How to Choose a Tarp

A tarp is a flexible sheet that covers and protects equipment, materials, and structures from weather, debris, and wear. Choose by material based on your timeline and application: polyethylene is lightweight and affordable for short-term projects, while PVC-coated polyester (vinyl) is the gold standard for long-term outdoor use, offering superior tear resistance and a five-to-ten-year lifespan. The single most common mistake at the counter is grabbing a thin poly tarp for a job that needs vinyl. It’ll shred in the first chinook or crack in the first hard freeze. Match the material to the work and it’ll do its job.

For broader project planning, explore WBC’s landscape and concrete resources.

For most Montana homeowners, gardeners, and small-scale landscapers, the choice comes down to four materials and a few honest spec numbers. Here’s how to read them.

Tarp Materials and What Each One Solves

Four materials cover nearly every job. They aren’t interchangeable.

Polyethylene (poly). Poly tarps are among the most affordable options available. They are lightweight and come in various thicknesses and sizes. They’re versatile and can be used for a wide range of applications, including covering garden beds, protecting plants from frost, and creating temporary storage areas. Good for a season, not a decade.

Vinyl (PVC-coated polyester). The workhorse for the long haul. Vinyl tarps are known for their strength and durability. They are resistant to tearing and can withstand harsh weather conditions, making them ideal for long-term outdoor use. These are perfect for covering equipment, creating temporary shelters, and protecting plants from extreme weather conditions. They can also be used to cover soil or mulch to keep it dry.

Canvas. The breather. Canvas tarps are made from natural fibers, which allow for better breathability compared to other tarp materials. This makes them ideal for covering plants without causing condensation buildup. That breathability matters for anything moisture-sensitive. There’s a polyester-canvas blend worth knowing about too — the kind that combines the best traits of polyethylene and cotton canvas, so whatever you’re covering is protected from rain, snow, and sun while mildew and condensation damage is avoided. The cold-weather angle is the real Montana selling point: that breathable polyester canvas is stronger than polyethylene of equal weight and won’t crack in cold. Poly gets brittle when the temperature drops. Canvas doesn’t.

Mesh. For airflow, not water. Mesh tarps provide excellent ventilation while offering shade. They are made from a durable mesh material that allows air and light to pass through. These are commonly used for creating shade structures in gardens and nurseries, protecting plants from excessive sunlight, and as windbreaks. The better mesh tarps are PVC-coated polyester that doesn’t rot or mildew and is UV treated.

Reading the Specs and Picking a Size

Forget vague “heavy-duty” labels on the package. Look at the numbers.

Thickness gets measured in mil. For reference, a serious debris-and-leaf tarp runs 16.1 mil thick polyethylene material. Canvas and polyester get rated by weight instead — the breathable polyester tarp mentioned above is a 14.5 oz polyester canvas. Heavier and thicker means more durable. Thicker tarps are generally more durable and provide better protection.

Grommets are where tarps live or die. Brass spur grommets don’t rust or tear out like standard grommets. On a premium tarp you’ll see stainless-steel grommets every two feet around the entire perimeter, with heat-sealed seams and a reinforced, double-stitched perimeter hem. That spacing matters in wind — fewer grommets means more fabric between tie-down points to catch a gust and rip.

Two sizing rules. First, buy bigger than the thing you’re covering. Add a couple feet of overhang per side so you’ve got room to tie down and let the tarp move in wind without straining the grommets. Second, know the labeled size isn’t the finished size. Actual finished size may be three to five percent shorter than the size listed due to the tarp-making process.

Color isn’t just looks. The color of the tarp can affect its performance. Black tarps are ideal for weed control as they block sunlight, while white or light-colored tarps are better for reflecting heat and providing shade.

One honest caveat for anyone planning to cover firewood or a soil pile through a wet spring: tarp seams are water-resistant, not waterproof. Tarps wider than five feet will have a seam. Plan the pitch so water sheds off rather than pooling on a seam.

What Western Building Center Carries

The stock list runs from small poly tarps up to large covers. Blue polyethylene tarps come in a 3.5-mil ProSource line in sizes like 8’x10’, 10’x12’, 12’x16’, and 16’x20’, plus a heavier 5-mil blue in 10’x20’ and a low-density blue in 30’x40’. There’s a 10-mil white plastic ProSource tarp in 6’x8’ and 10’x15’. Heavier green/silver and silver poly tarps come in 6’x8’, 8’x10’, 9’x12’, 16’x20’, and an 8-mil 20’x30’. Medium-duty blue and brown poly tarps fill the mid-range sizes. For yard work, there’s a DeWitt 9’x9’ polypropylene leaf and debris tarp, and for tough jobs an 8-mil Gorilla heavy-duty red tarp in 8’x10’.

