Using Galvanised Screws with Treated Pine
Galvanised screws are not recommended for use with treated pine because of a chemical reaction that can occur between the galvanised coating and the chemicals in the treated wood. Treated pine, also known as pressure-treated wood, undergoes a preservation process where chemicals are infused into the wood to protect it from decay, rot, and insect damage.
The chemicals used in the pressure-treatment process, such as copper, chromium, and arsenic (CCA), are intended to prolong the life of the wood but can be corrosive to certain metals. When galvanised screws come into contact with the treated pine, a process called “galvanic corrosion” can take place.
Galvanic corrosion occurs when two dissimilar metals come into contact in the presence of an electrolyte, such as moisture. In the case of treated pine and galvanised screws, the copper or other chemicals in the wood act as the electrolyte, while the zinc coating on the screws acts as a sacrificial anode. This means that the zinc coating corrodes rapidly, which weakens the screws and compromises their structural integrity over time.
This corrosion can weaken the screws and compromise the structural integrity of the project, such as a deck, fence, or other outdoor structures where treated pine is commonly used.
To avoid this issue, it is recommended to use fasteners made from materials specifically designed for use with treated wood, such as Stainless Steel, EP-5, Xylan or a similar rubberised/plastic coating. These materials are more resistant to the corrosive effects of treated wood and are less likely to undergo galvanic corrosion, ensuring a longer lasting and safer construction.
Using the correct fasteners ensures the structural integrity of your project and helps maintain its durability over time.
If you have any questions or would like to discuss the best fasteners for your project, please contact one of our friendly team members.