Clear vinyl tarps for porches and greenhouses

Clear vinyl tarps for porches and greenhouses

A clear vinyl tarp keeps rain and wind out while letting light in. That makes it the tarp for closing in a porch or patio for winter, covering a greenhouse frame, or protecting something you still want to see.

Clear vinyl versus clear poly

Clear PVC vinyl is genuinely see-through, flexible in the cold and heavy enough to hang straight. Clear polyethylene sheeting and "clear" woven poly tarps are cheaper and lighter, but they're translucent rather than clear, and they break down faster in the sun.

Thickness

Clear vinyl is sold by thickness in mils. Around 20 mil is a common heavy-duty weight; 30 mil is stiffer and stronger. Ours is 24 mil, in between: heavy enough to hang flat and resist tearing at the grommets, light enough to roll up.

Polytunnel greenhouses covered with clear plastic
Polytunnels covered with clear sheeting. A clear tarp lets the light through while keeping weather off. Photo: Val Vannet, CC BY-SA 2.0, via Wikimedia Commons.

Hanging it

  • Measure each opening and choose the closest size that covers it; add a little if you'll fasten it to a frame instead of tying through the grommets.
  • Fasten every grommet. Clear vinyl is heavier than it looks, and wind loads a closed-in porch like a sail.
  • Expect some cloudiness from heat and creasing, and store it rolled, not folded, when you take it down.
  • It isn't shade. Clear vinyl lets heat through; for shade, use shade mesh or a solid tarp.

Condensation behind clear vinyl

Closing in a porch traps air, and that air carries moisture from people, plants and the ground. When the outside temperature drops, the clear sheet becomes the coldest surface in the space. Where its temperature falls below the dew point of the air inside, water condenses on it, the same way a window fogs. A little venting, a gap at the top or bottom that lets moist air escape, keeps it clear.

Seasons and stiffness

Like all flexible vinyl, clear PVC gets stiffer as it gets colder and softer in heat. Hang it so it's snug but not drum-tight in warm weather, so it isn't over-stressed at the grommets when it contracts in the cold. Roll it rather than fold it when it comes down: sharp folds in cold vinyl leave permanent creases and can crack the sheet.

Polytunnels covered with clear sheeting
Clear sheeting lets light in and holds heat. The same physics fogs it on cold mornings. Photo: Val Vannet, CC BY-SA 2.0, via Wikimedia Commons.

Sources

  1. Tarps Now, 20 mil clear vinyl tarps
  2. Tarps Now, heavy duty clear vinyl tarps, 30 mil

Written by the TrueTarps team. Questions about your job? Contact us or request a custom tarp.