Strip Foundation Calculator 2026 | Concrete Volume & Cost Calculator
Strip Foundation Calculator 2026
Calculate Concrete Volume, Weight & Cost
Complete UK Strip Foundation Design Tool
Strip foundations are the most common foundation type for UK housing, supporting load-bearing walls by distributing weight across a continuous concrete strip. Our strip foundation calculator determines concrete volume, weight, materials, and costs based on BS 8004:2015 standards and Building Regulations Approved Document A requirements for 2026.
This calculator accounts for foundation width (typically 600-900mm), depth (450-1500mm), perimeter length, and wastage allowances. It calculates concrete cubic meters, aggregate tonnage, cement bags, ready-mix costs, and excavation volumes. Essential for project budgeting and NHBC compliant foundation design.
🧱 Strip Foundation Calculator
Calculate concrete volume and material requirements
Foundation Dimensions
Total length of all foundation trenches
Concrete Specification
Concrete Required
0 m³
Including wastage allowance
Material Quantities
Net Volume
0 m³
Total Weight
0 tonnes
Ready-Mix Loads
0
Excavation Volume
0 m³
If Site Mixing (Bags Required)
Cement (25kg bags)0 bags
Sharp Sand (tonnes)0 tonnes
Aggregate/Gravel (tonnes)0 tonnes
Water (litres approx.)0 litres
Cost Breakdown 2026
Concrete Material£0
Delivery/Pumping£0
Excavation£0
Labour (Pouring/Finishing)£0
Total Estimated Cost£0
Strip Foundation Types & Applications
Different strip foundation configurations suit varying ground conditions, building loads, and site constraints. Selection depends on soil bearing capacity, foundation depth requirements, and construction economics following NHBC Standards Chapter 4.2.
Traditional Strip Foundation
Width: 450-750mm typical
Depth: 450-1000mm
Application: Standard 1-2 storey houses on firm ground
Concrete: C20/25 (GEN3) unreinforced
Pros: Most economical, simple construction
Cost: £50-70/m³ concrete + £25-35/m³ excavation
Wide Strip Foundation
Width: 750-1200mm
Depth: 600-1000mm
Application: Weaker soils, heavier buildings
Concrete: C20/25, may need reinforcement
Pros: Distributes load over greater area
Cost: £60-80/m³ concrete, more excavation
Trench Fill Foundation
Width: 450-600mm (cavity width)
Depth: 900-1500mm+
Application: Clay soils, tree zones, deep foundations
Concrete: C20/25 mass fill to near ground level
Pros: Saves bricklaying time and labour
Cost: £70-90/m³ concrete, less labour
Stepped Foundation
Width: As per slope requirements
Depth: Variable with steps
Application: Sloping sites (> 10° gradient)
Concrete: C20/25, each step minimum 300mm
Pros: Follows ground contours economically
Cost: £60-85/m³, complex shuttering
Concrete Volume Calculation Method
Accurate concrete volume calculation prevents costly over-ordering or project delays from shortages. Calculate net volume, add wastage, and round up to nearest 0.5m³ for ordering. Most ready-mix suppliers have 6m³ minimum delivery charges.
📐 Strip Foundation Volume Formula:
Volume (m³) = Length (m) × Width (m) × Depth (m)
Example: 40m perimeter × 0.6m wide × 0.9m deep = 21.6m³ net volume
Add 10% wastage: 21.6 × 1.10 = 23.76m³
Order: 24m³ (round up to nearest 0.5m³)
Ready-mix loads: 24m³ ÷ 6m³ per truck = 4 loads
Weight: 24m³ × 2.4 tonnes/m³ = 57.6 tonnes total
Typical Strip Foundation Concrete Requirements
House Type
Perimeter
Width × Depth
Concrete Volume
Typical Cost
Small Bungalow
30m
600mm × 750mm
13.5m³ (15m³ with wastage)
£1,800-2,400
3-Bed Semi-Detached
40m
600mm × 900mm
21.6m³ (24m³ with wastage)
£2,900-3,800
4-Bed Detached
50m
750mm × 900mm
33.75m³ (37m³ with wastage)
£4,500-5,900
Large 5-Bed House
65m
750mm × 1000mm
48.75m³ (54m³ with wastage)
£6,500-8,500
Single Storey Extension
15m
600mm × 900mm
8.1m³ (9m³ with wastage)
£1,100-1,450
Two Storey Extension
15m
750mm × 900mm
10.1m³ (11m³ with wastage)
£1,350-1,750
3-Bed Semi-Detached
Perimeter40m
Dimensions600 × 900mm
Concrete24m³
Cost£2,900-3,800
4-Bed Detached
Perimeter50m
Dimensions750 × 900mm
Concrete37m³
Cost£4,500-5,900
Two Storey Extension
Perimeter15m
Dimensions750 × 900mm
Concrete11m³
Cost£1,350-1,750
Concrete Grades for Strip Foundations
Concrete grade selection depends on foundation design, ground conditions, and exposure. BS 8500:2015 specifies concrete specifications. Domestic foundations typically use C20/25 (formerly GEN3) or C25/30 for reinforced applications.
