From Site Photos to Part L Compliance: How SAPAPP Keeps New Build Evidence Organised
The site team had taken hundreds of photos.
Insulation. Window reveals. Loft spaces. Service penetrations. Heating plant. Ventilation terminals. Floor junctions. Meter boxes. Roof details.
The problem was not that nobody had recorded the work. The problem was that nobody could find the right photo when it mattered.
Some images were on the site manager’s phone. Some were buried in subcontractor message threads. Some were saved with no plot number. A few showed useful details, but not enough background to prove where they had been taken.
As the project moved towards final SAP checks and handover, the builder knew this could become a Part L evidence problem.
ATSPACE brought in SAPAPP to turn loose site photos into an organised evidence trail. The aim was simple. Make the evidence clear, traceable and useful before the final week.
Approved Document L Volume 1 gives guidance on meeting the energy efficiency requirements for dwellings in England, including the way building fabric, services, air permeability, commissioning and reporting evidence work together under Part L. SAP is the government methodology used to estimate the energy performance of homes.
Project overview
• Project type: New build housing
• Project size: 22 homes, made up of detached, semi detached and terraced plots
• Location: Newport, South Wales
• Client type: Regional house builder
• Project stage when ATSPACE joined: Mid build, with several plots approaching close up
• Primary goal: Keep Part L evidence organised from site photos to final SAP records
• Secondary goal: Reduce late queries, avoid duplicated work and give the site team a clear close out process
The project was a typical small housing scheme. It was not a flagship development or a complex high rise. That is exactly why it is a useful example.
Most builders do not struggle with Part L because they do not care. They struggle because the evidence gets messy while the site is busy.
The challenge, what was at risk
The builder already had an evidence habit. The site team regularly photographed key stages. That was a good start.
But photos alone are not enough.
For evidence to be useful, it needs context. It should be clear which plot it relates to, what detail it shows, when it was taken and why it matters to the SAP or Part L record.
On this project, the team had three main risks.
First, photos were not consistently labelled. The same cavity closer detail might appear in three plots, but the file name did not say which one was which.
Second, some important details were photographed too closely. A photo of insulation can prove very little if it does not show the room, junction or surrounding construction.
Third, product and installation evidence was sitting in different places. Window U values were in a supplier email. Heating data was in a folder. Ventilation commissioning information was expected later. Site photos were mainly on phones.
The risk was a final stage scramble where the builder, assessor and site team all had to chase basic evidence after the work had been covered.
That can lead to delays, repeated site visits, extra admin and avoidable uncertainty.
What made this job tricky
Several plot types were being built at the same time
The scheme had repeated house types, but not every plot was identical. Orientation, window layout and services varied. Evidence needed to be tracked by plot, not treated as one generic photo set.
The team had evidence, but not a system
A large number of photos had been taken. The issue was sorting them into usable Part L evidence.
Key details were close to being covered
Some fabric junctions, service penetrations and roof insulation areas were about to be hidden by finishes. That meant the evidence review needed to happen quickly.
Different people held different records
The site manager had photos. The contracts manager had supplier details. The ventilation contractor had commissioning information. The SAP assessor had the early design assumptions.
SAPAPP gave the team one place to bring those records together.
Our approach, step by step
ATSPACE used SAPAPP as a live evidence tracker for the project.
The aim was not to overload the builder with more paperwork. The aim was to make the evidence they already had easier to use.
Step 1: Review the design SAP assumptions
Before sorting photos, we checked what the evidence needed to prove.
This included reviewing the current SAP assumptions for:
• External walls
• Ground floors
• Roofs
• Windows and external doors
• Thermal bridging approach
• Heating and hot water systems
• Ventilation strategy
• Air permeability target
• Solar PV where included
• Plot type variations
SAP uses a range of building fabric and services inputs to estimate dwelling energy performance. The SAP 10.2 document explains that the calculation considers materials, heating systems, ventilation, solar gains, fuels and other factors that influence energy use.
Once the key SAP inputs were understood, we could set up the photo evidence around the items that mattered.
Step 2: Set up the SAPAPP evidence structure
ATSPACE set up each plot inside SAPAPP.
