Brick, Block & Mortar
274 sources in the library on brick, block & mortar. 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 2 of 7.
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BSI (BSI Knowledge catalogue)
Dated 14 March 2005, this gives recommendations for masonry walls above the ground level damp proof course and for walls between ground floor level and the top of foundation level. It applies to low-rise housing of traditional construction comprising detached, semi-detached and terraced houses and flats with not more than four self-contained dwelling units per floor accessible from one staircase, of not more than three storeys above ground and intended for domestic occupation, subject to the limiting conditions stated in the code. It also covers certain small single storey non-residential buildings such as domestic garages and annexes not exceeding 36 square metres in floor area. It is the reference for masonry wall thickness, buttressing and lateral support in ordinary housing without a bespoke engineering design.
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BSI (BSI Knowledge catalogue)
Dated 15 February 2006, this is the execution and durability part of Eurocode 6: it covers design considerations, the selection of masonry materials for a given exposure condition, and the execution of masonry on site, which is where masonry unit and mortar durability selection for exposure is set out. The catalogue page also carries the Eurocode transition note: the second generation of EN Eurocodes is being published between 2023 and 2026, UK adoptions of the first generation will be withdrawn by BSI on 30 March 2028, and until that date the first generation documents should be treated as the applicable standards for buildings and civil engineering works constructed in the UK.
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BSI (BSI Knowledge catalogue)
Dated 31 August 2013 with a 2016 amendment, this is the specification for wall ties, tension straps, hangers and brackets used to interconnect masonry or connect masonry to walls, floors, beams and columns. Where anchors or fasteners are supplied as part of an ancillary component the performance requirements apply to the complete product. Its scope expressly excludes anchors and fasteners other than as part of an ancillary component, shelf angles, wall starter plates for tying into existing walls, and products made from materials other than the listed austenitic stainless steels and other permitted materials. This is the standard a cavity wall tie or a remedial tie should be declared to.
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BSI (BSI Knowledge catalogue)
The standard behind UK masonry mortar specification, dated 30 October 2003. Its scope specifies requirements for factory made masonry mortars for bedding, jointing and pointing in masonry walls, columns and partitions, covering facing and rendered masonry and both loadbearing and non-loadbearing structures. For fresh mortar it defines performance for workable life, chloride content, air content, density and correction time (thin layer mortars only); for hardened mortar it defines compressive strength, bond strength and density against test methods in separate European standards. This is the source for the M classes (for example M4 and M12) that have replaced the older mortar designations i to iv used with cement, lime and sand ratios.
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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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Brick Development Association
BDA structural guide last updated March 2023, from the body whose members account for almost 99 per cent of bricks produced in the UK. It states around 20 per cent of the UK housing stock is more than 100 years old and mostly built of brick. It sets a strict repair sequence: survey first to establish whether the structure is stable and identify defects, then establish the cause (mainly foundations, overloading or unwanted water), then decide remedial measures, and only then consider appearance. The survey is in two parts, accurate drawings (now often by drone or 3D laser scan) and a structural and dilapidations survey using pin type tell-tales rather than strips so movement can be measured. On major alterations it warns that removing loadbearing walls redistributes loading and must be designed by a competent person, that removing internal cross walls can destabilise the external walls they tied, and that solutions include piers, a new loadbearing wall alongside, or transferring load to an independent frame, each of which may need new foundations. On openings it warns that widening concentrates load, and that for openings near a wall junction or chimney breast the lintel should be lengthened to tie into the cross wall or chimney breast, possibly with a matching tie at the threshold. On chimney breasts it states removal should only be considered if acceptable structurally because the heavy mass of brickwork is often providing stability, and that sealed flues need ventilation such as an air brick high in the breast and near the top of the stack to avoid condensation. Later sections cover pointing, matching bricks, foundation failure, leaning and bulging walls, cracking, overloading, failures of bricks and water penetration.
