UK Construction Resources 2026

Eurocodes – UK National Annexes and Key Parameters 2026

The Eurocodes are the primary suite of structural design standards used across Europe, adopted in the UK through BS EN publications with accompanying UK National Annexes (NA) that specify nationally determined parameters (NDPs). Following Brexit, the UK retains the Eurocodes as its structural design standards; BSI continues to publish and maintain UK National Annexes independently of CEN.

Eurocode Overview and UK National Annexes

Eurocode	BS EN Reference	Subject	UK NA Reference	Key NDPs for UK
EC0	BS EN 1990	Basis of Structural Design	NA to BS EN 1990	Load combination factors (ψ₀, ψ₁, ψ₂); reliability classes; design working life
EC1-1-1	BS EN 1991-1-1	Densities, Self-Weight, Imposed Loads for Buildings	NA to BS EN 1991-1-1	Imposed loads qk for residential (1.5 kN/m²), offices (2.5–5.0), car parks (2.5)
EC1-1-3	BS EN 1991-1-3	Snow Loads	NA to BS EN 1991-1-3	Ground snow load map sk; altitude correction; shape coefficients μ
EC1-1-4	BS EN 1991-1-4	Wind Actions	NA to BS EN 1991-1-4	Fundamental basic wind velocity vb,0 map; terrain categories; orography
EC1-1-5	BS EN 1991-1-5	Thermal Actions	NA to BS EN 1991-1-5	Temperature ranges for UK climate
EC2-1-1	BS EN 1992-1-1	Concrete Structures – General Rules	NA to BS EN 1992-1-1	Concrete cover to reinforcement; partial factors γC=1.5, γS=1.15; exposure classes
EC3-1-1	BS EN 1993-1-1	Steel Structures – General Rules	NA to BS EN 1993-1-1	Partial factors γM0=1.0, γM1=1.0, γM2=1.25; buckling curves
EC5-1-1	BS EN 1995-1-1	Timber Structures – General Rules	NA to BS EN 1995-1-1	Partial factors; kmod values; Service Class definitions
EC6-1-1	BS EN 1996-1-1	Masonry Structures – General Rules	NA to BS EN 1996-1-1	Partial factors γM for masonry; capacity reduction factor Φ
EC7-1	BS EN 1997-1	Geotechnical Design – General Rules	NA to BS EN 1997-1	Design Approach 1 (DA1) as UK approach; partial factors for GEO and STR

EC1 – Key UK Imposed Loads (NA to BS EN 1991-1-1)

Building Use / Category	Category	qk (kN/m²)	Qk (kN point load)	Notes
Residential – floors (houses, flats, bedrooms)	A	1.5	2.0	Standard domestic floor design load
Residential – stairs	A	3.0	2.0	—
Residential – balconies	A	2.5–4.0	2.0	Higher value for public balconies
Offices – general use (not open plan)	B	2.5	4.5	—
Offices – open plan / public areas	B	3.0	4.5	—
Public assembly – fixed seating	C1	3.0	4.0	—
Public assembly – moveable seating / restaurants	C3	5.0	4.5	—
Shopping areas / retail floors	D1	4.0	3.6	—
Storage areas – general	E1	≥7.5	7.0	Actual load from stored goods governs
Car parks – passenger vehicles (≤2.5t GVW)	F	2.5	10.0	Standard domestic car park design load
Roofs – accessible for maintenance only	H	0.4	1.0	Non-accessible roofs: 0.25 kN/m²
Roofs – accessible, used as terrace / amenity	I	As floor above	—	Design as equivalent occupied floor

EC0 – Load Combination Factors (UK NA to BS EN 1990)

Action	ψ₀	ψ₁	ψ₂	Notes
Imposed – residential, offices (Cat A & B)	0.7	0.5	0.3	Most common for domestic design
Imposed – congregation areas (Cat C)	0.7	0.7	0.6	—
Imposed – shopping (Cat D)	0.7	0.7	0.6	—
Imposed – storage (Cat E)	1.0	0.9	0.8	—
Imposed – car parks (Cat F)	0.7	0.7	0.6	—
Wind actions	0.5	0.2	0.0	—
Snow – altitude ≤1,000m (UK)	0.5	0.2	0.0	—
Temperature (non-fire)	0.6	0.5	0.0	—

