PREPARATION OF SITES, RESISTANCE TO MOISTURE AND ... … · Preparation of sites REGULATION 17 Resistance to moisture REGULATION 18 Resistance to condensation THE STANDARDS G1 Application

PREPARATION OF SITES,RESISTANCE TO MOISTURE ANDRESISTANCE TO CONDENSATIONG

2G

ContentsINTRODUCTION

REGULATION 16Preparation of sites

REGULATION 17Resistance to moisture

REGULATION 18Resistance to condensation

THE STANDARDSG1 Application of Part G G1.1-G1.5G2 Preparation of a site and resistance to

moisture from the groundPreparation of a site G2.1-G2.4Resistance to moisture from the ground G2.5-G2.6

G3 Resistance to precipitationResistance to precipitation G3.1

G4 CondensationInterstitial condensation G4.1Surface condensation G4.2

PROVISIONS DEEMED TO SATISFY THE STANDARDS(G2.2, Preparation of a site and resistance to moisture from theG2.3, groundG2.5,G2.6)(G3.1) Resistance to precipitation(G4.1) Interstitial condensation(G4.2) Surface condensation

PART G APPENDIX

ASTERISKSThroughout the Technical Standards an asterisk against a standard denotes that a provision deemed to satisfy the standardor some aspect of the standard is specified at the end of the relevant Part.

ITALICSThroughout the Technical Standards a term in italics is a defined term. The definition is listed in Part A (General).

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3G Amdt: December 1999

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Introduction1. The intention of this Part is to ensure that measures aretaken to protect people, and the fabric of a building, fromharm which could be caused by site conditions or the effectsof moisture in various forms.

2. In addition to surface soil and decaying or organic matterbeing removed from a site, thorough investigation is neces-sary to ensure that appropriate measures can be taken wherethere is evidence of any harmful or dangerous substances.An Appendix giving outline guidance is included at the endof this Part.

3. Subsoil drainage of the site is required where necessary tohelp prevent the penetration of ground water and flood waterto the interior of a building and damage to the building fabric.Any existing drains which will be affected by the constructionof a building must also continue to function properly.

4. A building must be constructed so that moisture in theground and from the weather will not damage the fabric orpenetrate to the inner surface of the building.

5. For the control of condensation in roofs thedeemed-to-satisfy specification quotes BS5250 which pro-vides guidance on the principal forms of constructionincluding cold deck roofs. There is evidence which suggeststhat condensation in this type of roof system is a problem.The Scottish Executive considers that in the climatic condi-tions of Scotland ventilation of the roof void in flat roofsshould not be endorsed as many instances of failure in colddeck roof systems have been recorded. Both the warm deckand warm deck inverted roof constructions, where the insu-lation is placed above the roof deck, are considered prefer-able. While the Regulations do not prevent the use of colddeck roof constructions, it is considered that much more reli-able forms of construction are likely to result from over-roofinsulation whenever this is possible.

6. A building of purpose group 1, a dwelling (ie a house,flat or maisonette) must be constructed to reduce the risk ofboth interstitial and surface condensation in order to preventdamage to the fabric and harmful effects on the health ofpeople using the building. The requirements for both inter-stitial and surface condensation are deemed to be satisfied bythe guidance given in BS5250: 1989 “British Standard Codeof Practice for the Control of condensation in buildings”.However, the guidance in BS5250, which covers buildingsgenerally, should be followed for other buildings where theinternal climate is quite stable.

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Regulations 16,17 & 18Preparation of sites

16.(1) Subject to paragraph (3), a site and groundimmediately adjoining a site shall be so pre-pared and treated as to protect the buildingand its users from harmful effects caused by -(a) harmful or dangerous substances;(b) matter in the surface soil; and(c) vegetable matter.

(2) Subject to paragraph (3), a site and groundimmediately adjoining a site shall be sodrained or otherwise treated as to protect thebuilding and its users, so far as may be rea-sonably practicable, from harmful effectscaused by - (a) ground water;(b) flood water; and(c) existing drains.

(3) Paragraphs (1)(b), (1)(c) and (2)(c) shall notapply to a limited-life building of purposegroups 2 to 7 inclusive.

