Extensions
109 sources in the library on extensions, 40 on this page cited in a published note. Each one says what the document covers and what it is good for. Name a source to see which document it is and where to read it. One at a time. Page 1 of 3.
- very strong RN-DNUSE8 cited
Department of Finance (Northern Ireland)
Northern Ireland's equivalent of Approved Document L Volume 1. This edition came into effect on 30 June 2022 and gives guidance on regulations 39 to 47 of the Building Regulations (Northern Ireland) 2012, which set the requirements for conservation of fuel and power in dwellings, including the limiting U-values a replacement window or door must meet in Northern Ireland. It replaced the 2012 version, and the Department publishes an awareness briefing and FAQ setting out the differences. The full text is at https://www.finance-ni.gov.uk/sites/default/files/publications/dfp/TB%20Part%20F1%202022_On-Line%20Publication.pdf. Cite this rather than Approved Document L whenever a note gives a window U-value for a reader in Northern Ireland.
Cited in Industrial Style Windows: Cheaper Alternatives, 2026 Costs, Insulation: The Complete Guide.
- very strong RN-ZYLCD2 cited
HM Revenue and Customs
The 5 per cent conversion rate and, importantly, what it does not cover. A qualifying conversion into single household dwellings arises where the premises after conversion contain a greater or lower number, but not fewer than one, of single household dwellings, and includes a property never lived in such as an office block or a barn, a bedsit block, non-self-contained living accommodation such as staff rooms above a pub, and a dwelling previously adapted in its entirety to another use such as offices or a dental practice. It expressly does not include the creation of living accommodation that is not a single household dwelling, naming most granny annexes and additional bedrooms at a care home, nor the renovation of living accommodation used for other purposes without adaptation, such as a flat above a shop used for storage, which is directed instead to the section 8 empty homes rate. Paragraph 7.3.1 makes clear that work unrelated to changing the number of dwellings cannot be reduced rated, and works three examples through a block of sixteen flats showing that parts of a building are examined independently. Goods that are not building materials, such as carpets or fitted bedroom furniture, remain standard rated along with their installation.
Cited in Church Conversion Cost: 2026 UK Price Guide, Who Buys the Materials: You or the Builder?.
- very strong RN-FX7S48 cited
HM Revenue and Customs
The section that carries the 5 per cent empty home rate, which most renovation budgets miss. A contractor may charge VAT at 5 per cent instead of 20 per cent on renovating or altering an eligible dwelling that has not been lived in during the 2 years immediately before the work starts. Paragraph 8.3.2 sets out what proves the two years: Electoral Roll and Council Tax records, utilities companies, or an Empty Property Officer at the local authority, and states that a letter from an Empty Property Officer certifying two years empty is sufficient on its own with no other evidence needed. Paragraph 8.3.3 lists occupation that can be ignored: illegal occupation by squatters, occupation by guardians installed to deter squatters and vandals, and non-residential use such as business storage, but expressly not occasional use as a second home, which defeats the relief. Paragraph 8.3.4 allows the reduced rate to continue on all the work even where people move in while the work is carried out, provided the two-year test was met when work started. Goods that are not building materials, such as carpets or fitted bedroom furniture, must still be standard rated including the installation charge.
Cited in Roof Repair Costs & Common Problems (UK), Who Buys the Materials: You or the Builder?.
- very strong RN-ZHMBKZ cited
LABC Front Door
LABC's homeowner guidance on steelwork in extensions. It says steel beams must be designed by a structural engineer and that the design is checked by building control.
