Insulation & Membranes
357 sources in the library on insulation & membranes. 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 5 of 9.
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Office for Product Safety and Standards
The searchable national database a reader can use to check whether a specific building product, appliance or tool has been recalled or flagged, run by the Office for Product Safety and Standards. Holds 3,692 reports at the date checked, filterable by alert type (product safety alert, product safety report, product recall), risk level (serious, high, medium, low, not provided), product category, measure type and date. Relevant product categories for renovation work include Construction products, Gas appliances and components, Electrical appliances and equipment, Lighting equipment, Adaptors, plugs and sockets, Hand tools, Machinery, Lifts, Pressure equipment and vessels, Furniture and Personal protective equipment. Measure types range from warning consumers of the risks and marking the product with warnings, through modification programmes and withdrawal from the market, to recall from end users, destruction of the product, import rejected at border and removal of the listing by the online marketplace. Entries carry a reference number and date, for example Sophie Allport Doorstops and Draught Excluders (2608-0008) recalled 13 August 2026.
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Scottish Government
The Scottish rule that explains why boarding out and over-stuffing a loft causes damp. Standard 3.15 requires the building to be designed and constructed so there is no threat to the building or to occupants' health from surface or interstitial condensation. For a cold pitched roof with insulation at ceiling level, cross-ventilation of the roof space is required, and the handbook states that ventilation is vital for preventing excessive build-up of condensation in cold pitched roof spaces. Where a metal roof finish is used, a high performance vapour control layer is recommended near the inner surface with a ventilated air space on the cold side of the insulation. The numerical opening areas and the assessment method are not restated in the handbook: it directs the reader to BS 5250:2002 Code of practice for the control of condensation in buildings, naming Section 8 and Annex D for detailed assessment and construction methods, and to BRE Report BR 262 Thermal insulation: avoiding risks for acceptable insulation performance. Cite it alongside the roof ventilation figures when advising on boarding a loft or raising insulation depth.
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Scottish Government (gov.scot)
The in-force Scottish handbook, 13.6 MB PDF, applying from 6 April 2026. Figures a note on Scotland needs: Standard 4.6 requires a dwelling to have at least 4 thirteen-amp socket outlets in each apartment, 6 in the kitchen of which at least 3 above worktop level in addition to any for floor standing or built-in appliances, and a further 4 anywhere in the dwelling including at least 1 in each circulation area per storey, with no equivalent requirement in England. Clause 4.6.1 requires at least one lighting point in every circulation space, kitchen, bathroom, toilet and any space of 2 m2 or more; clause 4.6.2 sets 100 lux on stair flights and landings and 50 lux elsewhere in common circulation areas. Table 3.11 sets background ventilator equivalent areas of 12,000 mm2 per apartment and 10,000 mm2 for a kitchen, utility, toilet, bathroom or shower room, doubled where ducted, with part of the ventilator at least 1.75 m above floor level. Table 3.12 sets intermittent extract rates of 30 l/s over a hob, 60 l/s elsewhere in a kitchen, 30 l/s utility, 15 l/s bathroom or shower, 6 l/s WC, with fan and background ventilator at least 0.5 m apart. Table 6.2 sets maximum U-values of 0.17 wall, 0.15 floor, 0.12 roof, 1.4 windows, roof windows and doors, 2.1 rooflights, with a Window Energy Rating or Doorset Energy Rating of B or better as an alternative for units in an existing building; for 1 or 2 matching replacement windows the frame may be disregarded if the centre pane U-value is 1.2 W/m2K or less, secondary glazing should reach about 3.5 W/m2K, and total glazed area should not exceed 25 per cent of dwelling floor area. Clause 4.8.2 requires glazing to BS 6262-4:2018 within 800 mm of floor level, in a door leaf, or within 300 mm of a door leaf and within 1.5 m of floor level, with manifestation between 850 mm and 1.0 m and between 1.4 m and 1.6 m above floor level. Clause 4.8.3 requires any window or rooflight more than 4 m above adjacent ground or floor to be cleanable safely from inside per Clause 8 of BS 8213-1:2004, from a loadbearing surface, or from a mounted access system, sets safe reach limits of 610 mm downward and an 850 mm radius arc from a point not more than 1.3 m above floor level, and bars ladder access to glazing more than 9 m above the ladder's footing.
