This 12 mil (0.30 mm) plastic tarp will hold through an entire season outdoors. Both faces are coated, so it works either way up: silver on the main side, green on the reverse. Go heavier than this (16 to 20 mil) only when the cover never comes down.
What you can use it for
Covering a woodpile
Cover the top and the upper third of the sides, then stop. Wrapping a woodpile to the ground traps moisture underneath and the wood will not season. Run a rope over the crown of the pile and tie off to stakes on both sides so the tarp cannot lift, and leave the two ends open so air moves through.
Protecting equipment through the winter
Lift the cover off the machine before you tie it down. A tarp resting directly on metal holds condensation against the surface, and something left under it for four months will come out with rust marks in every contact spot. Prop the centre with a batten or a length of pipe to build in a slope, then tension the corners so the whole thing sheds toward the ground.
Temporary roofing after storm damage
Run the tarp up over the ridge and down the far side by at least 4 feet, so wind driving up the slope cannot get underneath the edge. Fasten along battens rather than through the grommets alone: a screwed batten spreads the hold across the whole edge, where a grommet under wind load is a single point of failure. This is a stopgap while you wait on a roofer, not a repair.
Ground sheets and work surfaces
Green side up keeps the cover less conspicuous while you work, and the coating means you can hose mortar or paint splash straight off it afterwards. Sweep out grit before folding, because dirt trapped in a fold will abrade the coating over time.
Securing a load
Tie the front edge first and work backward, keeping tension as you go, so air cannot get under the leading edge and balloon the tarp. Any loose section will flap at speed, and flapping does more damage in an hour of driving than a month sitting still.
Material and construction
12 mil polyethylene
The body is woven polyethylene tape, laminated on both sides. Mil rating measures total thickness, and thickness is what decides how the tarp behaves when it is stretched between two fixed points in a gust. Thin poly stretches, then splits from a grommet outward. At 12 mil there is enough material to take that load and enough weight to keep the tarp sitting where you put it instead of lifting on every gust.
Coating on both faces
Both sides are coated, which is what makes the tarp waterproof rather than water resistant. Water does not pass through the fabric at all, so rain runs off instead of soaking in. Pitch the tarp so it sheds: a flat cover will hold water in a pocket, and a few gallons sitting in the middle will strain the grommets and eventually pull one through.
UV treatment
The polyethylene is UV treated. This slows the breakdown that sunlight causes in plastic, it does not stop it. A tarp left in full sun year after year will stiffen and lose strength eventually, and treatment buys you seasons rather than permanence. You will get considerably more life out of it by bringing it in over winter, or by taking it down between jobs.
Rope in the hem
A rope runs inside the folded hem around the full perimeter. This is the detail that separates a tarp that lasts from one that frays. The rope carries the tension along the edge instead of letting it concentrate on individual grommets, and it stops the hem stretching out of shape once the tarp has been under load for a while.
Grommets every 20 inches
Grommets are set at 20 inch (50 cm) intervals along all four edges, and they are rust proof, so runoff will not stain the fabric or seize the ring. Twenty inches is close enough spacing that you can tie every second grommet on a calm site and every one
Reinforced fabric, edges and grommets
Reinforced fabric, edges and grommets
