Dormer loft conversion drawings in Hounslow

Heritage and Article 4 in Hounslow

Hounslow has 33 conservation areas and 3 Article 4 directions. Historic England lists 519 entries, including 32 at Grade I. The borough also holds 1 World Heritage Site.

Class B roof enlargements are not permitted development on article 2(3) land. A dormer inside any of these areas needs an application, and a listed house needs its own consent.

Housing and green belt in Hounslow

54 per cent of Hounslow's 102,961 households live in a house or bungalow, and 45.7 per cent own their home. About 22 per cent of the borough is green belt. The adopted plan is the Hounslow Local Plan 2015-2030 (Volumes 1 and 2), from 2,015.

How Hounslow decides householder applications

Hounslow decided 689 householder applications in its latest year and granted 78.5 per cent, deciding 97.8 per cent in time. The speed is a useful sign for timetables, though the figures cover every home project.

Permitted development for a Hounslow dormer

Where the house is unlisted and outside a conservation area, volume is limited to 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume, and the dormer cannot sit on a slope that fronts a highway. Set-back: Original eaves maintained; enlargement set at least 0.2 m from the eaves measured up the roof slope, so far as practicable (not required for hip-to-gable or roofs joining a rear/side extension).

A Lawful Development Certificate records a compliant design.

Choosing the right size category for a Hounslow house

The council's clearances depend on the house: tighter gaps for terraced and small semi-detached houses, and a metre for larger ones. The line between the two is a judgement, so we state our reasoning on the drawing and keep to the cautious side where it is close.

We look at the width of the roof, the depth of the plot, the spacing of the neighbours and the scale of the house against the street. A small semi in a row of small semis is treated as small, even if it has been extended.

Once the category is fixed, the dormer is drawn to its gaps, and the elevation shows each dimension.

Stairs, fire and insulation in a Hounslow dormer

For the stair: Loft conversions where 2.0 m cannot be achieved: 1.9 m at the centre of the stair, 1.8 m at the side (half width). For fire in a converted loft: New storey above 4.5 m by loft conversion: protect the full escape route with fire-resisting doors (min E 20) and partitions (min REI 30).

The thermal rule for new roof elements is: 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.

We note each of these on the planning set where it affects the design, and develop them fully in the building regulations drawings, where a loft conversion is checked against each requirement in turn.

What we check on a Hounslow address before quoting

Hounslow has 6 registered parks and gardens and 6 scheduled monuments, so some roofs sit in a sensitive setting. We check the address against these, the conservation area list, the Article 4 directions and the 27 Heritage at Risk entries.

We then ask for photographs and a short description of the house. With the survey, that is enough to say which size category applies and what a dormer can reach.

Hounslow dormer drawings and related pages

Each set has plans, a section and four elevations with clearances dimensioned. Price: £695. If the council asks for changes, we redraw at no charge until approval.

See loft conversion drawings in Hounslow, house extension drawings in Hounslow and architectural drawings in Hounslow. Neighbours include Richmond upon Thames and Ealing.