(4) In paragraph (1)(a) “harmful or dangeroussubstances” includes deposits of faecal oranimal matter and any substance or mixture ofsubstances which is or could become corro-sive, explosive, flammable, radioactive ortoxic or which produces or could produce anygas likely to have any such characteristic.

Resistance to moisture

17.(1) Subject to paragraph (2), a building shall be soconstructed as to protect the building and itsusers from harmful effects caused by -(a) moisture rising from the ground; and(b) precipitation.

(2) This regulation shall not apply to a buildingwhere penetration of moisture from outsidewill result in effects no more harmful thanthose likely to arise from use of the building.

Resistance to condensation

18. A building of purpose group 1 shall be soconstructed as to protect the building and itsusers, so far as may be reasonably practicable,from harmful effects caused by condensation.

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6GAmdt: December 1999

The standardsG1 Application of Part G

G1.1 This Part sets out the required standards for Regulations 16 to 18.

G1.2 The standards in G2 apply to all buildings, except -

G2.3 and G2.4 do not apply to a limited-life building of purpose groups 2 to 7 inclusive.

G1.3 The standards in G3 apply to a building of any purpose group,except -

to a building where the penetration of moisture from outside would be no more harmful than that likelyto arise from the use of the building.

G1.4 The standards in G4 apply to a building of purpose group 1.

G1.5 In this Part -

FLOOR means any construction between the surface of the ground, or the surface of any hard-core laid upon the ground, and the upper surface of the floor, together with any floor finisheswhich are laid as part of the permanent construction;

WALL means any wall, including piers, chimneys, columns and parapets which form part of thewall.

ROOF means any roof, including eaves and junctions with other elements penetrating, or con-nected to, the roof; and

G2 Preparation of a site and resistance to moisture from the ground

PREPARATION OF A SITE

G2.1* A site, and ground immediately adjoining a site, must have harmful or dangerous substances removed ormade safe.

G2.2* A site, and ground immediately adjoining a site, which is liable to accumulate ground or flood watermust be drained, or treated, to overcome the effects of any such water.

G2.3* A site, and ground immediately adjoining a site, must be cleared of any surface soil and vegetable matter(including wood) to the extent necessary to prevent any harmful effect on a building and the solum (theprepared area within the containing walls of a building) treated to prevent vegetable growth.

G2.4 Where a building is erected over an existing drain, including a field drain, which is to remain active, thedrain must be re-routed if reasonably practicable or re-constructed in a manner appropriate to the condi-tions of the site.

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G1.1 – G2.4

RESISTANCE TO MOISTURE FROM THE GROUND

G2.5* The solum (the prepared area within the containing walls of a building) must be treated to reduce theevaporation of moisture from the ground to the inner surface of any part of a building which it coulddamage.

G2.6* A floor, wall or other building element adjoining the ground must prevent moisture from the groundreaching the inner surface of any part of a building which it could damage.

G3 Resistance to precipitation

RESISTANCE TO PRECIPITATION

G3.1* A floor, wall, roof or other building element exposed to precipitation must prevent penetration of mois-ture to the inner surface of any part of a building which it could damage.

G4 Condensation

INTERSTITIAL CONDENSATION

G4.1* A floor, wall, roof or other building element of a dwelling must minimise the risk of interstitial conden-sation in any part of a dwelling which it could damage.

SURFACE CONDENSATION

G4.2* A floor, wall, roof or other building element of a dwelling must minimise the risk of condensation onany inner surface where it could damage the health of people.

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G2.5 – G4.2

Provisions deemed to satisfy the standards

PREPARATION OF A SITE AND RESISTANCE TO MOISTURE FROM THE GROUND

(G2.1) The requirements of G2.1 will be met where protection against the ingress of radon gas into dwellingsis provided in accordance with the recommendations in ‘Radon: guidance on protection measures fornew dwellings in Scotland’.

(G2.2) The requirements of G2.2 will be met where sub-soil drains are provided and laid in accordance withthe relevant clauses of BS8301: 1985.

