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Building Regulations · England · for building control

The specification, written to the Approved Documents. Issued under your name.

Specline drafts Building Regulations specifications for extensions, lofts, conversions and new build, with the U-value working attached. You check it, put your practice's name on it, and issue it to building control.

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Founding-member pricing is held for the first 30 practices.

90 seconds · from the desk to the issued document · the app as it runs, recorded; the practice shown is fictional
Library default · full fill cavity wall 0.18 W/m²K · target 0.18 Within target Drawn to scale from the layers you specify — on the desk, in every calculator, on the working page.

What you issue

One document, three parts, all from the same library

Every specification is assembled from a library written from the Approved Documents in plain, confident prose. Not numbered legal clauses: the construction, layer by layer, with named products and their alternatives.

Part A

Construction build-ups

Numbered per job, in the order you pick them: EW1 GF1 RF1. The same references go on your plans and sections. Cavity walls, floors, basements and roofs are configurable layer by layer; the rest are written build-ups you tick.

Part B

General notes by topic

Structure, fire, ventilation, drainage, services and the rest, arranged in the order a building control officer reads a pack. One subject, one note: no repeated or contradicting clauses.

Section 4

U-value working

Every calculated build-up carries its working to BS EN ISO 6946 with the Annex F corrections, or BS EN ISO 13370 for ground floors and heated basements, with manufacturer-verified conductivities. It is what makes the figure defensible to a plan checker.

What comes out of it

The document, and the working behind it

A specimen house extension, produced in Specline and shown exactly as it prints. The practice name, address and accent on it are the practice's own — Specline's mark never appears on a specification.

Cover page of a Building Regulations specification for a house extension, showing the practice name and address, the project, site address, job number, local authority, application type and revision, above the construction build-up schedule.

Cover and schedule

Your identity, and the build-up schedule

The cover carries the practice's logo or name, the job record and the responsibility statement. Underneath it, every build-up on the job with its reference and the standard it meets.

Part A of the specification: trench fill foundation and full fill cavity wall clauses written out layer by layer, with target U-values and designer notes.

Part A

Construction, layer by layer

Flowing prose rather than numbered legal clauses: the construction described as it is built, with named products, their alternatives, the standards cited inline, and notes to the designer set apart in grey.

U-value working for a full fill cavity wall: layer by layer thermal resistances, upper and lower resistance limits, the Annex F air gap and wall tie corrections, and the resulting U-value of 0.18 W/m²K against a target of 0.18.

Section 4

U-value working you can hand over

Every calculated build-up prints its arithmetic: layer resistances, the upper and lower limits of the combined method, the Annex F corrections for air gaps and wall ties, and the conductivity source for each material.

A typical vertical section through a full fill cavity wall at 1:10, dimensioned and annotated, with each annotation quoted from the specification clause beside it.

Detail sheets

The section, drawn from the same clause

Each build-up draws as a dimensioned section at 1:10, and every annotation on it is quoted from the clause, so the drawing cannot drift away from the specification.

Specimen project. No client, address or job of anyone's appears on this page.

Project types · England

Eight residential project types

Each carries its own categories, build-ups and notes. Pick the type, work through the categories, and the document builds as you go.

EXT21 build-ups · 53 notesHouse extensionSingle and two storey, rear and side LFT15 build-ups · 36 notesLoft conversionDormer, hip to gable, room in roof FLT14 build-ups · 37 notesFlat conversionMaterial change of use, Part E GAR20 build-ups · 36 notesGarage conversionIntegral and detached NBH16 build-ups · 58 notesNew build houseFull notional dwelling assessment NBF16 build-ups · 55 notesNew build flatsSeparating construction, common parts BSM10 build-ups · 32 notesBasement conversionUnderpinning, tanking, BS 8102 GBD12 build-ups · 23 notesNew garageDetached and attached, unheated

Each type has its own page — see all eight. 124 build-ups · 330 notes · conductivities verified against manufacturer and BBA data · Wales planned as a second region

For practices

Written for the desk of an architectural technologist

Built in a practice that issues these documents every week, for architects, technologists and small practices that would rather spend the afternoon on the drawings. Your name on the document, on every plan.

