20 x 40 ft All-Purpose 5-mil Poly Tarp - Reversible Waterproof

In this review of the 20 x 40 ft all-purpose 5-mil poly tarp the bottom line is simple: it is a lightweight, versatile cover best suited to general outdoor needs where a large, reversible waterproof sheet is required. Reviewers will appreciate that the tarp arrives as a finished size close to what is advertised and offers practical features like rustproof grommets and reinforced edges. The single biggest reason to consider this tarp is its combination of size and affordability for tasks such as boat covers, ground or pool protection, and temporary shelter.

Key Features

• Finished Size: The tarp ships at a finished size of 19 ft. 4 in. x 39 ft. 4 in., giving an accurate real-world coverage area to plan projects around.
• Material Construction: Tightly woven, coated polyethylene provides a tear-resistant surface that balances light weight with useful protection for many outdoor tasks.
• 5-mil Thickness: The 5-mil thickness offers a middle ground between ultra-heavy options and very thin tarps, making it easier to handle while still resisting normal wear for casual use.
• Hardware and Reinforcement: Rustproof aluminum grommets every 3 ft and heat-sealed edges with polyethylene rope reinforcement make fastening straightforward and extend edge life.
• Reversible Design: Two-color reversible sides provide additional versatility for concealment or matching different environments.
• Water Resistance: Coated finish gives water protection suitable for covering gear, woodpiles, and temporary repairs, though performance varies by exposure and installation.

Who It's For

This tarp is well suited to homeowners, campers, and hobby boat owners who need a very large, inexpensive cover for occasional use: think covering a 19 ft boat, a woodpile, or creating a temporary shelter while working outdoors. The finished size makes planning straightforward for medium-to-large projects where full sheets are preferable to piecing smaller tarps together.

Those who need long-term, heavy industrial protection or a thicker, heavy-duty fabric for frequent abrasive use should look at heavier duty or ultra-heavy-duty options. If maximum puncture and tear resistance under constant load is required, a heavier grade tarp would be a better choice.

Pros & Cons

Pros

• Large finished coverage and clear sizing guidance reduces surprises when fitting the tarp to gear or structures.
• Reversible, coated polyethylene construction keeps the tarp lightweight and easy to position for recreational and temporary tasks.
• Reinforced edges and rustproof grommets spaced every 3 ft make tying down and securing the tarp simple and reliable for short-term jobs.
• Good value for the size, especially for occasional outdoor use like camping, pool cover, or emergency repairs.

Cons

• At 5-mil thickness some users find the tarp less durable than heavier alternatives for repetitive heavy-duty work.
• Water resistance reports are mixed, so prolonged exposure to driving rain or standing water may require additional protection or better fastening.

Specifications

Brand	Kotap
Finished Size	19 ft. 4 in. x 39 ft. 4 in.
Thickness	5-mil
Material	Woven & coated polyethylene
Grommet Spacing	Every 3 ft and at each corner (aluminum)
Edges	Heat-sealed with polyethylene rope reinforcement

Our Verdict

The Kotap 20 x 40 ft 5-mil tarp is a practical choice for anyone needing a very large, inexpensive, and easy-to-handle cover for occasional outdoor projects. It delivers accurate finished sizing, basic waterproofing, and useful reinforcement at a price that favors casual users; professionals facing heavy abrasion or constant outdoor load should consider heavier, ultra-heavy-duty alternatives.

Frequently Asked Questions

What is the actual size delivered?
The tarp ships as a finished size of approximately 19 ft. 4 in. x 39 ft. 4 in., which is the best measurement to plan coverage around.

Is this tarp fully waterproof?
The coated polyethylene offers good water resistance for many uses, but results vary by exposure and how well the tarp is installed; it is not a substitute for permanent waterproof structures.

Are the grommets durable?
Grommets are rustproof aluminum and spaced every 3 ft with reinforced edges, which work well for regular tie-downs on casual jobs.