Log construction – rotting or deteriorating logs

Causes

Logs remaining wet due to ground moisture, vegetation in close proximity or excessive rain wetting

Cracks/checks in the logs

Poorly sealed windows and doors

Listed under: Exterior, timber and wood-based, timber, cladding, walls, moisture, durability, rot, wall cladding, log construction

Cause

Logs remaining wet due to ground moisture, vegetation in close proximity or excessive rain wetting

Repair

  • a very basic way to test for rot or how deep the rot goes is to prod the logs with a screwdriver
  • before any repairs can be undertaken you will need to determine and fix the cause of the wetness. If heavy nearby planting is at fault, cut back the heavy planting and overhanging trees or take the plants or trees out and replace with something lower growing. If gardens have been built up against the logs, remove the soil to the original ground height. Ensure that the ground around the building allows rainwater to flow away from the building. If there is a fault with the guttering, repair or replace it
  • seek expert help for replacing or repairing rotting/deteriorating logs – this is not a job for the average DIYer. It should ideally be undertaken by the company that built the house – many of the log buildings in New Zealand are the products of specialist companies that have developed their own proprietary log construction systems
  • once repairs have been completed, consider a coating for the logs. Many log home manufacturers use and/or recommend a protective oil or stain. How often this will need to be reapplied depends on the preparation of the logs, the level of exposure the logs get to rain, salt, UV light etc. and the product being used but can typically range from every 2–5 years. The logs should be cleaned and allowed to dry completely before the oil or stain is applied. Follow the preparation and application recommendations of the coating product manufacturer
  • there is a Log Building Association of New Zealand that has some information on its website

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Cause

Cracks/checks in the logs

Repair

  • where rot is found, follow the advice in the first repair above
  • checks (cracks where the wood fibres in a log have separated) can hold water for extended periods and increase the risk of rot if they are upward facing. Cracks or checks from around 5 mm wide should be filled. Larger cracks, for example of finger width, should have a backing rod or foam inserted first and then sealant inserted over that. Any filler/sealant used must have elastic and UV-protection properties – ask a log construction company for recommended products. Do not use general purpose fillers or sealants

 

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Cause

Poorly sealed windows and doors

Repair

  • poorly sealed windows and doors have been one cause of leaky homes in conventional construction, and they are a risk with log homes too, particularly where cracks in the log can transport water behind the seal. Contact the company that built the home originally if you think this is the cause of rot

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