Party Wall Surveyor Hillingdon: Compare Quotes
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Post a Party Wall job for a property in the London Borough of Hillingdon. The administrator reviews the complete enquiry and could invite suitable qualified surveyors to provide independent quotes when the comparison service is available.
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The adopted plan still controls
Hillingdon’s development plan is in two principal borough parts. Local Plan Part 1: Strategic Policies was adopted on 8 November 2012. Local Plan Part 2: Development Management Policies, together with the Site Allocations and Designations document, was adopted on 16 January 2020 and replaced the saved UDP policies.
A new Local Plan is being prepared, but it is at an early stage. The council’s current timetable records:
- a scoping consultation from 9 July to 21 August 2026;
- consultation on plan content and evidence from 5 November 2026 to 14 January 2027;
- consultation on a proposed Local Plan from 15 June to 27 August 2027; and
- consideration of adoption on 1 May 2028.
Those are scheduled milestones, not adopted policy. The scoping page describes the first stage as consultation on key themes. As at 24 August 2026, the 2012 and 2020 documents remain the adopted borough plan and no successor policy should be presented as though it has replaced them.
The old residential-extension guide was withdrawn
The old Hillingdon Design and Accessibility Statement on Residential Extensions is not the current source of householder standards.
The withdrawal schedule published with the 2020 adoption is explicit: all Hillingdon Design and Accessibility Statements were withdrawn, including Residential Extensions. For householder development it directs readers instead to Appendix A of Local Plan Part 2 and:
- Policy DMHD 1 for alterations and extensions;
- Policy DMHD 2 for outbuildings; and
- Policy DMHD 3 for basements.
The council’s current supplementary planning documents page also does not list the old residential guide. A measurement quoted from that guide should not be carried into a current design without checking it against the adopted 2020 policy.
The rear-extension policy overlaps at five metres
Policy DMHD 1 gives the current planning standards for a single-storey rear extension:
- at a terraced or semi-detached house on a plot 5 metres wide or less, depth should not exceed 3.3 metres;
- at a terraced or semi-detached house on a plot 5 metres wide or more, depth should not exceed 3.6 metres;
- at a detached house on a plot at least 5 metres wide, depth should not exceed 4 metres;
- a flat roof should not exceed 3 metres in height; and
- a pitched or sloping roof should not exceed 3.4 metres in height, measured from ground level.
The wording creates a real overlap at a plot width of exactly 5 metres: both “5 metres or less” and “5 metres or more” apply. The policy does not say which depth controls at that exact width. Do not resolve that drafting point by assumption; confirm how the council applies it to the proposal.
These dimensions are planning standards where an application is assessed. They are not permitted-development entitlements and they are not Party Wall Act thresholds. A 3.3-metre extension can still involve work to a party structure, a new wall at the boundary or excavation below neighbouring foundations.
Hillingdon and the Act use different 45-degree lines
For a two-storey rear extension, Policy DMHD 1 says the proposal should not enter an area defined by a 45-degree line of sight drawn from the centre of the nearest ground- or first-floor habitable-room window of the adjacent property. It also says openings should not overlook another house at a distance of less than 21 metres.
That is a planning amenity test. It is not the 45-degree excavation plane in the Party Wall etc. Act 1996.
Under section 6(2), the statutory plane is drawn downwards towards the proposed excavation from the bottom of the adjoining building’s foundations. It matters where excavation is within 6 metres and meets that plane. The separate section 6(1) test applies within 3 metres only where the proposed work will extend below the bottom of the adjoining foundations.
A proposal can satisfy Hillingdon’s window-based planning line and still require an excavation notice. It can also fail the planning line without engaging section 6. The party wall notice guide explains the different notice categories.
A side gap is a townscape rule, not an Act exemption
Policy DMHD 1 says side extensions should not exceed half the width of the original property. For a two-storey side extension, it requires:
- at least 1 metre from the side boundary;
- at least 1.5 metres in the Copse Wood and Gatehill Estates, with more potentially needed on a wider-than-average plot; and
- at least 1 metre behind the main front elevation at detached and semi-detached properties.
The larger Copse Wood and Gatehill figure protects the characteristic separation and views between houses in those estates. It does not create a Party Wall Act safe harbour.
The excavation tests depend on distance from an adjoining building or structure, excavation depth and the adjoining foundation level. A planning setback does not establish any of those facts. Work may also be notifiable because of what is proposed to an existing party structure, regardless of the side-boundary gap.
Basements have an adopted policy
Hillingdon does not rely on an old SPD for basement control. Policy DMHD 3, adopted in 2020, requires an assessment of:
- drainage;
- flooding;
- groundwater conditions; and
- structural stability.
Basement and underground development is supported only where it avoids harm to the built and natural environment, local amenity, the water environment and structural stability. The policy does not permit habitable rooms or other sensitive uses in areas prone to flooding, and it does not permit basement schemes in listed buildings.