(G2.3, The requirements of G2.3, G2.5 and G2.6 will be met where the solum and building are constructed as G2.5, specified below (but note that the diagrams do not show all the structural bracing that might be required).G2.6)

Specified constructions

The thickness and other dimensions specified are the minimum required unless otherwise stated;greater figures are therefore permissible.

Ground supported concrete floors

A. The solum is brought to a level surface.

Hardcore bed 100mm thick of clean brokenbrick or similar inert material free from finematerial and water soluble sulphates inquantities which would damage the con-crete; blinded with suitable fine materialand consolidated to form a level crack-freesurface.

Concrete slab 100mm thick with insulation,if any, laid above or below the slab; with orwithout a screed or floor finish.

Damp-proof membrane above or below theslab or as a sandwich; jointed and sealed tothe damp-proof course or damp-proofstructure in walls, columns and other adjacent elements in accordance with therelevant clauses in Section 3 of CP 102: 1973.

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(G2.1 – G2.6)

�damp proofmembraneconcrete slab

hardcore

solum

insulationabove orbelow(if required)

�damp proofmembrane

concrete slab

hardcore

solum


��damp proof

membrane

concrete slab

concrete slab

hardcore

solum

A. Ground supported concrete floor


Suspended timber floors

B. The solum is brought to an even surface; anyupfilling to be of hard, dry material.

Hardcore bed as for A. above; with either adamp-proof membrane in accordance withSection 3 of CP 102: 1973; or concrete 50mm thick laid on 0.25mm (1000 gauge)polyethylene sheet; or concrete 100mm thick;so that in any case the top surface is not belowthat of the adjacent ground.

Suspended timber floor with or without insula-tion as required. Floor joists carried onwall-plates supported as necessary by sleeperwalls with a damp-proof course under thewall-plates.

Permanent ventilation of the underfloor spacedirect to the outside air by ventilators in 2external walls on opposite sides of the buildingto provide an open area in each wall of either1500mm2 for at least every metre run of thewall, or 500mm2 for at least every square metreof floor area, this open area also being pro-vided in internal sleeper walls or similarobstructions to maintain the underfloor ventila-tion; the ventilated space to be 75mm in heightfrom the site covering to the underside of anywall-plates and 150mm to the underside of thefloor joists.

Suspended concrete floors

C. The solum is brought to an even surface; anyupfilling to be of hard, dry material.

Suspended concrete floor of in-situ or precastconcrete slabs or beams with concrete or clayinfill units; with insulation, if any; with orwithout a screed or floor finish, or with boards.

Permanent ventilation of the underfloor spacedirect to the outside air by ventilators in 2external walls on opposite sides of the buildingto provide an open area in each wall of 1500mm2 for at least every metre run of thewall, or 500mm2 for at least every square metreof floor area, this open area also being pro-vided in internal sleeper walls or similarobstructions to maintain the underfloor ventila-tion; the ventilated space to be 150mm to theunderside of the floor slab or beams.

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(G2.3 – G2.6)

insulationanywherein this space

hardcore

damp proofmembrane

solum

�150

100


polyethylenesheet

concrete

solum

��150

50


concrete

solum

insulation

solum

��150

100

B. Suspended timber floor

C. Suspended concrete floor

�150

Walls and floors at or near ground level

D. Walls constructed in accordance with clause 10 of CP 102: 1973.

Floors constructed in accordance with clause 11 of CP 102: 1973, except -

ventilation of the sub-floor (clause 11. 8. 4) is to be as in B above.

Structures below ground including basements

E. Structures constructed in accordance with the relevant clauses in Section 2 of CP 102: 1973.

RESISTANCE TO PRECIPITATION

(G3.1) The requirements of G3.1 will be met where the exposed elements are constructed as specified in therelevant provisions below (but note that the diagrams do not show all the structural bracing that may berequired).

Specified constructions

The thickness and other dimensions specified are the minimum required unless otherwise stated;greater figures are therefore permissible.