Each plot had a clear evidence checklist covering:
• Wall insulation
• Floor insulation
• Roof insulation
• Window and door details
• Cavity closers and reveals
• Thermal junctions
• Air barrier and sealing points
• Service penetrations
• Heating plant
• Hot water cylinder or store
• Ventilation units, ducts and terminals
• PV installation where relevant
• Air test preparation and results
• Commissioning records
This gave the site team a simple view of what was complete, what was missing and what needed better evidence.
Step 3: Sort existing site photos
The builder uploaded existing images into SAPAPP. ATSPACE then reviewed and sorted them.
Each photo was checked for:
• Plot reference
• Location
• Detail shown
• Relevance to Part L evidence
• Image clarity
• Whether the photo showed enough context
• Whether further evidence was needed
Some photos were accepted as useful. Some were marked as supporting evidence only. Some were rejected because they did not prove enough.
This was an important step. A blurry close up of insulation is not always useful. A clear photo showing the plot, room, junction and installed detail is much stronger.
Step 4: Create a missing evidence list
Once the existing photos were sorted, SAPAPP produced a clear list of missing or weak evidence.
The missing list included:
• Loft insulation depth photos for eight plots
• Floor perimeter insulation photos for five plots
• Window reveal photos for six plots
• Service penetration sealing photos for nine plots
• Heating plant label photos for all completed plots
• Ventilation terminal photos for four plots
• PV inverter and roof layout evidence for two plots
The benefit was immediate. Instead of asking the site team to “send more photos”, we could tell them exactly what was needed.
Step 5: Train the site team on better photos
ATSPACE gave the site manager and assistant site manager simple guidance.
A good Part L evidence photo should show:
• The plot number or a clear location marker
• The detail being recorded
• Enough surrounding context to identify where it is
• A clear view of the installed product or workmanship
• The stage before the detail is covered
• Any label or model number where relevant
This avoided wasted effort. The site team did not need more photos. They needed better photos.
Step 6: Link photos to product evidence
Part L evidence is not only about images. Product data also matters.
The SAPAPP tracker linked site photos to the supporting documents, including:
• Window and door data sheets
• Insulation product information
• Heating appliance details
• Hot water cylinder data
• Ventilation system specifications
• PV information where relevant
• Air test certificates
• Commissioning records
This helped the SAP assessor check whether the as built specification matched the design assumptions.
What we found on site
The site was in good condition, but the evidence was uneven.
We found that early plots had fewer photos because the team had not yet started using SAPAPP. Later plots had better records because the site team had improved the way they captured details.
The most common issues were:
• Photos taken too close to the detail
• Missing plot references
• Similar details photographed across different plots with no clear naming
• Product labels not captured before boxing in
• Heating and ventilation evidence held separately from fabric evidence
• Some SAP assumptions based on early supplier schedules rather than final installed products
One important finding was that the builder had done many of the right things on site, but had not made them easy to demonstrate.
That is a common gap.
Good work still needs good evidence.
Solutions and actions taken
A photo naming approach was agreed
The team agreed a simple naming format inside SAPAPP:
Plot number, location, detail, date.
For example:
Plot 12, first floor bathroom, extract duct seal, date.
This made searching easier and reduced repeated questions.
Evidence was captured before close up
ATSPACE flagged details that were close to being hidden. The site team captured additional photos before plasterboard, loft boarding and boxing covered them.
Product changes were checked against SAP
The builder confirmed final installed product details for windows, insulation, heating and ventilation.
Where information differed from early design assumptions, the SAP assessor was told before final calculation work.
Air leakage risk areas were recorded
The team photographed sealing around common leakage points, including service penetrations, loft hatches, soil pipe boxing, external doors and duct collars.
This did not replace air testing. It supported preparation and gave the team a clearer evidence trail.
A final evidence pack was built by plot
Instead of one large folder of mixed images, SAPAPP organised the evidence plot by plot.
That meant the builder could answer queries faster.
Results, with numbers and evidence
The project moved from scattered photo records to a structured Part L evidence process.
