SAP calculations in Havering

A suburban borough with few designations

Havering has 11 conservation areas and 146 listed entries, with 15 at Grade II* and 12 on the Heritage at Risk Register.

The result for energy design is freedom: outside the conservation areas, many Havering houses can take external wall insulation, modern windows and a new roof covering without a heritage objection. The constraint is the plot and the Green Belt, not the street frontage.

Home owners and a settled housing stock

69.5 per cent of households own their home. A terraced house averaged £435,382 and a detached one £841,116 in the latest Land Registry data.

Lower values mean tighter budgets, and many Havering owners want a straightforward way to pass the energy check. That usually means simple limits, a sound specification and no calculation. When SAP is the right route we say so, and when it is not we say that too.

The limits that apply to your extension

For new elements the document says: 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. A pitched-roof rear addition on a Havering semi usually meets them with standard insulation.

The glazing cap reads: 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 wide patio-door opening onto a long garden is the likeliest breach, and the alternatives are: Alternative routes: area-weighted U-value (para 10.9) or a SAP calculation against a notional extension (para 10.10).

We put that check into rear extension drawings in Havering so the door width is settled with the plan.

Replacement homes and the change of edition

A new house on a Havering plot follows the dwelling 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. The deposit date sets the edition, and the new start is: AD L 2026 takes effect 24 Mar 2027 (24 Sep 2027 for higher-risk building work).

A new rural house also faces summer heat. Approved Document O (overheating) applies to new residential buildings. The assessor needs the roof form, glass area and orientation, all of which come from the drawings.

Straightforward routes for Havering extensions

A single-storey rear addition on a semi-detached house will often pass on the simple limits. The skill is in getting the details right: the thickness of insulation in the flat or pitched roof, the floor build-up and the junction where the new wall meets the old.

We draw those junctions, because thermal bridges at the corners are where a sound design often loses performance. A continuous layer around the opening and a clean wall-to-roof detail cost little to draw and are cheap to build.

If the design is simple we say so after the free constraints check. We would rather confirm that you do not need a full calculation than sell one that adds nothing.

Finally, keep the manufacturer paperwork for the insulation, windows and doors. Building control may ask for it at completion, and it is far easier to file it as you go than to chase it months afterwards.

Bringing the Havering drawings together

See architectural drawings in Havering for the planning context, and building regulations drawings in Havering for the technical set. The beams for a wide opening are in structural calculations in Havering.

The energy work is a fixed quote after a free constraints check, VAT included. Send the address and say whether it lies inside the Green Belt.