Why Builders Are Using SAPAPP to Capture Part L Photographic Evidence Before It Is Too Late
The plasterboard delivery was booked for Monday.
By Friday afternoon, the site manager realised several key insulation and junction details had not been photographed. The work looked right on site, but once the walls and ceilings were closed, proving it would become much harder.
That is the point where Part L photographic evidence can turn from a small admin task into a handover problem.
On this project, ATSPACE used SAPAPP to help the builder capture the right photographs before close up works, organise them by plot, and connect them to the final SAP and Part L evidence trail.
This case study is written in the ATSPACE case study format supplied in the brief.
Project overview
• Project type: New build housing
• Project size: 18 homes across three house types
• Location: Chelmsford, Essex
• Client type: Regional builder
• Project stage when we joined: Before close up works on the first phase
• Primary goal: Capture Part L photographic evidence before key details were covered
• Secondary goal: Keep SAP records, site photos and product evidence organised by plot
Approved Document L Volume 1 covers dwellings in England and includes guidance on reporting evidence of compliance, including the BREL report and photographic evidence. It states that photographic evidence should be provided for each individual dwelling, and that photographs should be taken at appropriate construction stages before close up works.
The builder did not want to wait until the final week to find out what was missing. They wanted a clear system while the work was still visible.
The challenge, what was at risk
The project was moving quickly.
Ground floors were complete. External walls were being closed. Roof insulation was starting. First fix services were in progress. The site team had taken some photos, but they were not sure if the images covered the right details for Part L.
The risk was simple. Once a detail is hidden, the chance to capture useful photographic evidence may be gone.
Approved Document L says photographs should be unique to each property and taken for typical details at the correct construction stage before close up works. It also says photographs should be made available to the energy assessor and building control body.
The builder had four concerns.
First, some early photos were not plot specific.
Second, several images did not show enough context.
Third, the site team did not know which details were most important.
Fourth, the SAP assessor had not yet received a complete photographic evidence file.
This created a real risk of late queries, duplicated work and avoidable pressure near completion.
What made this job tricky
The programme was moving faster than the evidence
Construction was not waiting for paperwork. If the evidence system did not catch up quickly, more details would be covered every week.
Photos were being taken by different people
The site manager, assistant site manager and subcontractors had all taken photos. Some were useful. Some were too close. Some were not labelled.
Repeated house types created false confidence
The builder had three repeated house types, but plot orientation, junctions and service routes varied. The evidence still needed to be captured for each dwelling.
The site team needed simple instructions
Nobody on site needed a long technical document. They needed a clear list of what to photograph, when to photograph it and how to upload it.
Our approach, step by step
ATSPACE used SAPAPP as a live photographic evidence workflow.
The aim was not to create extra work. The aim was to make normal site recording useful for Part L, SAP and handover.
Step 1: Review the SAP and Part L evidence needs
We began by reviewing the design information and SAP assumptions for each house type.
This included:
• Wall construction
• Floor insulation
• Roof insulation
• Window and door specifications
• Thermal bridging approach
• Heating and hot water systems
• Ventilation strategy
• Air permeability target
• Solar PV allowance where included
SAP is the UK Government methodology used to calculate the energy performance of homes. GOV.UK describes SAP as the process used to calculate a home’s energy performance, and the page was updated in May 2025.
This review gave the site team a practical evidence map. We were not asking for random photos. We were asking for photos linked to the specification that needed to be demonstrated.
Step 2: Set up each plot in SAPAPP
Each plot was set up in SAPAPP with its own evidence checklist.
The checklist covered:
• Ground floor perimeter insulation
• External door thresholds
• Wall insulation
• Cavity closers
• Window reveals
• Roof insulation
• Loft hatch details
• Service penetrations
• Air barrier sealing points
• Heating plant labels
• Hot water cylinder details
• Ventilation units and terminals
• PV equipment where relevant
The benefit was immediate. The site team could see what had been captured and what was still missing.
Step 3: Audit existing photos
ATSPACE reviewed the photos already taken by the site team.
Each image was checked for:
• Plot reference
• Location
• Detail shown
• Image clarity
• Construction stage
• Whether the photo was taken before close up
• Whether the photo matched a SAP or Part L evidence need
Some photos were strong and were accepted. Others were kept as supporting context. Several were marked for replacement because they were not clear enough.
A common example was insulation photographed too closely. The insulation could be seen, but the plot and location could not. That makes the photo much less useful.
Step 4: Create a missing evidence schedule
SAPAPP was then used to produce a plot by plot missing evidence list.
The first review found:
• 27 missing photo items
• 12 photos that needed better plot context
• 9 insulation details at risk of being covered within three working days
• 6 window reveal details that needed clearer photos
• 4 heating plant references still to be photographed
• 3 ventilation routes needing extra context
This gave the builder a manageable action list. Instead of asking the site team to take more photos of everything, we asked for specific photos of specific details.
Step 5: Capture evidence before close up
ATSPACE worked with the site manager to prioritise details that were about to be covered.
The team focused first on:
• Ground floor perimeter insulation
• Wall insulation continuity
• Service penetrations through the external envelope
• Window and door reveal details
• Roof insulation at eaves
• Loft insulation depth
• Duct routes before boxing
• Plant labels before cupboards were finished
This was the key turning point.
The builder captured the evidence while it was still visible. That avoided relying on memory, assumptions or disruptive checks later.
Step 6: Link photographic evidence to final records
SAPAPP was used to organise the photos by plot and detail type. Product data and specification records were then linked to the relevant areas.
