Frequently Asked Questions

Often not. Under householder permitted development rights in England, a single-storey rear extension can go up to 3 metres beyond the rear wall of the original house (4 metres for a detached house) and up to 4 metres high, without a planning application.

You can go up to 6 metres (8 metres detached) by applying for prior approval first: the council notifies your neighbours and has 42 days to decide.

Other conditions apply: extensions and outbuildings together can cover no more than half the land around the original house, materials must look similar to the house, and eaves within 2 metres of a boundary can be no higher than 3 metres. Flats and maisonettes do not have these rights, and they are reduced in conservation areas, on listed buildings and where an Article 4 direction applies.

Sources: GPDO 2015, Schedule 2, Part 1, Class A (legislation.gov.uk) · Planning Portal: extensions

The house as it was first built, or as it stood on 1 July 1948 if it was built before then. Any extensions added since (by you or previous owners) count towards the permitted development limits.

Source: Permitted development rights for householders: technical guidance (GOV.UK)

• Two-storey rear: up to 3 metres beyond the original rear wall, and at least 7 metres from the rear boundary. The roof pitch should match the house, and upper-floor side windows must be obscure-glazed and non-opening unless the opening part is more than 1.7 metres above the floor.
• Side: single storey only, no more than 4 metres high and no wider than half the width of the original house.

In conservation areas and other designated land, side extensions and rear extensions of more than one storey need planning permission.

Sources: GPDO 2015, Schedule 2, Part 1, Class A (legislation.gov.uk) · Planning Portal: extensions

A garden room, office or store used for purposes incidental to the house (not as a separate home) is usually permitted development if it is single storey, not in front of the house, and no higher than 2.5 metres within 2 metres of a boundary (otherwise 4 metres with a dual-pitched roof, or 3 metres for other roofs, with eaves no higher than 2.5 metres). It must not have a veranda, balcony or raised platform over 0.3 metres, and the 50% land rule applies.

Using an outbuilding as separate, self-contained living accommodation is not covered, so a self-contained annexe usually needs planning permission. Check with your council before you start.

Sources: GPDO 2015, Schedule 2, Part 1, Class E (legislation.gov.uk) · Planning Portal: outbuildings

Usually yes. Planning and building regulations are separate: most extensions need building regulations approval even when no planning application is needed.

For detached outbuildings, building regulations do not normally apply if the floor area is under 15 m² with no sleeping accommodation, or 15–30 m² with no sleeping accommodation and either at least 1 metre from any boundary or built substantially of non-combustible materials. Anything with sleeping accommodation needs approval.

Sources: Planning Portal: is building regulations approval needed for an extension? · Planning Portal: building regulations for outbuildings

It is a certificate from your council confirming that proposed work would be lawful for planning purposes, for example that an extension falls within permitted development. It is optional, but it gives you certainty before you build and is useful evidence when you sell the house.

Source: Lawful development certificates (GOV.UK)

In England and Wales, the Party Wall etc. Act 1996 requires written notice before certain work:

• work on an existing party wall (e.g. cutting in a beam): at least 2 months’ notice;
• building a new wall on or at the boundary: at least 1 month;
• excavating within 3 metres of a neighbour's building (deeper than its foundations), or within 6 metres in some deeper cases: at least 1 month.

If your neighbour does not agree in writing within 14 days, a dispute is treated as having arisen and party wall surveyor(s) are appointed to agree an award.

Sources: The Party Wall etc. Act 1996: explanatory booklet (GOV.UK) · Party Wall etc. Act 1996, section 6 (legislation.gov.uk)

Permitted development rights are reduced in conservation areas and other designated land, do not apply in the same way to listed buildings (which also need listed building consent for most works), and can be removed altogether by an Article 4 direction. In these cases, check with your council before planning any work.

Source: Planning Portal: extensions

Hertsmere Borough Council is the local planning authority for Borehamwood, Elstree, Radlett, Bushey and Potters Bar. For homes elsewhere, check with your own borough or district council.

Source: Hertsmere Borough Council: planning applications

Usually not. Solar panels on a house in England are normally permitted development if:

• on a pitched roof, they stick out no more than 0.2 metres from the roof slope and are no higher than the highest part of the roof (excluding chimneys);
• on a flat roof, their highest part is no more than 0.6 metres above the highest part of the roof;
• on a wall, they stick out no more than 0.2 metres on a wall next to a road, or 0.4 metres elsewhere.

They must be sited, as far as practicable, to minimise their effect on the look of the building, and removed when no longer needed. They are not permitted development on listed buildings, and wall-mounted panels on a wall facing a road are not allowed in conservation areas. These rules were updated on 27 August 2026, which also added rules for plug-in (balcony) solar and for ground-mounted panels.

Sources: GPDO 2015, Schedule 2, Part 14, Class A (legislation.gov.uk) · The Town and Country Planning (General Permitted Development) (England) (Amendment) Order 2026, S.I. 2026/896

Installing solar panels in homes in Great Britain is zero-rated for VAT until 31 March 2027. Battery storage installed with solar panels is also covered, and retrofitting a battery to existing solar has qualified since 1 February 2024. From 1 April 2027 the rate is due to return to 5%. As of September 2026 the government has not announced an extension.

Sources: HMRC VAT Notice 708/6: energy-saving materials · House of Commons Library: VAT on solar panels

Yes, through the Smart Export Guarantee (SEG). Licensed electricity suppliers offer SEG export tariffs; each sets its own rate (always above zero), contract length and terms, and you can shop around. You will typically need an MCS certificate showing the system was installed by an MCS-certified installer using certified products, and a smart meter that records exports.

Sources: Ofgem: Smart Export Guarantee · MCS: Smart Export Guarantee for consumers

Construction (extensions, renovations, new builds, conversions and commercial projects), building maintenance (planned and emergency repairs, electrical and plumbing, roofs and gutters, decorating) and solar installations (residential and commercial solar PV and battery storage), plus project management, safety consulting and energy audits.

Our office is at Unit 2, Moda Business Centre, Stirling Way, Borehamwood, WD6 2BW. Our completed projects are across Greater London and the surrounding area.

It depends on size, method and access. Some examples from our own projects: a SIPs extension with oak cladding took 2 weeks (watertight in under a week); a one-bedroom garden annexe 2 months; a timber-frame extension with limited access 4 months; and a large residential extension 6 months. We give a programme with every quote.

Yes. Our construction service includes planning and design consultation, project management, and quality assurance and inspections.

Yes. For urgent repairs, call our 24/7 emergency line on 07958 120 777. Office hours: Mon–Fri 8 AM–6 PM, Sat 9 AM–4 PM.

Yes. We offer a free consultation and quote for construction, maintenance and solar work. Contact us to get started.