General

In using any of the constructions on the following pages under ‘Wall types’ and ‘Roof types’, thefollowing general provisions apply for walls or roofs as appropriate.

a. Masonry walls of bricks and/or blocks incorporating damp-proof courses, flashings and othermaterials and components constructed in accordance with the relevant recommendations of BS5628: Part 3: 1985, using a construction to suit the degree of exposure to wind and rain in accordance with clause 21 and as described in BS8104: 1992.

b. Masonry walls incorporating external rendering which conforms to the relevant recommendationsof BS5262: 1991, to suit the degree of exposure and the type of masonry.

c. Masonry walls of natural stone or cast stone blocks constructed in accordance with the relevantrecommendations of Section 3 of BS5390: 1976 (1984) and to suit the degree of exposure to windand rain as described in BS8104: 1992.

d. Masonry cavity walls incorporating insulation material, either as a complete or partial cavity fill,where the insulating material is the subject of a current certificate issued under the relevant con-ditions of an independent testing body, the walls are constructed in accordance with the terms ofthe certificate and to suit the degree of exposure to wind and rain as described in BS8104: 1992and the relevant recommendations of the following British Standards.

Materials or conditions British Standards

Urea formaldehyde (UF) foam BS5617: 1985 and BS5618: 1985

Man-made mineral fibre (slabs) BS6676: Part 1: 1986 and Part 2: 1986

Assessment of walls for filling BS8208: Part 1: 1985

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(G2.3 – G3.1)

e. Walls or roofs incorporating cladding materials constructed in accordance with the recommen-dations of the following British Standards or Codes of Practice -

British Standards and Materials or conditions Element Codes of Practice

Aluminium wall or roof CP 143: Part 15: 1973 (1986)

Galvanised corrugated steel wall or roof CP 143: Part 10: 1973

Lead wall or roof BS6915: 1988

Copper wall or roof CP 143: Part 12: 1970 (1988)

Slates and tiles wall or roof BS5534: Part 1: 1997

Zinc wall or roof CP 143: Part 5: 1964

Non-loadbearing walls wall or steep roof BS8200: 1985

Precast concrete cladding wall BS8297: 1995

Natural stone cladding wall BS8298: 1994

Flat roofs roof BS6229: 1982

Bitumen felt roof BS8217: 1994

Mastic asphalt roof BS8218: 1998

f. Roofs with copper, lead, zinc and other sheet metal roof coverings require provision for expan-sion and contraction of the sheet material. In ‘warm deck’ roofs, in order to reduce the risk ofcondensation and corrosion, it may be necessary to provide a ventilated air space on the coldside of the insulation and a high performance vapour control layer between the insulation andthe roof structure. It may also be necessary to consult the relevant trade association.

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(G3.1)

Wall type 1: solid walls of masonry

A. Solid wall, 200mm thick of bricks, blocks orslabs of clay, calcium silicate, concrete or caststone.

Wall rendered or unrendered externally.

Insulation and plasterboard internally, with acavity 25mm wide.

B. Solid wall as A. above.

Insulation applied to the external surface of thewall; protected externally either by cladding(of sheets, tiles or boarding) with permanentventilation, or by rendering.

Wall with or without an internal surface finishof plaster or plasterboard.

Wall type 2: cavity walls of masonry

A. Cavity wall of 2 leaves of masonry separatedby a 50mm cavity; each leaf, 100mm thick, ofeither bricks or blocks of clay, calcium silicateor concrete.


Insulation applied as a lining to the internalsurface of the wall and plasterboard.

B. Cavity wall as A. above.


Insulation applied as a cavity fill.


C. Cavity wall as A. above.


Insulation applied to either leaf as a partialcavity fill so as to preserve a residual space of50mm wide.


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(G3.1)

��25

plasterboard

insulation

cavity

A. Solid wall with internal insulation

�insulationexternal protection

B. Solid wall with external insulation

insulation

� insulation

plasterboard

cavity

A. Cavity wall with internal insulation

B. Cavity wall with cavity fill insulation

50100 100

50100 100

�insulationcavity

C. Cavity wall with partial fill insulation

50

�

Wall type 3: framed walls

A. Framed wall of timber standards and rails, witha vapour permeable sheathing to the framingcovered with a breather membrane.

