Questions, feedback or enquiries — use the form below.
Material
Dimensions
Net volume—
Volume to order (inc. waste)—
Tonnes to order—
Bulk bags (850kg)—
20t artic loads—
💡 Always add 10% waste minimum on granular materials. 1.0m³ compacted MOT ≈ 1.18m³ loose.
⚠ Densities are industry standard reference values only. Actual density varies by quarry, moisture content and compaction. Always confirm with your supplier before pricing. These figures are a guide — not a guarantee.
Dimensions
Net volume—
Bulked spoil volume—
Approx weight of spoil—
Skips / wagons—
8-wheel tipper loads (~6m³)—
Artic loads (~20t)—
⚠ Bulk factors are indicative only — confirm from trial pit before pricing. Actual swell varies by soil type and moisture. Contaminated material requires specialist disposal — never assume standard tipping rates apply.
Element
Net volume—
Order volume (inc. waste)—
Ready-mix trucks (6m³)—
Approx weight—
Mix per m³
Cement—
Fine aggregate (sand)—
Coarse aggregate—
⚠ Use mix from engineer's drawings. C25 is minimum for domestic strip foundations (NHBC).
Ballast & Cement Calculator
Bags of cement (25kg)—
Ballast — bulk bags (850kg)—
Ballast — 25kg bags—
Cement (kg)—
Ballast (kg)—
3:1Strip foundations, structural concrete
4:1General purpose, fence posts, bases
5:1Paths, non-structural slabs
6:1Weak mix, haunching, filling
⚠ Ballast is pre-mixed aggregate — add cement only. 1 bulk bag ballast ≈ 850kg. Always add 10% waste. For structural work use ready-mix concrete where possible.
⚠ Always check civil engineer's drawings. Foul and surface water have different minimum gradients. Your drawings and specification take precedence over any reference values here.
Pipe Fall
Soakaway
Reference
Pipe Fall / Laser Calculator
Gradient—
As percentage—
Fall per metre—
Total fall over run—
End invert level—
Gradient Reference
1 in X
%
mm/m
Over 20m
Over 50m
1:20
5.00%
50mm
1000mm
2500mm
1:40
2.50%
25mm
500mm
1250mm
1:60
1.67%
16.7mm
334mm
835mm
1:66
1.52%
15.2mm
303mm
758mm
1:80
1.25%
12.5mm
250mm
625mm
1:100
1.00%
10mm
200mm
500mm
1:150
0.67%
6.7mm
134mm
335mm
1:200
0.50%
5mm
100mm
250mm
Soakaway Sizing — BS EN 752 / BRE Digest 365
Required volume—
Equiv. cube—
Crate modules (300L)—
Min distance from building5.0m (NHBC 5.3)
Drainage Reference — BS EN 752 / Part H
Min gradient — 110mm FOUL1:80 min · 1:40 max (BS EN 752 / Part H)
Min gradient — surface water1:80 min — confirm with engineer
Max run without chamber22m (Regs Part H)
Min cover — untrafficked600mm to top of pipe
Min cover — under road900mm to top of pipe
Pipe surround — untrafficked100mm pea gravel
Soakaway — min from building5.0m (NHBC Ch 5.3)
Separate foul / surfaceRequired — Regs Part H
Linear
Radius Table
Types
Kerb & Edging Calculator
HB2 standard 150mm · Edging standard 100mm · includes haunching
Units to order—
ST1 concrete — bed & haunch (m³)—
Standard Radius Kerb — Reference
Radius (m)
Radius (ft)
Units per full circle
Units per 90°
1.0
3
8
2
2.0
6
16
4
3.0
10
22
5.5
4.0
13
28
7
4.5
15
32
8
6.0
20
44
11
7.5
25
54
13.5
8.0
26
56
14
9.0
30
64
16
10.5
35
76
19
12.0
40
86
21.5
💡 Rule of thumb: 10 HB2 kerbs per m³ concrete · 80 edgings per 6m³ concrete
⚠ Over 12m radius — use standard straight kerbs. Confirm with engineer on adoption roads.