EC2 – Concrete Cover Requirements (UK NA to BS EN 1992-1-1)

Exposure Class	Description	Structural Class S4 Min. Cover (mm)	Typical Applications
X0	No risk of corrosion or attack – very dry	10	Concrete inside (low humidity); unreinforced
XC1	Dry or permanently wet	15	Internal RC slabs, beams, columns (dry internal)
XC2	Wet, rarely dry	25	Foundations, buried concrete
XC3	Moderate humidity / sheltered from rain	25	External concrete sheltered from rain; internal high humidity
XC4	Cyclic wet and dry	30	External concrete exposed to rain
XD1	Moderate humidity – chlorides from sources other than seawater	35	Concrete surfaces exposed to de-icing salts (at distance)
XD2	Wet, rarely dry – chlorides	40	Swimming pools, concrete in chloride-laden water
XD3	Cyclic wet/dry – chlorides	45	Bridge decks, car park slabs (direct de-icing salt exposure)
XS1	Exposed to airborne salt, not in direct contact	35	Marine structures – exposed to sea air
XS3	Tidal, splash, spray zones	45	Intertidal zone marine concrete
XF1	Moderate water saturation, no de-icing agents	25	Vertical concrete surfaces exposed to rain and freezing
XF4	High saturation + de-icing agents or seawater	35	Road slabs, bridge decks – severe freeze-thaw + salts

All cover values are nominal cover cnom = cmin + Δcdev. For structural class S4 (most common default class for 50-year design life), Δcdev = 10mm. For example, XC1 nominal cover = 15 + 10 = 25mm. Structural class may be reduced by 1 for high strength concrete (≥C30/37 for XC classes) or by 1 for slab elements.

Building Regulations Approved Documents – England 2026

The Building Regulations 2010 set functional requirements for building work in England. The Approved Documents provide practical guidance on how to comply with each Part. They do not have the force of law — alternative solutions that demonstrably meet the functional requirements are acceptable — but following the guidance is the standard route to compliance.

Approved Document	Part	Subject	Key 2026 Requirements / Notes
Part A	Structure	Structural stability of buildings	Foundation requirements; disproportionate collapse; loading tables for domestic construction (span tables for floors, roofs, walls)
Part B (Vol.1)	Fire Safety	Dwellinghouses	Means of escape; fire detection (smoke alarms); fire resistance periods; surface spread of flame; separating walls/floors
Part B (Vol.2)	Fire Safety	Buildings other than dwellinghouses	Means of escape; compartmentation; sprinklers; fire resistance; external fire spread; firefighter access
Part C	Site Preparation and Resistance to Moisture	Dampness, ground gas, contamination	DPC requirements; floor slab waterproofing; subsoil drainage; resistance to radon and methane; contaminated land
Part D	Toxic Substances	Cavity insulation	Use of urea-formaldehyde foam insulation in cavity walls
Part E	Resistance to Sound	Airborne and impact sound insulation	Separating walls and floors between dwellings; DnTw + Ctr ≥ 45 dB (airborne); LnTw ≤ 62 dB (impact); internal rooms; pre-completion testing or Robust Standard Details
Part F (Vol.1)	Ventilation	Dwellings	Trickle ventilators (8,000 mm² for habitable rooms, 4,000 mm² for kitchens/bathrooms); mechanical extract rates; whole-house ventilation systems (MVHR, MEV, dMEV)
Part F (Vol.2)	Ventilation	Non-domestic buildings	Ventilation rates; indoor air quality
Part G	Sanitation, Hot Water Safety and Water Efficiency	Water use and hot water	Water consumption target: 125 litres/person/day (optional 110 l/p/d); hot water safety; unvented systems; sanitary facilities
Part H	Drainage and Waste Disposal	Foul and surface water drainage	Foul drainage gradients and sizing; surface water drainage; septic tanks; cesspools; oil separators
Part J	Combustion Appliances and Fuel Storage Systems	Heating appliances and chimneys	Flue design; ventilation for combustion appliances; hearth construction; oil and gas storage
Part K	Protection from Falling, Collision and Impact	Stairs, ramps, guarding and barriers	Stair pitch ≤42°; rise 150–220mm; going 220–300mm; handrail height 900–1000mm; balustrade openings ≤100mm
Part L (Vol.1)	Conservation of Fuel and Power	New and existing dwellings	U-value targets; SAP calculation; air permeability ≤8 m³/h/m² at 50 Pa; thermal bridging; primary energy rate; Future Homes Standard transition
Part L (Vol.2)	Conservation of Fuel and Power	Non-domestic buildings	NABERS UK / BRUKL compliance; building energy modelling; lighting efficacy
Part M (Vol.1)	Access to and Use of Buildings	Dwellings	Category 1: Visitable; Category 2: Accessible & adaptable; Category 3: Wheelchair accessible (M4(3)). Doorset clear widths; level thresholds; accessible WC provision
Part M (Vol.2)	Access to and Use of Buildings	Non-domestic	Accessibility for buildings other than dwellings; parking; reception; WC provision; lifts
Part O	Overheating	New residential buildings	Overheating risk assessment (simplified or dynamic); solar shading requirements; cross-ventilation; applies to all new homes from 2022
Part P	Electrical Safety	Dwellings	Notifiable electrical work; Part P competent persons schemes; consumer unit replacement; kitchen/bathroom circuits
Part Q	Security	Dwellings	Doorsets and windows to agreed security standard (PAS 24 or LPS 1175 SR1) for accessible ground floor openings in new dwellings
Part R	High-Speed Broadband	All new buildings	Gigabit-ready physical infrastructure; in-building physical network; connection to nearest network distribution point
Part S	Infrastructure for Charging Electric Vehicles	New buildings with associated parking	EV charging point or cable route in new dwellings with parking; applies from 15 June 2022

