Raft Foundations vs Alternatives: Why the BCD Prefabricated Raft Reinforcement System Sets a New Standard
- caoimhe327
- Nov 19
- 4 min read
Updated: Nov 20
In residential construction across Ireland, the choice of foundation plays a critical role in structural stability, project timelines, and overall cost. While traditional strip or pad foundations remain common, raft foundations have rapidly grown in popularity - especially on sites with variable ground conditions or where efficiency is a priority.
Below, we explore why raft foundations are such an effective and economical choice - including how the BCD Civil Engineering Ltd.'s prefabricated raft reinforcement system further reduces labour, time, and total project cost.
1. What Is a Raft Foundation?
A raft (or mat) foundation is a large, reinforced concrete slab that supports the entire footprint of a building. Instead of transferring loads through individual trenches or pads, a raft spreads loads evenly across the full area, minimising settlement and improving long-term performance.
This makes it particularly suitable for sites with moderate or variable bearing capacity, or where deep excavations would be inefficient.
2. Advantages of Raft Foundations
Excellent Load Distribution
Rafts distribute loads uniformly, making them ideal for soft clays, reclaimed ground, peat margins, and other challenging soils commonly found in Ireland.
Reduced Excavation and Faster Construction
A shallow, uniform excavation speeds up groundworks and reduces spoil removal — a major advantage on unpredictable or soft ground.
Integrated Floor Slab
Raft foundations often double as the ground floor slab, reducing materials, labour, and project duration.
Improved Performance on Variable Soils
The raft acts as a single structural unit, better resisting differential settlement compared to strips or pads.
Enhanced Thermal Efficiency
Insulated raft systems can help achieve or exceed Part L of the Building Regulations (Technical Guidance Document L - Conservation of Fuel and Energy – Dwellings) through reduced thermal bridging and improved airtightness.
3. Cost Effectiveness: Why BCD Civil Engineering Ltd.'s Prefabricated Raft Foundations Are the Smarter Choice
While raft foundations are already efficient, BCD’s prefabricated raft reinforcement solution delivers even greater cost savings compared to traditional on-site steel fixing.
Key Cost Benefits of the BCD System
✔️ Reduced Need for On-Site Steel Fixers
Traditional raft reinforcement requires significant labour to cut, bend, and tie steel on site. The BCD prefabricated system arrives pre-cut, pre-bent, and ready for rapid placement, dramatically reducing steel fixing hours. Also included is a install guide for anyone unfamiliar with the installation process.
✔️ Faster Installation = Lower Labour Costs
Prefabricated reinforcement sections speeds up placement, reduces delays, and shortens overall foundation project time - meaning fewer labour days, fewer subcontractor hours, and reduced site overheads.
✔️ Reduced Waste
Factory-prefabricated steel solutions reduces offcuts and mistakes, improving material efficiency and lowering total reinforcement costs.
✔️ Higher Accuracy & Compliance
All BCD reinforcement steel is CARES-certified, ensuring full traceability and reliable quality - preventing costly rework or inspection delays.
The result: A raft foundation that is faster, more economical, and more predictable than both strip foundations and traditionally fixed raft reinforcement.
4. Comparison with Other Foundation Types
Foundation Type | Typical Use | Key Advantages | Key Limitations |
Strip Foundations | Good, uniform bearing soils | Simple, low-cost for light loads and in terms of concrete usage. | Poor performance on weak or variable soils; deeper excavation often needed |
Pad Foundations | Columns/point loads | Economical for discrete loads | Not suitable for continuous walls |
Pile Foundations | Very weak soils or heavy structures | Transfers load to deeper strata | Expensive, specialist equipment required |
Raft Foundations | Moderate/poor soils; full footprint | Even load spread, integrated slab, strong thermal performance | Higher reinforcement requirement - which BCD reduces with prefabricated solutions. |
Sources: buildingcontrolregister.ie, NSAI.ie, Engineers Ireland, eurocode7.com
5. Design Considerations in Ireland
Raft foundation design follows Eurocode 7 (EN 1997) and the Irish National Annex, supported by site-specific investigations under TGD Part C.
Important factors include:
Soil bearing capacity and settlement characteristics
Groundwater levels and waterproofing needs
Thermal detailing for Part L compliance
Reinforcement design for bending and shear
Construction certification and quality assurance
6. When to Choose a Raft Foundation
Rafts are ideal when:
Soil has low to moderate bearing capacity
Loads are uniform across the structure
Differential settlement must be minimised
Speed, predictability, and insulation performance are priorities
Labour reduction and cost efficiency are required
7. How BCD Supports Irish Builders & Engineers
At BCD, we supply prefabricated, CARES-certified reinforcement steel for raft foundations, designed specifically to:
Reduce steel fixing requirements
Minimise labour costs
Improve accuracy and site efficiency
Reduce waste
Streamline certification and inspections
Our team also supports TAMS, residential housing, commercial builds, and agricultural projects nationwide - ensuring compliance, quality, and speed on every foundation.
Conclusion
Raft foundations provide a powerful combination of strength, speed, and performance for Irish housing projects. When paired with BCD’s prefabricated reinforcement system, they become one of the most cost-effective options available, offering:
Faster installation
Reduced labour
Lower waste
Improved accuracy
Better project certainty
For builders, engineers, and developers seeking a reliable, economical, and future-proof foundation solution, a BCD-enhanced raft foundation is the clear choice.
About BCD Civil Engineering Ltd.
At BCD, we specialise in the fabrication and supply of high-quality steelwork and prefabricated reinforcement for agricultural, residential, and commercial projects nationwide. All reinforcement is CARES-certified, ensuring full compliance and performance.
Contact us today to discuss upcoming projects or learn more about our prefabricated raft foundation solutions.
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