Kerb Types — BS EN 1340
Type
Dimensions
Use
HB2
W125 × H255 × L914mm
HB1
W150 × H305 × L914mm
SP Bullnose
W125 × H255 × L914mm
BN Bullnose
W125 × H255 × L914mm
Edging 100
H100 × W50 × L914mm
Edging 150
H150 × W50 × L914mm
Edging 200
H200 × W50 × L914mm
Quadrant
305 × 305 × H150mm
Dished Channel
H255 × W125 × L914mm
Transition
H150 × W305 × L914mm
Dropped
Various — check drawing
Setting Out
VAT
% Calc
Add VAT (Net → Gross)
VAT @ 20%—
Gross (inc VAT)—
Formula× 1.2
Remove VAT (Gross → Net)
Net (ex VAT)—
VAT element—
Formula÷ 1.2
⚠ To remove VAT divide by 1.2 — not ×0.8. These give different answers.
Percentage Calculator
Add 20%—
Remove 20%—
20% of value—
💡 Adding 20% then removing 20% does NOT return to original. To reverse +20%, divide by 1.2.
Find Unknown Side — Pythagoras
Enter any two sides. Leave the one you want to calculate as 0.
Result—
Which side—
3-4-5 Setting Out
The 3-4-5 method gives you a perfect right angle anywhere on site. Measure 3 units along one line, 4 units along the other — if the diagonal between those two points is exactly 5 units, the corner is square. Scale up as needed.
Measure along first line—
Measure along second line—
Diagonal must equal—
Rectangle Diagonal — Check for Square
Measure both diagonals of your rectangle — if they match, it's square. This shows you what both diagonals should be.
Diagonal (measure both — must match)—
Perimeter—
⚠ Use foundation depths from engineer's drawings. Values here are general guidance only.
Quick Sizing — BS 8004 / NHBC Ch 4
Min foundation width—
Recommended width—
Min depth (NHBC / frost)—
Min concreteC25 (NHBC minimum)
Foundation Types
Type
Ground
Cost
Note
Strip
Firm/stiff clay, gravel
£
Trench Fill
Most soils
£
Raft
Soft/variable/mining
££
CFA Pile
Most soils
£££
Screw Pile
Soft / made ground
££
Block Paving
Asphalt
Block Paving Calculator
⚠ Block thickness matters: 60mm = pedestrian only. 80mm = cars & driveways. 100mm = HGV/commercial. Using 60mm blocks where cars drive will cause failure.
Blocks to order—
Sand bed volume—
Sand to order—
Type 1 sub-base (150mm)—
Asphalt Calculator
Min laying temp—
Volume (inc. waste)—
Tonnes to order—
20t wagon loads—
⚠ Check temp on every load. Never lay on wet or frozen surface.
Construction Type
⚠ Always check engineer's drawings. CBR test results govern sub-base thickness.
What is SHW?
SHW stands for Specification for Highway Works — the government rulebook for all road and infrastructure jobs. On any Highways or adoptable road scheme, every load of fill going in the ground must match one of these classes. Your delivery tickets should show the SHW class. If the material doesn't match what's on the drawings, reject the load. If you're not on a highways job, your engineer's spec will reference these classes — it's the universal language for fill material on civils.
Always check engineer's drawings and specification. The class on the drawing governs — not this reference.
1A
Well Graded Granular
General fill
Compaction
Vibrating roller
Layer thickness
Not specified
⚠ No organic content. Not saturated or frozen.
1B
Uniformly Graded Granular
General fill
Compaction
Vibrating roller
Layer thickness
Not specified
⚠ More susceptible to settlement than 1A.
1C
Coarse Granular
Fill / drainage layers
Compaction
Vibrating roller
Layer thickness
300mm max
⚠ Requires graded fines layer above.