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Ministry of Housing, Communities and Local Government
The second volume of Approved Document B, needed when a homeowner project crosses out of purely domestic use. Paragraph 0.1 draws the line: Volume 1 deals solely with dwellings INCLUDING blocks of flats, so a flat conversion stays in Volume 1, while Volume 2 covers every other building type. Table 0.1 sets the purpose groups: 1(a) flat, 1(b) dwellinghouse with a habitable storey at least 4.5m above ground up to 18m, 1(c) dwellinghouse with no habitable storey 4.5m above ground, then 2(a) residential institutional, 2(b) residential other (hotel, boarding house, hall of residence, hostel), 3 office, 4 shop and commercial, 5 assembly and recreation, 6 industrial, 7(a) storage and 7(b) car parks for vehicles up to 2,500kg gross. Its notes keep work within purpose group 1: surgeries, consulting rooms or offices forming part of a dwellinghouse and used by an occupant in a professional capacity stay in group 1 provided they total no more than 50m2, and a detached garage or open carport of no more than 40m2 stays in group 1(c). Paragraph 0.21 requires a separate purpose group for an ancillary use if that use is a flat, or if the building or compartment exceeds 280m2 and the ancillary use is more than one fifth of the total floor area; paragraph 0.22 requires separate purpose groups for genuinely independent uses such as shops with offices above, and the more onerous guidance applies where there is doubt. Paragraphs 0.23 and 0.24 require Volume 1 to be consulted as well for mixed use buildings that include dwellings, and paragraph 3.2 requires separate escape routes, or other effective protection of common escape routes, where a building has storeys or parts of storeys in different purpose groups.
Cited in Carpet Tile Installation Cost: 2026 UK Price Guide.
- very strong RN-SM6TRW cited
Ministry of Housing, Communities and Local Government
The statutory source for soakaway design and the discharge hierarchy every garden drainage note should state. Requirement H3(3) lists the order of priority for rainwater discharge: (a) an adequate soakaway or other adequate infiltration system, or where not reasonably practicable (b) a watercourse, or where not reasonably practicable (c) a sewer. Paragraph 3.25 bars infiltration devices within 5 metres of a building or road, in ground where the water table reaches the bottom of the device at any time of year, too close to other drainage fields or soakaways, or where contamination could pollute groundwater. Paragraph 3.26: soakaways serving less than 100 square metres are generally square or circular pits filled with rubble or lined with dry-jointed masonry or perforated ring units. Paragraph 3.27: design to a return period of once in ten years, and for small soakaways serving 25 square metres or less a design rainfall of 10mm in 5 minutes may be assumed as the worst case. Paragraph 3.28 requires percolation tests to derive the infiltration rate, and paragraph 3.30 sends larger soakaways to BS EN 752-4 or BRE Digest 365 Soakaway design. Paragraphs 2.10 to 2.12 cover pervious paving over a granular storage reservoir and warn against its use where sediment or oil spillage would block the pores. For foul drainage, paragraph 2.33 sets a minimum 75mm internal diameter, or 100mm for a WC, and Table 6 gives minimum gradients of 1 in 40 for 75mm and 100mm at peak flows under 1 litre per second.
Cited in Adding an Ensuite: Cost, Layout & Plumbing, Annexe & Granny Flat: Cost, Planning & Rules, Basins & Vanity Units: A Buyer's Guide, Baths Compared: Freestanding, Inset & Shower Baths and 33 more.
- very strong RN-X4J5YY cited
Ministry of Housing, Communities and Local Government
The 2026 edition takes effect on 24 March 2027 for work not connected with higher-risk building work, and 24 September 2027 where it is, with transitional arrangements in Circular Letter 01/2026. Table 3.1 sets limiting U-values for new dwellings: all roof types 0.16, wall 0.26, floor 0.18, window 1.6, rooflight 2.2, doors 1.6 W per square metre per kelvin, with air permeability 8.0 cubic metres per hour per square metre at 50Pa. Table 3.2 covers new elements in existing dwellings, that is extensions and loft conversions: roof 0.15, wall 0.18, floor 0.18, window 1.4 or Window Energy Rating Band B, rooflight 2.2. Table 3.3 covers upgrading existing elements: a roof with a U-value worse than the 0.35 threshold must be improved to 0.16, and note 2 confirms that for dormer windows the roof figure covers the roof parts and the wall figure the cheeks, while note 3 allows a higher U-value where the standard would limit head room provided the insulation plus air gap is at least the depth of the rafters.
Cited in External Wall Insulation (EWI) Systems & Finishes, Insulation: The Complete Guide, Triple Glazing: Worth the Cost?.
