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Asbestos cement sandwich panels

Description

Sandwich panel developed and marketed in mid-20th Century by Wunderlich Ltd as Insulabestos, an inner core of insulating material surfaced with a Durabestos AC sheet on both faces.

The insulating material has not been identified but may be Masonite mixed with other materials. Wunderlich advertising only details the core as insulating fibre.

Marketed for ceilings, walls, doors and partitions in dwellings, shops, factories and offices as a sound retardant.

Hardies produced and advertised a sandwich panel system from the late 1960s consisting of two AC sheet products at the time as the outside panels – Hardiflex and Versilux, with an unnamed insulating core. Interestingly, these both became cellulose based fibre cement boards when Hardies ceased using asbestos in the 1980s.

Other sandwich panel systems with AC sheeting were used in modular (kit) homes in late 1970s-early 1980s, incorporating a core of polystyrene. These panels may have been independently used in other structures.

See Modular homes.

Brands/products
  • Insulabestos
  • Incorporating Hardiflex and Versilux
Years of production/use
  • Insulabestos: 1930s – 1950s
  • Other systems: Late 1960s – early 1980s
Residential uses
  • Ceiling and walling, exterior and interior
  • Kit homes
Industrial uses
  • Ceiling and walling, possibly used as fire rating ceiling above suspended tile systems
  • Government buildings and infrastructure
Be aware

View from interior side will not identify as sandwich panel – may require check of panel depth

Low density board (LDB)

Description

Also known as asbestos insulating board (AIB). Sheeting of similar visual surface appearance to asbestos cement sheeting. Used for walls and ceilings between 1950s-70s. Solid or perforated. Produced in 4.5mm, 6.5mm, 9mm and 12mm thicknesses. Unpainted, it tends to have a slightly blue-grey appearance as opposed to a more whitish grey appearance of regular AC sheeting. 

Marketed as non-combustible light weight interior lining for insulation under hot water tanks, heaters, ironing boards, behind stoves and cupboard linings.

Often made from amosite asbestos mixed with chrysotile asbestos and calcium silicate plaster as the binder. Lighter material, more advantageous to logistics and installation. Amosite was thought to have better fire resistance qualities.

Rear side of LDB is usually dimpled. Edging often bevelled so sheet joints will appear to have V-shaped valley when butted together. Squared edges (stone cut) also produced.

It is a structurally softer material and easily dented from a slight impression with a tool.

Used in ceiling tiles, solid and perforated for acoustic qualities. Advantageous for noisy high human traffic areas such as schools. See ceiling tiles information page.

Hardie’s Asbestolux was advertised as ‘…protection from fire, sound, heat, cold and condensation.’

CSR/Wunderlich Bevelux was advertised as: ‘…will not shatter when exposed to intense heat.’

Often favoured in climates with high humidity (northern Australia), as its structure was more moisture resistant. 

Brands/products
  • Asbestolux
  • Duralux (Wunderlich Qld)

    • Duralux is also a current brand name for a fibre board product manufactured in Australia with no asbestos

  • Bevelux
  • F.R. Board

Since May 2021, LDB is classified as friable in all circumstances under Queensland law.

Years of production/use

1950s – 1970s

Residential uses
  • Interior walling and ceiling of houses and apartments. Also perforated sheets used in workshops as tool peg boards.
  • Soffit panels under eaves.
  • Generally ceilings in multi-storey buildings.
  • Floor insulation beneath hot tanks, heaters. Under floor insulation above lower floor garages. Lining of cupboards and behind stoves.
Industrial uses
  • Factories, workshops, shops (particularly as ceilings in flat-roofed rows of), community and government buildings (including military), schools, food processing plants, laundries, textile plants, kitchens, laboratories, bakeries, hospitals, interior of aircraft hangars, offices etc.
  • Underside of mezzanine offices or outer facing walls between factory and office spaces
  • Used as ‘fillets’ for fire rated structures – see: AC tween panels (Fillets) for fire rated ceilings information page.
  • Draught fire curtains, industrial ovens/driers, high temp trunking and ducting, heat shields, linings for foundry pallets, moulding boxes and electrical circuit boxes.
Be aware

LDB is easily damaged. Tears like cardboard. Estimated asbestos content is up to 70%.