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Brick Development Association
BDA technical support sheet on brick arches, each type drawn at 1:20 elevation. It defines an arch as an arch ring made of truncated wedge-shaped voussoirs that stay in place by mutual pressure, set out in a curved form to span an opening and carry a superimposed load, which is the mechanism a note explaining a failing arch needs. It names and describes the types: Gothic (lancet, drop and equilateral variants), Tudor, Perpendicular, Venetian, Triangular (also called pediment or mitre arch, two courses of stretchers leaning to a mitred apex, common in Anglo-Saxon work), Bullseye (a full circle of voussoirs that remain in compression), Horseshoe, Jack arch (a segmental arch spanning between iron beams to form a vault), Segmental (centre below the springing line), Semicircular (centre on the springing line) and Multi-centred or three-centred. It also establishes the vocabulary of springing line, intrados and voussoir.
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Brick Development Association
BDA technical support sheet describing the bricklaying bonds used in UK brickwork with a figure for each. Stretcher bond was originally used for single brick walls and became the obvious choice for cavity walls because it needs the least cutting, making it the most economical and the one used extensively in modern building. Header bond lays courses flat with the short end exposed so the wall width is the whole length of a brick, historically used for high quality buildings and curved brickwork. English bond alternates courses of headers and stretchers and gives a strong bond in a one brick thick wall, preferred for bridges, viaducts and embankment walls. Flemish bond can be replicated in the half-brick outer leaf of a cavity wall using whole bricks as stretchers and half bricks (bats or snap-headers) as headers, and is not as strong as English bond at one brick thick. Stack bond has no overlap and is inherently weak, so stainless steel ladder reinforcement is typically built into every third bed joint. Monk bond has two stretchers between headers with headers centred over the joint below.
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Brick Development Association
BDA technical guide, 2023 edition. States that brick dimensions declared by the manufacturer are the work size, and that the most widely used work size for UK clay bricks is 215 x 102.5 x 65 mm. Gives the dimensional tolerance categories declared under EN 771-1: for a declared 215 mm the T2 limits are 211-219 mm (plus or minus 4) and the T1 limits 209-221 mm (plus or minus 6); for 102.5 mm, T2 is 99-105 (plus or minus 3) and T1 98-106 (plus or minus 4); for 65 mm, T2 is 63-67 (plus or minus 2) and T1 62-68 (plus or minus 3), with Tm as declared by the manufacturer. Range categories R2/R1/Rm cover the spread within a sample: 4 mm and 9 mm on the 215 dimension, 3 mm and 6 mm on 102.5, 2 mm and 5 mm on 65. Critically for quantity take-off, it gives the coordinating size: allowing for the standard work size plus nominal 10 mm mortar joints gives 225 x 112.5 x 75 mm, which is where the familiar 60 bricks per square metre of single-leaf stretcher bond comes from (1 / (0.225 x 0.075) = 59.3).
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Brick Development Association
BDA technical guide last updated April 2023. It explains that prescribed mortars are specified by proportions whose properties are assumed from the stated proportions of the constituents and classified by designations, with a strength table (Table 1, page 11) offered as a guide rather than an exact equivalence, and that altering the proportions to suit strength, exposure, workability and weather can materially improve durability. Useful quantity figure: one tonne of ready mixed lime and sand, gauged on site with the specified quantity of cement, will generally lay approximately 1000 bricks. On weather it states mortar should not be used when conditions are 2 degrees C and falling, that frozen mortar must be discarded, that unfrozen mortar must not be used on frozen bricks, and that mortar should never be knocked up once it has started to set. It covers accurate gauging using a gauging bucket or box (inaccurate gauging harms structural performance, water demand, durability and sulfate resistance), the benefits of hydrated lime in cement mortars, sulfate resisting cement, and the factory made options: dry ready-to-use, wet ready-to-use retarded mortar delivered in tubs, and single and multi compartment site silos with integral mixers.
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Brick Development Association
BDA technical guide last updated April 2023, aimed at everyone in the delivery chain who needs long lasting results on external works. Its key rule for a spalling or frost damage note: freestanding garden walls, retaining walls and chimneys should always be treated as very severely exposed to frost attack regardless of geographic location, so brick and mortar selection for those elements cannot rely on a mild local exposure assumption. It sits alongside BDA Design Note 7 on brickwork durability and the Mortar for Brickwork guide, and is the document the BDA points to for design considerations on water penetration and exposure.