Key Part A Structural Span Tables (Domestic – England 2026)

The following are indicative maximum span values from the span tables in Approved Document A for common domestic structural elements. These are for guidance only — always confirm with the relevant AD table using the correct loading conditions and timber grade.

Element	Timber Grade	Section Size	Max. Span (m) – indicative	Spacing (mm)
Floor joist (domestic – 1.5 kN/m²)	C16	47 × 145mm	2.85	400
Floor joist (domestic – 1.5 kN/m²)	C16	47 × 170mm	3.36	400
Floor joist (domestic – 1.5 kN/m²)	C24	47 × 145mm	3.14	400
Floor joist (domestic – 1.5 kN/m²)	C24	47 × 170mm	3.69	400
Floor joist (domestic – 1.5 kN/m²)	C24	47 × 195mm	4.22	400
Flat roof joist (non-accessible – 0.75 kN/m²)	C16	47 × 145mm	3.28	400
Flat roof joist (non-accessible – 0.75 kN/m²)	C24	47 × 170mm	4.15	400
Ceiling joist (only ceiling load)	C16	47 × 97mm	3.00	400
Ceiling joist (only ceiling load)	C16	47 × 122mm	3.83	400
Rafter (tiles + insulation)	C16	47 × 100mm	2.31	400
Rafter (tiles + insulation)	C24	47 × 125mm	3.34	400

Concrete Mix Reference Tables – UK 2026

BS 8500 Designated Concrete Mixes – Full Reference

Designation	Strength Class	Max W/C Ratio	Min Cement (kg/m³)	Max Agg. Size	Typical Applications	Site Mix Equiv.
GEN0	C10/12	0.70	180	20mm	Blinding, non-structural fill, temporary works	1:3:6
GEN1	C15/20	0.65	240	20mm	Strip & trench fill foundations, fence posts, mass fill	1:2:4
GEN2	C20/25	0.60	280	20mm	Unreinforced domestic floor slabs, paths, patios, shed bases	1:2:3
GEN3	C20/25	0.55	300	20mm	Reinforced ground floor slabs, garage floors (light vehicles)	1:1.5:3
RC25	C25/30	0.55	300	20mm	Reinforced structural slabs, beams, lightly loaded elements	Designed only
RC30	C30/37	0.50	320	20mm	Driveways, reinforced slabs, structural concrete	Designed only
RC35	C35/45	0.45	340	20mm	Heavily loaded structural elements	Designed only
RC40	C40/50	0.40	360	20mm	High-strength structural elements, post-tensioned work	Designed only
PAV1	C30/37 (air)	0.50	320	20mm	Concrete driveways, car parks (residential)	Designed only
PAV2	C35/45 (air)	0.45	340	20mm	Heavily trafficked pavements	Designed only
FND2	C25/30 (SRPC)	0.55	300	20mm	Foundations – DS-2 sulphate exposure class	SRPC only
FND3	C25/30 (SRPC)	0.50	320	20mm	Foundations – DS-3 sulphate exposure class	SRPC only
FND4	C32/40 (SRPC)	0.45	360	20mm	Foundations – DS-4 sulphate exposure class	Designed only