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Scottish Government (gov.scot)
Scotland's equivalent of the Approved Documents, and the reason a note that quotes only English rules is wrong for a fifth of the UK. This edition is in force from 6 April 2026 and applies to building warrants submitted on or after that date and to work not requiring a warrant commenced from that date. It gives guidance on achieving the standards set in the Building (Scotland) Regulations 2004, arranged in sections rather than parts: section 3 environment (ventilation, drainage, condensation), section 4 safety (electrical safety and installations, glazing and danger from accidents, including clause 4.13 which invokes PAS 24 for security), section 6 energy (U-values for windows and doors) and section 7 sustainability. Scotland uses a building warrant and a completion certificate rather than a building notice, and has no Part P competent person scheme equivalent, so electrical work is covered by the warrant system instead.
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Scottish Government (gov.scot)
SCOTLAND, last updated 24 August 2026. Confirms the EPC in Scotland is administered separately from England and Wales: buildings are rated A to G with A most efficient, the certificate lists improvement measures with an indicative cost for each, and it is accompanied by a recommendations report. The assessment reflects the building not the occupants, using standard assumptions about occupancy and use, and carries no personal data other than the assessor's name and contact details. For non-domestic buildings the EPC shows an asset rating alongside primary energy use. The page states that EPCs in Scotland are being reformed by the Energy Performance of Buildings (Scotland) Regulations 2025, replacing the 2008 regulations, with new-style certificates and strengthened quality assurance. Enquiries go to EPCenquiries@gov.scot, not to an England service.
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The National Archives (legislation.gov.uk)
Sets out exactly what a declaration of performance must contain, which is what to look for when checking a product claim. Article 6(2) requires the product-type reference, the system or systems of assessment and verification of constancy of performance from Annex V, the reference number and date of issue of the designated standard or UK Technical Assessment used for each essential characteristic, and any Specific Technical Documentation reference. Article 6(3) requires the intended use or uses, the list of essential characteristics, the performance of at least one essential characteristic, performance stated by level, class or description, and crucially that any listed essential characteristic for which no performance is declared must carry the letters NPD, meaning No Performance Determined. Article 6(4) requires the declaration to follow the model in Annex III.
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The National Archives (legislation.gov.uk)
The instrument that made the 2021 changes real, so a note can date them exactly. Regulation 1 sets citation and commencement on 15 June 2022, extending to England and Wales but applying to buildings and building work in England. Regulation 11 amends Schedule 1: it adds "to a reasonable standard" to entry L1(b)(i), inserts new requirement L2 on on-site generation of electricity (systems must be appropriately sized, have effective controls and be commissioned to produce the maximum electricity reasonable in the circumstances), and inserts a whole new PART O OVERHEATING with requirement O1, reproduced in full and carrying NO limits on application. Regulation 4 inserts regulation 4(4) and 4(5), a rule renovation guides almost never mention: where Part L imposes a requirement on the work, then on completion the whole building must comply with Part F or be no more unsatisfactory in relation to Part F than before the work began, so a Part L job such as new glazing or wall insulation drags a whole-house ventilation duty with it. Regulation 8 inserts regulations 40A and 40B, requiring the person carrying out the work to give the owner information about an on-site electricity generation system, and about the Part O overheating provision, no later than five days after completion. Regulation 17 is the transitional provision: the amendments do not apply where a building notice or initial notice was given, or full plans deposited, before 15 June 2022, provided the work started before 15 June 2023.
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The National Archives (legislation.gov.uk), Acts of the Scottish Parliament
SCOTLAND. The default rules for organising and paying for common repairs in a Scottish tenement, in force since 28 November 2004. Rule 1.2 defines scheme property and rule 1.4 a scheme decision; maintenance expressly includes repairs, replacement, the installation of insulation, cleaning, painting, routine works and gardening, but not demolition, alteration or improvement unless reasonably incidental. Rule 2.2 allocates one vote per flat and rule 2.5 makes a scheme decision by simple majority of all votes allocated, so a single objecting owner cannot block a repair. Rule 2.6 requires at least 48 hours notice of a meeting, and rule 2.10 lets any owner who did not vote in favour and who would bear not less than 75 per cent of the costs annul the decision, within 21 days of a meeting they attended. Rule 4.1 lists the recoverable scheme costs including common insurance and door entry systems. Rule 4.2 shares maintenance costs equally among the flats unless the largest flat's floor area is more than one and a half times the smallest, in which case liability is apportioned by floor area; rule 4.3 applies that same floor-area test to the roof over the close.