✅ Concrete Grade Selection Guide:
C15/20 (GEN1): Blinding layer only (50-75mm under foundations), not structural. £95-110/m³
C20/25 (GEN3): Standard domestic foundations, unreinforced. Most common choice. £100-120/m³
Choose between ready-mix delivery or site-mixing based on project size, access, and budget. Ready-mix ensures consistent quality and faster placement. Site-mixing suits small volumes or restricted access situations.
Ready-Mix Concrete Delivery
Minimum Order: Usually 6m³ (£120-150 charge for less)
Truck Capacity: 6-8m³ per load typical
Cost: £100-120/m³ delivered (2026 prices)
Delivery Time: 90 minutes from batching to discharge
Access Required: 3m width, 4m height clearance
Pros: Consistent quality, faster, less labour
Best For: Volumes over 4m³, good site access
Volumetric Mixer (Mix-On-Site)
Minimum Order: No minimum (billed per m³)
Capacity: 6-9m³ per truck
Cost: £115-140/m³ mixed on-site
Advantages: Mix exact amount needed, no wastage
Call-out: £80-120 delivery charge
Best For: Small volumes, phased pours, uncertain quantities
Site-Mixed Concrete (Bags)
Cost: £180-250/m³ (materials + labour)
Cement: 8-9 × 25kg bags per m³ @ £6-8/bag
Aggregates: 0.6 tonnes sand + 1.2 tonnes gravel per m³
Labour: 4-6 hours per m³ (2 workers)
Quality: Variable, depends on mixing accuracy
Best For: Very small jobs (< 2m³), no access for trucks
Concrete Pump Hire
When Needed: Distance > 15m from truck position
Line Pump: £250-400 half day (up to 30m reach)
Boom Pump: £500-800 half day (up to 50m reach)
Setup Time: 30-60 minutes
Output: 20-80m³/hour depending on type
Accessibility: Can pump over obstacles
Site-Mix Concrete Proportions
If mixing on-site, use correct proportions for C20/25 equivalent strength. Proportions by volume using shovel method: 1 cement : 2 sand : 4 aggregate (1:2:4 ratio). Always use clean, sharp sand and 20mm graded aggregate.
Sharp Sand: 0.6 tonnes (approx. 14-15 shovels per bag cement)
20mm Aggregate: 1.2 tonnes (approx. 28-30 shovels per bag cement)
Water: 180-220 litres (adjust for sand moisture)
Mix Time: Minimum 2 minutes in mixer for uniform consistency
Workability: Add plasticizer if needed (follows manufacturer guidance)
Quality Control: Professional ready-mix far superior for structural foundations
Foundation Construction Process
Proper construction sequence ensures structural integrity and Building Control compliance. Follow NHBC Standards for each stage from excavation through concrete curing.
Step 1: Excavation
Set Out: Mark trench lines with string lines and pegs
Excavate: Dig to required depth, keep sides vertical
Check Depth: Verify foundation depth with laser or profiles
Services: Identify and protect existing utilities
Remove Soft: Dig out any soft/unsuitable material
Keep Clean: Remove loose material from trench bottom
Step 2: Inspection & Blinding
Building Control: Inspect trenches before concreting
Purpose: Provides clean working surface, protects DPM
Cure Time: 24 hours before laying DPM
Step 3: Concrete Pour
Timing: Pour within 90 minutes of batching
Placement: Deposit close to final position, don't drag
Compaction: Vibrate or rod out air pockets thoroughly
Level: Screed to correct height using profiles
Weather: Avoid pouring in rain, frost, or extreme heat
Continuity: Complete each section without cold joints
Step 4: Curing & Protection
Initial Set: 4-8 hours (don't disturb)
Curing: Keep moist for 7 days (cover with polythene)
Cold Weather: Protect from frost (< 5°C) for 3 days
Hot Weather: Prevent rapid drying with wet hessian
Loading: Can build walls after 3 days minimum
Full Strength: Achieves design strength at 28 days
Foundation Cost Breakdown 2026
Total foundation costs include materials, labour, plant hire, Building Control fees, and ancillary items. Prices vary regionally with London/Southeast typically 15-25% higher than Northern England.