- very strong RN-R7QZ7M cited
Ministry of Housing, Communities and Local Government
Supports Part O of Schedule 1 to the Building Regulations 2010 (requirement O1 and regulation 40B); the 2021 edition took effect on 15 June 2022 in England, with transitional relief for work notified before that date and started before 15 June 2023. Critically, paragraph 0.3 limits the guidance to NEW residential buildings only (dwellings, residential institutional and residential other, plus shared communal rooms, common spaces and live/work units), and paragraph 0.7 applies it only to the residential parts of mixed-use buildings. Compliance is by the simplified method (Section 1) or dynamic thermal modelling to CIBSE TM59 (Section 2); the simplified method splits England into a high risk location (urban and some suburban London listed in Appendix C, with guidance for parts of central Manchester) and a moderate risk location (the rest of England). Table 1.1 (cross-ventilated) caps glazing as a percentage of floor area at north 15 high risk / 18 moderate, east 18/18, south 15/15, west 18/11, with the most glazed room capped at north 37/37, east 37/37, south 22/30, west 37/22. Table 1.2 (no cross-ventilation) caps glazing at north 15/18, east 11/18, south 11/15, west 11/11, most glazed room north 26/26, east 18/26, south 11/15, west 18/11.
Cited in Glass Box & Bifold Extensions: Cost & Ideas, Glazed Extensions: The Complete UK Guide, Glazing Explained: U-values, Low-E, Argon & Spacers, Rooflights & Skylights: Materials & Types.
- very strong RN-70QMAN cited
Ministry of Housing, Communities and Local Government
The source that kills the widespread claim that Building Regulations set a minimum ceiling height in England. The gov.uk page states the standard is not a building regulation and remains solely within the planning system as a new form of technical planning standard, applied only where a local authority has adopted it in its Local Plan. The March 2015 standard itself (ISBN 978-1-4098-4567-6) sets Gross Internal Area minimums by bedrooms and bedspaces (3b4p notation) in Table 1, organised by storey height, and at paragraph 10(i) sets the minimum floor to ceiling height at 2.3m for at least 75% of the Gross Internal Area. Paragraph 2 records that the bedroom, storage and internal area requirements have no other statutory meaning or use. It also gives the counting rules: storage under stairs with 900 to 1500mm headroom counts at 50% of floor area and anything under 900mm not at all. Applies to new dwellings, not to extensions of existing houses.
Cited in House Extension Design Ideas.
- very strong RN-EKZF2G cited
Planning Portal
The official page for the larger home extension procedure: a single-storey rear extension over four and up to eight metres deep for a detached house, and over three and up to six metres for all other houses, is permitted development only after the local authority has been notified and has consulted the adjoining neighbours. This is the distinction between the standard 3 and 4 metre PD depths and the doubled depths, and it is the page a rear extension note should cite before quoting 6 or 8 metres.
Cited in Glazed Extensions: The Complete UK Guide.
- very strong RN-01MIE5 cited
Planning Portal
The government's Planning Portal guidance on extensions; it settles that most extensions need Building Regulations approval, separately from planning.
Cited in House Extension: The Complete Guide.
- very strong RN-DZ6JWK cited
Planning Portal
The Planning Portal's guidance on porches, summarising the Schedule 2 Class 7 exemption and its conditions on glazing, electrics and keeping the front door.
Cited in Adding Porch.
- very strong RN-CAOKOG cited
Planning Portal
The Planning Portal's porch guidance says the permitted development allowance applies to houses, not flats and maisonettes, and may be limited by a planning condition or an Article 4 direction.
Cited in Adding Porch, Porches & Canopies: Cost & Planning.
- very strong RN-OSL7G4 cited
Scottish Government (gov.scot)
SCOTLAND. Clause 4.3.2 Table 4.3 sets private stair geometry at minimum rise 100 mm, maximum rise 220 mm, minimum going 225 mm, tread not less than the going and maximum pitch 42 degrees, so Scotland's minimum going is 225 mm against England's 220 mm in Approved Document K. Any other stair, including within the common area of a building containing flats, is limited to 170 mm rise, 250 mm going and 34 degrees. The aggregate of the going plus twice the rise must be between 550 mm and 700 mm, and note 6 warns the maximum rise and minimum going must not be used together. The going at the narrow end of a tapered tread must be at least 50 mm. Clause 4.3.16 requires clear headroom of at least 2.0 metres over the whole effective width, with reduction permitted only outside the area needed to maintain effective width, so Scotland does not carry England's 1.9 metre centre and 1.8 metre edge loft conversion concession. Text verified identical in the April 2026 PDF handbook.
