Frequently asked questions (FAQ)

Q: Is RotStop safe on Humans?
A: Yes. In its liquid form during injection it can cause irritation if splashed into your eyes. RotStop should not be consumed. When the walls dry the active Boron represents approximately 1.5% by weight of the timber – where it is safe from humans.

The World Health Trust classified boron as 6650ppm to skin irritation and is registered as a pesticide in most countries. This is far safer than other treatments used by builders eg CCA (Copper Chrome Arsenic H3.2) and Tributal Tin (LOSP H3.1) which are classified as 224ppm to organ failure and death.

Q: You say RotStop creates a toxic environment inside the wall. Does that leak out into the room?
A: No. The RotStop is absorbed into the timber framing and other absorbent materials within the wall eg linings and cladding. If excess water is present in the wall (eg from a leak which may be the cause of the rotting) what normally happens is the wall sweats and forms high humidity and condensation. This effect dissolves some boron and fungicides the RotStop introduced and this becomes toxic to the fungi and moulds – inside the wall – not outside the wall.

Q: Why do rot fungi grow in the timber framing in walls?
A: Because when wet timber is left wet it rots. Rot growth is dependent on whether the framing is untreated or undertreated (eg H1). Even treated timber can rot if wet long enough. Fungi require 5 things to enable growth:

Spores:- Spores must be present for germination to occur and growth to begin.
Water:- Water must be inside the timber framing (as moisture content – mc). Liquid water is required for germination to take place then as long as the relative humidity remains above 80% the wood stays wet and rot keeps growing.
Food:- Wood contains cellulose – it’s a building block. In some instances lignin is consumed as well.
Air:- Fungi are nitrogen fixers so need air – 80% of which is nitrogen.
Warmth:- Fungi like temperatures between 10 – 40 deg C. Rot growth can totally destroy juvenile untreated pine timber framing in a matter of a few months at 30% mc, 30 deg C.

Q: How does RotStop kill rot fungi?
A: RotStop taints the water and food sources. As the fungi consumes this food source, the boron (basically a salt) destroys the fungi digestion system which is fatal. It can be likened to humans drinking salt water where the salt in RotStop is 100 times greater than the salt concentration in the ocean.

Q: Does injection speed up absorption of RotStop treatment into framing?
A: Yes. Unlike other forms of onsite applied treatments like paint-on borons that simply lie on the surface, RotStop uses the timber fibres (or trachea) within the timber to absorb and spread the RotStop throughout the framing. Injecting RotStop directly into the trachea fibres becomes bound water (held within the cells) and as the trachea become overloaded the ongoing pressure forces RotStop into neighboring trachea.

Thus fibre absorbency and the spread of RotStop is sped up dramatically with increased pressure killing rot fungi within the timber. The patented injection system basically feeds RotStop directly into the sap pathways in the timber.


Q: What if our home leaks again in the future. Will RotStop still work?
A: Yes. RotStop is held within the trachea deep inside the timber and will keep working forever. RotStop is water soluble so whenever the wood framing becomes wetted it will again dissolve tainting both the food and water sources essential for fungi to germinate and grow. If the leak goes undetected for too long (remember your MONITOR house protection system will alert you to this) RotStop can leach out lowering its potency against killing rot fungi. RotStop can be re-injected during the 50 year life at any time so its not fatal to the building if RotStop concentrations fall – provided the leak is stopped no damage should be possible.

Q: How long does RotStop last?
A: Forever as long as it is not washed out by serious leaks – which is almost impossible throughout the cross section of wood.
Q: If RotStop injection is not 100% complete does it matter and will it mean parts of the timber are unprotected?
A: No it does not matter. The object of RotStop is to inject into (what we term) the leak pathways. Leaks allow unwanted water to enter behind the cladding and into the timber framing. When a homes deflection mechanism is breached, water can get behind the cladding and be transported via gravity and absorbency pathways to much larger areas than immediately below a leak. This also occurs with RotStop during injection. What is important is that if a leak occurs in the future, water will pass the RotStop injection points and dissolve some of the boron thus tainting the water as it spreads, killing all rot fungi in the process. We target and deposit concentrated RotStop in the leak pathways where it will be useful as the dwelling ages.

Q: Can RotStop fix already decayed timber?
A: No. During the injection and PROBE process many samples of timber are taken that assist in determining whether structural damage has been done to the home. Where we inject RotStop before significant decay and rot has occurred the timber can safely be left in place. In some instances timber may be so decayed and if it is at structural locations we recommend either Framedoctor Restore or replacement. We will advise this in the normal process.