Site Mix Material Quantities per 1 m³ Compacted Concrete

Mix Ratio (C:S:A)	Designation	Cement (kg)	Cement (25kg bags)	Sharp Sand (kg)	Coarse Agg. (kg)	Water (litres)
1 : 3 : 6	GEN0	180	8	540	1,080	~105
1 : 2 : 4	GEN1	250	10	500	1,000	~140
1 : 2 : 3	GEN2	310	13	620	930	~160
1 : 1.5 : 3	GEN3	350	14	525	1,050	~175
1 : 1.5 : 2.5	~RC25	380	16	570	950	~185

Reinforcement Mesh Reference (BS 4483)

Mesh Ref.	Bar Dia. (mm)	Pitch (mm)	Area (mm²/m) – Main	Area (mm²/m) – Cross	Weight (kg/m²)	Typical Use
A98	5	200	98	98	1.54	Screeds, light crack control
A142	6	200	142	142	2.22	Lightly reinforced domestic slabs, garage floors
A193	7	200	193	193	3.02	Domestic ground floor slabs, light commercial
A252	8	200	252	252	3.95	Commercial ground floor slabs
A393	10	200	393	393	6.16	Heavy duty slabs, industrial floors
B196	5 / 7	100 / 200	196	98	3.05	One-way spanning slabs
B283	6 / 7	100 / 200	283	98	3.73	One-way spanning slabs
B385	7 / 7	100 / 200	385	193	4.53	One-way spanning slabs
B503	8 / 7	100 / 200	503	193	5.93	Heavily loaded one-way slabs
C283	6	100 / 400	283	70	2.61	Roads and pavements
C636	9	100 / 400	636	159	5.55	Heavy pavement slabs

Rebar Sizes and Cross-Sectional Areas (BS 4449)

Bar Size	Nominal Dia. (mm)	Cross-Section Area (mm²)	Mass (kg/m)	Common Use
T6	6	28.3	0.222	Links, stirrups, distribution bars
T8	8	50.3	0.395	Slab distribution, links
T10	10	78.5	0.617	Slab main bars, foundation ties
T12	12	113.1	0.888	Beam and slab main reinforcement – most common domestic bar
T16	16	201.1	1.579	Beam main bars, column ties
T20	20	314.2	2.466	Beam main reinforcement
T25	25	490.9	3.854	Heavy beam and column reinforcement
T32	32	804.2	6.313	Large columns, pile caps
T40	40	1,257	9.864	Major structural elements

Thermal Performance Reference Tables – UK Building Regulations 2026

Part L U-Value Targets – England 2026

The following U-value targets apply to new dwellings in England under Approved Document L Volume 1 (2021 edition, effective from June 2022). These are limiting fabric standards — notional targets used as the baseline for SAP calculation — not absolute maximum values for individual elements in all cases. The overall dwelling must achieve the target primary energy rate and emission rate.