Typical UK Strip Foundation Costs per Linear Meter
Foundation Size
Concrete (m³/m)
Material Cost
Labour & Plant
Total Cost/m
600mm × 600mm
0.36 m³
£40-45
£60-80
£100-125/m
600mm × 900mm
0.54 m³
£60-70
£75-95
£135-165/m
750mm × 900mm
0.68 m³
£75-90
£85-105
£160-195/m
750mm × 1200mm
0.90 m³
£100-120
£100-125
£200-245/m
Trench Fill 600mm × 1500mm
0.90 m³
£100-120
£70-85
£170-205/m
600mm × 900mm Foundation
Concrete per meter0.54 m³
Material Cost£60-70
Labour & Plant£75-95
Total per meter£135-165/m
750mm × 900mm Foundation
Concrete per meter0.68 m³
Material Cost£75-90
Labour & Plant£85-105
Total per meter£160-195/m
Strip Foundation Calculator FAQs
How much concrete do I need for strip foundations?
Calculate: Length (m) × Width (m) × Depth (m) = Volume (m³). Example: 40m perimeter × 0.6m wide × 0.9m deep = 21.6m³. Add 10% wastage = 23.76m³, order 24m³. Typical 3-bed house (40m perimeter, 600×900mm) needs 22-24m³. Always round up to nearest 0.5m³ for ordering. Check with structural engineer for exact specifications.
What is the cost of strip foundations per meter?
Typical costs in 2026: 600×900mm = £135-165/m, 750×900mm = £160-195/m including materials, labour, excavation. Total house foundation (40m perimeter): £5,400-7,800 for standard 600×900mm. Costs vary regionally: London/Southeast +20-25%, Northern England/Scotland -10-15%. Add Building Control fees £400-800 and structural engineer £600-1200 if required.
Can I calculate strip foundation concrete myself?
Yes, basic calculation is straightforward: multiply length × width × depth in meters. However, consider: corner overlaps, stepped foundations on slopes, wastage allowances, truck access limitations. Use our calculator for accurate results including all factors. Always verify quantities with your groundworker/builder before ordering. Under-ordering causes expensive delays; massive over-ordering wastes money.
What concrete grade for house foundations?
Standard UK domestic foundations use C20/25 (formerly GEN3) unreinforced concrete. C25/30 required for reinforced foundations or aggressive ground conditions (sulfates). C15/20 acceptable only for blinding layer beneath foundations. Never use lower grades for structural foundations. Building Control will specify grade based on ground investigation and structural engineer calculations. Ready-mix supplier can advise on sulfate resistance if needed.
How many cement bags per cubic meter of concrete?
Site-mixed concrete requires 8-9 × 25kg cement bags per m³ plus 0.6 tonnes sand and 1.2 tonnes aggregate. Total cost £150-200/m³ materials. However, site-mixing foundations is false economy: inconsistent quality, very labour intensive (4-6 hours per m³), Building Control may reject. Ready-mix concrete (£100-120/m³) is far superior, faster, more reliable for foundations. Only site-mix tiny volumes with absolutely no truck access.
What is minimum ready-mix concrete delivery?
Most UK suppliers have 6m³ minimum. Deliveries under 6m³ incur £120-180 small load surcharge. Consider: volumetric mixer (mix-on-site) for small quantities with no minimum charge (but £115-140/m³ premium), batching multiple projects same day, or ordering 6m³ minimum even if slight wastage (often cheaper than surcharge). Calculate carefully - cannot return unused concrete.
How long does foundation concrete take to set?
Initial set: 4-8 hours (walkable with care). Build walls: After 3-5 days minimum. Full strength: 28 days (achieves design 20/25 MPa strength). Keep concrete moist for 7 days curing (cover with polythene). In cold weather (< 5°C), protect from frost for 3 days minimum. Hot weather: prevent rapid drying with wet hessian covers. Building Control must inspect before walls commence.
What width for strip foundations?
Width depends on soil bearing capacity and building load. Typical domestic: 600mm single storey, 600-750mm two storey, 750-900mm three storey or poor soil. Minimum 450mm for any load-bearing wall. Structural engineer calculates exact width based on ground investigation results. Never guess foundation width - under-sized foundations cause settlement and cracking. See our Foundation Width Calculator for detailed sizing.
Do I need a concrete pump for foundations?
Pump needed if: distance from truck position > 15m, access restricted (narrow passages), obstacles between truck and trench. Line pump: £250-400 half day (30m reach). Boom pump: £500-800 half day (50m reach). Many foundations can be poured directly from ready-mix truck chute (saves £250-400). Discuss access with supplier when ordering - they advise if pump necessary. Include pump cost in budget.
What is trench fill foundation?
Trench fill = narrow trench (450-600mm) filled with concrete to near ground level (900-1500mm+ deep). Saves brickwork below DPC. Common on clay soils and where trees require deep foundations. Uses more concrete but less labour overall. Economical for depths > 1200mm. Example: 600×1400mm trench fill costs £170-210/m vs 600×1400mm traditional brick-to-DPC £180-240/m. Building Control approval required.