Safe Work Australia Guide: How to identify and handle low density asbestos fibre board 

Once painted, LDB sheeting with bevelled edges may have a Masonite-type appearance.

Often used as an insulation material in preference to Millboard, particularly in humid zones.

Asbestos cement flat sheeting – interior

Description

Surface appearance generally like plasterboard.
Sheet jointing may be covered with obtrusive AC cover moulding, wooden battens, or ‘Anaglypta’ paper strips, before painting. Shear point nails used for fixing in place – flat heads may be visible.

Villaboard was a water resistant AC sheeting for interior linings behind material such as wall tiles, behind/on top of cupboards and as a wallboard above decorative lining height within bathrooms. Produced with recessed and square edges. Non-ACM product with same name available today.

Duracast (1930s) had a rough cast appearance.

Flat AC sheeting used ad-hoc for providing vertical heat protection behind stoves and heating appliances, as well as shelving.

Years of production/use

Prior to 1990

Brands/products
  • Fibrolite
  • Fibrock
  • Tasbestos
  • Hardiflex
  • Villaboard
  • Durabestos
  • Asbestolite
  • Wunderflex
  • Versilux
  • Flexboard
  • Endurite
  • Duracast
Residential uses
  • Houses and other buildings on site.
Industrial uses
  • Foundries, factories, warehouses, substations, workshops, hospitals, community and government buildings.
  • Communal washrooms and changerooms
Be aware

Consider the age of the building. Unless assessed by a professional, 9mm and 12mm thick panels can be mistaken for plasterboard, particularly if painted or wallpapered.

When cutting, drilling or demolishing:

  • Cut edges may expose fibres.
  • Original AC sheeting may be left in place for additional insulation, with non-ACM panels or tiles attached over the top.
  • May have been intentionally used as an underlining sheet for ceramic tiling.
  • May have been used as an underlay for flooring such as tiles, linoleum or asbestos containing vinyl flooring.

Asbestos cement walls with non-asbestos rendered covering

Description

AC exterior wall panels rendered after construction to alter appearance and/or encapsulate ACM.

May have occurred at time of construction or in later years.

May have been applied by hand (trowel) or a sprayed on texture coating. Some portable accommodation hire companies had their transportable buildings covered with a non-ACM spray coating en masse during the 1970s.

Requires bulk core sampling to test or observance of damage around edging to identify AC sheeting/visible fibrous material underneath. 

This is not a reference to Hardie’s Stucco moulded AC panelling – refer AC siding sheets information page.

James Hardie instructions circa 1920s-30s provided guidance on the application of a ‘roughcast’ coating over newly installed Fibrolite exterior sheeting:

1.       Erect sheets with reverse side exposed.

2.       Cover all joints, both horizontal and/or perpendicular, with a narrow strip of ½ in. mesh wire netting.

3.       Thoroughly saturate the sheets after erection with water.

4.       Paint the exposed surface of the sheets with one good coat of neat cement and water.

5.       After thoroughly mixing the roughcast, composed of two parts of cement, one part of clean sand, and four parts of coke breeze (by measure), apply in the usual way.

Brands/products
  • n/a
Years of production/use

Any time after construction

Residential uses
  • External walls
Industrial uses
  • External walls
  • Transportable offices and accommodation
Be aware

Visual identifiers may require closer examination of edging and other structural ACM (gables/battens, windows, architraves).

Older portable buildings manufactured in late 1960s-1970s with an apparent spray on coating may contain ACM.

Galbestos – asbestos coated steel

Description

Imported product.

Galbestos was a steel core panel coated in asbestos bituminous felt and colour coated. 

Various corrugated panel styles were available.

Mainly used in industrial/commercial applications for roofing, curtain walling and fencing.

Brands/products
  • H.H.Robertson (USA)
  • Galbestos
Years of production/use

1948 – late 1970s

Residential uses

Fencing

Industrial uses

External walls and roofs on factories, warehouses and attached offices. Plant buildings such as power stations.

Be aware

Galbestos ACM coating can be affected by decades of weathering whereby the sealing coat cracks and shrinks, exposing asbestos fibres. Damage can also occur when the steel underneath degrades through rust.

