Fibrous Plaster

Up to around late 1960s, this type of plasterboard with ‘horse hair’ and similar fibre mixed into the plaster was commonly used for wall and ceiling linings along with decorative cornices, ceiling roses and other adornments.  When exposed to moisture such as a roof leak or due to heat build-up in ceiling voids, these ceiling linings over time can distort and in doing so, some of the plaster straps traditionally used to affix the plaster board to the ceiling joists or timber battens in the void can pull away or loosen.  Physical interference with these plaster straps such as walking on the same can also cause a weakening and this can transfer a load onto other fibrous plaster straps holding up the ceiling linings and over time these plaster straps can give way as they are no longer able to hold the weight of the plaster board.  

Sagging can usually be detected from inside the house but often with white paint cover this unevenness can be disguised.  There have been reports that in extreme cases where fixings have been compromised over a period of time, parts or all of a fibrous plaster ceiling can collapse without warning as this material is much heavier than Gyprock plasterboard commonly used since the 1970s and unlike Gyprock, which should be both nailed/screwed and adhered in place, fibrous plaster is secured only by way of fibrous plaster straps lapping over the ceiling joists.  

Where it is known that there is fibrous plaster material in service at a property, and despite the fact there may have been no visually accessible areas of detachment or sagging, or other defect like paint flaking etc, it cannot be excluded as a possibility for any houses that have this material in place, as often it can be concealed by insulation or accessibility factors.  Because of the difficulty this product can have in relation to various areas, i.e. restoration and rectification, we strongly advise that you seek immediate advice of a suitably qualified, licensed drywall plasterer about this material and in particular any impact or effect it may have on the property.

NB; Based on feedback received during our inspections over the years, the restoring this material, where it is obviously peeling etc, or where the material is deteriorated, can be extremely expensive.  In one instance to restore four rooms at a property in Karana Downs the charge was around $30,000.

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