Wed Jul 1
A window specification on a listed building is rarely just a design decision. It’s a professional judgement that the architect signs their name to, and if it turns out wrong, the consequences land on their desk first.
Get a sash profile wrong for a Grade II townhouse, or miss a detail that a conservation officer later challenges, and the fix isn’t just a drawing revision. It’s a delay, a client conversation nobody wants to have, and in the worst cases the start of a formal complaint.
This is where TRC Consult earns its place on a project team. It isn’t a sales function dressed up as advice. It’s a technical checkpoint that architects can use before a specification goes anywhere near a tender document.
A free technical checkpoint, not a sales pitch
TRC Consult is the advisory arm of TRC Contracts, offered at no cost to architects, specifiers and contractors working on timber window projects. The team works alongside the design team rather than selling into it, reviewing drawings, surveys and planning submissions before they’re locked in.
The point isn’t to push a particular product. It’s to catch the kind of error that only becomes visible once a project reaches site, when correcting it is expensive and the client is watching.
Where specification risk actually starts
Most window specification problems on heritage projects trace back to one of three moments:
1. The survey stage
A desktop survey based on old drawings can miss condition issues that only a site visit reveals. TRC offers detailed, basic and desktop surveys depending on what the project needs, so architects aren’t working from assumptions.
2. The planning submission
Conservation officers vary in what they’ll accept without formal consent. Advice that’s right for one local authority can be wrong for the next.
3. The written specification
An NBS clause that looks correct on paper can specify a product or performance standard that isn’t achievable within the building’s constraints.
Does TRC Consult reduce an architect’s liability exposure?
TRC Consult won’t replace an architect’s own professional judgement or their duty of care to the client. What it does is give architects a second, specialist opinion on window specification before drawings are issued, reducing the chance that an avoidable technical error reaches site.
Why this detail matters
The Architects Registration Board requires every registered architect to hold professional indemnity cover of at least £250,000 for each claim, a minimum set precisely because specification and design errors are a recognised source of liability in the profession.
On heritage projects, where planning requirements and thermal performance standards frequently pull against each other, the margin for error narrows further.
A vacuum-glazed sash that satisfies Part L on paper might not be the unit a conservation officer will approve. A security upgrade that meets PAS 24 might conflict with the original ironmongery a listed building consent depends on. These aren’t hypothetical tensions. They’re the everyday territory TRC Consult works in.
What TRC Consult puts on the table
Architects who bring TRC Consult into a project early get access to:
- Surveys at whatever level of detail the project stage requires
- Support with listed building consent and Article 4 direction applications
- Advice on conservation area consent, including where alterations may proceed without it
- Guidance on balancing PAS 24 security compliance with heritage constraints
- A library of NBS specifications and BIM objects covering new windows and refurbishment
- Budget costs at the early stages, followed by fixed quotations once specification is confirmed
Each item exists to close a specific gap between what looks right on a drawing and what a planning authority, a building control officer or a site team will actually accept.
Bring TRC Consult in before the drawing is issued
The cheapest point to fix a specification problem is before it’s written down. Once a drawing goes out for tender, correcting a mistake means variations, delay and an uncomfortable conversation with the client about why the budget has moved.
TRC Contracts has spent decades working on heritage and high-end timber window projects, and that experience is exactly what TRC Consult puts at an architect’s disposal, free of charge, from the earliest design stages.
If you’re currently developing a specification for a listed building, a conservation area scheme or a period property development, talk to TRC Consult before the brief is finalised.
Get in touch with the team to talk through your project.