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UK Health Security Agency
UKHSA's cold weather health guidance, first published 2 November 2012 and last updated 28 April 2026, applying to England, reference GOV-15292. Establishes the alerting framework a heating or insulation note can anchor to: the UKHSA Cold-Health Alerting system is operated by the Met Office and runs from 1 November to 31 March each year, and this guidance forms the cold weather part of UKHSA's Adverse Weather and Health Plan, whose aim is to protect health and reduce harm from adverse cold weather. Issued in several formats including an HTML main version, an easy read PDF of 8 pages, a British Sign Language video, a two-page print version of top tips, and a poster, with easy-read translations added on 28 April 2026 in Arabic, Bengali, Gujarati, Hindi, Italian, Kutchi, Punjabi, Portuguese, Somali, Tamil and Urdu.
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UK Health Security Agency and Centre for Climate and Health Security
UKHSA guidance published 7 August 2025, applying to England, on the allergens and irritants in indoor air, useful for any note that claims a renovation improves or harms air quality. States that indoor bioaerosols can contribute up to 34 per cent of indoor air pollution, and that people in Western countries spend the majority of their time indoors. Identifies the protein-based allergens as mould spores, which thrive in damp poorly ventilated spaces such as bathrooms and arise from leaks, condensation, poor heating or inadequate ventilation; house dust mites, which thrive in warm humid environments in bedding, carpets and upholstered furniture; and pet dander from skin flakes, urine and saliva. Separately names non-protein respiratory irritants: volatile organic compounds emitted by paints, cleaning agents and air fresheners, and particulate matter from cooking, smoking and open solid-fuel fireplaces. Warns that energy efficiency and adaptation measures can have unintended consequences for indoor environmental quality, and that poorly installed mechanical ventilation can worsen air quality.
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Welsh Government (gov.wales)
The Welsh Approved Document L Volume 1, in force until 3 March 2027, and the source for Welsh window figures, which are not identical to England's. Table 10.1 sets, for new and replacement windows and roof windows, a maximum U-value of 1.4 W/(m2K) or WER Band B, with an alternative for replacements of 1.2 W/(m2K) centre pane or low-E secondary glazing, and a threshold U-value for retained windows of 3.3. Rooflights: 2.2 for new and replacement, threshold 3.8. Doors more than 60 per cent glazed: 1.4 or DSER Band C, alternative 1.2 centre pane, threshold 3.3. All other doors: 1.4 or DSER Band B, threshold 3.3. External fire doorsets as defined in Approved Document B Volume 1 may be 1.8. Transitional easements allowed timber windows at 1.6 or WER Band C and timber doors at 1.8 or DSER Band E only where a building notice, initial notice or full plans were given before 23 November 2023. Paragraph 11.35 requires an existing window or door worse than the column (c) threshold to be replaced to column (a); paragraph 11.37 states that windows and doors mean the whole unit including the frame, so replacing just the glazing or the door leaf while retaining the existing frame is not building work and does not have to meet the energy efficiency requirements, though upgrading as close as practicable is sensible; paragraph 11.38 caps the total area of windows and doors at 25 per cent of total floor area where one is enlarged or created.
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Welsh Government (gov.wales)
The Welsh Government landing page that shows which edition of Approved Document L applies in Wales and when. Two editions of Volume 1 (dwellings) sit side by side: the current edition in force until 3 March 2027 at /sites/default/files/publications/2024-05/building-regulations-approved-document-l-vol-1.pdf, and the 2026 edition in force from 4 March 2027 at /sites/default/files/publications/2026-04/building-regulations-approved-document-l-vol-1-2026.pdf. Note the date differs from England, where the 2026 edition of Approved Document L takes effect on 24 March 2027, so a note giving a single UK-wide changeover date is wrong for Wales by three weeks.
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BBA (British Board of Agrement)
The certification body whose Agrement Certificate is what a note usually means when it says a system is approved, and the page that lists which schemes it actually runs. The BBA's certification team issues certificates for the BBA Agrement, HAPAS (Highways Authority Product Approval Services), European Technical Assessment (ETA), and the Microgeneration Certification Scheme. Alongside product certification it runs certification of people, including the BBA Approved Installer Scheme, the BBA Competent Person Scheme, the BBA Gas Membrane Approved Installer Scheme, TrustMark registration and the BBA PAS 2030 Scheme, plus a Client Managed Inspection Service. Its testing services are also available standalone and include durability, mechanical, physical and structural, weather resistance and wind serviceability, conformance and fit-for-purpose, thermal performance, and onsite testing and trials. An Agrement Certificate is the route by which a product without a harmonised European product standard, such as a tanking membrane, a multifoil or a proprietary EWI system, gets an independently assessed statement of fitness for a stated use.