Cited in Spiral Staircases: Sizes, Building Regs & Cost, Staircase Types & Costs: Straight, Winder & Spiral.
- very strong RN-JWMO0O cited
The National Archives
Regulation 21 of the Building Regulations 2010, which exempts Class 7 porches and conservatories from the energy efficiency requirements unless the separating wall is removed, heating is extended or a fixed heater is fitted.
Cited in Porches & Canopies: Cost & Planning.
- very strong RN-2EUD9L cited
The National Archives
The 2013 Welsh amending order sets out Class D for Wales: a porch is not permitted if its external ground area exceeds 3 m2 or any part is more than 3 m above ground level.
Cited in Porches & Canopies: Cost & Planning.
- very strong RN-99NNB9 cited
The National Archives
The 2011 Scottish amendment order inserted householder Class 1C for porches, not permitted where the footprint would exceed 3 m2 or the porch is within 2 m of a boundary with a road.
Cited in Do You Need Planning Permission for a Garden Room?, Porches & Canopies: Cost & Planning.
- very strong RN-TXATBT cited
The National Archives
Class D of the 1995 Order as substituted for Wales in 2013, which sets the same 3 m², 3 m high and 2 m from a highway limits for porches.
Cited in Adding Porch.
- very strong RN-WKDENH cited
The National Archives (legislation.gov.uk)
Section 2(2) lists the building owner's rights over a party structure: (a) underpin, thicken or raise; (b) make good, repair or rebuild a defective party structure; (c) to (e) demolish and rebuild non-conforming partitions, connected buildings and party structures of insufficient strength or height; (f) to cut into a party structure for any purpose, which may include inserting a damp proof course; (g) to cut away a footing, projecting chimney breast, jamb, flue or other projection to enable a wall to be built; (h) to cut away overhanging parts of an adjoining building; (j) insert flashings; (k) execute incidental works; (l) raise or rebuild a party fence wall; (m) reduce wall heights; (n) expose a previously enclosed party wall. Paragraph (f) is the one that catches chasing or breaking through a shared wall for pipework, which makes it party wall work requiring a party structure notice.
Cited in Building Regs for Loft Conversions: Homeowner Checklist, Cellar Tanking & Waterproofing, Chimney Repair, Removal & Flashing Costs, Do You Need Planning Permission for an Extension? and 13 more.
- very strong RN-C6XFB7 cited
The National Archives (legislation.gov.uk)
A party structure notice must be served at least two months before the date on which the proposed work will begin, and must state the building owner's name and address, the nature and particulars of the proposed work (with plans, sections and load particulars where special foundations are proposed) and the date the work will begin. The notice ceases to have effect if the work has not begun within twelve months of service or is not then prosecuted with due diligence. Two months for a party structure notice against one month for a section 6 excavation notice is the distinction to cite.
Cited in Building Regulations Explained for Homeowners, Building Regs for Loft Conversions: Homeowner Checklist, Cellar Tanking & Waterproofing, Chimney Repair, Removal & Flashing Costs and 26 more.
- very strong RN-QBUTY2 cited
The National Archives (legislation.gov.uk)
The exact wording of the two excavation triggers that decide whether a basement or a deep foundation needs a party wall notice, worth quoting rather than paraphrasing. Section 6(1) applies where the building owner proposes to excavate, or excavate for and erect a building or structure, within a distance of 3 metres measured horizontally from any part of a building or structure of an adjoining owner, and the excavation will within those 3 metres extend to a lower level than the level of the bottom of the neighbour's foundations. Section 6(2) applies within 6 metres measured horizontally where the work will within those 6 metres meet a plane drawn downwards in the direction of the excavation at an angle of 45 degrees to the horizontal. Section 6(5) requires the building owner to serve notice on the adjoining owner at least one month before beginning to excavate. Section 6(7) provides that if the adjoining owner does not serve a notice indicating consent within 14 days, they are deemed to have dissented and a dispute has arisen, which is what triggers the surveyor and award process.
