About Us
Specialist Expertise in Part L Compliance
TPLC Ltd exists to make Building Regulations Part L compliance straightforward for homeowners, architects, and builders working on highly glazed extensions across England and Wales.
Who We Are
A focused consultancy for a specific compliance challenge
TPLC Ltd was established to address a gap in the market: homeowners and building professionals regularly encounter the highly glazed extension requirement under Part L and struggle to find a specialist who understands it thoroughly and can produce a compliant report quickly.
We focus exclusively on Section 10.10 assessments. That focus means we understand the regulation in depth, we know what building control bodies expect to see, and we can turn assessments around efficiently without compromising on accuracy.
We work directly with homeowners managing their own projects, as well as architects, designers, and main contractors who need a reliable compliance partner they can call on across multiple projects.
What Sets Us Apart
Section 10.10 specialists
We focus on highly glazed extension assessments. It is not a side service — it is what we do.
Reports accepted by building control
Our reports are formatted to meet the expectations of both local authority building control (LABC) and approved inspectors.
Clear, jargon-free communication
We explain what we need from you, what we have assessed, and what the outcome means — in plain English.
Fast turnaround
We understand that build programmes are time-sensitive. We work to your timeline, not ours.
UK-wide service
We provide assessments for projects across England and Wales, regardless of local authority area.
Our Area of Expertise
Building Regulations Part L, Section 10.10
Approved Document Part L (Volume 1: Dwellings, 2021 edition) sets out the energy efficiency requirements for new, converted and existing dwellings in England. For most extensions, compliance is demonstrated using the elemental approach — a straightforward comparison against the minimum standards in Part L.
However, where the total glazed area of an extension exceeds 25% of its floor area plus the area of any "lost openings", this standard route is not permitted. Section 10.10 requires a "Whole House" assessment demonstrating that the original dwelling and the proposed extension combined meet the required carbon emission rate and energy efficiency standards through its own merits — taking into account the thermal performance of the glazing, the fabric of the extension, and the dwelling services.
This affects a wide range of common extension types: orangeries, garden rooms, large bifold or sliding door extensions, glazed kitchen extensions, and any design where glass is a dominant architectural feature. Without a compliant Section 10.10 assessment, building control cannot issue a completion certificate.
Approved Document L · Section 10.10
"the Standard Assessment Procedure may be used to show that the dwelling primary energy rate, the dwelling emission rate and the dwelling fabric energy efficiency rate for the dwelling and proposed extension do not exceed those for the dwelling plus a notional extension."
Our Clients
Who We Work With
Homeowners
Managing your own extension project and need a Part L compliance report before building control sign-off. We guide you through exactly what we need and handle the rest.
Architects & Designers
Working on a highly glazed extension and need a reliable compliance partner. We integrate smoothly into your project workflow and respond promptly to queries.
Builders & Contractors
On site and realising a Part L assessment is required before completion. We understand the urgency and work to your programme.
Ready to get started?
Send us your plans and we'll provide a fast, accurate Part L Section 10.10 assessment — no jargon, no delays.