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BRE (Building Research Establishment)
The document that decides how a U-value must be calculated in the UK, so it is the arbiter when a manufacturer's claimed U-value and a building control assessment disagree. Published by BRE Electronic Publications, authors Brian Anderson and Ludmilla Kosmina, A4, 80 pages, published date 18 November 2020, ISBN 9781848064812, and section 11.1 has been updated since the 2019 publication with the update appended at the end. It concerns the calculated U-values of new building elements including walls, roofs, floors, windows and doors. Section 3 gives guidance on thermal conductivity of materials, section 4 on the issues that commonly arise in a U-value calculation, and sections 7 to 14 on the individual construction element types, identifying which section 4 issues apply to which construction. It deliberately does not reproduce the calculation methods themselves, referring the reader to the relevant British Standards, which is why it is a conventions document rather than a method. The 2002 edition remains available separately.
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BRE Group
Important currency point for any note mentioning certification schemes: the Home Quality Mark no longer exists under that name. BRE has folded it into the BREEAM product range as BREEAM UK New Construction: Residential, with version 6.1 released in April 2025. HQM led residential sustainability assessment in the UK from 2015 with more than 50,000 homes registered. The scheme assesses homes against three sustainability indicators covering environmental performance (carbon emissions, resource efficiency, biodiversity, circular design), social performance (occupant health and wellbeing, indoor air quality, daylight, thermal comfort, noise, access to green space) and economic performance (efficient use of materials, future-ready infrastructure, running costs, adaptability). Homes are rated on a scale from pass to outstanding. BRE states the certification recognises performance BEYOND minimum regulations only, and that certification can open access to green mortgages and investment incentives. Separately, BREEAM Refurbishment and Fit-Out (currently V7) is the BREEAM standard covering refurbishment rather than new build, and BREEAM has run third-party certified standards since 1990.
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BSI (British Standards Institution)
The large-scale fire test that an external wall insulation or rainscreen system is put through when the route to compliance is a full system test rather than an A2 or A1 Euroclass on every component. Published 30 Apr 2020 and Current, superseding BS 8414-1:2015+A1:2017. Part 1 provides the test method for determining the fire performance characteristics of non-loadbearing external cladding systems, rainscreen over-cladding systems and external wall insulation systems fixed to and supported by a masonry substrate and exposed to an external fire under controlled conditions, recording fire propagation upwards, penetration through the system, falling debris and the extent of damage. Its stated exclusions matter when reading a manufacturer's test claim: it does not cover the performance of glass or its supporting frame for glazed window openings, the total configuration of a construction incorporating additional windows, doors, balconies or ancillary penetrations, or exposure to radiant heat from a fire in an adjacent building. Part 2 is the equivalent test on a structural steel frame.
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BSI (British Standards Institution)
The standard that governs how far a BS 8414 test result can be stretched to cover a system that is not identical to the one tested, which is the question behind most cladding compliance disputes. Published 30 Sep 2019 and Current. It specifies the procedures and rules used to evaluate variations and changes to products and systems tested to BS 8414-1:2015+A1:2017 or BS 8414-2:2015+A1:2017, and defines the options and limits for preparing reports on direct and extended application criteria. The systems covered are rainscreens, external thermal insulated composite systems (ETICS) and self-supporting double skin metal faced insulating sandwich panels. It expressly does not cover the performance of systems that include glazed elements, infill panels or external insulation finishing systems (EIFS), nor systems tested to BS EN 1364. A note explaining why a supplier's test certificate may not cover the exact build-up on a given house can cite this directly.
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BSI (British Standards Institution)
The test method that produces a lambda value, so it is the answer to how an insulation board's declared thermal conductivity is actually measured. Published 15 Mar 2001, current but under review. It specifies principles and testing procedures for determining thermal resistance by the guarded hot plate and heat flow meter methods, for specimens with a thermal resistance of not less than 0.5 m2K/W, and gives mandatory limits for equipment design and operation plus examples of compliant apparatus so accuracy can be assessed by performance check rather than error analysis. Two limits matter when a marketing claim is being checked: it does not cover measurements on moist products of any thermal resistance, nor on thick products of high and medium thermal resistance, and it must be used in conjunction with the relevant product standard because it does not itself say which heat transfer property to report or how to prepare a product-specific specimen.
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BSI (British Standards Institution)
The product standard for phenolic foam, the thinnest of the common rigid boards and the one behind premium products such as the Kooltherm range. Published 28 Feb 2013, Current, with Designated status for UKCA marking. It specifies requirements for factory made phenolic foam products with or without facings or coatings used for the thermal insulation of buildings, manufactured as boards and laminates, and also used in prefabricated thermal insulation systems and composite panels. Its exclusion thresholds are tighter than the other boards, which reflects phenolic's lower lambda: products with a declared thermal resistance below 0.40 m2K/W or a declared thermal conductivity above 0.050 W/mK at 10 degrees C fall outside it, against 0.25 m2K/W and 0.060 W/mK for mineral wool, EPS, XPS and PU. It does not cover in situ thermal insulation products or insulation of building equipment and industrial installations, and does not set the property level a product must reach in a given application.