2A
Dry Cohesive — Low Plasticity
General fill (dry conditions)
Compaction
Sheepsfoot roller
Layer thickness
150mm compacted
⚠ Not above optimum moisture content +2%.
2B
Dry Cohesive — High Plasticity
Fill — restricted use
Compaction
Sheepsfoot roller
Layer thickness
150mm compacted
⚠ Not within 500mm of formation or structure.
5A
Crushed Concrete
General fill / capping
Compaction
Vibrating roller
Layer thickness
300mm max
⚠ Sulphate test mandatory. Not within 500mm of fresh concrete.
5B
Recycled Asphalt
Capping / fill
Compaction
Vibrating roller
Layer thickness
200mm max
⚠ May bind in summer — advantage for base layers. Check delivery temp.
6F1
Granular Capping
Capping under sub-base
Compaction
Vibrating roller
Layer thickness
225mm (2 lifts)
⚠ Proof-roll formation before placement.
6F2
Recycled Brick Hardcore
Bulk fill / capping
Compaction
Vibrating roller
Layer thickness
225mm compacted
⚠ Sulphate test required. Check grading on delivery.
6F3
Recycled Bituminous Capping
Capping / path subbase
Compaction
Vibrating roller
Layer thickness
200mm
⚠ Binds in heat — good for base. Check delivery temp.
6F5
Crushed Demolition Hardcore
First-layer fill on soft ground
Compaction
Heavy vibrating roller
Layer thickness
300mm max
⚠ Coarse material — ensure graded fill above.
Always obtain test certificates. Check grading on delivery. Use aggregain.org.uk to find local recycled alternatives.
Type 3 / SHW 6G — Free-Draining GranularPrimary1.65 t/m³
20–75mm single-size — granite or limestone
⚠ High permeability — used in filter drains, soakaway surrounds, perforated pipe bedding, sports pitch sub-bases. Not suitable as structural sub-base without finer material above. Always specify single-size. Different from Type 1 — do not mix up on delivery.
6F2 Crushed Brick6F21.75 t/m³
75mm down to dust
⚠ Bulk fill, capping. Good in wet conditions. Sulphate test required.
6F5 Crushed Brick6F51.80 t/m³
100mm to 40mm
⚠ First-layer on soft ground. Coarse — put graded material above.
6F3 Road Planings6F31.85 t/m³
80mm down (0/80)
⚠ Binds in warm weather — good for base. Better than loose planings.
Type 1 Recycled Concrete5A1.75 t/m³
40mm down to dust
⚠ Can replace primary Type 1. Sulphate test mandatory. Not within 500mm of fresh concrete.
Type 4 Recycled AsphaltT41.80 t/m³
0/40 well graded
⚠ Same grading as Type 1. Binds in heat — advantage for low-traffic roads.
Crusher Run / Scalpings6F11.80 t/m³
Variable — check on delivery
⚠ Grading varies by quarry. Always check on delivery.
Hogging1A/2A1.65 t/m³
Natural — variable
⚠ As-dug sand/gravel. Small clay content = good binding. Variable CBR.
Crushed GlassT11.50 t/m³
0/20 to 0/40
⚠ WRAP/Highways England approved in trials but specialist and not routinely available. Mainly used on public realm sustainability projects. Do not assume you can order this from a local quarry.
⚠ Always use mesh and reinforcement specified on engineer's drawings.