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Brick Development Association
The Brick Development Association technical library, the trade body reference for UK clay brickwork. Guides include Designing to Brickwork Dimensions (brick sizes and coordinating dimensions), Designing for Movement in Brickwork (movement joint spacing), Mortar for Brickwork (mortar composition and designations), Severely Exposed Brickwork (weather and frost resistance), Resisting Rainwater Penetration (cavity wall construction and water management), Brickwork Durability, Brick Arches, Brick Bonds, freestanding and retaining wall design, Alteration and Repair of Clay Brickwork, and The Rigorous Testing of Clay Bricks. It also publishes an Eurocode 6 series covering vertical resistance, lateral resistance and an introduction to masonry design.
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Mineral Products Association (MPA Mortar)
MPA Mortar is the mortar arm of the Mineral Products Association, the trade association for the aggregates, asphalt, cement, concrete, dimension stone, lime, mortar and industrial sand industries. It publishes data sheets, learning texts, training materials and case studies on factory produced mortars, renders and screeds. It states that over 80 per cent of mortars used in the UK today come from factory produced sources, and that member products comply with BS EN 998-2, ISO 9001 and CE certification. Useful as the authority for the factory made versus site mixed mortar split that a mortar note needs.
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The Concrete Society
The index to the Concrete Society technical library and the place to check a concrete claim against an industry-independent source. Four publication families are listed: Technical Reports giving in-depth guidance on design, construction, maintenance and innovation (for example TR43, Post-tensioned concrete floors design handbook, at GBP 85 full price and GBP 51 to members, and Discussion Document DD51 on calcined clay as a supplementary cementitious material, free to all); Good Concrete Guides on practical aspects (GCG8, Concrete practice, and GCG11, Digital monitoring and measurement of fresh concrete); Advice Sheets on specific topics such as no-fines concrete and brushed and tamped surface finishes; and Fingertips, short free reference pages covering masonry densities, cold joints, consistence tolerance and the slump test, floated and trowelled finishes, core testing for compressive strength, delamination of concrete floor surfaces and hot weather concreting. The Society also runs an advisory service of engineers and concrete technologists giving impartial advice to members, including desk studies and site visits. The Fingertips pages are the freely readable part and carry real figures; the Technical Reports are mostly paid.
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The Concrete Society
A free, citable data sheet giving the density ranges a note needs when explaining block types or estimating dead load. Published 3 June 2025 and filed under Buildings, Domestic (low rise). Dense aggregate blocks have a density in the range 1,800 to 2,100 kg/m3. Lightweight aggregate blocks, also called medium dense, are in the range 650 to 1,500 kg/m3. Aircrete blocks are in the range 400 to 900 kg/m3. Concrete bricks are 1,900 to 2,100 kg/m3 for Commons, Facing and Engineering quality, and 1,400 kg/m3 for lightweight bricks. The sheet points onward to the Concrete Block Association and the Autoclaved Aerated Concrete Products Association for more detail.
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Citizens Advice
Covers the national remediation programme for defective solid wall insulation fitted under ECO4 or the Great British Insulation Scheme. The affected window is work carried out between April 2022 and January 2025 where the householder got help with the cost. Ofgem or TrustMark write to affected households quoting a 'unique measure reference' number, which is also what a doorstep caller must be able to produce alongside ID. A qualified professional inspects both internal and external wall insulation, and where defects are found TrustMark arranges an installer to put them right at no cost to the householder. Contacts given are the Ofgem helpline 0808 169 4447 and TrustMark 0333 555 1234.