Building Element	New Dwelling – Limiting U-value (W/m²K)	Extension / Renovation Threshold	Notes
Roof (flat or pitched)	0.11	0.16	Typically 250–400mm mineral wool or PIR equivalent
External walls (cavity)	0.18	0.30	Full-fill or partial-fill cavity insulation required
External walls (solid – new build)	0.18	0.30	External or internal insulation system required
Ground floor (solid or suspended)	0.13	0.25	Typically 100–150mm PIR below screed
Windows and glazed doors	1.20 (whole window)	1.60	Triple glazing typically achieves 0.7–1.0 W/m²K; double 1.2–1.6
Rooflights / skylights	1.40 (whole unit)	2.20	Fixed rooflights lower than opening rooflights
External doors (opaque)	1.00	1.80	Insulated composite doors typically 0.8–1.2 W/m²K
Party walls (between dwellings)	0.20	—	Also subject to Part E acoustic requirements
Air permeability (target)	≤5.0 m³/h/m² @ 50 Pa	≤8.0 m³/h/m² @ 50 Pa	New dwellings require pre-completion pressure test

Thermal Conductivity (λ) of Common Building Materials

Material	λ (W/mK)	Typical Use	Notes
Dense concrete (2,300 kg/m³)	2.00	Structural concrete, foundations	—
Lightweight concrete block (600 kg/m³)	0.19	Inner leaf of cavity wall	Good thermal performance
Aerated concrete block (AAC) – e.g. Thermalite	0.11–0.16	Inner leaf of cavity wall, partition	Excellent thermal mass / insulation balance
Clay engineering brick	1.20–1.50	Outer leaf, DPC courses	Poor insulator – relies on cavity
Facing brick (commons)	0.77	Outer leaf of cavity wall	—
Mortar (1:3 cement:sand)	0.88	Joints in masonry	Thermal bridge through mortar joints
Timber (softwood)	0.13	Structural framing, floor joists	Good insulator
Plasterboard (12.5mm)	0.21	Internal wall and ceiling lining	—
Sand cement render / screed	0.57	External render, floor screed	—
PIR / polyisocyanurate rigid board	0.022–0.026	Floor, wall, and roof insulation boards	Highest performance rigid insulation
EPS (expanded polystyrene) – standard	0.033–0.038	Below-slab insulation, cavity boards	—
XPS (extruded polystyrene)	0.030–0.036	Below-slab, inverted roof, ground-bearing	Higher moisture resistance than EPS
Mineral wool quilt (glass wool)	0.032–0.044	Loft insulation, stud wall insulation	Most common loft insulation material
Mineral wool slab (rockwool)	0.033–0.040	Cavity full-fill, acoustic insulation	Better fire performance than glass wool
Phenolic foam board	0.019–0.023	Floor, wall, roof – thin profile premium	Best λ value of all common insulants
Cellulose / blown-in insulation	0.035–0.040	Loft top-up, stud wall cavity fill	Good for retrofit; made from recycled paper
Aerogel blanket	0.013–0.018	Thin-profile high-performance insulation	Most expensive; used where space is critical
Timber frame panel (SIP)	—	Structural insulated panels	Whole-panel R-value specified rather than λ

U-value Calculation Summary – Simple Method

The total thermal resistance RT of a building element = sum of all layer resistances + surface resistances:

RT = Rsi + R1 + R2 + ... + Rn + Rse

Where: Rsi (internal surface resistance) = 0.13 m²K/W for walls; 0.10 for upward heat flow (floors); 0.17 for downward (ceiling/roof). Rse (external surface resistance) = 0.04 m²K/W. Each layer resistance Rn = thickness (m) / λ (W/mK). U-value = 1/RT (W/m²K).