This included:
• Insulation data sheets
• Window and door U values
• Heating system model details
• Hot water cylinder references
• Ventilation system information
• PV layout information
• Air test results when available
• Commissioning records
Approved Document L states that the as built BREL report should be signed by the SAP assessor to confirm the as built calculations are accurate and that supporting documentary evidence and photographs have been reviewed. It also says the developer should sign the as built BREL report to confirm the dwelling has been completed according to the specifications in the report.
That made organisation important. The photographs needed to be useful to the project team, not just stored somewhere.
What we found on site
The build quality was generally good. The evidence process was the weak point.
We found:
• Several useful photos were missing plot numbers
• Some images were taken after partial close up
• Some details had been photographed from too close
• Similar photos were mixed across different plots
• Subcontractor photos were not stored in the main evidence file
• Product labels had not been captured before boxing in
• The SAP assessor had not received a complete change log
The main issue was not poor workmanship. It was lack of structure.
That is why builders are using SAPAPP. It turns evidence capture into a live site process rather than a final week search exercise.
Solutions and actions taken
A simple photo standard was introduced
ATSPACE gave the site team a clear photo rule.
Each photo needed to show:
• The plot
• The location
• The detail
• Enough context
• The completed detail before it was covered
For product labels, the photo needed to show the model reference clearly.
Evidence responsibility was assigned
The site manager kept overall responsibility, but each trade was told which details they needed to flag before close up.
This made evidence capture part of normal sequencing.
SAPAPP was checked twice weekly
For the first three weeks, ATSPACE reviewed SAPAPP uploads twice weekly. This helped the builder catch missing items before the next close up stage.
The SAP assessor received cleaner information
Instead of sending a mixed folder of photos, the assessor received organised plot records with linked product information and notes on specification changes.
Results, with numbers and evidence
The project moved from uncertain photo records to a structured Part L photographic evidence process.
Results included:
• 18 plots set up in SAPAPP
• 142 existing site photos reviewed
• 64 photos accepted as direct evidence
• 39 photos kept as supporting context
• 39 photos replaced with clearer images
• 27 missing evidence items identified early
• 25 missing items closed before close up
• 2 items carried forward with named owners and dates
• 100 percent of first phase plots had plot specific photo folders before final SAP review
• SAP assessor queries reduced because the evidence was easier to check
The project still needed normal assessment, testing and review. SAPAPP did not replace the SAP assessor, the BREL report or the building control process.
What it did was make the evidence easier to find, easier to check and less likely to become a late programme problem.
We do not claim that SAPAPP guarantees compliance or building control acceptance. Decisions remain with the relevant building control body. ATSPACE provides evidence led support to reduce avoidable risk.
What the client received, deliverables
The builder received:
• SAPAPP project setup
• Plot by plot photographic evidence tracker
• Existing photo audit
• Missing evidence schedule
• Site photo guidance
• Product evidence checklist
• SAP change log support
• Final organised evidence folders
• Close out tracker for remaining items
The deliverables were designed for real site use. The site manager could see what needed doing. The contracts manager could see where information was missing. The assessor had a better record to review.
Lessons learned, what other projects can copy
Do not wait until completion
Part L photographic evidence should be captured during the build. If you wait until the end, many details will already be hidden.
Make photos plot specific
Repeated house types still need plot specific records. A photo from one plot should not be assumed to cover another.
Show context, not just detail
A close up photo may show workmanship, but it may not prove location. Step back enough to show where the detail sits.
Link photos to SAP inputs
Photographs should support the actual specification used in the SAP calculation. If the installed product changes, the evidence trail should change too.
Use a live evidence system
A live tracker helps the site team act before close up. It also gives managers a clearer view of risk across the scheme.
Why ATSPACE, beyond compliance support
ATSPACE works in the gap between design compliance and site delivery.
We understand that builders are dealing with programme pressure, supplier changes, trade sequencing and handover dates. Part L evidence needs to fit into that reality.
With SAPAPP, ATSPACE helps builders:
• Capture photographic evidence at the right time
• Organise records by plot
• Reduce late requests for missing information
• Keep SAP evidence aligned with the real build
• Support smoother handover preparation
The aim is not more paperwork. The aim is better evidence, captured earlier, with less stress at the end.
FAQ
What is Part L photographic evidence?
Part L photographic evidence is a record of key construction details used to support the energy performance evidence for a new dwelling. It can include insulation, junctions, openings, services and other details that affect the final SAP and BREL record.
When should Part L photos be taken?
They should be taken at the right construction stage, when the relevant detail is complete but before it is covered. Approved Document L refers to photographs being taken before close up works.
Does every plot need its own photos?
Yes, photographic evidence should be provided for each individual dwelling. Approved Document L states that information and photographic evidence should be provided for each individual dwelling.
Who can take the photos?
Approved Document L says anyone may take the photographs, but they should be made available to the energy assessor and building control body.
Does SAPAPP replace the BREL report?
No. SAPAPP does not replace the BREL report or SAP assessment. It helps collect and organise the evidence that supports the project team, the assessor and the final records.
What happens if photos are missed?
It depends on the detail and the stage of the build. Missing evidence can lead to extra queries, site checks and possible delays. The best approach is to identify missing items early, before the detail is covered.
What makes a good Part L photo?
A good photo is clear, plot specific and taken at the right stage. It should show enough context to prove where the detail is and enough detail to show what has been installed.
Does organised evidence guarantee Part L compliance?
No. Organised evidence does not guarantee compliance or approval. It helps the project team provide clearer records, reduce missing information and manage issues earlier.
Call to action
Part L photographic evidence is easiest when the details are still visible.
If your site is approaching close up works, speak to ATSPACE before it is too late. We can set up SAPAPP, review your current evidence, identify missing items and give your team a clear route to close out.
