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Camden, London

SAP calculations in Camden

SAP calculations in Camden show building control that an extension or a new home meets the energy rules, often on a house that cannot change its windows or its roof edge. Fixed quote after a free constraints check, VAT included.

Fixed quote after a free constraints check

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  • Fixed fees, VAT included

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    Architectural model of a four-storey London stucco townhouse in its terrace, with a portico, area railings, sash windows, a cornice and chimney stacks
    The house as it stands: four storeys over a lower ground floor.Existing Proposed worksAn illustrative model, built for this page.

    How we work on sap calculations

    Five steps from first call to approval.

    The same model cut through the middle: every floor, the stair, the chimney breasts, the new mansard, rear extension and basement in section
    Section through the model: every floor on one datum.

    1. Enquiry and constraints check

      We check the property against conservation areas, listed status, Article 4 directions, tree preservation orders, flood zone and planning history. We choose the right route and send a fixed quote.

    2. Measured survey

      We survey the house on one datum: rooms, levels, boundaries, drains, trees and the neighbours' windows that the 45° and 25° tests depend on.

    3. Independent check

      A second chartered technologist checks every sheet against the council's validation checklist and the policy. A senior review signs it off before anything is submitted.

    4. Building regulations

      Technical drawings are coordinated with the structural engineer's calculations, the drainage and the planning conditions.

    5. Approval and hand-over

      Building control approval, then a next-steps pack covering the commencement notice, party wall timing and CIL.

    Free redraws until approval. Every drawing set is checked independently, and the checker is never the person who drew it.

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    Pencil resting on a dimensioned technical drawing beside a scale rule

    SAP calculations in Camden and the Home Improvements guidance

    Camden's guidance for altering a home is the Home Improvements CPG (Camden Planning Guidance), one of a series that also includes the Design CPG (Camden Planning Guidance), all supporting the Camden Local Plan. They deal with scale, materials and the way an addition sits against its neighbours. The energy rules in Approved Document L deal with something else, and a Camden scheme has to satisfy both.

    The tension shows up in the details. A conservation area house may need its original sash windows kept, or replaced like for like, and old windows cannot reach the modern window figure on their own. The calculation then has to find the saving elsewhere, in the roof, the floor or the new walls, and we plan that before the planning drawings are frozen.

    Camden is also a borough of flats, not houses. Only 13.3 per cent of households live in a house or bungalow, and 29.7 per cent own their home, so a good share of our work here concerns conversions, mansion flats and top-floor alterations rather than detached extensions.

    Red-brick English house with rows of solar panels on its tiled roof

    Local figures for Camden

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Conservation areas40 named conservation areas published by the council—planning.data.gov.uk
    Article 4 directions21 Article 4 directions published by the council—planning.data.gov.uk
    Listed building entries1,971 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Households living in a house13.3 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Householder applications granted89.1 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder appeals allowed35.5 % of householder appeals alloweddecision dates 1 Jul 2021 to 30 Jun 2026assets.publishing.service.gov.uk
    Average price, terraced1,554,868 GBP2026-07publicdata.landregistry.gov.uk
    Approved Document L Vol 1 2021 incl. 2023 amendments, Table 4.2New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4—gov.uk
    Approved Document L Vol 1 2021, para 10.7(d)Windows, roof windows, rooflights and doors in an extension should not exceed 25% of the extension floor area plus the area of openings removed or covered—gov.uk
    Circular 01/2026 (transitional arrangements)AD L/F 2021 continue where plans/notices are deposited before 24 Mar 2027 and work starts before 24 Mar 2028—gov.uk

    A blank value means the figure has not been published, not that there are none. Check your own address with the council.

    Councils bordering Camden
    Building regulations, layer by layerPart A: structure: Approved Document A: Structure, 2004 edition incorporating 2004, 2010 and 2013 amendments. Part B: fire safety: All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604. Part L: insulation: New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4. Part K: stairs: 2.0 m clear headroom over stairs. Full plans application: Building control body must decide a full plans application within 5 weeks, or longer if agreed in writingPart A: structurePart B: fire safetyPart L: insulationPart K: stairsFull plans applicationABCDE

    Building regulations, layer by layer

    The Approved Documents that shape most house projects, from structure to the application itself.

