Wraparound extension drawings in Hillingdon

Trees and wraparound foundations

A wraparound needs deeper and wider foundations than a simple rear room because it spans two sides of the house. Near a mature tree, that can mean a piled or beam-and-pile foundation, which costs more but avoids cutting roots. We flag the tree on the survey and agree the foundation type with a structural engineer early, so the cost is known before the planning application.

The planning officer will want a tree survey and a protection plan where a protected tree stands within reach of the works. Raising that at the drawing stage avoids a validation delay later on.

Decisions, plans and prior approval in Hillingdon

The council grants 90.2% of householder applications and decides 94.3% on time. Its local plan is Hillingdon Local Plan Part 1: Strategic Policies, with Local Plan Part 2: Development Management Policies and Site Allocations and Designations (January 2020), so officers read your drawings against both parts.

For deeper rear extensions the council granted 29 larger home extension prior approvals and refused 13 in the latest return year, more grants than refusals. A wraparound with a side element normally goes in as a householder application, with the council fee at £548.

Where the plan fits the national limits, a Lawful Development Certificate confirms it, and Hillingdon handled 529 such applications in its latest return year.

Access, neighbours and building over services

Hillingdon plots vary a good deal, from interwar semis to larger detached houses on wide roads, so we begin with the survey, not an assumption. A wraparound closes the side passage, which affects bin routes, meter positions and drain access, and each has to be moved with the owner's agreement and the utility's rules.

Foundations near a boundary can trigger party wall notices. The Act applies where excavation falls within set distances of a neighbour's foundations and goes deeper than them, which a wraparound on two sides often does. We record the distances on the sections so the neighbour's surveyor has the facts.

We also record the position of any shared drain, because building over one needs the water company's agreement.

When a wraparound is the wrong answer in Hillingdon

A wraparound is not always the best use of a budget. Where a protected tree sits at the back, or where the Green Belt limits total floor area, a smaller rear extension may deliver most of the benefit at far lower cost and risk. We say so at the survey stage, and price the alternatives in the same conversation.

A useful test is to ask what the new room is for. A kitchen and dining space needs width more than depth, which a side infill supplies; a larger family room may need depth, which a rear arm supplies. Choosing the shape by purpose usually yields a design that officers read as proportionate.

Housing mix, levy and drawings

68.9% of households live in a house or bungalow and 56.6% own their home, with an average price of £470,875. Domestic gardens make up 18.6% of the borough's land. The borough CIL rate is £160.43/m² (Residential dwelling houses C3, borough-wide) for residential floorspace, which generally applies to larger additions, and we confirm liability on the measured area.

The set includes existing and proposed plans, elevations, sections, a roof plan, a location plan and a block plan. See rear extension drawings in Hillingdon for the simpler version, and party wall notices for neighbours.

For our wider service in the borough, visit architectural drawings in Hillingdon. We redraw without charge if the council asks for amendments before it decides.