Cited in Basement & Cellar Conversions: Cost, Basement Conversion Cost & Feasibility (UK), Bedroom Extension Cost: 2026 UK Price Guide, Build Basement Cost: 2026 UK Price Guide and 28 more.
- very strong RN-R4P8KA cited
The National Archives (legislation.gov.uk)
Regulation 4(1) requires building work to be carried out so that it complies with the applicable requirements of Schedule 1 and does not cause a previously compliant part of the building to breach a requirement. Regulation 4(3) is the rule that matters for extensions, loft conversions and re-roofing: on completion of an extension or material alteration the building must be no more unsatisfactory in relation to the requirement than before the work was carried out. It also sets out the narrower Part L and Part F only route for controlled services and fittings that are not material alterations.
Cited in How to Tell If a Wall Is Load-Bearing, Strengthening Loft Floors for Conversion, uPVC vs Timber vs Aluminium Windows.
- very strong RN-Y7MVZK cited
The National Archives (legislation.gov.uk)
Class 7 is the conservatory and porch exemption every extension note leans on: the erection at ground level of an extension consisting of a conservatory, porch, covered yard or covered way, or a carport open on at least two sides, is exempt from the building regulations where the floor area does not exceed 30 square metres. Where a conservatory or porch is wholly or partly glazed, the glazing must still satisfy Part K4 and K5.1 to K5.4 and Part N of Schedule 1. Class 6 exempts small detached buildings up to 30 square metres single storey and up to 15 square metres otherwise, which is the garden room threshold.
Cited in Bin & Bike Storage Ideas, Boot Rooms & Pantries: Design & Cost, Build Garage Cost: 2026 UK Price Guide, Building Control Inspections Explained and 20 more.
- very strong RN-4MVF6Q cited
The National Archives (legislation.gov.uk)
The determination periods behind every 'the council has 8 weeks' claim, in the legal text rather than a council summary. Article 34(2)(a): 13 weeks from the day after receipt for an application for major development. 34(2)(aa): 10 weeks for technical details consent for major development or for public infrastructure development. 34(2)(b): 8 weeks for development which is not major development. 34(2)(bb): 5 weeks for technical details consent which is not major development. 34(2)(c): any extended period agreed in writing between applicant and authority, unless notice of appeal has already been given. Note that article 34 contains no 16-week EIA period: that substitution is made by regulation 68(2) of the EIA Regulations 2017. Article 34(9) sets the 21-day and 14-day publicity waits before determination, and 34(9A) extends both to 30 days for an EIA application accompanied by an environmental statement.
Cited in Chain Link Fence Cost: 2026 UK Price Guide, Do You Need Planning Permission? A UK Homeowner's Guide, Do You Need Planning Permission for a Loft Conversion?, Do You Need Planning Permission for an Extension? and 5 more.
- very strong RN-YFQLLB cited
The National Archives (legislation.gov.uk)
SI 2019/907, in force 25 May 2019. Regulation 4 makes permanent the previously temporary right in Class A of Part 1 of Schedule 2 to the GPDO 2015 to enlarge a dwellinghouse by up to 8 metres for a detached dwellinghouse and 6 metres for any other dwellinghouse, by removing the time limiting date of 30 May 2019 and the conditions that required the development to be completed by that date. This is the instrument that settles the date of the larger home extension scheme: the right dates from 2013 as a temporary measure and became permanent on 25 May 2019, not in 2020. The Regulations also make amendments on advertisement consent and compensation. England only.
Cited in Do You Need Planning Permission for an Extension?, Loft Conversion vs House Extension: Which Adds More Value?, Orangery vs Conservatory vs Extension: Which Is Right?.