Imitation brick asbestos cement cladding

Description

Asbestos cement sheeting with moulded brick pattern on outside.  Also known as faux bricks.

Produced in varying colours and brick styles. Smooth and textured. Some rough textured bricks will have repeated texture patterns.

The moulded ‘brick’ material may or may not contain asbestos, but was usually attached to AC sheet backing.

May have been used to clad existing AC sheeting for change of façade.  Often by attaching wooden battens over existing and then fake brick sheet nailed to battens.

Refer below for identification hints.

Brands/products

Not yet identified

Years of production/use

Prior to 1990

Residential uses
  • External walls
  • Internal feature walls
Industrial uses
  • External walls
  • Internal feature walls
Be aware

Grout or adhesive may become degraded over time allowing sections to become detached and damage to occur with debris in same location.

Asbestos containing adhesive may have been used for attaching to structure.

Identification hints

Asbestos cement battens / cement strapping / cover strips

Description

Can be a moulded AC product for purpose, or sometimes just a cut piece of AC sheeting.  

Used to cover the join between two cement sheet panels on eaves, walls and ceilings, window and door architraves, as well as for decorative patterns.

Flat or D mould (curved exposed surface)

Interior and exterior application.

Tilux branded laminated skirting and moulded cover strips also marketed circa 1940s in two patterned colours, to match sheeting.

Brands/products
  • Fibrolite
  • Tasbestos
  • Flexboard
  • Fibrock
  • Asbestolite
  • Durabestos
Years of production/use

Prior to 1990

Residential uses

Houses, garages, sheds and external toilets

Industrial uses

Sheds, offices, factories, warehouses, substations, workshops, pubs, government and community buildings.

Be aware

Cut sheeting adapted by builder may have exposed fibres on edges if not sealed.

Weathered or damaged stripping may expose unsealed sheeting , increasing the risk of further damage and asbestos friability.

Asbestos cement spandrel panels

Description

Panelling within window frame, usually framed from floor to near ceiling, or on multi-level buildings to cover external surface of tween flooring structures.

Years of production/use

Prior to 1990

Brands/products
  • Fibrolite
  • Durabestos
  • Colorbord
  • Wunderflex
  • Tasbestos
  • Fibrock

Can be panel cut from any AC moulded sheeting design.

Residential uses

Housing, multi-storey apartments

Industrial uses

Commercial buildings and offices

Be aware

Windowsill mouldings and caulking may also contain asbestos if original fittings.

Flat coloured asbestos cement panels

Description

Coloured AC sheeting smoothed surfaced on both faces, with the colour appearing on one face only. Flat and curved sheets.

Used for curtain walling, spandrel panels and applied as double sheets back to back, such as in external balustrades.

Asbestos Products Ltd produced a coloured AC sheet named Artbestos in the 1930s for interior/exterior use. Colours listed as: Grove green, Sky blue, Stucco brown, Ochre, Shell pink, Cream and Buff.

Colorbord was a James Hardie product from 1960. Coloured AC sheeting market dominated by James Hardie. 

Colorbord range of colours and market names varied slightly from 1960s to end of production in mid 1980s.

Brands/products
  • Colorbord

    • Note: Not Colorboard –  a BurnieBoard wood product

  • Artbestos
Years of production/use

Prior to 1990

Residential uses

Houses and apartment blocks – spandrel panels on balustrades and curtain walls

Industrial uses

Government buildings and schools, office blocks, motels, all industrial building applications – advertised as interesting infill variation for construction of schools, shopping centres as well as interior partitions in offices and factories.

 

Be aware

Some approaches to commercial remediation may have incorporated leaving in situ and covering with non-ACM materials.

Asbestos cement curved sheeting – external

Description

Curved flat sheeting. Advertised by Wunderlich more than Hardie’s. More often in mid-20th Century built residences as a feature of front façade.

Required moulded AC curved battens/cover strips for fixing.

Years of production/use

Mainly 1930s-1940s

Brands/products
  • Durabestos
  • Fibrolite
Residential uses

Houses

Industrial uses

Small commercial offices

Be aware

Painted curved AC sheeting may have appearance of rendered material.

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Phone: 1300 326 148

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