Structural Reference Tables – UK Construction 2026

Steel Section Properties – Universal Beams (UB) – Common Sizes

Designation	Mass (kg/m)	Depth (mm)	Width (mm)	Flange t (mm)	Web t (mm)	Ix (cm⁴)	Zx (cm³)	Wpl,x (cm³)
127×76×13 UB	13.0	127.0	76.0	7.6	4.0	473	74.6	84.2
152×89×16 UB	16.0	152.4	88.7	7.7	4.5	834	109	123
178×102×19 UB	19.0	177.8	101.2	7.9	4.8	1,357	153	171
203×102×23 UB	23.1	203.2	101.8	9.3	5.4	2,105	207	234
203×133×25 UB	25.1	203.2	133.2	7.8	5.8	2,340	231	258
254×102×22 UB	22.0	254.0	101.6	6.8	5.8	2,840	224	259
254×102×28 UB	28.3	260.4	102.2	10.0	6.4	4,005	308	353
305×102×28 UB	28.2	308.7	101.8	8.8	6.0	5,537	359	408
305×127×37 UB	37.0	304.4	123.3	10.7	7.1	7,162	471	539
356×127×33 UB	33.1	349.0	125.4	8.5	6.0	8,249	473	543
356×171×45 UB	45.0	351.4	171.1	9.7	7.0	12,070	687	775
406×140×39 UB	39.0	398.0	141.8	8.6	6.4	12,452	626	718
406×178×54 UB	54.1	402.6	177.7	10.9	7.7	18,626	925	1,055
457×152×52 UB	52.3	449.8	152.4	10.9	7.6	21,370	950	1,096
533×210×82 UB	82.2	528.3	208.8	13.2	9.6	47,500	1,800	2,060

Universal Columns (UC) – Common Sizes

Designation	Mass (kg/m)	Depth (mm)	Width (mm)	Ix (cm⁴)	Iy (cm⁴)	Zx (cm³)	Wpl,x (cm³)
152×152×23 UC	23.0	152.4	152.2	1,263	403	165.7	184
152×152×30 UC	30.0	157.6	152.9	1,742	560	221	248
203×203×46 UC	46.1	203.2	203.6	4,564	1,539	449	497
203×203×60 UC	60.0	209.6	205.2	6,088	2,047	581	656
254×254×73 UC	73.1	254.1	254.6	11,410	3,870	898	992
305×305×97 UC	97.1	307.9	304.8	22,250	7,308	1,445	1,592

Steel Grades and Design Strengths (S275 and S355) – EC3

Steel Grade	Thickness (mm)	fy (yield, N/mm²)	fu (ultimate, N/mm²)	E (GPa)	Typical Use
S275	t ≤ 16	275	430	210	General structural steelwork – domestic and light commercial
S275	16 < t ≤ 40	265	430	210	—
S275	40 < t ≤ 80	255	410	210	—
S355	t ≤ 16	355	510	210	Higher strength – spans and heavily loaded elements
S355	16 < t ≤ 40	345	510	210	—
S355	40 < t ≤ 80	335	470	210	—

Foundation Bearing Pressures – Indicative Values (EC7 / BS 8004)

Ground Type	Presumed Bearing Capacity (kN/m²)	Notes
Made ground / fill	Not presumed without investigation	Investigate before designing any foundations
Soft clay (Cu < 40 kN/m²)	25–50	Very low bearing; piles may be required
Firm clay (Cu 40–75 kN/m²)	75–100	Strip foundations at 1m+ depth typically adequate
Stiff clay (Cu 75–150 kN/m²)	100–150	Most common UK domestic foundation ground
Very stiff / hard clay (Cu > 150 kN/m²)	150–300	Excellent bearing for strip foundations
Loose sand / gravel	100–200	Check for settlement under load
Medium dense sand / gravel	200–400	Good domestic foundation bearing
Dense sand / gravel	400–600+	Excellent – shallow foundations adequate
Weak rock (chalk, soft sandstone)	150–400	Variable; investigation recommended
Hard rock (granite, limestone, gritstone)	2,000–10,000+	Effectively unlimited for domestic loading

Timber Strength Class Properties (BS EN 338:2016) – C16 and C24

Property	C16	C24	C30	Unit
Bending strength fm,k	16	24	30	N/mm²
Tension // to grain ft,0,k	10	14.5	18	N/mm²
Compression // to grain fc,0,k	17	21	23	N/mm²
Shear strength fv,k	3.2	4.0	4.0	N/mm²
Mean MOE E0,mean	8,000	11,000	12,000	N/mm²
5th percentile MOE E0,05	5,400	7,400	8,000	N/mm²
Characteristic density ρk	310	350	380	kg/m³
Mean density ρmean	370	420	460	kg/m³

Materials Reference Tables – Densities, Weights & Properties UK 2026

Bulk Densities and Self-Weights of Common Construction Materials (EC1-1-1)