Mesh Sheet Calculator
Sheets to order (11.52m² each)—
Total area inc. laps—
Approx weight—
A-Type Square Mesh — BS 4483 (Slabs)
Ref
Wire
Pitch
kg/m²
Typical Use
A98
5mm
200×200
1.54
A142
6mm
200×200
2.22
A193
7mm
200×200
3.02
A252
8mm
200×200
3.95
A393
10mm
200×200
6.16
Cover Reference — BS 8500 / EC2
Foundations — aggressive ground75mm
Foundations — normal ground50mm
Ground-bearing slabs (on blinding)40mm
External concrete — exposed40mm
CFA / bored piles75mm
Bearing
Trench Battering
Soil Type
CBR
Bearing kN/m²
Made Ground
1–3
25–50
Peat / Organic
<1
<25
Soft Clay
1–3
25–75
Firm Clay
3–8
75–150
Stiff Clay
8–15
150–300
Loose Sand/Gravel
5–15
75–200
Dense Sand/Gravel
15–40
200–600
Chalk
10–30
125–500
Rock
30+
300+
Trench Battering Calculator
Angle of repose—
Batter back each side—
Total trench width at top—
Ratio (H:V)—
⚠ Always confirm soil type from trial pit before work starts. Wet or disturbed ground requires a flatter slope or engineered support. Never rely on battering alone in waterlogged, made ground or sand. HSE GS36 — always inspect before entry. Seek specialist advice if in doubt.
Angle of Repose Reference
Soil Type
Condition
Angle
Ratio
Clay
Dry
30°
1:1.7
Clay
Damp (well drained)
45°
1:1
Clay
Wet
15°
1:3.7
Earth
Dry
30°
1:1.7
Earth
Damp
45°
1:1
Gravel
Moist
48°
1:0.9
Sand
Dry / Moist
35°
1:1.4
Sand
Wet
25°
1:2.1
Loam
—
40°
1:1.2
Concrete
Asphalt
Earthworks
Workers
STOP — Frost risk (<2°C): Do not place if temp forecast below 2°C within 24hrs. Never pour on frozen ground.
STOP — Ground frozen: Thaw first. Min ground temp 2°C before pouring.
CAUTION — Cold weather (2–5°C): Min 10°C concrete on delivery. Insulated blankets. Extend curing ×2.
CAUTION — Hot weather (>25°C): Pre-cool water/aggregate. Place early morning. Target ≤32°C.
CAUTION — Heavy rain: Cover immediately. Rain on fresh concrete causes surface dusting.
⚠ Always add 5% waste minimum. Engineering bricks are heavier — check delivery limits. Mortar calculated at ~0.03m³ per m² for standard stretcher bond.
Course Height Calculator
Courses needed for target height—
Actual height achieved—
Height of N courses—
Common Block Course Heights (225mm/course)
Courses
Height
1
225mm
2
450mm
3
675mm
4
900mm
5
1125mm
6
1350mm
8
1800mm
Common Course Heights — Standard Brick (75mm/course)
Courses
Height
1
75mm
4
300mm
6
450mm
8
600mm
13
975mm
16
1200mm
20
1500mm
27
2025mm
Standard Brick Sizes
Type
L × W × H
Per m²
kg each
Use
Standard
215×102×65mm
59.5
2.7kg
Engineering A
215×102×65mm
59.5
3.5kg
Engineering B
215×102×73mm
53.5
3.2kg
Thermalite block
440×100×215mm
10
6.5kg
Dense concrete block
440×100×215mm
10
18kg
Mortar Mix Reference
Mix
Ratio
Use
1:3
1 cement : 3 sand
1:4
1 cement : 4 sand
1:1:6
1 cement : 1 lime : 6 sand
1:6
1 cement : 6 sand
Semi-dry
1:4 stiff mix
DPC & Substructure Rules
DPC minimum height
150mm above external finished ground level — Building Regs Part C
DPC material
Bituminous felt (BS 6398), polyethylene, blue engineering brick (3 courses min), or slate
Cavity fill below DPC
NHBC-approved products only — standard mortar not permitted below DPC in cavity. Typically weak mix concrete or approved fill product.
Below DPC brickwork
Engineering bricks Class A or B. 1:3 mortar minimum. Frost resistant.
Cavity width
50–75mm typical. Min 50mm clear from any wall tie or insulation to inner face of outer leaf
Cavity fill — partial
Leave 150mm clear from top of fill to underside of DPC minimum
⚠ Manhole construction must follow engineer's drawings and relevant BS/sewers standards. These are indicative reference values only.