- very strong RN-1MN06H cited
The National Archives (legislation.gov.uk), Northern Ireland Statutory Rules
NORTHERN IRELAND, and the part letters mean different things from England, so quoting an England part letter into an NI note is a straight error. The parts are A interpretation and general, B materials and workmanship, C site preparation and resistance to contaminants and moisture, D structure, E fire safety, F conservation of fuel and power, G resistance to the passage of sound, H stairs, ramps, guarding and protection from impact, J solid waste, K ventilation, L combustion appliances and fuel storage systems, N drainage, P sanitary appliances, unvented hot water storage systems and reducing the risk of scalding, R access to and use of buildings, and V glazing. So NI Part D is England's Part A, NI Part E is England's Part B, NI Part F is England's Part L, NI Part K is England's Part F, NI Part L is England's Part J, NI Part N is England's Part H, NI Part P is England's Part G and emphatically NOT electrical safety, NI Part R is England's Part M, and NI Part V is glazing. There is NO part covering electrical safety anywhere in these regulations, so domestic electrical work in Northern Ireland is not notifiable building work as it is under England's and Wales's Part P. Regulation 41 imposes consequential improvements, regulation 42 change of energy status and regulation 43 renovation of thermal elements.
- very strong RN-KXCXCY cited
Welsh Government (gov.wales)
WALES. First published 3 April 2017, last updated 7 April 2026. Wales publishes its own Approved Document F, and the page carries the current volume 1 for dwellings (910 KB PDF) and volume 2 for buildings other than dwellings, plus replacement volumes that TAKE EFFECT ON 4 MARCH 2027, the same changeover date as the Welsh Approved Document L and distinct from England's 24 March 2027. Welsh Part F diverged from England's when England issued its 2021 edition alongside Part L and Part O, so extract rates and background ventilator provisions for a Welsh bathroom, kitchen or loft conversion should be taken from this document rather than from England's Approved Document F.
Cited in Trickle Vents & Background Ventilation.
- very strong RN-NUL2UK cited
Welsh Government (gov.wales)
WALES. The Welsh Government publishes its own Approved Documents, and this collection page, last updated 19 June 2025, lists them with their current dates so the right edition can be cited: A structure 3 April 2017, B fire safety 19 June 2025, C site preparation and resistance to contaminants and moisture 3 April 2017, D toxic substances 3 April 2017, E resistance to the passage of sound 13 April 2022, F ventilation 7 April 2026, G sanitation, hot water safety and water efficiency 10 May 2023, H drainage and waste disposal 3 April 2017, J combustion appliances 6 January 2025, K protection from falling 19 March 2025, L conservation of fuel and power 7 April 2026, M access 20 March 2025, N glazing 5 April 2017, O overheating, P electrical safety, Q security and R volumes 1 and 2. Wales still has a live Approved Document N on glazing safety, opening and cleaning, which England withdrew in 2013 when its content moved into Part K, so an England-based note that says Part N no longer exists is wrong for Wales.
- very strong RN-156U72 cited
Welsh Government (gov.wales)
WALES, and this contradicts England outright. Wales has NO larger home extension prior approval route and no neighbour consultation scheme, so the 6 metre and 8 metre single-storey rear extensions England allows are simply not available. Under Class A a single-storey rear extension must not project beyond the rear wall of the original dwellinghouse by more than 4 metres for any house type, must not exceed 4 metres in height, must not exceed 50 per cent of the total area of the curtilage under A.1(a), must not have eaves higher than the eaves of the part it projects from, and must not be within 2 metres of a boundary where its eaves exceed 3 metres, nor exceed 4 metres in height within 2 metres of a boundary. A rear extension of more than one storey is limited to 4 metres at ground floor and 3 metres at first floor or above, and any storey above 4 metres in height must be at least 10.5 metres from the boundary opposite the rear wall. A side extension must be set back at least 1 metre from the principal elevation and must not make the widest part of the resulting house more than 50 per cent wider than the original. Verandas, raised platforms, roof terraces and balconies are excluded except a balcony complying with A.1(l)(ii), and materials must match under A.3(a).
Cited in Do You Need Planning Permission for a Garden Room?, Renovating a 1930s House.
- strong locally RN-HSIQRS cited
Law Commission
The Law Commission's project page on rights to light; it states that the planning system does not take account of private rights to light.
Cited in House Extension: The Complete Guide.
- strong RN-JHE485 cited
BRE Group
The correct reference for the daylight and sunlight methodology that planning officers and inspectors apply, and the fix for the common mis-citation 'BRE 209'. The report number is BR 209; the current edition is the 2022 (third) edition, published 8 June 2022, ISBN 9781848064836, authored by Paul Littlefair, Stephanie King, Gareth Howlett, Cosmin Ticleanu and Adam Longfield. It supersedes the 1991 first edition and the 2011 second edition, and is intended to be used alongside the interior daylight recommendations of BS EN 17037. New material in the 2022 edition covers dense urban areas, trees and hedges; a special section covers loss of solar radiation for solar panels and passive solar buildings, plus sunlighting of gardens and amenity areas.