Material	Bulk Density (kg/m³)	Self-Weight (kN/m³)	Notes
Normal weight concrete (reinforced)	2,500	25.0	Standard RC – most common structural concrete
Normal weight concrete (plain)	2,300	23.0	Mass concrete, blinding, fill
Lightweight concrete	800–2,000	8–20	Depends on aggregate type
Aerated concrete (AAC block)	400–900	4–9	Thermalite / Celcon type
Screed – sand and cement	2,000	20.0	75mm screed = 1.50 kN/m²
Screed – lightweight	800–1,300	8–13	—
Steel (structural)	7,850	78.5	S275, S355
Aluminium	2,700	27.0	Structural aluminium alloys
Softwood timber (dry)	350–550	3.5–5.5	C16/C24 structural timber
Hardwood timber (dry)	600–900	6–9	Oak, iroko, balau
Plywood (structural)	500–700	5–7	—
Clay brick (engineering)	2,000–2,200	20–22	Dense engineering bricks
Clay brick (facing)	1,700–2,000	17–20	Standard UK facing bricks
Mortar (set)	1,800	18.0	—
Glass (float)	2,500	25.0	—
Sand (dry, loose)	1,400–1,600	14–16	Sharp / building sand
Sand (saturated)	1,900–2,100	19–21	—
Gravel / shingle (dry)	1,400–1,700	14–17	Round aggregate
MOT Type 1 (crushed stone, loose)	1,750–2,100	17.5–21	—
MOT Type 1 (compacted)	2,100–2,200	21–22	—
Soil – clay (typical)	1,600–2,000	16–20	Saturated clay higher end
Soil – sand (loose)	1,400–1,700	14–17	—
Water	1,000	10.0	At 4°C; seawater ~1,025 kg/m³
Concrete roof tiles	—	0.50–0.70 kN/m²	Per m² of roof area
Clay roof tiles	—	0.50–0.80 kN/m²	Per m² of roof area
Natural slate (thin)	—	0.30–0.45 kN/m²	Per m² of roof area
Felt / EPDM flat roof	—	0.05–0.10 kN/m²	Per m² of roof area
Green / sedum roof	—	1.20–3.00 kN/m²	Saturated; verify with system manufacturer
Plasterboard (12.5mm)	900	0.11 kN/m²	Per m² of board

Mortar Mix Designations (BS EN 998-2)

Designation	Compressive Strength (N/mm²)	Approx Mix by Volume (C:L:S)	Typical Use
M1	1	1:3:12 or 1:2:9	Internal non-loadbearing partitions only
M2	2	1:2:9 or 1:1:6	Internal walls, lightweight partitions
M4	4	1:1:5.5 or 1:0.5:4.5	General external brickwork – most common UK spec
M4	4	1:1:5.5	Standard facing brickwork in sheltered/moderate exposure
M6	6	1:0.5:4.5 or 1:0:3	Engineering brickwork, below ground, exposed positions
M12	12	1:0:3 (SRPC)	Engineering brickwork below ground (sulphate resisting)

C = cement (Portland CEM I); L = lime (hydraulic or hydrated); S = sand. Sulphate-resisting Portland cement (SRPC) or Portland blast-furnace slag cement (PBFSC) should be used for all below-ground mortar joints in engineering brickwork and drainage structures.

UK Planning and Regulatory Reference – England 2026

Permitted Development Rights – Common Domestic Works (England)