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BSI (British Standards Institution)
The product standard for the VCL, the warm-side sheet that stops interstitial condensation in a vaulted ceiling or timber frame wall. Published 31 Mar 2013, Current, with Designated status for UKCA marking. It specifies the characteristics of flexible sheets of plastic or rubber intended for use as water vapour control layers in buildings, and applies to both reinforced and unreinforced products. It is the counterpart to BS EN 13859-1 and -2 for underlays: a note explaining that a VCL and a breather membrane are opposite-facing products with opposite jobs can cite this standard for the vapour control layer and the 13859 parts for the breather side, with the condensation risk method itself in BS 5250 and BS EN ISO 13788.
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BSI (British Standards Institution)
The standard at the centre of the multifoil insulation argument, because it is the agreed route to a declared figure for a product whose performance depends on airspaces rather than thickness alone. Published 29 Feb 2012 and withdrawn 13 Jul 2023, so it should be cited as the historic test route rather than a live one. It describes procedures for using existing CEN and ISO test and calculation methods to determine the declared thermal performance of reflective insulation products, and it supports rather than replaces those methods. It applies to any thermal insulation product deriving a proportion of its claimed thermal properties from one or more reflective or low emissivity surfaces together with the associated airspaces, and does not replace the procedures for products already covered by a harmonised product standard where the declared value makes no claim attributable to facing emissivity. It classifies four product types: Type 1 insulation material with a reflective facing on each side, Type 2 bubble foil with reflective surfaces, Type 3 stitched multi-foil, and Type 4 multiple layers used under flooring. It also sets general requirements for testing, for measuring specimen thickness, and for establishing measurement uncertainty.
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BSI (British Standards Institution)
STATUS: WITHDRAWN on 28 February 2014. BS EN ISO 140-4:1998 was published 15 October 1998 and gave the methods for measuring the airborne sound insulation of interior walls, floors and doors between two rooms on site, producing frequency dependent values that are converted to a single number rating using ISO 717-1 so that performance can be compared against a specification. It was replaced by the BS EN ISO 16283 series, with BS EN ISO 16283-1 covering field measurement of airborne sound insulation, and the laboratory measurements formerly in other parts of BS EN ISO 140 moving to BS EN ISO 10140. Any note describing a pre completion sound test to BS EN ISO 140 is quoting a standard withdrawn in 2014: Approved Document E testing is now to the BS EN ISO 16283 series with rating to BS EN ISO 717. Catalogue page confirms number, title, publication date, withdrawal date and scope.
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BSI (British Standards Institution)
STATUS: CURRENT. BS EN ISO 717-1:2020 was published 31 December 2020 and supersedes BS EN ISO 717-1:2013, which is withdrawn. It defines the single number quantities for airborne sound insulation in buildings and building elements, that is the method for converting a frequency dependent measurement into one figure, and it covers spectrum adaptation terms for different noise sources including internal noise and external traffic noise. The 2020 revision moved content in from ISO 10140-1:2016 and ISO 10140-5:2010 and updated the references. This is the standard behind the Rw, DnT,w and DnT,w + Ctr figures quoted in soundproofing notes and in Approved Document E, and its companion BS EN ISO 717-2:2020 does the same for impact sound (Lnw, LnT,w). Catalogue page confirms number, title, date, status, supersession and scope; the calculation method is paywalled.
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BSI Group
What the Kitemark actually certifies, which matters because it is often confused with CE or UKCA marking and with BSI standards themselves. States that Kitemark certification confirms a product or service's claim has been independently and repeatedly tested by experts, so it is third-party certification of continued conformity rather than a manufacturer's own declaration. Records that the mark was originally known as the British Standard Mark and was first registered as a trademark in June 1903, giving it more than 120 years of use. Cites BSI's own consumer research that the Kitemark is recognised by 67 per cent of UK consumers, and that 70 per cent are more confident in products carrying it than in products that do not. Certification spans products, services and processes, including building information modelling and inclusive service certification, and BSI publishes a searchable Kitemark directory and a Verify a Certificate service for checking a specific certificate.
