When using a heavy-duty tarp as a cover for outdoor materials or equipment, moisture will play a role in which product will provide the best protection. Some, like a canvas material, are breathable so moisture can pass through them. Others, like a poly material, are waterproof and will form a barrier that blocks the passage of water and traps moisture inside. Choosing the right heavy duty product depends on how water and moisture will affect the stored materials and can be a crucial decision.

Let’s take a look at how different materials will handle water and which ones are better for certain applications.

Canvas

Canvas is a natural material so it is breathable. While the canvas is water resistant, it is not waterproof. Moisture will slowly pass through a canvas tarp over time. For this reason, the moisture below will not be trapped and will not form condensation on the underside of the cover. On the other hand, standing water on top of a tarp will eventually seep through. If it stays constantly soaked, the tarp will eventually start to grow mold and mildew.

Canvas is a good material for many outdoor applications. Since it won’t trap moisture underneath, tarp covers will work well if used directly on the ground. Moisture from dirt and mud will escape, keeping covered items more or less dry. This same property will also allow heat to escape if temperature is an issue.

However, this material should not be used as a storm cover or in extremely wet situations. A tarp tarp will allow water to seep slowly if it is used as a shelter or roof cover and there is standing water on the tarp. The canvas is treated with chemicals, wax and dyes. Dyes and waxes can rub off during use, making canvas tarps poor covers for boats and cars.

polytechnic school

Polyethylene, or poly for short, is a waterproof material. Moisture will not get through the material as long as there are no tears or holes. This is a two-way street, the water will not seep through a polythene tarp, but the moisture underneath will stay there. A polyethylene product is an effective barrier against moisture and water infiltration, even in standing water or during a storm.

For this reason, they are very effective as shelters and temporary roof coverings. However, it’s not a good idea to lay a poly tarp directly on the ground if the materials underneath need to stay completely dry; moisture from the ground will condense on the inside of the tarp. For example, covering a pile of lumber sitting directly on the ground with a polyethylene sheeting can result in wet lumber. Also, be careful when using polyester material outdoors, as it is possible for it to be damaged by the sun’s rays and ultraviolet radiation.

When considering the effects of moisture and water, remember that hard covers can act as a water barrier when using a polyester material or allow water to pass through if using a canvas material.