What happens if fire-retardant plywood gets wet? Fire-retardant wood can be a true lifesaver in the event of a building fire. Treated using fire-retardant chemicals, this type of wood can resist ignition and slow the spread of a fire. This is very useful in building fires when every second counts. In order for it to retain its fire-retardant properties, this type of plywood generally needs to stay dry. To understand why this is important, it is helpful to have some background knowledge of the process used to create it.
When Plywood Gets Wet: Step By Step
This type of wood begins as traditional wood or plywood that is dried thoroughly in a kiln. The plywood then goes through these steps to become fire-retardant again:
Retort Chamber
This wood is placed inside a special retort chamber that can create the pressure necessary to infuse the wood with fire-retardant chemicals. It is this infusion that sets this type of plywood apart from types that have only been given a surface treatment of fire-retardant chemicals; only the fully infused varieties meet fire code standards and many manufacturers’ quality control systems. After the untreated wood has been placed inside the retort, it is closed tightly and all the air is removed. The vacuum created within provides the appropriate conditions for the flame-retardant chemicals to be added.
Pressure Is Used
Once the chamber has been filled with flame-retardant chemicals, the pressure is used to ensure the chemicals are fully and evenly infused into the wood. Different products will require different treatment times and pressure levels, taking into consideration factors such as thickness and wood type.
Quality Control Tests
To ensure the plywood has been fully infused and will offer the expected benefits, the wood is then subjected to a series of quality control tests. Samples are tested for fire-retardant concentrations and burn rates, along with the depth of charring produced under specific burn conditions. Charring helps protect the wood from further damage in a fire, helping it to retain some of its structural integrity.
This may give people inside a building extra time to get outside safely. These tests are quite rigorous, and the wood must not only resist ignition but also actively slow the fire’s spread in order to pass. If it fails even one of the quality checks, the batch will not be approved.
What Happens To Wet Fire Retardant Plywood?
Fire-retardant wood must be stored in a place where it will not be exposed to water or moisture. What happens to this type of plywood if it does get wet depends on a few factors. Below is a closer look at the most important considerations.
If The Plywood Was Pressure Treated
Some types of fire-retardant plywood can indeed get wet. Some varieties will be given a special treatment to control dampness, which can offer dual protection.
First, it stops the wood from warping and swelling too much when it is exposed to moisture. Second, and more importantly, it stops chemicals from leaching out of the wood upon exposure to water. Although there are several ways that water leaching can be problematic, the degradation of the plywood’s flame-retardant properties is the biggest concern. Another issue is the potential for polluting nearby soil and groundwater with chemicals.
It is important to keep in mind that even leach-resistant fire-retardant plywood should not be placed into direct contact with ground soil. Even in dry weather, soil can possess a significant amount of moisture which can degrade the fire-retardant chemicals in the plywood and even the wood itself over time.
If The Plywood Was Coated With The Correct Chemicals
The chemicals used for treating fire-retardant wood labeled as “Exterior” are made to stand up to weather conditions such as rain and moisture. Water-repellent preservatives can also be applied to this type of wood for applications that will give it direct exposure to water and moisture.
For example, Exterior Fire-X products are made for use outdoors. They are tested for endurance to moisture and heat in addition to the standard fire-retardant properties using testing that simulates prolonged exposure to the moisture and heat they would see on a finished structure. In addition, these products are dried in a kiln after treatment to guarantee their workable moisture levels. They can also be painted and stained.
Fire-retardant plywood that is labeled for interior use, on the other hand, must always stay dry and is shipped in enclosed trailers or wrapped and sealed to ensure its properties will not be compromised by moisture.
Reach Out To A Knowledgeable Fire-Rated Plywood Provider
If you want to ensure that your construction project will offer maximum safety in the event of a fire, consider hiring a company that specializes in fire-retardant plywood. The experts at Curtis Lumber & Plywood have the skill and experience necessary to select the right wood for every project and ensure it is properly treated and stored. Call us at (703) 972-1947 or contact us online today to get started.
