Deleterious MaterialsJo Williams MRICS

Partner at Sanderson Weatherall

Deleterious Materials

Agenda

• What is a deleterious material

• Historic context

• Some examples and misconceptions

• What to watch out for in the future

Deleterious Materials

What is a deleterious material?

It means different things to different people

A Lawyer will say:A prohibited material - Blacklisted

The HSE will say:A material that has the potential to cause harm

Building Control will say:A material that’s not used in accordance with Regulations

Deleterious Materials

A Building Surveying definition is:

Deleterious materials are those materials which are capable of

causing damage or harm to the individual, the environment or to

buildings and infrastructure

Deleterious Materials

The Historical Context

Blacklists in legal documents such as leases or development agreements

Once a material has had negative publicity it was blanket blacklisted

Kneejerk reaction

Minimal intelligent consideration on the correct use of the material

Deleterious Materials

Some Examples of Deleterious Materials

• Can you recognise them?

• Do you know how to report on them?

• What do you specify repair?

Deleterious Materials

Asbestos or asbestos containing products

Deleterious Materials

High Alumina cement or concrete

Pre-stressed AND structural

1950’s to 1970’s then banned

Calcium aluminate

Structural collapse

Poor detailing

Water ingress and chemical changePhoto Credit: Sandberg

Deleterious Materials

Woodwool Slab

As permanent formwork• Voids• Compaction• Water degradation

As insulation materials• Water degradation

Stramit Board or StrawboardPaper lining

Deleterious Materials

MMMF

Materials which are generally composed of mineral fibres either man made or naturally occurring which have a diameter of 3 microns or less and a length of 200 microns or less which contain any fibres not sealed or otherwise stabilized to ensure that fibre migration is prevented

• Precautions on installation

• Saturation/detailing

Deleterious Materials

Mundic Blocks

Marine or beach dredged aggregates

1900’s – 1950’s but some up to 1960’s

Mostly residential in South West

Loss of strength

Mortgagability

InsurabilityPhoto Credit: RICS.org

Deleterious Materials

Black Ash Mortar

Waste product from power stations

Corrosive to mild steel wall ties

Can contain un-fired particles

Mortgagability

Insurability

Photo Credit: DIYNot.com

Deleterious Materials

Trussed rafters and truss plate connectors

EN IOS 1461 Hot dipped galvanising

1960’s design, technology and workmanship

1976 Roof collapse at Birkenhead school sports hall

Moisture changes in roofs can change life expectancy of galvanised plates

Deleterious Materials

Polyisocyanurate foam (PIR)

Used in Grenfell Tower

Hydrogen Cyanide

PIR and PUR flame retardance tests small scale only

Post-Grenfell mock-up failed fire tests

Photo Credit: Sealle - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=48128386

Deleterious Materials

Polystyrene and Extruded Polystyrene

Good thermal properties

Not water or vapour resistant

Gives off carbon dioxide and water when burnt

Does not Biodegrade and limited re-use

More uses outside the building industry

Photo Credit: InsulationExpress

Deleterious Materials

Urea Formaldehyde

Insulation blown into cavities

Binder for particle boards, mdf, plywood, laminates

Also used in clothing and textiles

Health issues as breaks down

Photo Credit:TombKonrad

Deleterious Materials

Other Examples of Deleterious Materials

• Lead or any materials containing lead which may be ingested, inhaled or absorbed

• Lightweight or air entrained concrete bricks or blocks

• Vermiculite plaster

• All tropical rain forest hardwoods

• Any product which contains or uses Montreal listed CFC gases in its manufacture

Deleterious Materials

• Marine dredged aggregates

• Concrete or mortar additives containing calcium chloride

• Calcium silicate bricks or tiles

• Slipbricks

• Light bulbs, batteries, Building Services disposals

Deleterious Materials

What to watch out for in the future

• Mild steel welding and associated fumes

• MDF (92% wood and 8% urea formaldehyde resins)

• Breathable felts and geotextiles

• Expanding foam fire stopping

• Oil-based products

Deleterious Materials

What do Building Surveyors need to do

• Understand the material, not just the marketing material• Think about how you’re specifying the material• Use manufacturers guidance• Use published research and guidance

RICS Practice Notes and CodesBRE DigestsBBA CertificatesBritish standards and CE standards Building Regulations – Materials and WorkmanshipBCO ‘Good Practice in Selecting Construction Materials’

• Common Sense

sw.co.uk

Any Questions?