SAP Calculations for Conversions
Barn, garage, loft and commercial-to-residential conversions. Full SAP Calculations for Part L compliance, completed by an Elmhurst-accredited OCDEA.
- Barn, garage, loft and commercial conversions
- Design Stage and As-Built assessments
- BREL report and Energy Performance Certificate
- Practical advice for working with existing structures
Prefer to talk? Give us a call on 0333 567 9010 and we'll be happy to help.
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- Small Conversion <80m² £275
- Medium Conversion 80-130m² £350
- Large Conversion 130-200m² £425
- Extra Large Conversion >200m² Get a quote
Volume discounts available for multiple units
- Elmhurst Accredited
- Fully Insured
- 100s Projects Delivered
- FHS Ready
What Is a SAP Calculation for Conversions?
A SAP Calculation for a conversion shows that a change-of-use project meets the Part L energy efficiency standards when an existing building becomes a home.
Conversions are treated differently from new builds. There is no single carbon or primary energy target to hit, but Building Control still need evidence that the fabric and services are reasonable for the new dwelling. Under Approved Document L, new or upgraded thermal elements (walls, floors and roofs) must meet the limiting U-values for existing dwellings, and the heating, hot water and ventilation must be reasonably efficient.
We assess the existing structure, any new or upgraded elements, the glazing and doors, and the services for the finished dwelling, then produce the SAP and EPC that Building Control need to sign off the conversion.
Which Conversions Need a SAP Calculation?
If you are turning an existing building into one or more homes, a conversion SAP is very likely required. Common projects include:
- Garage conversions, where an attached or detached garage becomes living space, an annexe or a separate dwelling.
- Barn and agricultural conversions, checking new thermal elements, glazing and heating so rural homes meet current standards.
- Commercial to residential, where shops, offices and other buildings become flats or houses, usually needing a SAP for each new dwelling.
- Loft conversions forming a new dwelling, where the work creates a self-contained flat or home.
- Outbuildings and annexes that become separate homes or long-term living space.
Not sure if yours qualifies? Send your drawings and a short description and we'll confirm what is required before you commit.
What's Included
Every conversion SAP includes:
- SAP conversion calculation for garages, barns, commercial buildings, lofts and annexes
- Assessment of existing and new thermal elements (walls, floors, roofs)
- Checks against the limiting U-values for existing dwellings
- Review of glazing and doors for heat loss and solar gain
- Heating, hot water and ventilation checks
- Clear pass or fail result with practical recommendations
- Reasonable design stage revisions included
- As-Built SAP and EPC available at completion
How the Conversion SAP Process Works
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1
Send Your Drawings and Details
Upload floor plans, elevations, sections and a site plan, plus what you know about existing and proposed construction, glazing, heating and ventilation.
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2
We Build Your Conversion SAP
We model the existing building and your proposed upgrades, checking new thermal elements, glazing and services against Part L.
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3
Report for Building Control
Once it meets the standards, we issue your Design Stage SAP report and Part L documentation.
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4
As-Built and EPC
When the conversion is finished, we update the SAP with the final specification and air test, then lodge the EPC.
What We Need
Conversions often start from imperfect information. We work with what you have and help fill the gaps:
- Floor plans with dimensions for the existing building and proposed layout
- Elevations and sections showing openings, floor levels and roof form
- A site plan showing orientation
- Details of existing construction where known (wall, floor and roof build-ups)
- Proposed insulation upgrades to new and existing elements
- Window and door schedule with U-values if available
- Heating, hot water and ventilation specification
- Any renewables, such as solar PV or a heat pump
Unsure on any of these? We can work from reasonable assumptions and refine the SAP as the design develops. Our practical SAP checklist covers it.
Conversion SAP Pricing
As a non-VAT-registered business, SAPgen does not charge VAT. All prices shown are the total payable.
Why Choose Us
Conversions rarely fit a standard pattern. You want an assessor who can balance existing construction, new elements and modern services without unnecessary cost.
- Elmhurst-accredited OCDEA experienced across conversion and change-of-use projects
- Conversion SAP for garage, barn, commercial, loft and annexe projects
- Fixed, transparent pricing with no hidden extras
- Fast turnaround and clear communication
- Practical recommendations that work on real sites
- Design Stage and As-Built from one assessor
Frequently Asked Questions
Does my conversion need a SAP Calculation?
What drawings do you need?
What are new thermal elements?
Do all loft conversions need a SAP Calculation?
What if my conversion fails the SAP?
Do you provide the EPC at completion?
Will Building Control accept your reports?
Planning a Conversion?
Send us your drawings and we'll advise on the best route to compliance and quote a fixed price.