RICS Spray Foam Insulation Guidance 2024: Official Standards Explained
The Royal Institution of Chartered Surveyors (RICS) sets the standards for spray foam roof insulation in the UK. Understand the official guidance, how it's evolved, and whether your spray foam complies.
What is RICS and Why Does Its Guidance Matter?
RICS (Royal Institution of Chartered Surveyors) is the world's leading professional body for qualifications and standards in land, property, and construction. Established in 1868, RICS has 134,000+ members worldwide and sets the standards that surveyors, valuers, and property professionals must follow.
RICS's Role in Spray Foam:
Sets Professional Standards
Publishes guidance on how surveyors should inspect, assess, and report on spray foam insulation.
Defines Best Practice for Installation
While not writing building regulations, RICS guidance establishes what "proper" spray foam installation looks like.
Influences Lender Policies
Mortgage lenders base their spray foam acceptance criteria almost entirely on RICS guidance. If RICS says it's risky, lenders won't lend.
Protects Professional Surveyors
Surveyors who follow RICS guidance are protected from negligence claims. Those who ignore it are not.
"RICS guidance represents the accumulated professional consensus on best practice. It's based on decades of experience, research, and—crucially—learning from failures." — Senior RICS Building Surveyor
Evolution of RICS Spray Foam Guidance (2010-2024)
RICS's position on spray foam has changed dramatically over 15 years—from permissive to highly restrictive—as evidence of problems mounted.
Early Adoption Phase: "Generally Acceptable"
Spray foam seen as innovative energy-saving technology. Minimal RICS guidance—treated similarly to other insulation types.
Key Stance:
- • "Spray foam can be an effective insulation solution"
- • Basic recommendation: ensure adequate ventilation
- • No specific surveyor protocols for spray foam inspection
- • Most lenders accepted spray foam properties without hesitation
Concerns Emerging: First Restrictions
Reports of timber rot and ventilation issues prompted RICS to issue cautionary guidance.
Updated Guidance (2018 Revision):
- • "Surveyors should pay particular attention to ventilation when spray foam is present"
- • Recommended 50mm ventilation gap minimum
- • Advised against spray foam in heritage/traditional buildings
- • Suggested inspecting timber where accessible
- • Still broadly accepted by most lenders with caveats
Crisis Point: Nationwide Ban & Industry Reckoning
Widespread failures led to major lender withdrawals. RICS tightened guidance significantly.
Major Changes:
- • Nationwide Building Society banned spray foam properties (Sep 2022)
- • RICS issued emergency update: "Spray foam requires specialist inspection"
- • Mandatory invasive surveys introduced (remove foam samples to inspect timber)
- • Clear stance: pre-2020 installations often don't meet current standards
- • Lenders began requiring RICS Level 3 surveys instead of Level 2
Current Standards: Strict Compliance Required
RICS published comprehensive spray foam guidance. Clear, stringent requirements that most existing installations fail.
2024 Official RICS Position:
- • 50mm minimum ventilation gap mandatory (measured, not estimated)
- • Foam must NOT adhere to roof felt, tiles, or sarking boards
- • Eaves and ridge ventilation must remain unobstructed
- • Timber moisture content must be <20% throughout
- • Invasive inspection required for ALL mortgage surveys
- • Properties failing these criteria are "unsuitable for mortgage lending"
RICS 2024 Standards: The Complete Requirements
1. Ventilation Gap Requirements
RICS Standard:
"A clear, unobstructed ventilation path of minimum 50mm depth must be maintained between the spray foam insulation and the underside of the roof covering (tiles, slates, or sarking boards) throughout the entire roof area."
✓ Compliant:
- • 50mm+ gap measured at multiple points
- • Consistent gap throughout (no pinch points)
- • Foam does not touch roof felt/tiles at any point
- • Eaves vents and ridge vents fully functional
✗ Non-Compliant:
- • Gap <50mm anywhere in the roof
- • Foam sprayed directly onto roof felt (common!)
- • Inconsistent gaps (varies 30-60mm)
- • Ventilation paths blocked by foam overspray
2. Timber Preservation Standards
RICS Standard:
"Timber structural elements (rafters, joists, purlins) must remain dry and accessible for inspection. Spray foam application must not prevent timber from breathing or trap moisture that accelerates rot."
Moisture Content Limits:
- • Ideal: 12-18% moisture content (timber is dry and healthy)
- • Acceptable: 18-20% (borderline—requires monitoring)
- • Concern: 20-25% (risk of wet rot developing)
- • Failure: >25% (active rot likely present or imminent)
Visual Inspection Requirements:
- • No discoloration (darkening indicates moisture exposure)
- • No soft/spongy areas when prodded (rot symptom)
- • No fungal growth (white/brown stringy growth = rot)
- • No musty smell (indicator of hidden moisture/rot)
Why This Matters: Spray foam encapsulates timber, preventing visual inspection and natural drying. If moisture gets trapped (from roof leaks or condensation), timber rots invisibly until structural failure occurs.
3. Installation Quality Standards
RICS Standards for Proper Installation:
Proper Adhesion
Foam must be securely bonded to rafters/joists without sagging, delamination, or gaps. Loose foam provides no insulation and can fall creating hazards.
Uniform Thickness
Consistent depth throughout (typically 100-150mm for closed-cell, 200-300mm for open-cell). Thin patches create cold spots and condensation risk.
No Overspray Contamination
Foam should only be on intended surfaces. Overspray on electrical wiring, chimneys, or ventilation pathways creates safety hazards and building regulation breaches.
Appropriate Foam Type for Application
Closed-cell for moisture-prone areas; open-cell where breathability needed. Using wrong type is non-compliant.
