HETAS Approved Installer in Harold Wood and Harold Hill. Stove installation, chimney lining and twin wall flue systems. Internal twin wall surveyed and installed to Approved Document J specification.
Harold Wood and Harold Hill together make up the RM3 postcode area north of Romford. The housing stock is predominantly post-war — a large proportion of the Harold Hill area was developed as an LCC overspill estate in the 1950s, while Harold Wood carries a mix of older and inter-war residential streets. Many properties here were built without chimney stacks, making twin wall flue systems — particularly internal twin wall — a frequent requirement when a stove installation is planned.
HETAS registered installer, HETAS approved installer, HETAS certified installer — these three terms all refer to the same registration under the HETAS Competent Person Scheme. If you have searched for any of these terms, you are in the right place.
Internal twin wall installation is specialist work within the HETAS competence scope. When a twin wall flue system runs through the interior of a property — rising through ceilings and floors rather than climbing the outside wall — it penetrates structural elements at every level. Approved Document J sets specific requirements for how these penetrations are handled, and they are not optional guidance.
The primary requirement at each ceiling or floor penetration is a firestop plate: a non-combustible collar that fits tightly around the outer surface of the twin wall pipe and seals the gap in the ceiling or floor. Its purpose is to prevent hot gases, combustion products or fire from passing through the structural void between floors via the penetration gap. Firestop plates must be fitted at every penetration — not just the first one. A three-storey internal twin wall run requires firestop plates at each of three separate penetrations.
Alongside the firestop plate requirement, Approved Document J specifies a minimum clearance from combustibles. The outer surface of the twin wall pipe must maintain sufficient clearance from timber joists, floorboards, roof insulation, and any other combustible material at every level through which it passes. Where a standard run cannot achieve this clearance, heat shielding may be specified — a non-combustible shield open at the top and bottom with a required air gap, allowing the twin wall to run closer to combustibles than the standard clearance would permit. The shielding must remain accessible at every firestop position. We assess all of this at survey before internal twin wall is confirmed as the route.
We cover Harold Wood and Harold Hill postcodes within RM3. Harold Wood village, Gooshays Drive, Pages Wood, Hilldene Avenue and surrounding streets all within our standard area.
We cover stove installation, chimney lining and twin wall flue systems across Harold Wood, Harold Hill and surrounding areas. HETAS compliance certificate on every job.
Pre-installation survey. Professional installation to Approved Document J. CO alarm confirmed in room. Smoke draw test and commissioning. HETAS compliance certificate issued on the day — legal record of building regulation compliance.
Can a stove be fitted in a Harold Wood property that has no chimney?
Yes. Where there is no existing chimney, a twin wall flue system provides the flue route. External twin wall rises on the outside of the building. Internal twin wall passes through ceilings and floors with firestop plates at every penetration. We survey and specify the correct route at your property.
What is a firestop plate and why does it matter for internal twin wall?
A firestop plate is a non-combustible collar that seals around the twin wall pipe at every ceiling and floor penetration. Approved Document J requires one at each level. It prevents hot gases from reaching the void between floors and reduces fire risk at the structural penetration point.
Get in touch to discuss your project. Contact us for a survey and quote.
We also cover Hornchurch. See all areas covered.
