Grand Designs Australia

How to check timber stumps

Re-stumping - also known as re-blocking in Victoria- is the process whereby timber stumps that support a house are replaced due to being rotted and defective.

In some States, houses with timber floors built more than 30 years ago will mostly have their floors supported on timber stumps. The life expectancy of these stumps can vary from 20 to more than 80 years depending on the type of timber, soil conditions and external influences such as surface drainage and insect attack.

Archicentre found that up to 30% of timber stumped homes investigated needed immediate re-stumping either partially or completely.

Some signs that you might need to restump your home

• Uneven floors. In brick houses, where the bearers are supported on brick piers at the ends, rotten stumps will cause a sinking or 'trampoline' effect in the centre of rooms. Contrary to popular belief, the condition of stumps in weatherboard homes cannot be definitely confirmed by jumping on the floors.
• If the stumps have rotted evenly, the floors may appear firm and flat, however they will almost always slope away from brick fire-places. Use a spirit or dumpy level to see exactly how much they're sloping.
• Crooked door or window frames.
• Large cracks in plaster.

It should be remembered that these symptoms are only evident after the stumps have failed completely. A house may appear quite sound during a visual inspection, but could start to sink shortly afterwards if the stumps have just reached failure point.

How to check your stumps

Before undertaking any renovation work on older homes, it is essential to check the condition of the stumps. Many people have watched in dismay as newly completed alterations have been virtually destroyed as the structure subsides.

• The condition of stumps can be ascertained by scratching away 50mm to 100mm of soil from the base of the worst stump to check its condition below the ground.
• Stumps deteriorate most quickly in wet conditions and generally the worst stumps are those with the highest and most prominent water marks.
• If only a few appear faulty, individual replacement may be the best solution. However, if more than 20% to 30% of stumps show serious deterioration, total re-stumping should be considered.
• In Victoria, bulky sub-floor heating ducts can often hamper proper investigation of stumps and supporting walls. Walls and stumps are sometimes removed when ducts are installed, without it being obvious, leading to structural problems.If you are contemplating installing central heating, the possibility of this happening to you should be considered.

Our guide to restumping explains the next steps of the process - how to select new stumps and choose the right contractor to do the job.

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