Work Type	Permitted Development?	Key Conditions / Limits	Notes
Single-storey rear extension – detached house	Yes – up to 4m deep	Max height 4m; not to forward of principal elevation; not to cover >50% of garden	Neighbour Consultation Scheme allows up to 8m
Single-storey rear extension – semi / terraced	Yes – up to 3m deep	As above; NCS allows up to 6m	—
Double-storey rear extension	Usually No	Permitted only if within very limited parameters; usually requires PP	Always check with LPA
Side extension (any storey) – terraced/semi	Usually No	Side extensions on non-detached houses almost always require PP	—
Side extension – detached house (single storey)	Conditional Yes	Must be <50% width of original house; max 4m height; single storey only	—
Loft conversion (no dormer)	Yes	Max 40m³ additional volume (terraced) or 50m³ (other); no higher than existing ridge; no front roof slope alteration	—
Loft conversion with rear dormer	Yes (with conditions)	Within 40/50m³ limit; set back 20cm from eaves; no side dormers; no higher than ridge; materials to match	—
Garage conversion (internal works)	Yes (usually)	No external changes that affect the character; Building Regulations always required	—
Outbuilding in rear garden	Yes (conditions)	Max 2.5m height if within 2m of boundary; single storey; not forward of principal elevation; not >50% of garden	—
Gravel / permeable front garden driveway	Yes – any size	Permeable surfacing; no planning required regardless of area	—
Impermeable front garden driveway >5m²	No – planning required	Must be permeable or drain to border / soakaway	—
Garden fence / wall up to 1m (adj. highway)	Yes	Max 1m height adjacent to highway; max 2m elsewhere	—
Garden fence / wall up to 2m (not adj. highway)	Yes	Over 2m requires planning permission	—
Solar panels (roof mounted – not listed)	Yes (conditions)	Must not protrude more than 200mm beyond roof plane; not on principal elevation where visible from highway	—
Works on listed building	No – LBC required	Listed Building Consent required for any works affecting character	Applies to all grades of listing
Works in Conservation Area (front elevation)	Often No	Many PD rights removed; check Article 4 directions with LPA	—

Planning Application Fees – England 2026

Application Type	Fee (2026)	Notes
Householder application (extension, loft, outbuilding)	£528	Single flat fee for most domestic householder applications in England from 6 December 2023
Prior Approval – larger home extension (NCS)	£258	Neighbour Consultation Scheme notification fee
Change of use – dwellinghouse to flats (1–50 units)	£578 per unit	—
New dwellinghouse	£578 per unit	Up to 50 units; larger sites different fee scale
Listed Building Consent	No fee	LBC applications are free; planning permission if also required is charged separately
Certificate of Lawful Development (proposed)	50% of equivalent PP fee	Useful for confirming PD without full planning; creates legal certainty
Certificate of Lawful Development (existing)	50% of equivalent PP fee	For confirming existing development is lawful
Appeal (to PINS)	No fee	Planning appeals are free to submit; professional costs apply

Building Regulations – Key Dimensional Requirements (England 2026)

Element	Minimum / Maximum	Approved Document	Notes
Stair – maximum pitch	42°	Part K	Steeper stairs permitted in very limited circumstances (e.g. loft ladders)
Stair – rise (private stair)	Min 150mm, max 220mm	Part K	All risers in a flight to be equal
Stair – going (private stair)	Min 220mm, max 300mm	Part K	2R + G = 550–700mm rule of thumb
Stair – min headroom	2,000mm	Part K	Measured vertically from pitch line; loft stairs 1,800mm
Stair – handrail height	900–1,000mm	Part K	From pitch line or landing floor level
Balustrade / guarding height (floor >600mm above)	Min 900mm (domestic); 1,100mm (other buildings)	Part K	Baluster openings max 100mm (sphere test)
Door minimum clear width – accessible dwelling (M4-2)	Min 775mm clear	Part M Vol.1	Leading door to principal rooms; 850mm preferred
Habitable room – minimum ceiling height	2,300mm	Guidance (not mandatory)	Not a statutory minimum in England; industry standard
Foundation depth – minimum (clay, UK typical)	1,000mm from finished ground level	Part A / AD A	Deeper in shrinkable clay; adjacent trees require deeper foundations
Foundation width – cavity wall on good ground	Min 600mm wide (450mm min)	Part A / AD A Table 12	Depends on wall load and ground bearing capacity
Foundation thickness	Max projection from wall, or 150mm min	Part A	Projection must not exceed thickness; typically 225–300mm
Cavity wall – minimum cavity width	50mm	Industry standard / NHBC	75–100mm preferred for full-fill insulation
DPC height above external ground level	Min 150mm	Part C	Approved Document C; engineering brick DPC or proprietary DPC membrane
Smoke alarm – ground floor (new dwelling)	At least 1 per floor	Part B Vol.1	Interlinked; heat alarm in kitchen; all to BS 5839-6
Escape window (habitable room above ground)	Min 0.33 m² openable area; min 450mm clear opening height and width	Part B Vol.1	Sill max 1,100mm from floor