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Guide · Jobsite supplies · Poly tarps, heavy-duty tarps and roof tarps

Which tarp do you buy: poly or vinyl, 5, 8, 12 or 16 mil, blue or silver? Tarp thickness in mil, cut size vs finished size, the standard sizes, how waterproof a tarp is, how long one lasts, and how to tarp a roof and keep it from blowing off

A blue poly tarp is a woven polyethylene scrim laminated between two polyethylene films; its thickness is given in mil (thousandths of an inch) and its strength by the weave count. A 5 mil blue tarp is the light-duty cover for lumber, debris and a weekend; a 10 to 12 mil silver or green tarp with a 12 x 12 or 14 x 14 weave is the heavy-duty tarp for a roof that has to stay dry for weeks; 16 to 20 mil is as heavy as poly tarps go before the material changes to vinyl (PVC-coated polyester), which is heavier, more abrasion resistant, longer lived in sun and several times the price. Any intact tarp sheds rain; the leaks are at the seams, the grommets and the edges, which is why a roof tarp is run over the ridge and fastened with battens, not just tied.

Bayshore Safety. Industrial safety, roofing tools and jobsite supplies since 2017. · Current as of November 2026 · the C&R tarp product data on this site (blue poly tarps, 5 mil, 24 sizes from 5x7 to 100x100 ft; heavy-duty green/silver tarps, 12 x 12 weave, 30x40 and 40x60 ft, aluminum eyelets); the way poly tarps are sized and rated across the trade (cut size vs finished size, mil thickness, weave count per square inch, grommet spacing); ASTM D751 as the test method tarp fabric weights and strengths are reported against
Tarps we stockAll roofing tools
C&R 5X7 Blue Poly Tarp, 24 sizes, 5 milC&R 5X7 Blue Poly Tarp, 24 sizes, 5 milThe product data lists the heavy-duty tarp as a 12 x 12 weave green/silver tarp with aluminum eyelets in 30x40 and 40x60 ft
$24.80See the product

Reading a tarp label. Three numbers describe a poly tarp: mil (thickness of the finished sheet), weave (threads per inch in each direction of the scrim; 8 x 8 is light, 12 x 12 heavy, 14 x 14 and up super heavy) and size, which is almost always the cut size of the fabric before hemming, so a tarp sold as 20 x 30 finishes about 19 ft 6 in by 29 ft 6 in. Grommets every 18 to 36 inches and a rope in the hem finish it. Everything people ask — poly or vinyl, which mil, which color, which size, whether it is really waterproof, how to put one on a roof — is answered from those numbers below.

Tarps, question by question

Mil, weave and size are the figures printed on the tarp bag and in our product data; the size rule (cut vs finished) is how the trade labels poly tarps.

