Chemical Delignification Treatment

Chemical delignification treatment is relatively new, with Powerdrive Roofing providing the only recognized treatment for chemical delignification Australia-wide. Powerdrive Roofing’s delignification treatment was first introduced in early 2006 but has gone through several refinements since and obtained an Australian patent in 2020. Up until 2022, our treatment was only available in Perth, but the calls were coming from all over Australia, so the team at Powerdrive Roofing has made a move nationally.

Chemical Delignification Treatment Cost

We will first acknowledge the cost of the treatment, which is, in most cases, less than the cost of a full roof replacement. A roof replacement, including the replacement of the tiles, is the only other rectification for chemical delignification. The cost of chemical delignification treatment is around $25 – $37. This will vary due to the severity of the delignification, whether it is isolated to battens or has progressed to other roof frame members also.

Replacing Roof Tile Battens

It is important to note that the roof tile battens alone cannot be replaced. The tiles cannot be reused as the chemical delignification starts from the Terracotta roof tiles themselves. Terracotta roof tiles become porous and once this happens, the salts and other chemicals found in the tiles are leached into the timber via and points of contact, such as the roof tile lugs that secure the tile to the back of the batten. Without changing the tiles, the process will continue with whatever new timbers are reintroduced.

Chemical Delignification Treatment By Powerdrive Roofing

With the Chemical delignification treatment provided by Powerdrive, Roof tile replacement is not required as the treatment itself stops the whole process.

Our process is essentially quite simple yet very effective.

  1. A quote will be sent subject to site inspection and based on the initial building or pest report that identified the issue.
  2. On acceptance of this quote, a subsequent inspection by Powerdrive Roofing staff may be required. This will depend on the body of the report and potentially other factors – spalling tiles, major deflections, etc.
  3. The quote is finalised and chemical delignification treatment is booked.
  4. Day of treatment – Our team will arrive on-site and power will be switched off – (Please make sure all computers are off and all perishables are tended to prior to our arrival).
  5. Roof tiles will be removed in different locations around the roof. The customer is asked to have at least five spare tiles on site in case of accidental damage.
  6. Entry to the roof void will be either via a manhole or drop-in through the roof if required.
  7. All battens will be scraped back and prepared for the application of the chemical delignification treatment (please note, some lower courses may not be physically reachable for scraping, but they will still have the chemical applied.
  8. Any tiles identified to be a concern for leakage will be marked with a strap sticking through the overlap. This way, they are able to be found easily and changed from above at a later date.
  9. Powerdrive Roofing’s chemical treatment will then be applied to all battens and other affected timbers.
  10. Power will be switched back on and previously removed tiles replaced (we do not change tiles identified when prepping for treatment of chemical delignification).

Chemical Delignification is a Major Structural Defect

Chemical delignification is generally identified when conducting a pre-purchase inspection prior to the sale of a home. In this case, chemical delignification will be identified as a major structural defect in material deterioration. The AS4349.1 definition of a major defect includes the continued deterioration of the property.

 It is worth noting that the continued deterioration is not limited to the loss of tensile and compressive strength or the timber members. It also relates to the terracotta tiles above, which are broken down due to the moisture and salts that are being leached out of them.

There are also tile-to-batten connections. These are generally wire ties or nails. On older homes with wire ties, it is obvious see the corrosion caused by excessive moisture and salts.

The batten to rafter connections, generally nails which, like the battens and rafters, are classified as a structural element. These connections are affected as the lignin breaks down. It weakens the grip that the mechanical anchor has to fix the two members together.

Delignification is a Timber Pest

On a timber pest inspection (not related to pre-purchase), it is identified as a structural timber pest, not unlike termites. Chemical delignification is an infestation of sorts, the chemical breakdown of the lignin that impacts the structural integrity of the timber.

Lignin is what provides the tensile and compressive strength of any timber. Once this is compromised, it becomes a matter of treatment at the earliest possible stages to prevent any further loss of integrity.

Our chemical delignification treatment is the easiest and best solution to timber-destroying pest.

Is Linseed Oil A Treatment For Chemical Delignification

Some inspectors are indicating that linseed oil can be used as a treatment. Please DO NOT USE LINSEED OIL – linseed oil is well known to spontaneously combust, meaning that using linseed oil in your roof void is actually adding a potentially deadly situation to an issue that is easily rectified by Powerdrive Roofing. See video below

Linseed oil is also the worst waterproofing sealant on the market in terms of oil sealants. Add this to the fact that it does not stop the delignification process at all. The salts and moisture will continue to enter the timber and find their way soaking through to other members of the roof frame before pushing the dead lignin out.  See the image below;

Chemical Delignification In Rafters - Oil Treatment
Battens Have Been Oiled and Chemical Delignification Has Absorbed Through To The Rafters

Chemical Delignification and Paint

Other inspectors will advise that paint can be used to seal and prevent further deterioration of the timber. Again, this is not the case, as chemical delignification is not a surface issue. Instead, it is moisture drawn through deep into the timber and then forces the dead lignin to the surface. If the surface is painted, it will simply push through the paint and continue to form. See the images below;

Chemical Delignification Behind Paint Being Revealed
Chemical Delignification Found Behind Sealed Painted Timber

The only way to fix chemical delignification without a full roof replacement is to contact us today. Our chemical delignification treatment is the only patent-protected treatment for chemical delignification on the Australian market.

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