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Chartered Institution of Building Services Engineers
The design guide a heating engineer sizes a domestic system from, and the right citation for any note about radiator or cylinder sizing. Publisher CIBSE, status Active, 415 pages, publication date January 2026, ISBN 9781918034196, priced GBP 45 plus VAT for the book and GBP 60 plus VAT for the PDF at standard rate, so the text itself is paywalled and only the catalogue page is public. The catalogue page confirms what the 2026 edition changed: heat loss assessment now follows the BS EN 12831-1:2017 method, domestic hot water cylinder sizing follows BS EN 12831-3:2017 including sizing for storage below 60 degrees C and a thermal disinfection procedure, U-value tables have been updated for modern construction methods, and the latest CIBSE weather data is used with 28 zones and four outdoor design temperatures. It also introduces a System Criteria Document recording design decisions and client and designer sign-off, explicitly in line with the Building Safety Act, plus a new controls section and expanded hydraulic and system configurations. Note the versioning trap: version 2026-02 published in July 2026 supersedes version 2026-01, and CIBSE advises reading the accompanying corrigendum alongside the guide.
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Chartered Institution of Building Services Engineers
The core CIBSE reference for design criteria and calculation methods, cited whenever a note needs an authority for indoor design temperatures, fabric performance or heat loss and ventilation sizing. Publisher CIBSE, status Active, 402 pages, publication date March 2015 with a 2021 update, ISBN 9781906846541. The text is paywalled at GBP 200 plus VAT standard rate for the book and GBP 150 plus VAT for the download, free to CIBSE members, so only the catalogue page is public. The page confirms the scope: design criteria and calculation methods covering fabric performance, heating and ventilation system sizing, methods for thermal comfort evaluation and energy demand. Two currency notes recorded on the page matter for anyone citing it: Chapter 2 of Guide A supersedes TM34 Weather data with climate change scenarios (2004), and the Guide references BS EN 779:2012 for air filters, which has since been superseded by BS EN ISO 16890. The supplementary data files are downloadable free and include external design data, UK wind roses (Figure 2.8), solar irradiation on inclined planes (Table 2.12), sol-air temperatures (Table 2.14) and UK cooling load tables (Tables 5.16 and 5.17).
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Chartered Institution of Building Services Engineers
TM59 is the dynamic thermal modelling methodology that Approved Document O Section 2 names as its alternative to the simplified glazing and free-area route, so it is a required citation for any note about overheating. This page is for the 2026 edition, published July 2026, 39 pages, ISBN 9781912034123, and it is FREE to download at both standard and member rate, unusually for CIBSE. The critical compliance point stated on the page: TM59 (2017) is still the version required for compliance with Part O, and CIBSE recommends TM59 (2026) only for industry best practice while it discusses with the Building Safety Regulator how the updated weather files and new version might be incorporated into the Approved Documents. So a note must not tell a reader that the 2026 edition satisfies Part O. The 2026 update adds a new bedroom overheating criterion based on Loughborough University research, updated ceiling fan modelling presenting fans as an effective passive comfort solution, and mandates that all homes be tested under unconstrained conditions using 2050s weather data. TM59 applies to houses, apartments, sheltered accommodation, care homes, student accommodation, prisons and bedrooms in hotels and hospitals, and covers new dwellings and major refurbishments. The page also records that in 2026 the Climate Change Committee raised risks to buildings and communities from heat to its highest category, Critical Action needed.
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UKAS
The body that sits one level above every certification mark a product carries, and the answer to the question of who checks the checkers. UKAS states that it is the National Accreditation Body for the United Kingdom, appointed by government to assess and accredit organisations providing services including certification, testing, inspection, calibration, validation and verification. Its site carries a searchable directory of accredited organisations, an explanation of the difference between accreditation and certification, and an impartiality statement. This matters for the insulation and cladding clusters in particular: a performance claim tested at a UKAS accredited laboratory, or certified by a UKAS accredited certification body such as the BBA or WRAS, sits on a different footing from an in-house test result or a self-declared figure, and the directory lets that be checked rather than assumed.
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United Kingdom Accreditation Service
UKAS explains what each sanction means in practice. A suspension is normally temporary, with the body expected to regain accreditation within three months and up to nine in exceptional circumstances. While suspended an organisation cannot provide accredited services, cannot issue new accredited certificates, and must tell existing and prospective customers of its status. Certificates issued before the suspension remain valid unless they were issued incorrectly, though annual surveillance or renewal visits falling inside the suspension period may not be supportable.