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Energy Saving Trust
How to identify a cavity wall and what filling it costs. About 33% of all heat lost from an uninsulated home escapes through the walls. Houses built after the 1920s usually have cavity walls; pre 1920 houses are usually solid; houses from the 1990s onwards usually already have wall insulation. Identification: cavity walls show an even stretcher bond with all bricks laid lengthways, solid walls show an alternating pattern with header ends visible; a brick wall 260mm to 350mm thick is likely a cavity wall, narrower is likely solid, stone walls are solid up to about 500mm thick and earth walls run 300mm to over a metre. Typical installed cost around £2,200 in Great Britain and around £1,000 in Northern Ireland, with payback usually five years or less. Unsuitable where the wall is exposed to extreme weather or flooding, in poor condition, at risk of overheating, or where the cavity is narrower than 50mm. External repairs to brickwork, pointing, roofs, gutters and downpipes must be completed first or damp can be trapped. Underfloor grilles, airbricks, wall vents and trickle vents must not be blocked. Post installation damp is chased through the installer, then the Cavity Insulation Guarantee Agency guarantee or an independent insurance backed guarantee.
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Energy Saving Trust
Condensation control by the numbers. A household typically produces up to 100 litres of moisture a week, which builds on surfaces or stays in the air unless ventilated out. Run a bathroom extractor for at least 15 minutes after a shower or bath and a cooker extractor for at least 15 minutes after cooking, or where there is no fan open a window for the same period. Leave a gap of at least 10mm under internal doors, measured from the top of the floor covering to the bottom of the closed door, so air can move between rooms. Distinguishes condensation from rising and penetrating damp and sets out the order of works.
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Energy Saving Trust
Solid wall insulation costs and the quality problem. Typical installation £12,000 to £15,000, split as around £15,000 for external wall insulation and around £12,000 for internal. Around 33% of the heat lost from an uninsulated home goes through the walls. Homes built before 1920 are more likely to have solid walls, of brick, stone, earth or timber frame with panels. A registered installer should guarantee the work for 25 years, and any TrustMark solid wall insulation company offers a 25 year guarantee backed either by an insurer or through the Solid Wall Insulation Guarantee Agency. Records that in October 2025 the National Audit Office reported on quality failures in wall insulation under government schemes, and that 98% of homes fitted with external wall insulation under ECO4 and the Great British Insulation Scheme have problems needing fixing, with affected households sent an Ofgem letter carrying a Unique Measure Reference Number in early 2026 and a remediation line on 0333 555 1234 option 1.
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HomeOwners Alliance
Identification and cost of the three damp types. Rising damp is recognised by a tide mark typically up to 1m above floor level, sometimes higher, with salt deposits in the plaster from groundwater. A damp proof course in a newer house sits about 15cm above external ground level and links to a damp proof membrane under the floor; many older houses have neither. Costs: a standalone damp survey £200 to £600 depending on property size and depth of investigation, best taken from a Property Care Association approved specialist; a good extractor fan for a condensation problem from £500; a remedial damp proof course with associated replastering to a flat 5m wall from £1,200. Advises at least 3 quotes. Condensation reduction tips include running cold water into the bath before hot, which cuts up to 90% of the steam.
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HomeOwners Alliance
Costed flood resilience measures for a house. Air brick covers £50 to £300, to be removed once flooding passes so the bricks can dry. Non return valves on drains and pipes to stop sewage backflow £50 to £500. Raising electrical sockets to about 1.5m £1,000 to £4,000. Raising door thresholds above flood level, front door and porch, £1,000 to £10,000. Sealing exterior walls around £500, with a warning it can trap damp in poor condition brickwork. Water resistant air bricks £500 to £1,000, needing careful maintenance to avoid seepage. Flood boards or flood resistant doors and windows £500 to £3,000, requiring permanently visible fixings. A pump, the most effective answer to groundwater, £50 to £2,500, with the inlet installed lower than the water being pumped. Basement tanking £10,000 to £20,000. On insurance, Flood Re is funded by a levy all UK home insurers must pay, and a home qualifies only if it was built before 2009 and is in council tax bands A to H.
