as reasonably practicable, any harmful effect on the building or the health or safety of the occupants caused by—

(a) vegetable soil; and

(b) dangerous or harmful substances.

(2) Without prejudice to the generality of paragraph (1) measures shall be taken to prevent or limit the ingress of radon from the ground into any dwelling situated in a zone marked on the map set out in Schedule 3.

Subsoil drainage

C3  The site of a building and the ground adjacent to it shall be drained as far as reasonably practicable, or the building otherwise protected so as to prevent any harmful effect on the building or the health of the occupants caused by—

(a) ground water; and

(b) existing subsoil drainage.

Resistance to ground moisture and weather

C4  Every wall, floor and roof shall be constructed so as to prevent any harmful effect on the building or the health of the occupants caused by the passage of moisture to any part of the building from—

(a) the ground; and

(b) the weather.

Condensation

C5  A building to which this regulation applies shall be designed and constructed so as to prevent, as far as reasonably practicable, any harmful effect on the building from moisture in the form of interstitial condensation.

Deemed-to-satisfy provisions for regulations C2(2), C4 and C5

C6—(1) The requirements of regulation C2(2) shall be deemed to be satisfied, in the case of a building specified in column (2) of Table C opposite the reference to that regulation, if the measures to prevent or limit the ingress of radon into the building are in accordance with the relevant provisions of the publications or measures specified opposite thereto in column (3), as amended by the publications specified opposite thereto in column (4).

(2) The requirements of regulation C4 shall be deemed to be satisfied, in the case of a building specified in column (2) of Table C opposite the reference to that regulation, if the walls, floors and roofs of the building are constructed in accordance with the relevant provisions of the publications specified opposite thereto in column (3), as amended by the publications specified opposite thereto in column (4).

(3) The requirements of regulation C5 shall be deemed to be satisfied, in the case of a building specified in column (2) of Table C opposite the reference to that regulation, if the building is designed and constructed in accordance with the relevant provisions of the publications specified opposite thereto in column (3), as amended by the publications specified opposite thereto in column (4).