  • Tick
    the build-ups that are on the drawings.The schedule writes itself, referenced the way you tag them on the plan — EW1 on the specification is EW1 on the section.
  • Change
    a layer, and the U-value follows.Recalculated to BS EN ISO 6946 with the working shown; the bar is drawn to scale. Practice standards — FD30S doorsets, Grade D1 LD2 alarms, hot water to G3 — stated the same way on every job.
  • Review
    before anything goes out.What is not set, what was left off, and the 2027 flag every specification carries — named, not hidden behind a tab.
  • Issue
    P01, then P02.Issuing records the revision against the job and moves the working revision on. Job numbers are typed, never generated. Reopen any job and carry on.
Specline drafts · Building control approves · The designer stays responsible

Nothing Specline produces is a certificate, an approval or a plan check. The named designer at your practice remains responsible for the suitability of the specification for the project, and every clause and table reference is to be confirmed against the Approved Documents in force at the date of submission.

That sentence prints on the cover of every document, in your practice's voice, so the responsibility is exactly where it has always been.

Pricing · ex VAT

A subscription, because the regulations change

A perpetual licence would leave you with a library that stops being current. Specline is maintained against the Approved Documents in force, and that is what the subscription pays for.

Solo

£39 / month

or £390 a year · ten months' money

  • 1 user
  • All 8 project types
  • Unlimited specifications
  • Your practice's identity on every document
Create an account

Practice

£89 / month

or £890 a year · ten months' money

  • Up to 5 users
  • Shared job library
  • Your practice's own added clauses
  • Your practice's identity on every document
Create an account

Per spec

£25 / issued spec

no subscription

  • Pay when you issue
  • All 8 project types
  • Your practice's identity on every document
Create an account
Founding membersThe first 30 subscribing practices keep their joining price for as long as they stay subscribed.

All prices exclude VAT. Card payments are taken by Stripe at checkout.

Questions

Straight answers

What is a Building Regulations specification?
A written description of how a building will be constructed, clause by clause, submitted to building control alongside the drawings. It states the construction of each element layer by layer, the U-values achieved, fire and sound performance, ventilation rates, drainage and services. The drawings show where things are; the specification says what they are.
Do I need one for a house extension?
A full plans application is assessed on the drawings and the written information sent with them. Generic notes on a drawing sheet are where most queries come from, because they are rarely project-specific. A separate specification answers those questions before they are asked.
Does it include U-value calculations?
Yes, and it shows the working. Cavity walls, framed walls, floors, basements and roofs are calculated to BS EN ISO 6946 by the combined method with the Annex F corrections for air gaps and wall ties, and to BS EN ISO 13370 for ground floors and heated basements. The arithmetic prints as its own section so a plan checker can follow it rather than take the figure on trust.
Is this a specification template?
No. A template is a document you edit and hope you edited everywhere. Specline assembles the specification from a maintained library for the project type, numbers the build-up references per job, calculates the U-values for the construction you specify, and produces the PDF and the Word file under your own identity.
Does Specline certify Building Regulations compliance?
No. Specline drafts the specification. The named designer at the practice remains responsible for its suitability for the project, and compliance of the work is determined by the building control body. Nothing Specline produces is a certificate, an approval or a plan check.
Which regions and project types does it cover?
England, across eight residential project types: house extension, loft conversion, flat conversion, garage conversion, new build house, new build flats, basement conversion and new garage. Wales is planned as a second region.
Whose name goes on the specification?
Yours. The logo, address, named designer and running header come from your practice profile on every plan, including per-specification purchases. Specline's mark never appears on a generated document.
What happens when the Approved Documents change?
The 2026 editions of Approved Documents L1 and F1 were published on 24 March 2026 and come into force on 24 March 2027. Every specification carries that flag, and the library is maintained against the editions in force. That is why Specline is a subscription rather than a one-off licence.
Where does the wording come from?
It is written from the Approved Documents and the British Standards they cite, in our own words. Nothing is copied from a commercial specification library. Every figure in it has been checked against the source, with the date recorded.
Can I export to Word?
Yes. Every specification downloads as a PDF and as an editable .docx, both carrying the U-value working as their own section. The Word file is the one to edit if you want to add a project-specific clause of your own before issue.