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HomeOwners Alliance
Costed menu of efficiency measures. EPC £60 to £120 by property size. Loft insulation about £900 for a three bedroom semi, £1,100 detached, £1,200 detached bungalow per Energy Saving Trust, needing between 12cm and 30cm of thickness in most homes. PVC windows about £4,250 for a typical semi, roughly £325 per window, against about £15,000 for hardwood, roughly £1,500 per timber sash, with double glazing saving around £95 a year and requiring a FENSA accredited installer because building regulations apply to any window replacement. Cavity wall insulation about £22 to £26 per m2 for polyurethane foam or £13 to £18 per m2 for glass wool, averaging £725 for a detached house and £370 for a mid terrace. Internal wall insulation about £7,500 for a three bedroom semi saving around £210 a year, at a cost of about 10cm of lost floor depth. External wall insulation around £100 per m2, from £8,000 for a small flat to £22,000 for a large detached house. Solid concrete floor insulation £950 to £2,200 per room; suspended timber floor insulation £300 to £750 per room, saving about £50 a year or up to £85 in a detached house. Air source heat pump £3,000 to £18,000, ground source £13,000 to £35,000. Solar panels £2,500 to £8,000, with OVO estimating a 3.5kW array in southern England returns around £300 in year one.
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Leeds Beckett University, Leeds Sustainability Institute
The research that changed Building Regulations on party walls. Leeds Sustainability Institute produced the empirical evidence that the cavity between party walls separating adjoining properties was responsible for a significant, previously unrecognised, heat loss, and that this bypass accounted for part of the discrepancy between predicted and measured heat loss in new dwellings. That heat loss mechanism is now formally recognised and developers must insulate walls between adjoining properties; previously heat could escape through and between party walls to the external environment. Context given: energy consumption in homes is responsible for around 15 per cent of UK carbon emissions. Underpinning paper: Lowe, Wingfield, Bell and Bell (2007), Evidence for heat losses via party wall cavities in masonry construction, Building Services Engineering Research and Technology 28(2), 161-181.
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Leeds Beckett University, Leeds Sustainability Institute
37 pressurisation and co-pressurisation tests on attached UK homes, measuring how much of the measured leakage is actually air moving between neighbouring dwellings rather than to outside. On average 21 per cent of the air leakage measured by a fan pressurisation test was inter-dwelling rather than inside-to-outside, meaning attached homes are more airtight than the test says. Consequences: not accounting for this risks under-ventilation and misclassifying homes as suitable for natural ventilation. When the measured airtightness replaced the EPC default for 11 case study homes the energy efficiency rating improved, showing EPC default airtightness values were over-estimating air leakage, and using the co-pressurisation value gained a further rating point; the improvements equated to reductions of 5 per cent in predicted annual carbon emissions, 8 per cent in space heating demand and 3 per cent in fuel bills. The paper concludes the elevated pressures of the test itself create leakage paths not present in normal use, which affects the accuracy of fan pressurisation in attached homes and its use for regulatory compliance, ventilation decisions and energy models.
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Leeds Beckett University, Leeds Sustainability Institute
Coheating test results from 25 new build dwellings built to Part L1A 2006 or better, the study that put a number on the fabric performance gap. The mean measured whole building U-value was just over 1.6 times greater than predicted, and for individual dwellings the gap between measured and predicted fabric performance could exceed 100 per cent, varying with dwelling form and construction type. Context: dwellings account for just under 30 per cent of the UK's total CO2 emissions, against a national target of an 80 per cent cut by 2050 on 1990 levels; around 80 to 85 per cent of the dwellings that will be in use in 2050 already exist. The practical implication for a homeowner is that a design SAP figure or an EPC is a prediction, not a measurement, and a real house can lose over half as much heat again as the paperwork says.
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Leeds Beckett University, Leeds Sustainability Institute
Eight brick cores 100mm in diameter were taken from the outer leaf of solid walled homes across the UK (sites including Bedford, London and Loughborough) and lab tested, then modelled as a 110mm outer brick, 10mm air/mortar gap, 110mm inner brick, 10mm gypsum plaster wall. Results: modelled U-values of the uninsulated solid walls ranged from 1.6 to 2.6 W/m2K with an average of 2.1 W/m2K, against CIBSE Guide A book values averaging 1.7 W/m2K and ranging 1.4 to 2.0 W/m2K, so real bricks lost noticeably more heat than the standard assumption. EPCs assume a single default solid wall U-value of 1.7 W/m2K. Six of the eight homes carried surface condensation risks. Simulated moisture content of the inner brickwork varied between 0.1 and 5.8 per cent, meaning some bricks are at far higher risk of moisture accumulation than others, which is why an identical insulation detail can succeed in one house and fail in another.
