Knowledge Centre
Blogs, FAQs, technical downloads and guided journeys — everything you need to understand insulated raft foundations.
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Self-Builders
First principles, costs, and getting started on your self-build project.
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Thermal data, CAD details, specifications, and RIBA stage guidance.
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Precision tolerances, thermal performance, and trade partnership.
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Programme savings, compliance, and cost comparisons at scale.
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Insulated Raft Foundation Details: 5 Junctions to Resolve Before Construction
Five wall, threshold and service interfaces architects should coordinate before the raft is detailed and poured.
Why Repeatability Matters in Large-Scale Construction
What the University of Staffordshire Student Village shows about repeatable details, predictable interfaces and designing for consistent delivery at scale.
Guy Martin's House Without Bills: What a Passivhaus Retrofit Tells Us About New Builds
What the Channel 4 programme shows about the order of work in a retrofit, and why the ground floor is the part you cannot easily fix later.
Passivhaus at Scale: What Weavers' Hall Tells Us About Early Design Coordination
What a 459-bedroom Passivhaus development teaches us about early contractor involvement, technical interfaces and resolving details before site.
What Is the Best Foundation for a Passivhaus Home?
Why the wall-floor junction and its Psi-value matter more than choosing a foundation type by name.
What Rising Energy Bills Mean for the Business Case for Fabric-First Design
Why low energy demand, smaller heating equipment and durable running-cost claims matter more as energy prices rise.
Why Housing Associations Are Choosing Passivhaus Before They Are Forced To
Lower tenant bills, reliable performance and fewer retrofit liabilities are making the case now.
What is an insulated raft foundation?
An insulated raft foundation is a reinforced concrete slab that sits on top of a layer of load-bearing insulation, with more insulation wrapped around its...
Why Use an Insulated Raft Instead of a Traditional Raft with Insulation Above?
Insulation below the slab does more work, with less effort. When insulation sits above a concrete raft, the concrete sits outside the building's thermal...
What Is the Minimum Concrete Thickness for an Insulated Raft Foundation?
200mm for most houses. 250mm for taller buildings. If a supplier is showing you anything less, ask them to explain why. Structural calculations alone might...
Technical Details (PDF Library)
Typical Section
All
Standard Edge Detailing
All
Edge & Base Combinations
All
Edge Details — Common Variations
All
Brick Plinth Detail
Brick & Block
SD-0022 — Brick Support, DPM Under Slab
Brick & Block
SD-0022A — Brick Support, DPM Above Slab
Brick & Block
SD-0022B — Brick Support, Waterproof Concrete
Brick & Block
Solid Aircrete Wall with EWI
Brick & Block
Hollow Clay Blocks Detail
Brick & Block
Timber Frame & SIPs Wall Junction
Timber Frame, SIPs
Larsen Truss Detail
Timber Frame
I-Stud Twin Wall — Dual Bearing
I-Stud
Twin Wall I-Stud — Inner Bearing
I-Stud
Sole Plate Location Guidance
Timber Frame
ICF Wall Detail
ICF
Wood-Cement Fibre Blocks Detail
Brick & Block
Slate & Tile Edge Detail
All
Party Walls Detail
All
SD-0023 — Threshold Detail
All
SD-0031 — EM10 Threshold Support
All
SD-0032 — EM15 Threshold Support
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SD-0033 — EM20 Threshold Support
All
ISOQUICK Threshold Support Brochure
All
SD-0018 — Drains and Ducts
All
SD-0015 — External Tanking
All
SD-0003 — General Sub-Base Arrangements
All
Stepped Footing — Large
All
Stepped Footing — Small
All
DPC & Full Radon Protection
All
Underfloor Heating Options Guide
All
Installation Guide — Part 1: Groundworks
All
Installation Guide — Part 2: ISOQUICK Installation
All
Installation Guide — Part 3: Brick Support System
Brick & Block
ISOQUICK Brick Support System — Introduction
Brick & Block
ISOQUICK Brick Support System — How It Works
Brick & Block
IQ Technical Specification
All
IQ-60e U-Value Tables
All
IQ-90 U-Value Tables
All
IQ-210 U-Value Tables
All
Kiwa BDA 3rd Party Certification
All