Masonry external cladding of 100mm thickclay brick or block, concrete or calcium silicatebrick or block, dense in-situ concrete, light-weight concrete or autoclaved aerated concrete, with an externally ventilated cavityof 50mm but not more than 100mm widebetween the cladding and the framing, thecavity ventilated to the outside by means of oneopen perpend joint for at least every 1.2 metrerun at the top and bottom of the wall.

Masonry cladding rendered or unrenderedexternally.

Insulation applied as an infill to the framing.

The framing lined internally with a vapourcontrol layer and plasterboard.

B. Framed wall of timber standards and rails witha breather membrane.

Cladding material, on battens and counterbattens as required, of timber weatherboarding,tile or slate.

Insulation and internal lining as A. above.

C. Framed wall of timber or metal standards andrails.

Sheet or panel cladding material of fibrecement, plastic, metal, GRP or GRC.

Insulation applied either to the internal face ofthe framing with permanent ventilation behindany impervious cladding, or as an infill to theframing; in either case the wall lined internallywith a vapour control layer and a lining.

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(G3.1)

50 to 100

��A. Masonry cladding

vapour controllayerplasterboard

insulationsheathingbreathermembrane

�B. Weatherboarding, tile or slate cladding

vapour controllayerplasterboard

�insulationsheathingbreathermembrane

C. Sheet or panel cladding

vapour controllayer

lining

� insulation

C. Sheet or panel cladding (with ventilated cavity)

vapour controllayer

lining

ventilated cavity

�insulation

Roof type 1: flat roofs [Note 1]

A. Flat roof structure of in-situ or precast concretewith or without a screed; with or without aceiling or soffit.

External weatherproof covering; with insula-tion laid on a vapour control layer between theroof structure and the weatherproof covering.[Note 1]

B. Flat roof structure as A. above.

External protective covering; with low perme-ability insulation laid on a waterproof mem-brane between the roof structure and theexternal covering.

C. Flat roof structure of timber or metal framedconstruction with a board decking 19mm thick;with or without a ceiling or soffit.

External weatherproof covering, insulation andvapour control layer as A. above. [Note 1]

Note:1. Roof types 1A. and 1C. are not suitable for

sheet metal coverings that require joints toallow for thermal movement. See also‘General’, f. of the provision deemed to satisfyG3.1.

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(G3.1)

�weatherproof covering

insulationvapour control layerscreed if required

A. Concrete - warm roof

B. Concrete - inverted roof�protective covering

insulationwaterproof membranescreed if required

�weatherproof covering

insulation

vapour control layer

C. Timber or metal frame - warm roof

D. Flat roof structure as C. above.

External protective covering, insulation andwaterproof membrane as B. above.

E. Flat roof structure of timber or metal framedconstruction with a troughed metal decking;with or without a ceiling or soffit.

External weatherproof covering and insulationand vapour control layer as A. above. [Note 1]

F. Flat roof structure as E. above.

External protective covering, insulation andwaterproof membrane as B. above.

Note:1. Roof type 1E. is not suitable for sheet metal

coverings that require joints to allow forthermal movement. See also ‘General’, f. of theprovision deemed to satisfy G3.1.

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(G3.1)

D. Timber or metal frame - inverted roof

protective covering

insulationwaterproof membrane

�E. Troughed metal decking - warm roof

weatherproofcoveringinsulationvapour control layer�

F. Troughed metal decking - inverted roof

protective covering

insulation

waterproofmembrane�

Roof type 2: pitched roofs [Note 1]

A. Pitched roof structure of timber or metalframed construction.

External weatherproof covering of slates ortiles on under stating felt with or withoutboards or battens.

Insulation laid on a level ceiling with a venti-lated space between the insulation and the roofstructure.

B. Pitched roof structure as A. above.

External weatherproof covering as A. above.

Insulation and vapour control layer laid on asloping ceiling, with a ventilated air space50mm in depth between the insulation and theboards of the pitched roof covering.

C. Pitched roof structure as A. above with adecking of low permeability insulation fitted toand between the roof framing.

External weatherproof covering of slates ortiles, with tiling battens and counter battens(located over roof framing), and a breathermembrane laid on the insulation decking; witha sloping ceiling.

