🛡️ Best Roofing Tarps & Synthetic Underlayment of 2026
The best heavy-duty roofing tarps and synthetic underlayment of 2026.
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A good tarp buys you weeks. A great synthetic underlayment lasts the lifetime of the shingles under it. Both matter more than most homeowners realize — a leaky underlayment on a $15K re-roof is a $15K mistake. Here's what to buy for 2026.
A tarp is what stands between an open roof and the inside of the house when the weather turns. Underlayment is the permanent version of the same job. Both are chosen on the same axis: how long it has to hold and how much abuse it will take.
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What to look for
Tarps: weight in mils and the weave count. A thin blue tarp is a two-day product; a heavy poly tarp with reinforced grommets lasts a season.
Grommets every 18 to 24 inches, and reinforced corners — the corners are what tear.
UV rating on any tarp that will stay up more than a couple of weeks.
Underlayment: synthetic over felt if the deck may be exposed. Check the stated UV exposure limit on the roll.
Walkability when wet. This is a real safety feature on a synthetic underlayment, not a marketing line.
Self-adhering ice barrier separately for the eaves and valleys in cold climates — it is a different product from field underlayment.
What is not worth paying for
Cheap thin tarps for anything but a one-night emergency. They shred and then you are doing it again in worse weather.
Coloured or branded underlayment at a premium. Nobody sees it.
Buying more ice barrier than the code requires, which is generally to 24 inches inside the exterior wall line measured along the slope.
Common mistakes
Nailing a tarp flat to the roof with no batten. Wind gets under it and it becomes a sail.
Not running the tarp over the ridge. Water runs under anything that stops short of it.
Leaving felt exposed past its rating, where it wrinkles and then telegraphs through the finished shingles.
Skipping the end laps. Underlayment needs about 6 inches at end joints as well as the horizontal lap.
Fixing a tarp through the fascia or into the gutter rather than over the ridge and down both sides.
Frequently asked questions
How do I tarp a roof properly?
Run the tarp over the ridge and down both sides, and fix it with battens screwed through the tarp into the roof rather than nailing it flat. A tarp that stops short of the ridge lets water straight under it.
How long can synthetic underlayment stay exposed?
Most synthetics are rated for weeks rather than days — the exact figure is printed on the roll. Felt is rated in days and wrinkles once it gets wet, which then shows through the finished shingles.
Is synthetic underlayment worth it over felt?
On any job that will not be dried in the same day, yes. It is lighter, covers more per roll, tears far less at fasteners and walks better when wet.
What weight tarp do I need for a roof?
For anything beyond an overnight emergency, a heavy poly tarp with reinforced corners and grommets every 18 to 24 inches. Thin blue tarps shred in the first strong wind and you end up doing the job again in worse weather.