Selecting The Correct Type Of Fastener For Pressure Treated Wood Applications
Pressure treated lumber constitutes an excellent material in terms of resistance to water and various type of fungi as well as termites. This is why it is widely utilized in commercial, industrial and residential applications. From indoor swimming pools to railroad ties, from playground structures to docks and patio decks, pressure treated wood is up […]
Pressure treated lumber constitutes an excellent material in terms of resistance to water and various type of fungi as well as termites. This is why it is widely utilized in commercial, industrial and residential applications. From indoor swimming pools to railroad ties, from playground structures to docks and patio decks, pressure treated wood is up to the challenge. However, before selecting the most appropriate type of pressure treated lumber for a certain project – be it large or small scale – learning the treatment methods as well as the optimal fastening solutions is mandatory. Let’s elaborate.
How pressure treated wood is obtained?
Based on the type of preservative employed in the treatment of the lumber, we have:
Water-born preservatives treated wood, featuring compounds like CCA, AZCA or ACQ (safest category, reliable for indoor applications and outdoor structures like traffic posts, noise cancelation barriers, etc.)
Creosote preservatives treated wood
Oil-born preservatives treated wood
In order to create an effective shield against water and insects, the wood is introduced in a cylinder and subjected to a high level of pressure. This forces the chemical compounds to penetrate the structure of the wood and guarantee the long-term protection.
The EPA has determined that in spite of substances like arsenic being present in the list of chemicals imbedded in the wood via pressure, the risk of leakage is null. Therefore, this material can even be employed for sensitive projects such as tomato supports or vineyard pillars.
Why is selecting the correct type of fastener particularly important for pressure treated lumber?
First of all, opting for pressure treated lumber implies that the structure or assembly will be subjected to a considerable amount of moisture, either from the machinery operating within its proximity or the climate conditions. Secondly, keep in mind that even though the wood has a dense chemical coat that prevents moisture from pervading its molecular structure for a long time, the standard fasteners do not. Therefore, selecting corrosion resistant screws, bolts, connectors and nails is imperious.
Stainless steel fasteners
Stainless steel, and particularly the fasteners made from the 304 and 305 rated alloys constitute the most potent corrosion free solutions for pressure treated wood projects. However, structures and assemblies erected in coastal regions could benefit more from 316 rated stainless steel alloys. It is important to note that the 410 rated stainless steel alloys offer limited protection against corrosion and should not be employed in this type of construction.
The downside of stainless steel is that the price is considerably higher than HDG (hot dipped galvanized) fasteners. At the same time, the two types of materials cannot be used in conjunction because the chromium coating of the stainless steel alloy tends to accelerate the development of corrosion by interacting with the zinc of the HDG.
Hot dipped galvanized fasteners
Considerably less expensive to produce – and obviously to purchase – the zinc coating applied to the steel via their introduction in a vat of 850 degrees Fahrenheit molten zinc should offer an above decent resistance to corrosion in applications that utilize pressure treated wood. In addition, even dents of up to a quarter of the fastener’s zinc coating will ‘heal’. Therefore, budget wise HDG fasteners constitute a superior fastening solution in this case.