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Leeds Beckett University, Leeds Sustainability Institute
Field trials plus thermal modelling (Brooke-Peat and Glew, 2021) showing that insulating one house internally can push a damp problem next door. Adding IWI reduces heat transfer from the room into the external wall, so the external wall behind the insulation becomes colder than the neighbour's uninsulated wall; heat then flows towards the colder side, and surface temperatures fall not only behind the insulation but also in the adjacent dwelling around the party wall junction, raising the risk of mould growth and surface condensation in a neighbouring property that has had no work done. The paper notes the legal as well as health implications, and that standard thermal modelling conventions do not cover thermally asymmetric party wall junctions, so the modelling had to split heat flow and surface temperature for each dwelling separately, using linear thermal transmittance (psi-value) and temperature factor (fRsi). Context figures: roughly 10 per cent of UK households are in fuel poverty, rising to 16 per cent of households in uninsulated solid walled homes, and only 7 per cent of ECO measures have been solid wall insulation.
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Leeds Beckett University, Leeds Sustainability Institute (for BEIS)
Measured comparison of thin internal wall insulation (TIWI) against conventional internal wall insulation on solid brick walls, using coheating tests for the whole-house heat transfer coefficient in W/K plus dynamic simulation for bills. Findings with numbers: TIWI is only 20 to 30 per cent of the thickness of conventional IWI and gives U-values between 0.8 and 1.4 W/m2K on solid brick, yet delivers between 40 and 70 per cent of the fuel bill savings conventional IWI achieves. Diminishing returns are stark: conventional IWI was in some cases four times thicker than TIWI yet gave only 22 per cent more benefit. TIWI can take up to a third less floor area than conventional IWI, and TIWI products needing no decoration were the cheapest to install, though some require multiple visits which raises labour cost. Moisture caution stated plainly: neither IWI nor TIWI removes moisture risk, both can increase condensation risk on adjacent surfaces and in neighbouring homes, and both must be fitted to walls in good repair. Policy context: solid wall insulation appears in only around 7 per cent of ECO retrofits and IWI accounts for less than 1 per cent of ECO measures; the report argues the 0.3 W/m2K target for solid walls deters uptake, noting cavity wall retrofits are allowed 0.55 W/m2K.
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National Grid Electricity Distribution
Contains the rules on where a meter may sit and two fully worked cost examples. Permissible meter locations: in an external meter box (recommended), inside the property on an external wall, or in a suitable weatherproof meter cubicle; the cubicle detail is 1.5m high by 0.6m wide by 0.45m deep, and the internal-wall position allows 1,250mm by 550mm. Meters must not be located inside a dustbin, coal or refuse store, above doorways, in a bathroom, toilet or shower room, in a basement or cellar, under stairs where headroom is less than 2m, on plasterboard or drywall partition walls, close to a water source that could damage the equipment or cause an electrocution risk, or anywhere in breach of BS 7671. A surface mounted meter box protrudes 230mm from the wall, so check it will not obstruct or be damaged; a flush fit box is best built into new brickwork. Once the works are complete the meter box and cable guard become the customer's property to maintain. Worked example 1, overhead supply: overhead re-connection £1,091 plus £182 plus £91, no trench, total £1,364. Worked example 2, underground supply, customer excavation: underground re-connection £980 plus 10m of cable at £26/m (£260), total £1,240; the same job with NGED excavation: underground re-connection £2,437 plus £260 of cable plus 5m grass trench at £83/m (£415) plus 5m tarmac trench at £169/m (£845), total £3,957. A joint hole is needed to expose the existing cable, with at least 200mm of excavated ground below the cable, and warning tape is laid 75mm above the cable depth. Preparatory work such as installing the meter box must be finished before the visit or the job may be cancelled and an aborted visit charged. Bespoke offers are needed to move a three phase supply, to replace an overhead cable with an underground one, for routes crossing third party land, and for routes needing traffic lights or road closures.
