Party Walls- Engineering implications

Simon Pole BSc C Eng FIStructE MICE MRICS

A brief overview in 30 minutes.

Context- for basement developments.

Summary of problems.

Reasons for problems.

What we might do about these problems.

www.pole.co.uk

Why a party wall talk?

Subterranean boom, high property values, pressure on land etc

Suburbia being consumed by basements; with generic designs, no soil/ ground water investigations, standard drawings and calcs etc.

Huge public anxiety, generally and to neighbours.

Local Authorities turning to Structural Engineers to address Town Planning issues

Party Wall Surveyors turning to Structural Engineers to advise. This system is in chaos, not working and court cases, PI claims loom.

We as designers and engineers are both the cause of the problem (!) and the solution (!)

Complex solutions

Special foundations- piles, rafts

INTEGRAL foundation system entirely owned by BO

Load ‘distributed’ into BO substructure.

Party wall relies on “BO” building remaining in place.

Distributing load 2

OK OK ish- ‘Special’ but

no problem!

Distributing load 1

Pressure for designers to maximise space, including below ground.

Modern construction techniques allow sophisticated engineering solutions which when built well are safe….

but do not accord with party wall best practice, ie do not look

after the neighbours’ interests.

Problems include;

Compromise the Adjoining owners interests- short and long term.

losses and compensation claims.

Put design engineers and party wall surveyors at risk if they do not make their clients/ appointing owners aware of risks.

Prevent/ restrict future development.

Create dangers to subsequent dismantling (removal of raft slab).

Construction methods causing predictable damage when alternatives available. “Enabling” spirit of Act gone too far.

Summary of problems ;

Don’t shoot the messenger…..please !

The problems are NOT about poor engineering design

It is about the law of property ownership and the rights of the neighbour, whose wall and land is about to be built upon…………..(if they consent, assuming special foundations involved).

It is about legal and neighbourly “best practice” not engineering “best practice”.

Party Walls etc Act 1996-

A very quick recap…..

Applies to England and Wales only Replaces 1939 London Building Act (Part 6, ss 44-59), derived from 1930, 1895 Act. Essentially applying long understood principles applied in Greater London to the rest of England and Wales. Antecedents; Post fire of London 1667 Act for rebuilding City of London, subsequent centuries developed 1894, 1930 Act with emphasis on forming new party walls and their repair.

Parties involved-

Developers/ clients (Building Owners) Neighbours (Adjoining owners) Designers particularly engineers Construction team Party Wall Surveyors- As agreed (AS)

As Building owners surveyor (BOS) As Adjoining owners surveyor (AOS) “Advising Engineers” Advising the AS or usually AOS Local Authorities Building control- Health and safety only Town Planning- neighbourly issues

When does the PW Act apply

Party Wall Act arises when; Repairing, altering a party wall (eg removing chimney breasts) Raising, lowering a wall Underpinning- mass concrete- permitted. - RC.- Special foundation (express consent required)

Excavation below PW foundation within 3m Excavation below the 45 degree line of foundation/wall within 6m New walls built on line of junction ie boundaries. Others scenarios, with less engineering implications beyond scope here.

Loss , damage and compensation

Extract from Party wall etc Act 1996

Any type of loss, not just physical and consequential of the physical building work eg losses created by limitations in the design of the developers work ;

eg loss of amenity, diminution in value/ more difficult to sell, appeal, less development potential, unreasonably difficult for the AO to subsequently enjoy, etc.

Prejudicing AO future rights (a future loss). Eg degree of inconvenience and complexity to allow subsequent use of party wall and foundations- eg to be able to add load or further underpin without unreasonable measures.

Eg underpinning a piled slab or stiff raft.

What is loss and damage in law?

Design “out” Loss, Damage +Compensation issues where possible. Keep party wall foundations separate from developers substructure. See RBKC December 2012 guide by Alan Baxter

Neighbour (Adjoining Owner) to appoint an experienced Party Wall Surveyor (AOS) who understands the law of loss and damage and asks their advising engineer to check same. They

cannot assess the limitations concealed within the design assumptions without engineering advice.

AOS to appoint an Advising Engineer who understands the PW Act including the loss and damage issues in addition to normal checks for quality and method statements etc.

AO can simply say NO to Special Foundations if in doubt.

How to avoid loss, damage and compensation

Basements are complicated because they significantly change the traditional support of shallow foundations if integral with party wall.

‘Special Foundations’ are special’ (complex) because of the consequences of ‘distributing’ load on the BO land, not just a physical nuisance on AO land.

Current problems include loss and damage potential which is going undetected by PWS and engineers (designers and advising PWS).

Practical issues include, future redundancy (limited load capacity) and dangers when dismantling and adapting buildings.

Significant claims against building owners, designers and party wall surveyors are looming over us all if we do not change current trends.

Summary 1

Party wall surveyors are finding it difficult to administer the Party Wall etc Act 1996 with current engineering solutions.

It is for the “advising engineer” to the AOS to point out the loss and damage issues associated with a design proposal. (PWS to ask)

Ideally the surveyors would steer the design towards one which does not cause these issues.

In party wall terms the “best practice” solution is to keep party structures separate from a developers other foundation systems and avoid special foundations.

It is time we assessed the longer term interests of our building stock and the interests of reluctant neighbours. The “enabling” spirit of the PW Act has gone too far and irretrievable damage is occurring.

Summary 2

Hopes for the future….

Section 7 of PW Act; Loss damage and compensation to be more widely understood, particularly amongst PWS. Role of “advising engineer” to be understood, re loss and damage so we can advise PWS and the Adjoining Owner (neighbour) on that which PWS cannot assess alone (that is why they appoint engineers!)

Set up working Party with RICS/ISE/ICE to achieve better understanding across professions. I Struct E to issue technical guidance to industry. It is time we were more proactive in this important area where engineering is key and not leave it to the Surveyors to muddle through without help. Try and keep PW foundations separate from rest of the developers substructure. Remember the Adjoining Owner can simply say “no thank” you to Special Foundations, without reason…or issue a counter notice with their requirements to make stronger and deeper but to pay for same.

www.pole.co.uk

The End ! or hopefully only the beginning !

Thanks to all our professional colleagues, friends and clients

for kind permission to use the photographs, particularly

messrs Abbey Pynford and Alan Baxter/ RBKC.