Most construction professionals can recite Part L U-values from memory. They’ll know Part B fire classifications and Part F ventilation rates without blinking. But ask about BS3632, and you’ll usually get a blank look. Park homes sit outside the Building Regulations framework entirely, governed instead by a British Standard that few specifiers ever need to open.
And yet, this parallel regime covers over 100,000 permanently occupied dwellings across roughly 1,800 licensed sites in England. The 2023 revision tightened performance requirements significantly, and several targets now sit surprisingly close to mainstream Building Regulations. We’ll map BS3632:2023 against Part L, Part B and Part F to show where the two frameworks converge and where they don’t.
Thermal Performance: How BS3632 Stacks Up Against Part L
The headline figures in BS3632:2023 are the maximum U-values for the external envelope. Any UK retirement park home built to the current standard must achieve no worse than 0.30 W/m²K for walls, 0.26 W/m²K for floors (calculated as exposed), and 0.20 W/m²K for roofs. These values are calculated in accordance with BR 443, so the methodology will be familiar to anyone who’s worked with Part L submissions.
Compare that to Part L 2021 (as amended 2023) for new-build dwellings in England. The notional dwelling targets are 0.18 W/m²K for walls, 0.13 W/m²K for floors and 0.11 W/m²K for roofs. The limiting (backstop) values are 0.26 for walls, 0.18 for floors and 0.16 for roofs.
BS3632 wall targets sit between the Part L notional and limiting values. Floors are less demanding, and roofs are notably more lenient. But the gap is narrower than most people in mainstream construction would expect. The 2023 revision cut the floor U-value from 0.35 to 0.26 W/m²K, a major jump that forced many producers to move to thicker insulation or structural insulated panels.
Fire Safety and Internal Linings
Park homes are classified as “caravans” under the Caravan Sites and Control of Development Act 1960, so they don’t fall under Building Control jurisdiction. Fire safety provisions are written directly into BS3632 instead.
The 2023 revision strengthened these requirements. Smoke and heat alarms must now be installed to a defined grade and category, and all entrance doors need to meet means of escape requirements with minimum clear opening widths. There are also new provisions around exterior window and door safety, covering fall prevention and restricted openings.
Internal linings and furnishings must comply with the Furniture and Furnishings (Fire) (Safety) Regulations 1988, as amended. Cladding and internal finishes have their own fire performance criteria within the standard. It doesn’t mirror Part B’s Euroclass system (A1 through to F), but the intent is the same: control flame spread and give occupants time to evacuate.
Ventilation and Moisture Control
This is where BS3632:2023 made some of its biggest changes. Trickle vents are now required in every room for continuous background ventilation. Wardrobe ventilation requirements have been increased, and the roof ventilation section was substantially rewritten to cover designs that the previous edition missed.
BS3632-compliant homes must incorporate ventilation aligned with the principles in Approved Document F. In practice, this means many newer park homes will feature MEV or MVHR systems, particularly as tighter thermal envelopes increase condensation risk. The standard also introduced specific performance criteria for vapour control, targeting interstitial condensation within the external structure.
Part F sets extract rates for wet rooms and whole-dwelling ventilation rates based on floor area and number of bedrooms. BS3632 follows a broadly similar logic, though its requirements are written specifically for factory-built, single-storey dwellings.
Structural Loads: Wind, Snow and Stability
Park homes are lightweight timber-framed structures, typically transported to site in one or two sections and craned into position on a concrete base or steel chassis. BS3632 requires structural calculations for wind and snow loading, and the 2023 revision tightened specifications for foundations and weather resistance.
The load calculations reference the same Eurocodes (BS EN 1991 for actions on structures) that mainstream construction uses. A retirement park home is a single-storey, factory-built dwelling installed on a managed residential site and designed for permanent year-round occupation. Once sited, it needs to handle the same wind and snow loads as any other building in that location.
A Parallel Regime That Deserves a Closer Look
The biggest difference between BS3632 and Building Regulations comes down to jurisdiction, not technical performance. Park homes are legally chattels, not buildings. They don’t go through Building Control, and there’s no SAP calculation or EPC rating. Compliance is industry-managed through the NCC’s self-certification scheme, which will be unfamiliar territory for most construction professionals.
But the technical demands are real. BS3632 governs a sector with over 100,000 permanently occupied homes in England, housing well in excess of 160,000 residents based on the most recent estimates. And the 2023 revision brought its requirements closer to mainstream Building Regulations than ever before. For anyone working across multiple housing sectors or with an interest in off-site manufacturing, it’s a standard that deserves more attention than it currently gets.