Professional Installation Certificate
RICS expects evidence of professional installation to recognized standards (PAS 2030, BBA certification). DIY spray foam is automatically non-compliant for mortgage purposes.
4. RICS Surveyor Inspection Protocol
RICS mandates specific inspection procedures for surveyors assessing spray foam properties. This is what your surveyor should be doing:
Mandatory Inspection Steps:
- 1.
Loft Access & Visual Assessment
Document foam type, coverage, obvious defects. Take photos.
- 2.
Ventilation Gap Measurement
Measure at 5+ points across the roof. Document minimum, maximum, average.
- 3.
Invasive Foam Removal (Sample Testing)
Remove 3-5 sections of foam (200mm²) to expose timber. RICS: "Essential—visual inspection through foam is inadequate."
- 4.
Timber Moisture & Condition Testing
Moisture meter readings at each exposed timber section. Visual + tactile assessment for rot.
- 5.
Overall Roof Condition Assessment
Check for leaks, structural movement, tile condition—problems compounded by spray foam.
- 6.
Detailed Report with Specific Compliance Statement
Must state whether spray foam complies with RICS guidance. Vague language ("appears acceptable") is not sufficient.
Common Misconceptions About RICS Spray Foam Guidance
Myth #1: "If my installer said it's compliant, it must be fine"
Reality: Installers have financial incentive to say their work complies. Many installers operated before current RICS standards existed or simply didn't follow them. RICS guidance is for surveyors, not installers—installer claims don't override surveyor findings.
✓ What to do: Independent RICS survey is the only reliable compliance check.
Myth #2: "RICS bans spray foam"
Reality: RICS doesn't ban spray foam. It sets standards for safe installation. However, those standards are so strict that most existing installations fail. It's not a ban—it's that 60-70% of spray foam was installed incorrectly.
✓ The truth: Properly installed spray foam (50mm gap, timber protected) can pass RICS standards. It's just rare in practice.
Myth #3: "If there's no visible damage, my spray foam is compliant"
Reality: The whole problem with spray foam is that damage is hidden. You can't see timber rot or ventilation gaps without invasive inspection. Absence of visible problems ≠ compliance with RICS guidance.
✓ The catch: By the time damage is visible (ceiling stains, sagging), it's usually severe and expensive to repair.
Myth #4: "Older guidance was fine—my 2018 installation is grandfathered in"
Reality: RICS guidance isn't legislation—there's no "grandfathering." Current standards apply to ALL properties regardless of when spray foam was installed. 2024 lenders assess 2015 installations against 2024 RICS guidance.
✓ Impact: Installations that were "acceptable" in 2018 often fail 2024 standards. This has caused the mortgage crisis.
Myth #5: "Building Control approval means it meets RICS standards"
Reality: Building Control checks compliance with Building Regulations (Part L for insulation). RICS guidance is separate—higher standards focused on long-term timber preservation and mortgage risk. Building Control approval ≠ RICS compliance.
✓ Example: You can have Building Regs-compliant spray foam that fails RICS standards due to inadequate ventilation gap.
How to Check If Your Spray Foam Complies with RICS Guidance
If you have spray foam insulation and need to know whether it meets current RICS standards, follow these steps:
Commission RICS Level 3 Survey with Spray Foam Specialist
This is the ONLY definitive way to assess compliance. Cost: £1,100-£2,300.
Do this: Before remortgaging, before selling, or if you suspect problems. Early diagnosis saves money.
DIY Initial Check (Not Definitive)
If you have loft access and feel confident inspecting, you can do preliminary checks:
- • Measure ventilation gap with ruler/measuring tape (need 50mm+ everywhere)
- • Check if foam is stuck to roof felt (red flag if yes)
- • Look for water stains, discoloration, or musty smells
- • Feel timber (if accessible) for softness or sponginess
⚠ Warning: DIY checks can't replace professional survey. Hidden damage is common.
Review Installation Documentation
If you have installer paperwork, check for:
- • Installation date (pre-2020 = higher risk of non-compliance)
- • Foam type specified (closed-cell vs open-cell)
- • Mention of ventilation gap provision
- • BBA certification or PAS 2030 compliance claim
- • Installer company still trading? (for potential warranty claims)
Note: Documentation claiming compliance doesn't guarantee it—only way to verify is professional survey.
Assess Red Flags
Certain factors make RICS compliance unlikely:
High Risk (Likely Non-Compliant):
- • Installed before 2018
- • Free government scheme installation
- • Installer no longer trading
- • No paperwork/certification
- • DIY installation
Lower Risk (Worth Checking):
- • Installed 2020 or later
- • Paid installation by reputable company
- • Documentation mentions ventilation gap
- • Installer offers post-install survey
- • BBA-certified installer
Official RICS Resources & Further Reading
Official RICS Documents:
RICS Guidance Note: Surveys of Residential Property (4th Edition, 2023)
Includes updated spray foam inspection protocols. Available via RICS website (members only).
RICS Practice Information: Spray Foam Insulation (2024)
Specific guidance on spray foam—covers ventilation, timber protection, surveyor duties.
RICS Building Survey Technical Note
Level 3 survey requirements including invasive inspection procedures.
Related Standards & Regulations:
- Building Regulations Part L (Conservation of Fuel & Power): Sets insulation U-values but doesn't address ventilation/timber protection like RICS does.
- PAS 2030: Standard for energy efficiency improvements—covers spray foam installation best practice (but less strict than RICS on ventilation).
- BBA Certification: British Board of Agrément approval for spray foam products—verifies product quality but doesn't guarantee compliant installation.
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