Q: What areas of the building benefit most from RotStop?
A: All areas found to be affected by Rot Fungi and historical positions known for leaks and product failures.

Q: How long does RotStop Injection take?
A: Normally 2-3 days per area.

Q: Do I get a RotStop treatment warranty?
A: Yes.

Q: Does RotStop get verified by anyone?
A: Yes.

Q: Does Council get involved?
A: Yes. RotStop injection is a major improvement to your home so it needs to get onto the house LIM. This is done through the consent process or by raising an amendment if the consent is still open. Treatment is described by the Department of Building and Housing as a very important “compensatory factor” in controlling the effects of leaks and making a building more durable against decay fungi so the framing can last the required 50 years. It is therefore essential official records show that your home has RotStop treatment and when it was applied

Q: When RotStop is injected does it affect the moisture readings around the home?
A: Yes. RotStop injection process involves fully wetting the framing above fibre saturation levels (above 36%). The boron within RotStop increases electrical conductivity thus making moisture meters read higher moisture contents than actually present. We calculate what is termed “adjusted” mc once we have finished injection and as the building dries out. These become your new mc range of adjusted figures. This is accepted by council.

Q: Will RotStop injection damage my home?
A: Not structurally. To fully treat the framing RotStop injection involves wetting the timber and other materials it touches eg linings and cladding. When these materials wet out they can increase dimensionally and then when they dry small cracks not seen before to the naked eye increase in size until in some cases become visible. The framing is not damaged in any way – but some linings can crack and lining fixings become visible. These are similar to normal leak tell tale signs.

Q: Can RotStop be injected one room at a time so we can live in the home whilst the process continues?
A: Yes. RotStop is safe to humans but the process involves some disruption within rooms to protect furnishings and fittings. Some owners have found RotStop during injection has a sweet smell – but none have suggested it is unacceptable to live with. Once injected the smell disappears.

Q: What happens to the RotStop holes?
A: They can be stopped and painted or wall papered over after the walls have dried out. We hope to have small plastic caps within a few months so the walls can be left until budgets or repair programs provide for linings to be repaired.

Q: How does RotStop treatment compare to Building Standards treatment requirements?
A: Current standards have recently returned to pre 1987 treatment levels of 0.4% boron active equivalent. This means boron as a percentage by weight of timber is 0.4%. RotStop’s target is 1.5% which is approximately 4 times NZS 3602. Once fungi have germinated and growth has begun boron concentrations must be above 1% to kill them. RotStop concentrations are intentionally stronger than NZS 3602 and strong enough to eradicate growing rot fungi. RotStop is an essential treatment process to protect untreated and undertreated framing that has become affected by rot or may be affected during the buildings life time. After 1987 treatment levels became voluntary. Between 1987 and 1996 treatment levels varied between suppliers. Between 1996 and 2005 many timber suppliers supplied timber without treatment at all. All homes with low levels of boron (or none at all) have no protection against rot fungi. RotStop is therefore considered the most important step repairing and protecting homes that are or may be leaking.

Q: If rot fungi is well established and deep into the wood can RotStop still work?
A: Yes. Because RotStop is injected deep inside the wood where fungi get their food source from. As the wood becomes tainted and toxic the fungi dies. Interestingly most buildings dry out in the summer when rainfall that cause leaks is minimal. As winter approaches, water introduced through leaks becomes contaminated with RotStop and further assists in killing the fungi.

Q: How did the idea of RotStop start?
A: During 2006 a leaky building was purchased as a research project. The idea of “outleaking the leak” was introduced with a concentrated cocktail of chemicals deadly to rot fungi that was drip fed into the building’s failure points where water ingressed. The wall was later opened up (18months later) and it was found that the fungi including toxic moulds such as stachybotris had been killed. The process took several months but was so successful it was decided a quicker method was required along with a means of verifying the results. This led to a pressure injection process and house trials. Results so far have been far more encouraging than originally foreseen.

Q: Is all my wood fully impregnated with RotStop?
A: No. It does not need to be. Provided RotStop is positioned along leak pathways in a concentrated form any water that does get in will dissolve the RotStop and distribute the boron to any wetted timber.

Q: Will RotStop also kill borer?
A: Yes. RotStop concentrations are 40 times that required to control borer.


1 Response to FAQ

  1. nick says:


    Is RotStop available to purchase? if so where can it be sourced from?



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