Termites can chew into treated pine, but pine treated to the right hazard level for where it is used resists termite attack, and the building code accepts it for a house frame. The catch is that treatment protects that piece of timber, not the house. Termites still travel over or around it to reach untreated skirting boards, cupboards, door frames and anything stored against a wall, and pine used in the wrong place, such as H2 interior framing left out in the weather or above-ground timber dug into the soil, loses the protection it was sold with.
What do H2, H3 and H4 actually mean?
Treated pine in Australia is sold by hazard level, a code for the conditions the timber was treated to survive. The NSW Environment Protection Authority's treated timber hazard level chart sets them out:
- H1: inside, above ground, protected against lyctid borer only. Not termite protection.
- H2: inside, above ground, against borers and termites. Used for framing, flooring and joinery in dry interior spots. H2F is the blue pine framing sold south of the Tropic of Capricorn.
- H3: outside, above ground, against moderate decay, borers and termites. Weatherboards, fascia, decking and pergola posts that stay above ground.
- H4: outside, in the ground. Landscaping timbers, fence posts and in-ground pergola posts.
- H5: in the ground or in contact with fresh water. Retaining walls, piling, house stumps and building poles.
Each level only holds for the use it was treated for. A fence post cut from H3 decking stock and sunk into the soil is in-ground timber with above-ground protection.
Does a treated pine frame mean the house is termite proof?
No. The National Construction Code's termite risk management provisions treat a primary building element made of preservative treated timber, to Appendix D of AS 3660.1, as not subject to termite attack. Primary elements are the parts that carry the building's loads, such as the wall frames and floor framing.
That rule is about keeping the house standing, not about protecting everything inside it. Skirting boards, architraves, built-in cupboards, kitchen carcasses, door jambs and timber flooring laid over the slab may be untreated or treated only against borers. Termites that enter through a gap in the slab or along a wall can walk past a treated stud and eat the cupboard next to it.
Grays Point houses are tightly held and often stay within one family for generations. A Grays Point home where a newer section was framed in blue pine but the original kitchen, skirting and floorboards are older timber still needs a termite inspection in Grays Point that checks the untreated timber, not just the new frame.
Where does treated pine leave gaps?
The weak points are usually about how the timber was used, not the treatment itself:
- H2 framing that ends up exposed to rain or damp, which the EPA chart rates for dry interior use only
- above-ground timber placed in soil or garden beds, such as H3 offcuts used as edging or packing
- untreated timber left touching the ground beside treated work, such as formwork, packers or old sleepers
- untreated fittings fixed to a treated frame, such as skirting, architraves and cupboards
A deck or pergola fixed to the house is the common case. The NSW Government's home building safety and standards page says the builder is responsible for installing a termite risk management system for building or renovation work, and that a system combined with regular inspections can significantly reduce the risk of damage. It also warns that some contracts try to shift that responsibility to the owner.
Woronora Heights is bounded by the Woronora River on the west and the top of the escarpment on the north. A Woronora Heights deck built on the low side of a sloping block, where the subframe sits close to damp ground and the deck joins the house wall, is worth a termite inspection in Woronora Heights to check that the deck has not become a hidden bridge into the wall.
How do you tell what timber you have?
Treated timber carries a stamp or label. The EPA chart shows a typical label as a plant number, a preservative code number, the hazard level and a suffix, for example 505 74 H2 F. Older timber, offcuts and painted boards often have no visible label, and timber in a wall or under a floor cannot be checked without a proper inspection.
A newer house should also have a durable notice. The construction code requires a notice fixed in a prominent spot, such as the meter box, stating the termite management system used, the date it was installed, the life expectancy of any chemical, and the recommended scope and frequency of future inspections. That notice tells you more about your protection than the timber stamp does.
Oyster Bay's first house was built in 1910, and the suburb has grown from early subdivisions such as the By the Water Estate shown on a 1913 parish map. An Oyster Bay buyer looking at a house where the meter box notice is missing and an extension joins an older timber section should book a timber pest inspection in Oyster Bay before settlement.
What if termites are already in treated timber?
Finding termites in or on treated pine means the colony has found a way through, around or over the protection, and it is often feeding on something nearby that is not treated. Leave the timber and the mud alone. Breaking open galleries or spraying them can make the termites move to another part of the house, which makes the colony harder to locate and treat.
Como sits on the southern bank of the Georges River, with Bonnet Bay, Scylla Bay and Carina Bay along its shoreline. A Como household that finds mud on an old pine retaining wall that runs up to the back steps should arrange quick termite inspection and treatment in Como, so the technician can trace where the termites are travelling before they reach the house frame.
Before you book
Note these details so the technician knows what to look at first:
- the age of the house and of any extension, deck or pergola
- whether you can see timber stamps such as H2, H3 or H4, and where
- what the meter box notice says, or that there is none
- any mud, soft timber or damage you have found, without breaking it open
- garden beds, sleepers or retaining walls that touch the house
Send those details when you contact us for Sutherland Shire termite and pest control: call Sutherland Shire Pest Control Pro on 02 8360 3033 or email [email protected].