Which is better, poly or vinyl tarps, and what is the difference between PVC and vinyl?PVC and vinyl are the same thing: polyvinyl chloride coated onto a polyester scrim, 10 to 22 oz per square yard, heat-welded seams, brass grommets. Vinyl is tougher, more abrasion and tear resistant, more UV stable and stays flexible in cold; it is the material of truck tarps, long-term covers and salvage covers, and it costs several times what poly does and weighs two to four times as much. Poly (woven polyethylene) is light, cheap and comes in every size; it is the right tarp for debris, temporary roof covers, lumber and anything that will be thrown away in a season. For a roof that will be covered for weeks, heavy-duty poly does the job; for a cover that stays up for a year, vinyl.
What is a heavy-duty tarp, and how many mil is the thickest tarp?The trade uses light duty for 5 to 6 mil with an 8 x 8 weave (the blue tarp), medium or heavy duty for 10 to 12 mil with a 12 x 12 or 14 x 14 weave (silver, green, brown, white), and super heavy duty for 16 to 24 mil with 14 x 14 or 16 x 16 weave. Poly tarps top out around 20 to 24 mil; beyond that the material is vinyl at 18 to 22 oz, or canvas. Our heavy-duty tarp is a 12 x 12 weave green/silver; the blue tarps are 5 mil.
Is a 5 mil tarp strong? Is an 8 or 12 mil tarp good? Which is thicker, 12 or 16 mil?Mil is thickness, so 16 is thicker than 14, which is thicker than 12, which is thicker than 10. A 5 mil blue tarp is strong enough to cover a lumber pile, a debris trailer or a tear-off for a few days of weather, and it is the tarp roofers cut up to protect landscaping; it tears at the grommets if it flaps for a week. An 8 mil tarp is a step up for the same jobs. A 12 mil tarp with a 12 x 12 or 14 x 14 weave is the heavy-duty roof tarp: it holds up for weeks in sun and wind if it is fastened flat. 16 mil and up is for longer exposure or abrasion.
What size tarp do I get, and what are the common sizes?Poly tarps come in standard cut sizes: 5x7, 6x8, 8x10, 9x12, 10x12, 10x16, 10x20, 12x16, 12x20, 16x20, 18x24, 20x20, 20x25, 20x30, 20x40, 30x40, 30x50, 30x60, 40x40, 40x50, 40x60, 50x50, 50x100 and 100x100 feet (our blue tarp list). For a roof, measure the damaged area, add 4 feet past it on every side and enough to run over the ridge and down the other slope at least 4 feet; a 20 x 30 covers one slope of a small house, a 30 x 40 most of one side of an average roof. For a debris pile or trailer, add 2 feet per side for tie-down.
What is the size of a 2x3 tarpaulin in inches, and why is my 20 x 30 tarp short?A 2 x 3 metre tarp is about 79 x 118 inches (6 ft 7 in x 9 ft 10 in). A tarp sold by cut size loses 3 to 6 inches in each direction to the hem, so a 20 x 30 cut size finishes about 19 ft 6 in x 29 ft 6 in. Some sellers list finished size; the bag or the product page says which. Our product pages list the sizes as the tarps are labeled.
Will a tarp stop rain completely? Is a tarp 100 percent waterproof? Are all blue tarps waterproof?The laminated poly sheet itself is waterproof; the tarp leaks where it is sewn, grommeted, pierced by a nail or lapped the wrong way. A new blue tarp sheds rain until the sun degrades the film (a season or two of UV for an untreated light tarp) or the scrim shows through at a worn fold. Water also runs under a tarp that ends short of the ridge or lies in a puddle on a low slope. So: a tarp stops rain where it is intact, lapped like a shingle and fastened flat; it is a temporary cover, not a roof.
What is a roof tarp, and how do you temporarily tarp a roof?A roof tarp is any heavy-duty poly tarp used as an emergency cover; some are sold with a reinforced hem for it. The method: run the tarp from at least 4 feet past the damage on the low side, up over the ridge and 4 feet down the far slope so water cannot run under the top edge; roll each edge around a 2x4 batten and screw the battens to the roof through the tarp (the screws go through the batten, which spreads the load, not through free tarp); add battens across the slope every 6 to 8 feet on large tarps; do not leave loose tarp to flap. On a low-slope roof, pitch the tarp so water runs off, and weight the field with sandbags, not loose lumber. A tarp fastened this way holds for weeks; one tied to the gutter and a tree lasts one windstorm.
How do you secure a tarp to a roof and keep it from blowing away?Battens on every edge, screwed through the batten into rafters where they can be found; a sandbag every few feet in the field on low slopes; never rely on rope to grommets, which tear out in the first gust. Where the tarp cannot be screwed down (tile, metal), use weighted edges (sandbags in a continuous row) and run the tarp over the ridge so the wind cannot get under the high edge. Anyone on a roof doing this is subject to the fall protection rules; see the OSHA roof rules and the tie-off guide linked below. We do not sell the fall protection as part of a tarp kit; it is its own set of gear.
What do tarp colors signify, and which color lasts longest?Color is mostly a weight class convention, not a rule: blue is almost always light duty 5 to 6 mil; silver, green, brown and white are usually 10 to 12 mil medium or heavy duty, and silver reflects heat; black and brown are often the super heavy grades. Silver and white run coolest under the sun and the UV-stabilized heavy grades last longest; a 5 mil blue tarp left in full sun is brittle in a year.
Which tarp lasts the longest, and which is toughest?In poly: the heaviest mil with the highest weave count and a UV-treated film, kept flat and fastened so it does not flap. Flapping, not sun, kills most tarps: the scrim fatigues at the folds and the grommets tear. For anything that stays up more than a season, vinyl outlasts any poly tarp. Our heavy-duty 12 x 12 weave tarp is the longest-lived poly we stock; the blue 5 mil is the throwaway cover.
Where can I find cheap tarps, and why is a tarp so expensive?Light blue tarps are inexpensive everywhere because 5 mil poly is a commodity; the price climbs with mil, weave and size because the fabric weight climbs with them, and a 40 x 60 heavy-duty tarp is a lot of material. We sell both grades nationwide by the piece; the band below has the current price for each size.