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Shelter England
Using the council's environmental health team to force repairs. They investigate serious repair problems that affect health or create risk, and can be approached where the landlord or letting agent ignores reports or fails to fix things in a reasonable time. Their tools include inspecting under the housing health and safety rating system, serving an improvement notice that tells the landlord how to fix the problem and sets a deadline, and taking emergency action. The council must give the tenant a copy of any notice within 7 days.
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Shelter England
Gives the fixed timescales that bind social landlords in England: investigate within 24 hours if the damp and mould is an emergency, or within 10 working days if it is very serious but not an emergency; make the home safe within 24 hours for an emergency, or within 5 working days of finishing the investigation for a very serious non emergency case. The landlord must offer alternative accommodation if it cannot fix very serious damp and mould inside those limits. Escalation is to the landlord's complaints procedure and then the Housing Ombudsman.
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Shelter England
Practical route through a damp complaint in a private tenancy. The landlord must try to find the cause, and must fix the building defects behind it: a leaking roof, defective gutters and downpipes, rising damp through a failed or missing damp proof course, penetrating damp through walls, leaking pipes, and rotten or badly fitting windows. Where condensation is the cause the landlord must still fix inadequate ventilation, extractor fans, heating and insulation. Advises the landlord should re-check at least 6 weeks after the repairs, and notes a disrepair claim can usually be started up to 3 years after the harm, so it can be brought after moving out.
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Shelter England
Sets out when a rented home counts as unfit: conditions that seriously affect health, risk physical injury, or stop full use of the home. Lists examples including gas safety risks, unsafe electrics, fire safety failings, vermin, serious damp and mould, no hot water or heating, a leaking roof and unsafe stairs. Applies to all private, housing association and council tenancies for the whole tenancy, not just at the start. Emergency hazards must be made safe within 24 hours and the landlord must provide free rehousing if that is not possible.
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Shelter England
Splits the repairing duty. Landlord: structure and exterior, walls, windows, roof, gutters and drains, basins, sinks, baths, toilets, pipes, wiring, boilers, heaters, radiators and anything the landlord supplied. Tenant: use the home in a 'tenant like manner', report repairs and damp, and allow access. States the home must be fit to live in for the whole tenancy, that a landlord has 24 hours to fix an emergency hazard and must offer temporary housing if it cannot be made safe in that time, that all landlords must look for the cause of damp rather than blame the occupant, and that a tenant must be given at least 24 hours' written notice before an inspection.
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Society for the Protection of Ancient Buildings
Douglas Kent's technical advice note on dampness in buildings predating about 1919. Key figures: relative humidity becomes detrimental at 70% or higher; rising damp usually extends only 10 to 50mm above internal floor level, though it can reach 900mm or more depending on external ground levels, masonry type, water table and evaporation rate; timber in a normal dry living environment sits at roughly 9 to 16% moisture content and becomes susceptible to fungal decay above 21%. States that most pre 1919 buildings were built without damp proof courses or damp proof membranes by design, that rising damp is usually far less of a problem than commonly supposed, and that inserted DPMs and chemical injection are frequently unnecessary treatments applied after misdiagnosis, where maintenance and occupancy changes plus respecting the building's need to breathe are the appropriate response. Also covers rainwater penetration, condensation on porous lime surfaces and hygroscopic salts, and notes listed building consent may be required.
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Society for the Protection of Ancient Buildings
Marianne Suhr and Sally Stradling on diagnosing and repairing fireplaces, flues and chimneys in old domestic buildings, including fire risk, alterations and energy efficiency. Dimensional guidance includes a 300mm (12 inch) diameter flue 3m (10 ft) high, an iron or copper canopy finishing about 750mm above the fire bed and measuring roughly 900mm wide by 600mm deep, reducing a fireplace opening height to 600mm, a restricted throat 100mm (4 inches) from the back of the grate, and traditional grouped flues of about 225 by 225mm (9 by 9 inches) with slender withes between them. Historic parging used lime or earth with fresh cow dung, mixes cited as 1 part lime putty to 3 parts cow dung, sometimes 1:1, and 1 part cow dung to 4 parts haired lime mortar made from 1 part lime to 3 parts sand. Also covers downdraught from a nearby tall building, tree or hill, spalling, and combustion air inlet sizing.