    A · Part A: structure
    Approved Document A: Structure, 2004 edition incorporating 2004, 2010 and 2013 amendments
    B · Part B: fire safety
    All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604
    C · Part L: insulation
    New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4
    D · Part K: stairs
    2.0 m clear headroom over stairs
    E · Full plans application
    Building control body must decide a full plans application within 5 weeks, or longer if agreed in writing

    How an extension or roof alteration complies

    The limits for new elements in an existing home are: New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4. Where a rear extension or a roof is genuinely new, we can meet them with standard build-ups.

    Glazing has its own cap: Windows, roof windows, rooflights and doors in an extension should not exceed 25% of the extension floor area plus the area of openings removed or covered. A garden-level extension at the back of a terrace, with a large glass wall facing the garden, reaches that cap fast.

    The other routes are: Alternative routes: area-weighted U-value (para 10.9) or a SAP calculation against a notional extension (para 10.10). For Camden's tightest sites, where the glass is fixed by planning and the wall thickness is fixed by the party walls, the SAP comparison is often the only route that works.

    Conservation, listing and Article 4 in Camden

    Camden has 40 conservation areas and 21 Article 4 directions, and Historic England lists 1,971 entries in the borough, including 57 at Grade I. The density of constraint is the defining feature of work here.

    On a listed home, the energy upgrade is part of a consent process. Insulation behind original plaster, a new roof covering and secondary glazing all touch historic fabric, so the SAP assumptions have to follow what the conservation officer will permit, not what a catalogue offers.

    Camden decided 394 householder applications in its latest year, granting 89.1 per cent, with 77.7 per cent in time. Appeals add a note of caution: 35.5 per cent of 76 householder appeals were allowed over five years. Our planning drawings in Camden cover the application, and a lawful development certificate in Camden can confirm permitted development where it exists.

    New homes, conversions and the rule dates

    A newly built dwelling is assessed on a different basis. The guidance says: For new dwellings AD L 2026 names two methods: the Home Energy Model (HEM) and SAP; validity dates are in the Notice of Approval. The start date of the next edition is given as: AD L 2026 takes effect 24 Mar 2027 (24 Sep 2027 for higher-risk building work).

    The transitional rule is: AD L/F 2021 continue where plans/notices are deposited before 24 Mar 2027 and work starts before 24 Mar 2028. For a mews house or a flat created from a larger home, the date plans are deposited decides which edition applies, so we fix it at the start.

    A new dwelling also needs an energy certificate at the end: An energy performance certificate is required on construction of a new dwelling. A terraced house here averages £1,554,868, so the design-stage figure is worth building exactly as drawn.

    Cost and how the calculation joins the rest of the set

    You get a fixed quote after a free constraints check, VAT included, before committing. The assessor uses our model, so the figures match the drawings, and the output supports the submission in building regulations drawings in Camden.

    Floor area added also carries a levy. The Mayoral band here is band 1, at an indexed £96.97 per square metre, and the borough's own schedule is the London Borough of Camden Community Infrastructure Levy Charging Schedule.

    For the beams, see structural calculations in Camden; for the full range of local work start at architectural drawings in Camden; and for the neighbouring borough, compare SAP calculations in Barnet.

    What you receive

    Building regulations section drawing showing the construction build-up
    Sample drawing. Building regulations section showing construction build-up for a building control check.
    House extension under construction with scaffolding, new glazed doors and building materials
    Energy in
    Move the pointer up — the plug rises toward the socket.

    Other services in Camden

    SAP calculations nearby

    Questions

    Can I keep original windows in a Camden conservation area and still comply?

    Often yes. The calculation compensates elsewhere in the building, which is the purpose of the alternative routes: Alternative routes: area-weighted U-value (para 10.9) or a SAP calculation against a notional extension (para 10.10).

    Which Camden guidance covers home alterations?

    The Home Improvements CPG (Camden Planning Guidance). Energy limits come from Approved Document L.

    Does a flat conversion need a SAP calculation?

    A new dwelling is assessed by a calculation method: For new dwellings AD L 2026 names two methods: the Home Energy Model (HEM) and SAP; validity dates are in the Notice of Approval.

    How much does it cost in Camden?

    Fixed quote after a free constraints check, VAT included.

    Sources and dates

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    Tell us about your property.

    We check the constraints, then send a fixed fee. Messages before 3pm get a reply the same working day.

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