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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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Not open for sign-up yet. Founding-member pricing for the first 30 practices.

EW1 · Full fill cavity wall

Calculating
0.35W/m²Ktarget 0.18 · new element

103 mm facing brickwork · 10 mm residual cavity · 90 mm Kingspan Kooltherm K106 (λ 0.019) · 100 mm aircrete block 0.15 W/mK · 12.5 mm plasterboard on dabs

EW1Full fill cavity wall

To achieve minimum U-value of 0.18 W/m²K (actual U-value achieved 0.17 W/m²K)

External cavity wall to be built up as a 103mm facing brick outer leaf matched to the existing dwelling, a 100mm cavity fully filled with 90mm Kingspan Kooltherm K106, and a 100mm aircrete blockwork inner leaf… calculated to BS EN ISO 6946 allowing for mortar joints, wall ties and an air-gap correction.

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.

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.

EXT18 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
GAR18 build-ups · 35 notesGarage conversionIntegral and detached
NBH14 build-ups · 58 notesNew build houseFull notional dwelling assessment
NBF14 build-ups · 51 notesNew build flatsSeparating construction, common parts
BSM10 build-ups · 32 notesBasement conversionUnderpinning, tanking, BS 8102
GBD10 build-ups · 23 notesNew garageDetached and attached, unheated

113 build-ups · 325 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.

  • 01
    Your name on the document, on every planLogo, address, named designer and running header come from your practice profile. Specline's mark never appears on a specification.
  • 02
    References that match the drawingsBuild-ups number themselves per job in the order you choose them, so EW1 on the specification is EW1 on the section.
  • 03
    Practice standards stated the same way every timeFD30S doorsets, BS 5839-6 Grade D1 LD2 alarms, the escape window figures, hot water to Approved Document G3. Where the standard exceeds the Approved Document minimum, the document says so.
  • 04
    Current, and flagged when it is about to changeApproved Documents L1 and F1 2026 come into force on 24 March 2027. Every specification carries the flag, and the library is maintained against the editions in force.
  • 05
    Saved jobs, revisions, issue historyP01 to P02 with a record of what went out and when. Reopen any job and carry on.
Specline drafts the specification. Building control approves the work.

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

Coming soon

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

Coming soon

Per spec

£25 / issued spec

no subscription

  • Pay when you issue
  • All 8 project types
  • Your practice's identity on every document

Coming soon

Founding membersThe first 30 subscribing practices keep their joining price for as long as they stay subscribed.

All prices exclude VAT. No payments are being taken yet. Join the waiting list and you will hear first.

Waiting list

Be told when it opens

Specline is not open for sign-up yet. Leave your email and you will hear first, with founding-member pricing held for the first 30 practices.

We will only email you about Specline, we will not pass your address to anyone, and every message has a one-click way off the list. What we keep and for how long is set out in the privacy notice.

Questions

Straight answers

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?
PDF at launch, with an editable Word export to follow. The PDF carries the U-value working as its own section.