The supporting text goes further. It says full-length or full-width subterranean development will not be supported, front or side lightwells are unacceptable, and the applicant must fund independent assessment of structural reports submitted in support of a basement proposal.
Those requirements concern planning evidence and planning harm. They do not authorise work under the Party Wall Act or replace a section 6 notice. A qualifying excavation notice must describe the work and include plans and sections showing the site and depth of the excavation. Neighbouring foundation information therefore matters to both the technical design and the statutory test, but the two processes remain separate.
The borough-wide Article 4 starts beyond four metres
Hillingdon’s current Article 4 directions page states that a direction removes permitted-development rights for a single-storey enlargement extending more than 4 metres beyond the original rear wall. It applies across the whole borough and came into force on 22 September 2014.
That direction means a qualifying extension beyond four metres cannot use the right the direction withdrew. It does not mean every proposal at four metres or less is permitted development: the other national conditions, the property’s planning history and any address-specific restrictions still need to be checked.
The council also reports 31 conservation areas, ranging from village centres and planned estates to canal-side and industrial heritage. Conservation designation can alter the planning assessment and the available permitted-development route. Neither conservation status nor the borough-wide Article 4 changes which work is notifiable under the Party Wall Act.
More than 35,000 properties date from the 1930s
The adopted plan says many Hillingdon houses have a distinctive 1930s character. The current Valuation Office Agency figures support that description.
As at 31 March 2025, Hillingdon had 118,260 domestic properties on the Council Tax list, including:
- 40,240 flats or maisonettes;
- 31,660 semi-detached houses;
- 29,640 terraced houses;
- 10,130 detached houses; and
- 5,840 bungalows.
The largest build-period band is 1930 to 1939, with 35,220 properties, or 29.78 per cent of the total. The 1919 to 1929 and 1930 to 1939 bands together contain 43,530 properties, or 36.81 per cent. The agency rounds the counts to the nearest ten.
The household measure tells a similar story from a different source. At Census 2021, Hillingdon recorded 109,225 households, including 38,338 in semi-detached houses and 21,773 in terraced houses. Together those forms accounted for 60,111 households, or 55.03 per cent.
Neither dataset identifies the legal status or construction of an individual wall. A semi-detached or terraced label does not prove which walls are party structures. In flats, the Act’s definition can include a floor partition or other structure separating parts of buildings approached solely by separate staircases or entrances. The figures explain why property form and approximate age belong in the brief; they do not replace inspection or title evidence.
If the council owns the adjoining property
Hillingdon publishes a specific route for notices where the adjoining property is council-owned. Its planning advice section says the notice should be served on the Mayor and Burgesses of the London Borough of Hillingdon at the Capital Programme Works Service and emailed to the published party-wall-notices address. The council says it will generally appoint a surveyor to protect its assets.
That process is relevant only where the council has an adjoining-owner interest. It does not make the council the Party Wall authority for disputes between private owners, and submitting a planning or Building Regulations application does not serve the statutory notice.
Explain the property and proposed work
Provide:
- the full property address;
- whether the property is terraced, semi-detached, detached, a bungalow or a flat;
- the plot width and how it was measured;
- the approximate construction date and the evidence for it;
- which walls, floor partitions or other separating structures are involved, and with whom;
- whether the adjoining interest is privately or council-owned;
- whether the address is in a conservation area, the Copse Wood Estate or the Gatehill Farm Estate;
- whether an Article 4 direction or another restriction covers the address and proposed work;
- whether the work involves a rear extension, side extension, loft steel, chimney breast, boundary wall or basement;
- proposed depths, heights and boundary setbacks;
- excavation depth and distance from each neighbouring building or structure;
- known or assumed adjoining-foundation depths and the basis for them;
- flood-zone, groundwater, drainage and tree information for basement work;
- structural, geotechnical, hydrological and planning reports where available;
- whether you are carrying out work or responding to a neighbour’s work;
- drawings, notices, responses and correspondence already exchanged; and
- known dates and access constraints.
Compare the proposed appointment
Each quote should explain who would appoint the surveyor and the work included. That may involve reviewing drawings, notices, inspections, a schedule of condition, preparation of an award, liaison with another surveyor or later visits.
The Party Wall surveyor guide explains when a surveyor may be needed, and the Party Wall surveyor cost guide explains the factors that can affect the proposed fee. Neighbouring coverage includes Party Wall surveyors for Harrow properties and the wider Party Wall surveyor west London guide.
What happens after you post
Your verified enquiry is available to the administrator for review. Invitations are not currently available. In a later comparison service, a participating surveyor would receive only the outward postcode and a restricted brief before an authorised introduction.
When comparison is available, complete quotes and the surveyor’s private profile can be shown on your private customer page. Availability varies, so a request may receive several quotes, one, or none. Submission does not guarantee an invitation, quote or introduction.
If introductions are available and the administrator records your chosen introduction, only that surveyor receives your full contact and property details. FindTheSurveyor charges neither party a fee. You pay the professional fee directly to the surveyor.