D. Pitched roof structure as A. above.

External weatherproof covering of metal orfibre cement sheet sandwich construction laidon purlins; with insulation sandwichedbetween the external and soffit sheeting; andwith or without a ceiling. [Note 1]

Note:1. Roof type 2D. is not suitable for sheet metal

coverings that require joints to allow forthermal movement. See also ‘General’ f. of theprovisions deemed to satisfy G3.1.

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(G3.1)

�underslatingfelt

ventilatedspaceinsulation

slates or tiles

A. Slates or tiles - insulation on a level ceiling

�underslatingfelt50mmventilatedspaceinsulation

insulation

insulationsandwich

externalsheetcovering

breathermembrane

counter battens

slates ortiles onbattens

vapourcontrol layer

slates or tiles

B. Slates or tiles - insulation on a sloping ceiling

C. Slates or tiles - insulation as decking (longitudinal section)

D. Metal or fibre cement sheet - sandwich insulation

��

INTERSTITIAL CONDENSATION

(G4.1) The requirements of G4.1 will be met where the walls, roofs and floors are assessed and/or constructedin accordance with Appendix D and Clauses 9.1 to 9.5.5.2 of BS5250: 1989.

SURFACE CONDENSATION

(G4.2) The requirements of G4.2 will be met where openings and junctions in or between the specified ele-ments are constructed in accordance with Clauses 9.6.1 to 9.6.3 of BS5250: 1989 to a thermal trans-mittance (U-value) which does not exceed 1.2 W/m2K at any point.

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(G4.1), (G4.2)

Appendix

THIS APPENDIX IS NOT PART OF THE TECHNICAL STANDARDS OR THE DEEMED TO SATISFY PROVISIONS AND ISTHEREFORE NON-MANDATORY. IT GIVES OUTLINE GUIDANCE ON THE PREPARATION OF A SITE WHERE HARMFULOR DANGEROUS SUBSTANCES ARE SUSPECTED OR IDENTIFIED AND ON FLOOD DAMAGE TO BUILDINGS AND RADONPROTECTION MEASURES FOR NEW DWELLINGS.

Preparation of a site

1. Harmful or dangerous substances includes deposits of faecal or animal matter and any substance ormixture of substances which is, or could become, corrosive, explosive, flammable, radioactive ortoxic or which produces, or could produce, any gas likely to have any such characteristic.

2. Where records or local knowledge of previous use identifies land which may contain, or give rise to,harmful or dangerous substances, planning permission will normally be subject to conditions. Theseconditions will be imposed to ensure that the development proposed for the land will not exposefuture users or occupiers, or any building or services, to hazards associated with the contaminants.Examples of land likely to contain contaminants are given in Table 1.

3. There may be occasions when land containing harmful or dangerous substances has not been identi-fied at the planning stage, and the presence of contaminants is only suspected later. Some signs ofthe possible presence of contaminants are given in Table 2.

4. If any signs of possible contaminants are present the Local Authority should be told at once. If thepresence of any of the contaminants listed in Table 2 is confirmed, it is likely that some form ofremedial action will be required. For guidance, the normal course of remedial action is listed againsteach contaminant noted in Table 2. In all cases these courses of action assume that the ground to becovered by the building will have at least 100mm of in-situ concrete cover. Expert advice may berequired to provide an economical and safe solution to the hazards encountered, especially wherecontaminants are present in large amounts or where there is imminent danger to health or safety.

5. With the increasing re-development of former industrial land in the UK, attention is also drawn tothe British Standards Institution publication, first issued in April 1988 as a Draft for Development,DD 175: 1988 (1992), “Code of practice for the identification of potentially contaminated land andits investigation”. This is designed to provide guidance on the identification and investigation of landwhere contaminants may exist and where hazards from undesirable substances may occur.

6. The subject is still relatively new and continues to develop, hence publication of DD 175 as a Draftfor Development which is intended to complement both BS5930: 1981, “Code of practice for siteinvestigations” and the guidance notes issued by the Department of the Environment’s Inter-Depart-mental Committee on the redevelopment of Contaminated Land.