Tarps in plain words

  • Mil is thickness in thousandths of an inch: 5 mil light, 10–12 heavy duty, 16–24 super heavy; above that the material is vinyl.
  • Weave is threads per inch of the scrim: 8 x 8 light, 12 x 12 heavy, 14 x 14 and up super heavy.
  • Size is usually cut size; the finished tarp is 3 to 6 inches smaller each way.
  • Poly is light and cheap for temporary covers; vinyl (PVC on polyester) is for covers that stay up a year or ride on a truck.
  • The sheet is waterproof; the seams, grommets, nail holes and short laps are where it leaks.
  • A roof tarp runs 4 feet past the damage, over the ridge and 4 feet down the far side, with every edge rolled on a batten and screwed through the batten.
  • Blue is almost always 5–6 mil light duty; silver, green and white are usually 10–12 mil.
  • Flapping kills tarps faster than sun. Fasten them flat.

Questions people ask

Which is better, poly or vinyl tarps?

Poly for temporary, light and cheap covers; vinyl for covers that stay up a year, ride on a truck or take abrasion. Vinyl costs several times more and weighs two to four times as much.

Which heavy-duty tarp do you buy?

A 10 to 12 mil poly tarp with a 12 x 12 or 14 x 14 weave in silver, green or white; our heavy-duty tarp is a 12 x 12 weave in 30x40 and 40x60 ft.

What size tarp do I get?

For a roof, the damaged area plus 4 feet each side plus enough to run over the ridge and 4 feet down the far slope; for a pile or trailer, the load plus 2 feet per side.

What is a heavy duty tarp?

In trade terms a 10 to 12 mil poly tarp with a 12 x 12 or heavier weave; super heavy duty is 16 to 24 mil.

How many mil is the thickest tarp?

Poly tarps run to about 20 to 24 mil; past that the material is vinyl rated in ounces per square yard (18 to 22 oz).

Is a 12 mil tarp good?

Yes, it is the standard heavy-duty roof tarp when it carries a 12 x 12 or 14 x 14 weave and is fastened flat.

What is the difference between PVC and vinyl tarps?

None; PVC is vinyl. Both names mean polyvinyl chloride coated on a polyester scrim.

What are the common sizes of tarps?

5x7, 6x8, 8x10, 10x12, 12x16, 16x20, 20x30, 30x40, 40x60 and on up to 100x100 feet, sold by cut size.

Will a tarp stop rain completely?

Where the sheet is intact and lapped and fastened properly, yes; it leaks at seams, grommets, nail holes and short laps.

What is a roof tarp?

A heavy-duty poly tarp used as an emergency roof cover, run over the ridge and fastened with battens.

Can I put a tarp on my roof to stop leaks?

Yes, as a temporary cover: over the ridge, 4 feet past the damage, edges rolled on 2x4 battens and screwed through the battens. Working on the roof brings the fall protection rules with it.

Is a tarp 100 percent waterproof?

The laminated sheet is; the finished tarp is only as waterproof as its seams, grommets and the way it is lapped.

What do tarp colors signify?

Mostly weight class by convention: blue is light duty, silver, green, brown and white are medium to heavy, black and brown often the heaviest.

Which tarp lasts the longest?

The heaviest UV-treated poly fastened flat, or vinyl for anything over a season.

How do you secure a tarp to a roof?

Battens on every edge screwed into framing, battens across the field every 6 to 8 feet on large tarps, sandbags on low slopes, and no reliance on rope through grommets.

What is the size of a 2x3 tarpaulin in inches?

About 79 by 118 inches, or 6 ft 7 in by 9 ft 10 in.

Related guides

Rope: poly, sisal, manila and nylonStrength by size and what each fiber doesRatchet straps and bungee cordsUse, release, working load and when to replaceRoof cement, sealant and primerASTM D4586 and D41, and removing tarOSHA roof fall protection rulesLow-slope and steep roofsHow do you tie off on a roof?Anchor, lifeline, rope grab and SRL

The ratings, test results and standards shown here are the manufacturers' published values, reproduced as published. Nothing on this page is a recommendation by Bayshore Safety that any product is suitable for a particular task, hazard or workplace. Selecting safety products and protective equipment is the responsibility of the end user and the employer, based on their own hazard assessment and the regulations that apply to their work. Confirm every value on the manufacturer's own documentation before use.

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