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AECB (Association for Environment Conscious Building)
The AECB retrofit standard page, and a useful source of real certified-project performance figures rather than manufacturer claims. The standard requires all-round insulation, minimised summer overheating, moisture risk addressed at junctions, and a low carbon heating system, with certifiers trained specifically in moisture and other risks and junctions assessed for moisture. The page lists certified projects with their measured or designed outcomes: Ward Grove, a 1983 to 1992 private house completed 2023, external insulation, triple glazed, MVHR heat recovery ventilation, space heating 37 kWh/m2 per year; Foxlow, a 1900 to 1918 private house completed 2023, wood fibre internal wall insulation, triple glazed, MVHR, space heating 32 kWh/m2 per year and airtightness 1.9 m3/m2.hr; and a Wrexham retrofit of a 1960s house, external insulation, triple glazed, MVHR, space heating 30 kWh/m2 per year. These are the numbers to quote when a note needs a realistic UK deep-retrofit space heating figure. The page also confirms the step-by-step route exists for households retrofitting in phases.
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AECB (Association for Environment Conscious Building)
The AECB CarbonLite family, the main UK alternative to Passivhaus for a homeowner who wants a measurable low-energy target rather than minimum Building Regulations compliance. The page names four standards and three supporting guidance documents: CarbonLite New Build for new domestic and non-domestic projects; CarbonLite Retrofit for individual or multifamily homes and non-domestic buildings; CarbonLite Retrofit Step-by-Step, designed principally for retrofitting individual or multifamily homes in stages rather than in one go; and the Water Standard for water efficiency in domestic and non-domestic projects, plus Daylighting design guidance (with an AECB CarbonLite software tool) and Airtightness guidance. Each standard has its own detailed guidance PDF. Two facts worth citing: AECB set up the Passivhaus Trust in 2010, so the two bodies are related rather than rivals, and AECB CarbonLite certified homes qualify for Ecology Building Society C-Change mortgage discounts of up to 1.50 percent off the standard variable rate, applied for the lifetime of the mortgage on completion of the project, which is a rare concrete financial consequence of a voluntary standard.
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BSRIA (Building Services Research and Information Association)
BSRIA is UKAS accredited for airtightness testing and this page sets out what a test involves and when it is required, which is the practical detail behind a Part L conversation. It confirms BSRIA is an ATTMA member, UKAS accredited to test to CIBSE TM23, BS EN 13829 and ATTMA TS L1, and that its certificates are recognised by building control. On when testing bites: the page states airtightness testing of new dwellings is mandatory for developments of over two units, that a sample of each dwelling type must be tested and must fall within the air leakage rate stated in that dwelling SAP calculation, and that for developments of one or two units testing is not mandatory but an assumed air leakage rate above the industry norm must be used instead, so it is usually simpler and cheaper for a builder to test and prove a lower rate. It also lists the information needed to plan a test regime: SAP calculation worksheets, floor plans and sections for each dwelling, the regulation or standard being met, site layout and build programme. Diagnostics offered on a failure include infrared thermography and smoke tests to find leakage paths. Note the page still uses the pre-2021 label Part L1A alongside Section 6 of the Scottish Building Standards, so check the current Approved Document L Volume 1 wording before quoting the sampling rule as current.
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CIGA (Cavity Insulation Guarantee Agency)
The route to getting failed cavity wall insulation put right under the 25 year CIGA guarantee, which is the part homeowners most often do not know exists. CIGA maintains both a register of registered installers, whose work carries the guarantee, and a separate list of remediation contractors used where an existing installation has failed and needs extraction or repair. The site also carries the consumer complaints process, a route to report a concern online, guidance on misuse of the CIGA logo, and its annual review and statistics with published performance targets. A note about damp or cold spots after cavity fill should send the reader to the guarantee and the complaints process here rather than back to the original installer alone.
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INCA
INCA is the recognised trade association for the external wall insulation industry in the UK, established in 1981, representing system designers, installation contractors and component suppliers in three membership categories: EWI installers, EWI system designers, and INCA Associates. Members must meet published criteria, set out in Membership Criteria Combined 2025, so that a client is engaging a specialist contractor meeting recognised standards of competence. Its knowledge hub carries EWI Retrofit PAS 2035 guidance, external wall insulation FAQs, technical guidance, the EWI Industry Report 2025 and publications on the benefits of EWI and the fabric-first approach. Useful for the PAS 2035 requirement behind grant-funded EWI and for pointing a reader at a competent installer.
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INCA (Insulated Render and Cladding Association)
The trade association's collected answers on external wall insulation, useful for the practical questions a cost or how-to note has to handle: whether EWI suits a given construction type, what survey and system design precede specification, how insulant type and thickness are chosen against overhangs and boundaries, what render and brick slip finishes are available, and how INCA member systems are certified. Sits within INCA's Knowledge Hub alongside its technical guidance, its EWI Retrofit PAS 2035 material and the INCA EWI Directory of system designers and contractor members, which is the register to check an installer against.
