An EPC assessment booked this spring, after England’s record wet winter, gives homeowners and landlords something that many current certificates cannot: an accurate picture of where their property actually stands. After the wettest winter England has recorded in years — with rainfall running 42% above average according to the Met Office and some areas seeing rain on 41 consecutive days — the gap between what an old EPC assumes and what a property’s fabric is actually delivering has never been wider.
Why This Spring Is a Particularly Critical Moment
Three factors make spring 2026 an unusually important time to get an EPC assessment, even for properties that already have a valid certificate.
The building fabric has just been tested by extreme conditions. The winter of 2025 to 2026 was England’s eighth wettest on record. Cavity insulation, floor insulation, loft insulation, and the walls and mortar of millions of properties have been exposed to sustained saturation unlike anything seen in recent years. An assessment done now — while the effects of that saturation are still visible to an experienced assessor — captures an accurate current state.
The methodology changed in June 2025. RdSAP 10, introduced in June 2025, updated the way EPC assessors calculate ratings for existing homes. Properties assessed before this date used the old RdSAP 9.94 methodology. Some property types — particularly solid brick properties with walls thicker than 280mm — may score differently under the new methodology. If your certificate predates June 2025, a new assessment under RdSAP 10 may produce a different rating.
The 2030 landlord compliance deadline is approaching. Landlords must achieve EPC band C for all tenancies by 1 October 2030. A property assessed in spring 2026 and found to be at D 62 has a clear roadmap to C. A property operating from a certificate issued in 2019 under the old methodology may have an inaccurate baseline that leads to poorly targeted investment.
Who Specifically Needs an EPC Assessment This Spring
Landlords Planning Improvements
If you are a landlord planning insulation or heating improvements to reach EPC C before 2030, a current assessment under RdSAP 10 is the correct starting point. The recommended improvements table on a 2026 certificate reflects the current methodology, current U value assumptions for your wall type, and the current SAP weighting of each measure.
Investing in improvements guided by a certificate from 2021 means your improvement plan may be based on inaccurate starting assumptions. The same money spent guided by a current certificate typically delivers a more efficient route to C.
Properties With Cavity Insulation Installed Before 2000
Older mineral wool cavity insulation that has settled, degraded, or been affected by moisture over multiple wet winters may not be delivering the performance assumed in the existing EPC. Under RdSAP 10, an assessor who can evidence the current condition of the insulation records the accurate state rather than the theoretical state. If your cavity insulation has been investigated and found to be degraded, a new assessment captures this and produces an accurate baseline for improvement planning.
Solid Brick Properties
Solid brick properties with walls thicker than 280mm may score better under RdSAP 10 than under the previous methodology, because the updated default U value for thick solid brick walls is 1.4 W/m²K rather than the previous 2.1 W/m²K. If your property has thick solid brick walls and your existing certificate predates June 2025, a new assessment may produce a higher rating without any physical improvements to the property.
Properties Close to the D to C Boundary
If your property currently holds a D rating anywhere from 55 to 68, and you or a previous owner have made improvements since the last assessment — loft insulation top up, a new boiler, double glazing, solar panels — a new assessment is very likely to produce a higher score. Even without improvements, a solid brick property may rate higher under RdSAP 10.
For a property at D 65 or above, a new assessment alone — reflecting documented improvements and the updated methodology — may be enough to secure band C without any further work.
What Happens During a Spring EPC Assessment
An EPC assessment takes 30 to 60 minutes for a standard domestic property. Under RdSAP 10, the assessor uses an evidence hierarchy that prioritises documented performance over default assumptions. Gathering your paperwork before the assessor arrives makes a real difference to the outcome.
Bring out documentation for:
Boiler make, model, and installation certificate. The manufacturer’s efficiency rating, if evidenced, produces a more accurate score than a default assumption.
Loft insulation depth and installation records. If loft insulation was installed or topped up since the last assessment, a completion certificate or dated invoice allows the assessor to record the current depth accurately.
Cavity or wall insulation certificates. Any installation completed under a government scheme should have a completion certificate. This is the evidence the assessor needs to record the insulation as present.
Window installation records. FENSA certificates for double or triple glazing installed since the last assessment allow the assessor to record the correct glazing specification.
Solar panel MCS certificates. Photovoltaic panels are recorded based on system size and specification. The installation certificate provides this information.
The assessor also observes:
Wall construction and thickness — relevant to the RdSAP 10 U value revisions for solid brick properties.
Heating system controls — programmers, thermostats, and thermostatic radiator valves all contribute to the rating.
Hot water cylinder insulation — an uninsulated cylinder records differently from an insulated one.
The Cost of Getting an EPC Assessment
A domestic EPC assessment costs approximately £60 to £120 in 2026, depending on property size, assessor availability, and location. For a landlord with a portfolio of properties, volume rates may apply.
This is a modest cost relative to the value of the information it produces. A landlord who spends £10,000 on improvements based on an inaccurate 2019 baseline may not reach the C rating they need and face additional expenditure. The same landlord working from a £90 assessment conducted in May 2026 has accurate information and an efficient improvement plan.
The 2027 Home Energy Model: Another Reason to Act Now
The government is developing the Home Energy Model (HEM) as a replacement for the current SAP and RdSAP framework. HEM is expected from late 2027 and will introduce four headline metrics — fabric performance, heating system, smart readiness, and energy costs — rather than the current single band rating.
EPC certificates issued under the current methodology remain valid for 10 years. A property that achieves a valid EPC C under RdSAP 10 before October 2029 locks in current methodology compliance for up to 10 years — avoiding the more demanding dual metric requirements that HEM will introduce.
Getting an accurate assessment this spring, followed by targeted improvements to reach C, is therefore not just useful for current planning. It is the most efficient route to securing long term compliance before the goalposts change in 2027.
For detailed guidance on what each EPC band means and how the RdSAP 10 changes affect your rating, visit our guide to EPC band ratings explained.
Frequently Asked Questions
Do I legally need a new EPC after a wet winter? No. A valid EPC certificate remains valid for 10 years regardless of weather conditions. However, commissioning a voluntary new assessment is sensible if your certificate predates June 2025, if significant improvements have been made since the last assessment, or if you are planning improvement works and need an accurate baseline.
Will a new assessment always produce a better result? Not necessarily. If insulation has been degraded by this winter’s moisture and the assessor records this accurately, the new rating may be lower than the existing certificate. However, an accurate lower rating is more useful than an optimistic one when planning improvements.
How do I find an accredited assessor? Search the national EPC Register at epcregister.com, or contact an accreditation body such as Elmhurst Energy, Stroma, or ECMK. Always verify accreditation before booking.
Can I get a new EPC assessment if my tenants are in the property? Yes. The assessor needs access to all rooms, the loft, and the heating system, but does not need the property to be vacant. Give tenants advance notice of the assessment and explain what it involves.
What if my property cannot reach C even after improvements? If the cost of reaching C exceeds £10,000 and no grant funding covers the balance, a cost cap exemption can be registered on the PRS Exemptions Register. The exemption requires evidence that all available improvements have been made within the cost cap. Always exhaust grant funding options first — ECO4 and GBIS may fund measures that bring the cost within the cap.
Met Office winter 2025 to 2026 seasonal data published March 2026. RdSAP 10 methodology information from DESNZ published guidance, June 2025. The national EPC Register for England and Wales is available at epcregister.com.