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Society for the Protection of Ancient Buildings
Philip Hughes on why modern impervious materials fail in old buildings. Old walls of brick or stone were bedded in lime and sand, sometimes earth or earth and lime mortars, rendered in lime and decorated almost exclusively with limewash, so the fabric absorbed and released moisture. Modern buildings instead rely on an impervious barrier. Sets the rule that pointing mortar should be a soft lime mix weaker than the surrounding brickwork, and shows the failure mode when it is not: strong cement pointing is forced off the wall, efflorescence and decay migrate into the brick faces instead of the joints, and cement render traps moisture and causes decay of earth and lime mortars behind. Cement render can sometimes be removed by working the surface over and taking it off in small pieces by forming hairline cracks, then making good with a lime mix. Paint should be replaced with limewash once existing impermeable coatings have broken down.
- fair RN-0DRMNN
UCL (Institute for Environmental Design and Engineering)
A comparison table of insulation materials by thermal conductivity (lambda, W/mK) and vapour diffusion resistance factor (mu), the two numbers that decide whether an insulation suits a breathable old wall. Bio-based: high-density wood fibre board 0.038-0.050 lambda, mu 5-10; low-density wood fibre quilt 0.035-0.040, mu 1-2; cork 0.037-0.040, mu 5-10; sheep's wool 0.035-0.040, mu 1-2; hemp 0.040-0.045, mu 1-5; straw 0.045-0.050, mu 1-2. Insulating lime plasters: hydraulic 0.800-0.900, mu 10-15; non-hydraulic 0.700-0.800, mu 5-10. Mineral board: calcium silicate 0.050-0.060, mu 5-10. Foams: open cell spray foam 0.035-0.040, mu 3-5; EPS 0.030-0.040, mu 30-70; XPS 0.025-0.035, mu 80-200; closed cell spray foam 0.023-0.026, mu 30-60; PIR 0.023-0.025, mu 50-100; phenolic foam 0.020-0.025, mu 50-100. Others: mineral wool 0.030-0.045, mu 1-5; aerogel 0.013-0.018, mu 5-10. The paper's central caution is that vapour permeability, moisture storage and liquid transport are not directly linked, so labelling a material simply 'vapour permeable' or 'breathable' is not sufficient: mineral wool is vapour permeable but is neither moisture-storing nor capillary active, and permeability is a gradual scale rather than a binary.
- fair RN-2GQRWD
University of Bath
Peer-reviewed measurement of a real hemp-lime building (Lawrence, Fodde, Paine and Walker, Key Engineering Materials 517, 2012, pages 413 to 421). Findings: the unique pore structure of the woody core of the hemp stem, the shiv, gives hemp-lime both low thermal conductivity and thermal and hygric buffering, so the wall damps swings in external temperature and passively controls internal humidity; the monolithic construction technique promotes good airtightness and minimal thermal bridging in the envelope. The paper also reports a computerised environmental model that accounts for the phase change effects seen in hemp-lime, which conventional steady-state U-value modelling misses. Material context: the hemp plant grows up to 4m in four months with low fertiliser and irrigation demand, and every part is used, the seed for food, the bast fibre for paper, clothing and resin reinforcement, and the woody core as the aggregate in hemp-lime.
- fair RN-9Y9BUQ
University of Bath
Laboratory testing of retrofit options on single-skin and cavity brick walls between two opposing climate chambers, with temperature, relative humidity and heat flux logged by surface sensors every 10 minutes under steady-state winter and summer scenarios (Journal of Building Engineering vol 23, pages 241-249, 2019). Findings a specifier can act on: single and cavity brick walls behaved significantly differently, and there was a high condensation risk in the non-ventilated air cavity of the double wall. A pervious lime-cement mortar render substantially improved the thermal performance of the single wall but increased the condensation risk of the cavity wall, so the same render is a good move on one construction and a bad one on the other. Adding an insulation layer reduced thermal conductance as expected, but the improvement in the summer scenario was considerably lower than in winter. The paper concludes effective retrofit depends on the material, the wall layout and the climate together, not on the material alone.