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INCA (Insulated Render and Cladding Association)
The EWI trade association's own homeowner guide, and one of the few published UK sources with a rate per square metre for external wall insulation. As a very general guide it puts a standard system of 90 mm EPS board fixed to a masonry substrate finished with a lightly textured silicone render at somewhere between 65 and 95 pounds per square metre, with thicker insulation and different finishes increasing that. In whole-house terms it gives roughly 4,000 to 6,000 pounds for a small terraced property, 8,000 to 10,000 pounds for an average semi, and up to 12,000 to 14,000 pounds or more for larger detached homes. On savings it states a reduction in energy usage of up to 40 per cent and cites an Energy Saving Trust estimate of up to 455 pounds a year, expressly noted as a pre-2022 energy price figure. On planning it says in most cases planning permission is not required but the local planning office should always be checked first. On certification it states that all INCA member EWI systems are covered by British Board of Agrement certification, accredited to ISO 9001, and conform to current building and EWI fire regulations. Insulant is typically EPS or mineral fibre, with thickness set by the target thermal improvement and constrained by existing overhangs and by not encroaching on neighbouring property, walkways or public land; finishes include thin coat render, thick coat render, dry dash with local stone chips, stone effect, brick effect and timber panel effect, and these can be mixed on one elevation.
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Insulation Manufacturers Association
The trade association for UK insulation manufacturers, covering PIR/PUR and phenolic foams, polystyrene in both XPS and EPS forms, mineral wools in glass wool and stone wool, natural materials such as sheep's wool, and spray foam. It publishes performance guides on thermal performance, water resistance and fire performance, application guides for wall, roof and floor insulation, separate regulatory information for England, Wales, Scotland and Northern Ireland, sustainability material on end-of-life waste, and CPD courses including Achieving zero carbon and Seven Steps to Fire Safety. It states that PIR insulation is one of the most thermally efficient insulation materials available, which is the manufacturer-side claim a note comparing PIR with mineral wool should attribute rather than assert.
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Insulation Manufacturers Association (IMA)
The IMA's worked explanation of R-value, with a usable number in it. An R-value is a measure of thermal resistance that takes both the lambda value of a material and its actual thickness into account, calculated by dividing thickness by thermal conductivity. The worked example given is a 100 mm PIR board with a lambda value of 0.022 W/mK, which divides out to an R-value of 4.5 m2K/W. The higher the R-value the better the material resists heat flow, and the R-values of the individual components of a wall or roof are what feed the element's U-value calculation. The page also makes the practical trade the site's readers care about: because PIR reaches a given R-value in a thinner layer, using a thicker lower-performance material means either a larger building footprint or smaller internal dimensions.
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Insulation Manufacturers Association (IMA)
The trade association's plain definition of the lambda value, which a note comparing insulation materials needs to get right. Thermal conductivity, also called the lambda value or K-value, is defined as the rate of transmission of energy through 1 square metre of material 1 metre thick with a 10 degrees C temperature difference across it, measured in W/mK. The lower the lambda value, the better the product performs. The lambda value is the input used when calculating an R-value, which in turn feeds a U-value calculation, so the three figures form a chain rather than being alternatives. The site sits alongside IMA pages on R-values and U-values, on fire performance and water resistance, on individual material types (PIR/PUR, phenolic, XPS, EPS, glass wool, stone wool, sheep's wool), and on the building regulations as they apply separately in England, Wales, Scotland and Northern Ireland.
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Passivhaus Trust
The UK body page for the Passivhaus standard, and the right citation for a note explaining low-energy standards above Building Regulations. It confirms EnerPHit is the separate, slightly relaxed Passive House Institute standard for RETROFIT projects, used where existing architecture and conservation constraints make full Passivhaus infeasible, which is the distinction most renovation articles blur. The Trust defines eight Passivhaus principles: the five building principles of insulation, airtightness, ventilation, minimised thermal bridging and high-performance windows, plus three principles of approach, namely detailed performance and comfort criteria, accurate design modelling using the Passive House Planning Package (PHPP), and rigorous quality assurance. It states the UK performance gap between designed and in-use energy conservatively results in a 60% increase in space heating demand in residential buildings, and often considerably more in non-residential, whereas Passivhaus buildings on average perform as designed. On claims: a building may reasonably be called a self-declared Passivhaus provided it satisfies all requirements of the standard, but certification must be by a registered Passivhaus Certifier independent of the design team. Caution when citing numbers: the headline criteria table on this page is published as an image and linked PDF rather than as text, so the numeric targets must be taken from the Passive House Institute criteria document itself.