Flooding

7. Serious river and coastal flooding which has occurred in a number of areas in Scotland is, unfortu-nately, not entirely preventable. Pressure for land development may mean that development proposalscould be given planning approval on land subject to some risk of flooding. Paragraph 8 below refersto sources of information on measures to reduce the effects of flood damage to buildings.

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8. Where development is to take place on land assessed by the planning authority as having a floodrisk, advice should be sought from sources such as the local planning authority, the Scottish Environ-mental Protection Agency (SEPA) and those responsible for coastal defences. Further information isin “National Planning Policy Guideline 7: “Planning and Flooding”, 1995”. Detailed guidance on thelikely effects of flooding on building materials and fabric and on the precautionary measures that canbe taken in the design of dwellings to reduce the effects of flood damage can be obtained from“Design Guidance on Flood Damage to Dwellings, 1996”. Both publications are available from theStationery Office.

Radon

9. Radon is a naturally occurring, radioactive, colourless and odourless gas that is formed whereuranium and radium are present. It can move through cracks and fissures in the subsoil, and so intobuildings. Where this gas occurs under buildings, the external walls contain it and the containment ofradon can build up inside the buildings over the long term posing a risk to health and increasing therisk of developing cancer.

The precise areas where measures will require to be taken to reduce radon penetration into dwellingsare regularly reviewed by the Scottish Executive in light of advice from the National RadiologicalProtection Board. These are listed the the Building Research Establishment’s document “Radon:guidance on protection measures for new dwellings in Scotland”.

Table 1 to Part G Appendix: Examples of land likely to contain contaminants

Examples of land likely to contain contaminants is land on which there has been -

asbestos works;

chemical works;

gas works, coal carbonisation plants and ancillary by-products works;

industries making or using wood preservatives;

landfill and other waste disposal sites;

metal mines, smelters, foundries, steel works and metal finishing works;

munitions production and testing sites;

nuclear installations;

oil storage and distribution sites;

paper and printing works;

railway land, especially the larger sidings and depots;

scrap yards;

sewage works, sewage farms and sludge disposal sites; and

tanneries

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Table 2 to Part G Appendix: Possible contaminants and actions

Signs of possible Possible contaminant Probable remedialcontamination action required

a. Vegetation metals, metal compounds none(absence, poor orunnatural growth) organic compounds, gases removal

b. Surface materials metals, metal compounds none(unusual colours andcontours may indicate) oil and tarry wastes removal, filling or

sealing

asbestos (loose) removal, filling orsealing [Note 1]

other fibres none

organic compounds removal or fillingincluding phenols

potentially combustible removal or inert fillingmaterial including coal andcoke dust

refuse and waste removal

c. Fumes and odours flammable, explosive, toxic removal(may indicate organic and asphyxiating gaseschemicals at very low including methane and the construction is toconcentrations) carbon dioxide be free from

unventilated voids

corrosive liquids removal, filling orsealing [Note 1]

faecal, animal and vegetable removal or fillingmatter (biologically active)

d. Drums and containers various removal with all(whether full or empty) contaminated ground

[Note 1]

Note:1. The local authority may require the removal to be done by specialists.

2. In the table -REMOVAL means that the contaminant itself and any contaminated ground to be covered by thebuilding should be taken out to a depth of 1m (or less if the Local Authority agrees) below thelevel of the lowest floor and taken away to a place to be named by the Local Authority;

FILLING means that the ground to be covered by the building is to be covered to a depth of 1m(or less if the Local Authority agrees) with a material which will not react adversely with anycontaminant remaining and will be suitable for making up levels. The type of filling and thedesign of the ground floor should be considered together;

INERT FILLING means that the filling is wholly non-combustible and not easily changed bychemical reactions; and

SEALING means that a suitable imperforate barrier is laid between the contaminant and thebuilding and sealed at the joints, around the edges and at the service entries. Note that polyethyl-ene may not be suitable if the contaminant is a liquid such as a tarry waste or organic solvent.

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22G

Documents

PREPARATION OF SITES, RESISTANCE TO MOISTURE AND ... … · Preparation of sites REGULATION 17 Resistance to moisture REGULATION 18 Resistance to condensation THE STANDARDS G1 Application