SAP Calculations for Timber Frame Houses

Timber frame is the most sustainable, environmentally-friendly, cost-efficient way to build new homes in the UK. It’s also the quickest and cleanest method of construction. It’s also why they are favoured by most self-builders and a rapidly growing number of professional builders. Around 23% of all new homes in the UK are now constructed using timber frames due to the vast number of benefits.

But there’s another, equally important reason for its popularity. Timber frame is a true fabric-first high-performance construction material that comes out on top when it comes to insulation, airtightness, and energy efficiency.

High-quality insulated timber frame wall panels can achieve some of the lowest U-values in the market. They can also achieve an SAP assessment pass as a stand-alone solution.

This means that builders can save thousands of pounds on every house they build.

timber frame partitions and closed panels

What are SAP Assessments?

SAP is the Standard Assessment Procedure that measures the energy and environmental performance of new or updated dwellings. The assessment is mandatory for all new homes built in the UK and ensures compliance with Approved Document Part L of the building regulations.

SAP Assessments must be carried out by a qualified assessor who will provide SAP and EPC certification.

Timber frame luxury house

Achieving a SAP Pass with Target Timber Frames

Timber frame construction inherently provides high insulation potential for the structure. So, to achieve the best possible outcome in terms of efficiency, we design the structure to achieve the practical and achievable wall U-values.

We do this by eliminating any potential for heat loss through the timber studs. Eliminating the thermal bridge using carefully modelled and accredited Psi values is the best way of achieving improved SAP and EPC ratings.

Project Example

Thermal bridging through timber studs can account for between 15% and 45% of a building’s heat loss. You can have two wall panels, both with the same U-Value, but if one panel eliminates the thermal bridge by having a layer of insulation across the inside face of the stud, it will get a significantly better result within SAP. This can often lead to more savings made elsewhere within the energy specification of the building.

Do you need MVHR if you build using a timber frame?

Mechanical Ventilation with Heat Recovery (MVHR) is often used in airtight homes to prevent moisture and mould and to provide clean, filtered air. MVHR is considered to be the ‘norm’ in self-build properties and is often used as an expensive addition on developer properties to gain a SAP Pass.

Do you need MVHR if you build a house with a timber frame?

No, in the majority of cases.

Our Enhanced insulated Open Panel with 25mm high-performance PIR provides superior thermal and moisture resistance. This means there’s often no need for MVHR, and SAP compliance will still be achieved.

 

timber frame housing development

SAP Calculations for timber frame can lead to more savings

In addition to eliminating the need for MVHR on new builds, there are additional savings on pozi floor joists and airtightness detailing, which is difficult to achieve.

It can also mean that triple glazing or solar PV is not required, without any detriment to the SAP rating.

Furthermore, without MVHR, there will be no additional electrical running costs of the MVHR fans, as well as annual maintenance bills for homeowners and self-builders.

High-quality custom-design timber wall panels can save builders thousands of pounds per house.

Free SAP Calculations for Target Timber Frame Houses

Target Timber offer free SAP calculations to self-builders and professional builders as part of any full timber frame package for residential properties.

Detailed drawings should first be submitted to receive a full package quotation. Upon receiving the order or letter of intent, we will begin SAP calculation work to achieve the best possible airtightness through custom-engineered timber frame panels.

Our SAP calculations are carried out by dedicated fully qualified assessors. During assessment, the customer is provided with an APP to enable them to date-stamp and Geo Stamp imagery for building control.

Following the assessment and a SAP PASS, the customer is provided with a shopping list of additional insulation for roofs/floors, making the whole process seamless and easy.

SAP Calculation Savings Case Study

Date: March 2026
Project: 2 x 3-bedroom detached houses

Initial requirements

The developer submitted drawings for a quotation for timber frames for two new houses. At the time of quoting, we were unaware of the intention to install MVHR. We therefore quoted for closed panels using an average £/m2 rate for 253mm Posi-joists.

Following discussions, we became aware that the initial SAP assessor had introduced MVHR as a quick and easy way of gaining SAP compliance. This meant the building contractor would have added unnecessary costs, time and complicated airtightness detailing that we felt could be avoided. We offered to undertake the SAP calculations at zero cost.

This led to the elimination of the need for MVHR pozi joists and complicated airtightness detailing and testing, resulting in significant savings.

Summary of outcome

Upon completing SAP calculations, the quotation was changed to use enhanced wall panels – Open (Insulated) panel instead of a Closed Panel to achieve a U-value of 0.13. The developer to site fit 25mm PIR.

Without MVHR with site-fitted insulation/VCL and battens

  1. There is no longer a need for pozi joists, saving £1,100/house = £2,200
  2. Switching to an Open (insulated with 120mm PIR) panel = Saving of £8,024
  3. Add on-site installed 25mm PIR/VCL and battens, £1,200/house = £2,400
  4. Remove MVHR* @ £4,000/house = £8,000

TOTAL build costs savings – £18,224 

*MVHR cost for this project. Typical conservative costs of £4,000 for a single house.

Build Better, Build Smarter

Target timber is a full-service timber frame manufacturer with over 40 years’ experience working with professional builders and self-builders. We provide our customers with expert technical support both before a project begins, right through to completion.

Whether you’re planning to build your own home, or if you’re a developer looking to build high-quality homes, our experts can design timber frame to pass SAP assessments and save you time and money too.

Please submit your drawings via the form below and ask our team about SAP calculations for your project.

TELL US ABOUT YOUR PROJECT

We would love to hear about your project. If you have full architectural plans or drawings, please upload them using the form below and request a quotation. Or if you are planning a project and have questions about building with timber frame, complete the form below or call us on 01403 782 600.

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