Cited in Planning Appeals: How to Appeal a Refusal, Right to Light & Boundary Disputes in Extensions.
- strong RN-NIFJ8S cited
BSI (British Standards Institution)
STATUS: CURRENT. BS 8485:2015+A1:2019 was published 31 January 2019 and supersedes BS 8485:2015, which is withdrawn. It gives recommendations on ground gas site characterisation, risk assessment and the choice and design of integral gas protective measures to stop methane and carbon dioxide entering new buildings and to provide a safe internal environment, for designers, regulators and constructors. The A1:2019 revision added more detail on interpreting gas monitoring data and assigning the gas screening value, defined four building types with amended gas protection scores for the characteristic situations, added recommendations for reporting protection measures at design, installation and post construction verification stages, and added worked examples. It does NOT cover other hazardous ground gases (radon is separate, under BRE guidance and Approved Document C) nor methane and carbon dioxide arising from the building's intended use. Catalogue page confirms number, title, date, status and scope; the scoring tables are paywalled.
Cited in Damp Proof Membranes (DPM) & DPC: Types & Installation.
- strong RN-IKHYR0 cited
BSI (British Standards Institution)
The residential fire safety code of practice that professionals use as the alternative to the Approved Document B route, described by BSI as the UK most widely used fire safety standard. Paywalled, so only the catalogue page is public; it confirms the current edition is BS 9991:2024, page-dated 24 September 2025, status Current, and that it superseded BS 9991:2015, which was withdrawn on 21 November 2024, which in turn superseded BS 9991:2011, withdrawn 31 October 2015. Scope for the 2024 edition covers dwellings (single-family houses, self-contained flats or maisonettes), blocks of flats, residential accommodation blocks with individual bedrooms and kitchen or sanitary facilities, specialized housing and care homes. Care homes are new to the 2024 scope: the 2011 edition expressly excluded residential care and nursing homes. The earlier editions confirm the standard applies not only to new buildings but to material alterations, extensions and material changes of use of an existing building, which is why it is cited on loft conversions and flat conversions, and that it complements BS 9999, the equivalent code for non-residential buildings. The 2015 edition renamed sheltered and extra care housing as specialized housing and added expanded recommendations for escape from basements, lifts, power supplies, cluster accommodation and management of additional needs and disabilities.
Cited in PIR vs Mineral Wool Insulation Compared.
- strong RN-FMD1BX cited
BSI (British Standards Institution)
STATUS: WITHDRAWN on 31 January 2014. BS EN 1194:1999 was published 15 September 1999 and gave the strength classes for glued laminated timber and the method of determining its characteristic values, covering bending, tensile and compressive strength, modulus of elasticity and density. It is the origin of the GL24, GL28 and GL32 class names, and it has been replaced by BS EN 14080, Timber structures. Glued laminated timber and glued solid timber. Requirements, which now carries both the product requirements and the strength classes. A note specifying a glulam beam to BS EN 1194 is quoting a standard withdrawn in 2014 and should cite BS EN 14080; note also that the class designations changed with the move, with homogeneous and combined layups distinguished as GL28h and GL28c. Catalogue page confirms number, title, publication date, withdrawal date and scope but does not name the replacement.
Cited in Structural Materials: The Complete Guide.
- strong RN-02VRB9 cited
BSI (British Standards Institution)
STATUS: CURRENT (marked Under Review). BS EN 13670:2009 was published 28 February 2010, is identical to EN 13670:2009 and sits under ICS 91.080.40. It specifies the execution (workmanship) requirements for concrete structures in buildings and other engineering works, covering falsework and formwork, reinforcement and prestressing, concreting, curing, inspection and permitted geometric tolerances, for reinforced, prestressed and precast concrete. It is the site counterpart to design under BS EN 1992-1-1 and to the concrete specification standards BS EN 206 and BS 8500, so a note describing how a slab or foundation should actually be placed and cured should cite BS EN 13670 rather than the design code. It replaced the execution content previously carried in the withdrawn BS 8110. Catalogue page confirms number, title, date, status and scope; the tolerance tables are paywalled.