Brick Manhole Reference — BS EN 1917
Internal dia.
Wall thickness
Brick type
Mortar
675mm
215mm (1B)
Engineering B
1:3
900mm
215mm (1B)
Engineering B
1:3
1050mm
215mm (1B)
Engineering B
1:3
1200mm
327mm (1.5B)
Engineering B
1:3
Manhole Construction Details
Base slab
Minimum C25 concrete, 150mm thick. Haunched to channel at 45°.
Channels & benching
Half-round channel brick — benching falls min 1:12 to channel. Smooth render finish 1:2 cement:sand. Benching to spring of channel.
Step irons
300mm centres, galvanised or polypropylene coated. Staggered alternate sides. First step max 500mm below cover.
Cover slab
RC concrete or precast. Min 100mm deep. Frame bedded in 1:3 semi-dry mortar.
Rendering
Internal: 1:2 cement:sand, 12mm thick, two coats. Waterproof additive for deep manholes or high water table.
Cover frames
D400 (road) or B125 (footway/light traffic). Set to finished level — allow for adjustment.
Backdrop connections
Any pipe entry >600mm above channel invert requires backdrop. SE design required for deep manholes (>3m).
Inspection Chamber Reference
Shallow chamber (to 600mm)
Precast or in-situ. 450×450mm min internal. Polypropylene chamber acceptable on private drain.
Deep chamber (600mm–1.0m)
Minimum 750×450mm internal. Brick or precast concrete. Step iron if >600mm deep.
Manhole (>1.0m)
Min 1050mm internal diameter brick or precast. Full step iron provision. Confined space permit required to enter.
BT Openreach (now Openreach) chambers are encountered on most infrastructure jobs. These are the standard precast concrete boxes housing telecoms cables and joints. Always check with Openreach before excavating near telecoms routes.
⚠ Never excavate within 0.5m of any marked BT/Openreach duct or chamber without hand-digging. Telecoms cables carry live circuits — damage causes major disruption and significant liability. Contact Openreach on 0800 023 2023 before works near telecoms infrastructure.
Standard Openreach Chamber Sizes
Type
Internal size
Cover size
Load rating
Use
Small (SSB)
450×300mm
450×300mm
B125
Medium (Type A)
610×457mm
600×450mm
B125/D400
Large (Type B)
762×610mm
750×600mm
D400
Extra Large (Type C)
1219×762mm
1200×750mm
D400
Openreach Duct Reference
Standard duct sizes
50mm, 63mm, 100mm OD HDPE or PVC. Multi-way duct (4-way, 6-way) common on major routes.
HDPE duct in concrete encasement for road crossings. Min 600mm cover.
Damaged duct/cable
Stop work immediately. Call Openreach: 0800 023 2023. Do not attempt repair.
Chamber bedding
100mm compacted granular bed. Haunched in C20 concrete if in trafficked area.
Other Telecoms Providers — Cable Colours
Provider
Duct colour
Emergency
Openreach / BT
Grey or black
0800 023 2023
Virgin Media
Green
0800 052 0800
Warning tape
Yellow — all telecoms
—
For reference only. Always consult current NHBC Standards, Building Regulations and British Standards. Structural design must be by qualified engineers.
NHBC Key Chapters
Ch 4.1 — Land Quality
Site investigation mandatory. Desk study + walkover minimum. Phase 2 if Phase 1 identifies risk.
Ch 4.2 — Building Near Trees
Min 1.5m depth for large trees within 5m on high-shrinkage clay. See NHBC Table 4.2-1.
Ch 4.2 — Strip & Trench Fill
Min C25. Width from NHBC Table 3 by soil type and load. Min 450mm below FGL.
Ch 4.3 — Raft & Piled Foundations
SE design required. Ground movement analysis needed. NHBC acceptance required.
