Can I assume consent if I never hear back?

Categorically no — silence is deemed dissent (s5 Act) NOT deemed consent. Starting works without an Award after deemed dissent is trespass on the neighbour's rights — exposes you to injunction (works stopped mid-build), damages, and personal liability. Many DIY builders + small builders make this mistake — costs typically £15,000–£75,000+ in injunction + rectification + delay damages. Always wait for written consent OR complete the Award process before commencing.

What if I can't even contact the neighbour?

Notice service can still be perfected: serve to last-known address by first-class post (deemed served +2 working days), or fix to a conspicuous part of the premises (s15(2) Act). 14-day clock then runs from deemed service. If still no response, appoint surveyor on their behalf. Surveyor may proceed with Award on best-evidence basis even where adjoining owner remains uncontactable. Diligent enquiry record (proof of address research, postal receipts, dated photographs of fixed notice) protects building owner if later challenged.

Does deemed dissent cost more than active dissent?

Usually slightly more — process is identical but the adjoining-owner side requires more proactive surveyor input (locating + accessing property, often without owner cooperation), more correspondence to formalise appointment-on-behalf, and sometimes additional access notices. Typical premium £300–£950 on adjoining-owner surveyor fees. Plus building owner pays both sides' fees per s10(13), so absorbed by the same party. Building owner saves nothing by hoping for deemed dissent over consent.

Party Wall Deemed Dissent London | Builderr

What Is Deemed Dissent on a Party Wall Notice?

Deemed dissent occurs under s5 Party Wall Act 1996 when an adjoining owner fails to respond in writing within 14 days of a valid party wall notice. Silence is NOT consent — it is statutorily treated as dissent, triggering full s10 surveyor appointment + Party Wall Award process. Building owner must appoint a surveyor on the adjoining owner's behalf if they still don't respond. Adds 4–10 weeks + £2,400–£9,000 surveyor costs to programme.

The statutory mechanism

Party Wall Act 1996 s5: 'If an owner on whom a notice has been served... does not serve a notice in reply within 14 days... a dispute shall be deemed to have arisen between the parties.' The architecture deliberately prevents silence from becoming consent — Parliament wanted active engagement, and treats non-response as opposition for procedural purposes. The deemed dissent then activates s10 dispute resolution: surveyor appointment by each owner (or jointly), Award production. Building owner cannot simply proceed because neighbour didn't reply — a dispute exists statutorily even though no actual disagreement may exist. Common scenarios: neighbour out of country, neighbour elderly + missed letter, notice served to old address, rental property where landlord doesn't share with tenant + tenant doesn't respond. Adjoining owner who 'meant to consent but didn't get round to it' is procedurally in dissent.

Building owner response to deemed dissent

Where adjoining owner has not appointed a surveyor within 10 days of being requested (s10(4)(b) Act), the building owner may appoint a surveyor on the adjoining owner's behalf. This appointed-on-behalf surveyor acts independently — they are not the adjoining owner's representative, but a statutorily-appointed neutral expert with the same role + duties as any party wall surveyor. They will inspect the adjoining property if access can be obtained (s8 14-day access notice), prepare a Schedule of Condition, and negotiate the Award with the building owner's appointed surveyor. Process: (1) wait 14 days from notice for response; (2) write to adjoining owner requiring appointment of surveyor within 10 days; (3) if no appointment, appoint surveyor on their behalf (FPWS or RICS senior member preferred); (4) surveyor proceeds with Award process. Building owner pays all surveyor costs (s10(13)). Access to adjoining property: surveyor will serve s8 notice for 14-day access for SoC; if refused, Award can be made on best-evidence basis (external photos + drawings + lesser SoC) but building owner exposed to higher damage-claim risk.

Avoiding deemed dissent — pre-engagement strategy

Builderr practice for residential schemes: (1) door-knock conversation 6–8 weeks before notice — flag scope, drawings, neighbour rights; (2) confirm correct postal address + occupant (leaseholder, tenant, freeholder for flats — sometimes 3 separate parties); (3) follow up notice with phone call or 2nd door-knock at day 7 — confirm receipt + offer to walk through; (4) where neighbour is non-resident landlord (common in London buy-to-let), find tenant + ask for forwarding of post + landlord contact; (5) where neighbour is elderly or vulnerable, suggest they speak with adult child or party wall surveyor at building owner's cost — removes barrier to engagement. Cost of pre-engagement (~6 hours building owner time) saves £3,000–£9,000 surveyor cost + 6–10 week delay where consent achievable. Where deemed dissent looks likely (neighbour absent, hostile, vulnerable + non-responsive), build the Award timeline into programme from outset — don't expect to recover later. For flats with multi-let buildings: 3–6 adjoining owners (flat above, flat below, flat beside × multiple) all needing notice — programme 12–16 weeks minimum for full deemed-dissent process across all parties.