Cited in Rebar & Steel Mesh: Sizes, Grades & When You Need Them.
- strong RN-2FH5S1 cited
BSI (British Standards Institution)
STATUS: CURRENT. BS EN 13956:2012 was published 31 January 2013, is identical to EN 13956:2012 and supersedes BS EN 13956:2005. It gives the definitions and characteristics for plastic and rubber sheets used for roof waterproofing, specifying the requirements and test methods and providing for evaluation of conformity, with thermoplastic rubber blends and alloys covered and typical materials and applications set out in Annex E. This is the harmonised product standard behind single ply flat roof membranes such as EPDM, TPO and PVC, so it is what a note should cite when it says a single ply membrane is CE or UKCA marked, as distinct from BS EN 13707 for reinforced bitumen membranes and BS 6229 for the design of flat roofs with continuously supported coverings. Catalogue page confirms number, title, date, status and scope; the characteristic tables are paywalled.
Cited in Flat Roof Materials: EPDM vs GRP vs Felt.
- strong RN-K45EY4 cited
Royal Institution of Chartered Surveyors
The rulebook behind every professional cost per square metre figure, and free to download as a PDF from RICS, which makes it directly citable rather than paraphrased. NRM 1 is issued by the RICS Quantity Surveying and Construction Professional Group as one of a suite of three (NRM 1 order of cost estimating and cost planning, NRM 2 detailed measurement for building works, NRM 3 order of cost estimating and elemental cost planning for building maintenance works), all reissued in October 2022 as practice information having been published in October 2021 as guidance notes, with no material change to content. NRM 1 covers quantification of building works for cost estimates and cost plans, and also how to quantify the items that are not measurable building work: preliminaries, overheads and profit, project team and design team fees, risk allowances, inflation, and other development and project costs. It sets out the floor area method for order of cost estimates and defines the terms a note should use precisely: cost per m2 of gross internal floor area (cost/m2 of GIFA) is the unit rate which, when multiplied by the gross internal floor area, gives the total building works estimate, and gross internal floor area (GIFA, also gross internal area or GIA) is defined in Appendix A with reference to the latest edition of the RICS Code of Measuring Practice. It also distinguishes GEA (gross external area) and NIA (net internal area). This is the source to cite for why a cost per m2 figure is meaningless without stating which area basis it uses.
Cited in Quantity Surveyors for Homeowners: Do You Need One, Quote vs Estimate: What's the Difference.
- strong RN-ZGS3SN cited
TrustMark
TrustMark is the government endorsed quality scheme for work in and around the home, endorsed by the Department for Energy Security and Net Zero and the Department for Business and Trade. It vets registered businesses against required standards and holds ISO 9001, ISO 27001 and Cyber Essentials accreditation. Registration is the marker to check for grant-funded energy efficiency work, so a note about a subsidised loft insulation installer should point readers here rather than to a lead generation directory.
Cited in How to Find & Vet a Good Builder, How to Get & Compare Building Quotes, Insulation: The Complete Guide, Project Managing Your Own Renovation and 2 more.
- good RN-9GR88V cited
SCI and BCSA (steelconstruction.info)
Describes the hot rolled open sections used in UK construction: universal beams (UB), universal columns (UC), parallel flange channels (PFC), equal and unequal angles, and circular, square and rectangular structural hollow sections. Sections are designated by a serial size (nominal section depth and flange width) plus a weight per metre, which is why a beam is quoted as, for example, 203 x 133 x 25 UB. Dimensions for UB, UC and PFC are given in BS EN 10365, angles in BS EN 10056, and design and detailing dimensions in SCI publication P363 (the Blue Book). Hot rolled open sections are produced in lengths up to about 25 m, and S355 is the grade most commonly used in construction.
- good RN-4XLSRL cited
Structural Timber Association
The Structural Timber Association's SIPs guide says the SIPs market was led by North America, that certified SIPs have been available in the UK since 2000, and that SIPs are now recognised as mainstream.
Cited in SIPs Extension Cost: Are Structural Panels Worth It?.