Lawn, Garden, and Jobsite Uses

A tarp is more versatile than “covering things.” The uses that matter most in a short Montana growing season:

Frost protection. This is the big one when late spring and early fall frosts threaten. Drape a heavy-duty tarp over your flower beds, bushes, or young trees to trap in warmth and keep your plants from freezing overnight. Do it right: the open space around the plants avoids direct contact of cold air with the leaves and allows the trapped heat to settle beneath. So prop up the cover with some stakes so it doesn’t squash your greenery, and remember to put it away once the sun comes out.

Hauling material. Tarps come in handy for transporting mulch, gravel, soil, compost, and other materials from one spot to another. Lay a tarp down on the ground and empty everything on top of it. Then grab the four corners and drag it where you want it to go. It’s also a smart solution for collecting raked leaves in autumn.

Killing weeds before planting. If you’re preparing to plant a fresh garden, you’ll need to kill off the grass and weeds in that area. Instead of using chemicals, stake down a tarp over the grass, and that patch will be ready for planting come springtime.

Raised-bed liner. Place a heavy-duty tarp down to serve as a bottom liner for the raised bed. This helps prevent critters from sneaking in and weeds from sprouting. Cut small draining holes in the tarp to allow water to drain properly, and then top with soil mix.

Equipment and material protection. Vinyl or poly tarps can be used to cover mowers, tools, and other equipment. This protects the equipment from weather damage and keeps it clean and ready for use. The same goes for piles of soil, mulch, or compost, and firewood waiting out the season.

Temporary structures. Build an inexpensive frame and place the tarp over it. A simple greenhouse constructed out of a tarp lets you control temperature and guard against bad weather. A blue tarp also buys time on a damaged roof — it can temporarily keep water from penetrating before you hire a professional crew. Hang the tarp over the damaged area and nail, screw, or tie it down so water won’t leak under it. That prevents further damage until a professional repairs the roof.

Fastening and Care

Most tarp failures start at the tie-down points in wind — and Montana has plenty of wind. Fasten robustly at every grommet. Grommets, bungee cords, tarp clips, and tie-down straps are the supporting accessories, and for a temporary roof or pool cover, bungee cords, sandbags, or other fastening materials keep it from blowing away in strong winds. On a long-term outdoor cover, lean toward a tarp with closely spaced grommets and a reinforced hem — that’s what holds in a gust.

For care: if the tarp will be exposed to sunlight for extended periods, choose one with UV resistance to prevent degradation and prolong its lifespan. Keep it clean, inspect for tears, and store it dry. A little maintenance is the cheapest way to get a second or third season out of any tarp.

Frequently Asked Questions

What’s the difference between poly and vinyl tarps? Timeline and toughness. Polyethylene is lightweight and affordable for short-term projects, while PVC-coated polyester (vinyl) is the gold standard for long-term outdoor use, offering superior tear resistance and a five-to-ten-year lifespan. Use poly for a quick cover; reach for vinyl when the tarp needs to last years outdoors.

Which tarp is best for covering firewood or a soil pile through winter? A heavier poly or vinyl tarp pitched so water sheds off. Remember tarp seams are water-resistant, not waterproof, so don’t let water pool on a seam. Tie it down hard at every grommet — wind, not water, is what tears a cover apart.

Won’t a poly tarp crack in the cold? It can. That’s the knock on cheap poly in a Montana winter. The breathable polyester-canvas type is built to handle it — it’s stronger than polyethylene of equal weight and won’t crack in cold. If the tarp’s staying out through the freeze, weigh that against the lower cost of plain poly.

How big a tarp should I buy? Bigger than the thing you’re covering. Add a couple feet of overhang per side for secure tie-downs and wind movement. And size up slightly, because the actual finished size may be three to five percent shorter than the size listed.

Does tarp color matter for garden use? Yes. Black tarps are ideal for weed control as they block sunlight, while white or light-colored tarps are better for reflecting heat and providing shade. Pick the color for the job, not the looks.

How do I keep a tarp from blowing away? Fasten at every grommet point with the right hardware — grommets, bungee cords, tarp clips, and tie-down straps. A tarp with closely spaced grommets and a reinforced hem holds far better in wind than a bargain tarp with a grommet every few feet.