Technical information

Use this page to find technical information and resources on how to maintain heritage items.

You can download or order a wide variety of technical sheets. We also occasionally post recommendations from conservation experts on technical and maintenance issues.

Technical reports

Suspended awnings in commercial areas: structural assessment of risks in Mudgee Shire

By Bill Jordan & Associates Pty Ltd 2003

Heritage Consultant and Consulting Engineer, Bill Jordan, has made the following report on suspended awnings available. It will be of particular interest to local engineers. Note that the report should not be used for assessments outside the Mudgee Shire without Bill Jordan's permission. He can be contacted by email at

Download the report: Suspended awnings in commercial areas

Technical notes

Technical note: commercial limewashes

How suitable are the new commercial limewashes for old masonry walls? Download the technical note: Commercial limewashes 

Technical note: repointing mortar joints - some important points

Some practical guidance on repointing mortar joints in brick and stone buildings. Download the technical note:
Repointing mortar joints - some important points

Technical note: treating biological growths on historic masonry

Disfiguring stains on materials like stone and render are often caused by growths of micro-organisms such as algae, bacteria, fungi, moulds and lichens. Cleaning these biological growths requires a different approach to that used for dirt, soot or other soiling materials. Download the technical note:
Treating biological growths on historic masonry 

Technical note: cracking of buildings due to shrink/swell in clay soils

The purpose of this technical note is to provide basic guidance to the owners and custodians of heritage buildings which are suffering cracking due to shrink and swell in clay soils. There are many potential causes for cracking and approaches to mitigating the problem. Specialist engineering and geotechnical advice is usually necessary. Download the technical note: Cracking of buildings due to shrink/swell 

Technical note: drought related cracking of buildings

Property owners are often concerned when cracks appear in their buildings. The following note provides some advice to assist owners with understanding the causes and provides some direction for assistance with the problem. Download the technical note: Drought related cracking of buildings 

Technical note: why sodium bicarbonate blasting should not be used on historic buildings

Need to remove paint from historic buildings? Download the technical note on why Sodium bicarbonate blasting should not be used. 

Questions and answers

There is lichen growing on the terracotta roof tiles of our 1927 church. Is cleaning recommended?

Response: David West, materials scientist (and former Technical Advisory Group member)

Lichen, as an organism, is a symbiotic (mutually dependent) combination of algae and fungus. The fungus provides the structure within which the algae can survive. The algae photosynthesizes to provide food for the fungus.

There is research into the effect of lichen on porous building materials. I am not up to date on the findings, but believe that the academics usually find there to be some minor deleterious effects. These relate to the effect of organic acids by products of the lichen) and the increased water retention in the porous building materials. Furthermore, the penetration of fungal strands into the pores of the material can cause disruption of the surface.

The maximum damage, however, seems to be caused by the process of removing the lichen. Consequently, the best outcome is usually to leave the lichen alone unless it is interfering with the roof drainage.

Recommendation in most situations therefore is to leave the lichen as it is.

The marble headstones in our local (historical) cemetery have been cleaned with hydrochloric acid. Is there anyway I can do anything about the damage that must have occurred. The marble now feels very rough where before it was smooth.

Response: David Young, heritage consultant (and former Technical Advisory Group member) 

Unfortunately there is very little that can be done about the damage and in most cases doing nothing to the headstones will be the correct response. The rough surface will collect dirt faster than it did before and this may be a problem in some areas, particularly those with high levels of pollutants. Smoothing the surfaces to a honed finish is an option in circumstances where the rate of dirt and pollutant accumulation is too great, but this must be done with great care and should only be attempted by someone with specialised skills. The aim should not be to produce a polished finish as this will make it look too new, a honed finish (with a resinous lustre) should be acceptable. Many marble headstones have incised lead lettering and great care will be required not to loosen or further damage the leadwork. Depending on the condition of the headstone and how well it is fastened to its plinth, removal to a workshop may produce further damage: if it can not be honed in-situ, then doing nothing is the best response.

One thing that can be done is to inform and educate those responsible for the cemetery and those that undertook the acid cleaning. That way there's a chance that the next cemetery down the road won't suffer the same fate. For more information see the National Trust's Guidelines for Cemetery Conservation. 

Heritage Branch publications

Free publications on materials conservation available to download include:

The Maintenance Series is our principle resource for technical information on conservation. Most of the technical sheets can be downloaded for free from the Publications page. Topics include:

  • 1.1 Preparing a Maintenance Plan
  • 1.2 Documenting Maintenance and Repair
  • 1.3 Temporary Access
  • 2.1 Rising Damp
  • 2.3 The Need for Old Stone Buildings to Breathe
  • 3.1 Metalwork
  • 4.1 Corrugated Roofing
  • 4.2 Slating, Tiling and Roof Plumbing
  • 5.1 Wood Preservation
  • 5.2 Timber Repairs
  • 5.3 Patching Old Floorboards
  • 5.4 Repair of Tongue and Groove Floorboards
  • 6.2 Removing Paint from Old Buildings
  • 7.1 Plaster Finishes
  • 7.2 Paint Finishes
  • 7.3 Basic Limewash
  • 8.1 Fire and Heritage
  • 9.1 Heritage Gardens and Grounds

Another good reference if you are seeking material on the maintenance of old buildings for homeowners is A Stitch in Time; Maintenance Guide, a recent English publication. To purchase, check the list of technical pamphlets on the SPAB website.

How to find products and services

We have developed a directory of specialist products and suppliers to help those undertaking conservation work. Conservations products and services directory.