Renovation and retrofit architects

A whole-house retrofit is a planned set of energy-saving changes to an existing building, designed so that each measure suits the others. The aim is a warmer, drier, cheaper-to-run home without trapping moisture or causing damp. An architect's part is the thinking before the trades arrive: what the building is made of, how it behaves, and the order of work.

Why does the condition of the home come before the measures?

Because the cheap, obvious upgrades have often been done already. The English Housing Survey puts 56% of homes at band C or better in 2024, and 42% with at least 200mm of loft insulation (GOV.UK). What remains tends to be the awkward stock: solid walls, suspended timber floors, old windows, and roofs that cannot simply be topped up.

The same survey reports 1.4 million homes, 5% of the stock, with a damp problem in 2024 (GOV.UK). Insulating over an unresolved leak or rising-damp source seals the problem in. A good retrofit brief starts with a survey of defects, ventilation and how the household uses the home, and only then moves to a list of measures.

What does a retrofit coordinator do under PAS 2035?

PAS 2035 is the British specification for domestic retrofit, and PAS 2030 covers the installers. Under it, a retrofit coordinator is responsible for the project as a whole. They look at the building's condition and the occupants' needs, help set the sequence of measures, and check that designs and installations fit together. Government-funded schemes such as ECO4 are delivered to it.

An update to PAS 2035/2030:2023 came into force on 30 March 2025, adding a requirement for coordinators to make site visits. ECO4 itself now runs to 31 December 2026 (GOV.UK). If you are paying for the work yourself, PAS 2035 is not a legal requirement, but many owners ask for it because it gives a documented method and one accountable person.

Insulation or ventilation: what are the trade-offs?

Every measure that stops heat escaping also stops moisture escaping, and moisture is what damages old buildings. That is why the usual advice is to treat the home as a system. Tightening a draughty house without planning ventilation can raise humidity, condensation and mould risk.

Solid walls and traditional buildings

Older solid walls generally manage moisture by letting it move through. Impermeable insulation or sealed paint can stop that and trap water in the masonry. Historic England publishes retrofit advice for traditional buildings, and its pages are the place to start for any pre-war house. A listed building needs listed building consent for changes that affect its character.

Airtightness, ventilation and heating

Draught-proofing helps, but a more airtight home needs a deliberate ventilation route: extract fans, trickle vents or a mechanical system, sized to the dwelling. Approved Document F sets the ventilation standard and Volume 1 for dwellings has been in force since 15 June 2022 (GOV.UK). Heating is usually last in the sequence, because a better-insulated home needs a smaller heat source.

Which Building Regulations apply to a renovation?

Part L (conservation of fuel and power) is the one most owners miss. Regulation 23 of the Building Regulations 2010 says that where you renovate a thermal element, such as a wall, roof or floor, it must be brought up to the Part L standard if the work is a major renovation or covers more than 50% of that element's surface, in so far as that is technically, functionally and economically feasible (legislation.gov.uk).

In practice that means stripping the plaster off most of a solid wall, or re-covering most of a roof, can bring the whole element into scope. Replacement windows, new boilers and controls have their own rules. Your building control body, either the council or an approved inspector, will tell you how it reads your scheme.

What changes on 24 March 2027?

The current Approved Document L for dwellings is the 2021 edition incorporating 2023 amendments (GOV.UK). A 2026 edition has been published, and Building Circular 01/2026 says the new regulations come into force on 24 March 2027. They do not apply where a building notice, initial notice or full plans were given before that date and the work starts before 24 March 2028 (GOV.UK).

If your project straddles that date, ask your architect and building control which edition applies to your application, and say so in writing. The circular does not set out how the changes affect renovation work in existing homes, so do not assume. The circular covers England only; Wales sets its own Building Regulations, so check if you are building there.

Which grants are open now?

The Boiler Upgrade Scheme covers England and Wales. GOV.UK lists £7,500 towards an air source heat pump, £7,500 for a ground source heat pump, £5,000 for a biomass boiler and £2,500 for an air-to-air heat pump. Until March 2027 an extra £1,500 is available for a heat pump in a home heated by oil or LPG with no mains gas (GOV.UK).

There is one grant per property, hybrid systems are not eligible, and you cannot use it to replace a low-carbon system. Check who applies, and when, before you sign an installer's quote. ECO4, the supplier-funded scheme, ends on 31 December 2026, and the government says its extension is solely to let suppliers complete existing obligations, so do not count on new ECO4 funding. Grant rules change often, so check GOV.UK for the figures on the day you commit.

What should you ask a retrofit architect before hiring?

• Which similar homes have you retrofitted, and can I speak to a past client?
• Will you survey for damp, ventilation and condition before recommending insulation?
• Who is the retrofit coordinator, and do they hold the qualification and registration for it?
• How will you sequence the work, and what happens if we do it in phases?
• Which edition of Part L do you expect to apply, and why?
• What does your fee cover, and what is excluded? Please put it in writing.
• What professional indemnity insurance do you hold?

Get at least two written quotes on the same brief so that the figures can be compared. Our guide to architect fees explains what usually moves a fee up or down.

How do you check a retrofit architect is registered with ARB?

1. Open the Architects Register, run by the Architects Registration Board.
2. Search by name or practice, and check the person is listed and in good standing.
3. Match the name and practice to your quote and to the contract you are asked to sign.
4. Remember the rule on the ARB site: if someone is not on the Register, they are not an architect.

Adding space as well as upgrading? See extensions. Converting commercial premises? See commercial and interiors. You can also browse guides or look at cities to find a practice near you.