The results included:
• 22 plots set up in SAPAPP
• 386 site photos reviewed
• 214 photos accepted as direct Part L supporting evidence
• 97 photos marked as supporting context only
• 75 photos replaced with clearer evidence
• 53 missing evidence items identified before close up
• 48 items closed within seven working days
• 5 items carried forward with named owners and dates
• Final SAP information updated before handover stage
• Evidence folder prepared by plot and detail type
The biggest benefit was not just the number of photos sorted. It was the reduction in uncertainty.
The site team knew what to capture. The contracts manager knew what product information was missing. The SAP assessor had a cleaner route to final review. The builder had less risk of a final week evidence chase.
We do not claim SAPAPP guarantees building control acceptance or a particular outcome. Building control decisions remain with the relevant body. What SAPAPP did on this project was make the evidence clearer, earlier and easier to check.
What the client received, deliverables
The builder received:
• SAPAPP project setup
• Plot by plot Part L evidence tracker
• Reviewed and sorted photo record
• Missing evidence schedule
• Product evidence checklist
• Site photo guidance for the construction team
• SAP input change log
• Air test preparation evidence notes
• Final structured evidence folder
The deliverables were practical. They were written for a busy project team, not just for the file.
Lessons learned, what other projects can copy
Take photos before details disappear
Do not wait until the end. Record insulation, junctions, penetrations and product labels while they are still visible.
Make every photo traceable
A useful photo should show the plot, location, detail and date. Without context, the value of the photo drops quickly.
Connect photos with SAP inputs
Photos should support the actual SAP assumptions. If the installed product changes, the evidence and calculation information should be updated.
Use a live tracker
A live tracker stops evidence becoming a last minute admin job. It also helps managers see what is outstanding before it becomes urgent.
Do not assume repeated plots are identical
Even repeated house types can have different orientations, openings, services or installed details. Evidence should still be managed by plot.
Why ATSPACE, beyond compliance support
ATSPACE understands the pressure of live construction.
We know that the site team is not short of things to do. That is why our approach is practical. We do not ask for evidence for the sake of it. We focus on the details that help support Part L, SAP finalisation and handover.
With SAPAPP, ATSPACE helps builders:
• Organise site photos into usable evidence
• Find gaps before details are covered
• Keep SAP information aligned with site changes
• Reduce repeated queries from the office, assessor and project team
• Build a clearer record of what was installed
Part L evidence does not need to be chaotic. With the right system, it can become part of the normal build process.
FAQ
What is Part L evidence?
Part L evidence is the record used to support the energy performance information for a building. For new homes, this can include SAP inputs, drawings, product data, site photos, air test results, commissioning records and as built specification details.
Why are site photos important for Part L?
Site photos can help show that key fabric and services details were installed as intended. They are especially useful for details that become hidden, such as insulation continuity, junctions, air sealing and service penetrations.
Does SAPAPP replace the SAP assessor?
No. SAPAPP does not replace the SAP assessor or the SAP calculation. It helps organise the evidence that supports the assessment and helps the project team manage missing information.
What makes a good Part L evidence photo?
A good evidence photo is clear, labelled and traceable. It should show the plot, location, detail, surrounding context and date. Product labels should be photographed before they are boxed in or covered.
When should builders start using SAPAPP?
The best time is before close up works begin. It can still help later, but early use gives the team more chance to capture details while they are visible.
Can poor photo evidence delay handover?
It can contribute to delays if information has to be chased, repeated or checked late in the programme. Good evidence does not remove the need for testing and assessment, but it can reduce avoidable back and forth.
What if a product changes during construction?
The change should be recorded and checked against the SAP assumptions. Windows, insulation, heating, hot water, ventilation and PV changes can all affect the final calculation.
Does organised evidence guarantee Part L compliance?
No. Organised evidence does not guarantee compliance or building control acceptance. It helps the project team present clearer, more accurate information and deal with gaps earlier.
Call to action
If your project has site photos everywhere but no clear Part L evidence trail, ATSPACE can help. Speak to ATSPACE before the final week. We can set up SAPAPP, review your evidence, identify missing items and give your team a clear route to close out.
