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Bathtub floor

What is a bathtub floor?

A bathtub floor is a tent floor whose waterproof fabric curves up the sides several inches before meeting the walls, so the seams sit above ground level. Water running under the tent has no seam to get through.

Bathtub floor at a glance

Typical height
3 to 6 in
Puts seams
Above ground level
Beats
A high floor rating with a ground-level seam
The corner of a pitched tent at ground level, the olive waterproof floor curving several inches up the side before meeting the gray mesh wall, with a puddle beside the stake.
The floor fabric curves up the side before it meets the mesh, so the seam sits well above the puddle rather than in it. That is the whole idea.

Why the floor seam is the weak point

The weak point in any tent floor is the seam where it joins the wall. Put that seam on the ground and every stitch hole sits in whatever water is flowing under you. A bathtub floor takes the waterproof floor fabric and continues it up the sides, typically 3 to 6 inches, so the seam is above the waterline.

Why it beats a high hydrostatic head

It's the single most effective piece of tent waterproofing, and it's why hydrostatic head ratings on floors matter less than people think: a high rating with a seam at ground level will still let water in, and a modest rating with a well-lifted bathtub floor keeps you dry through a night of rain.

How well it is tensioned

Look at how it's tensioned as well as how high it is. Some designs use small guy points or corner tension to hold the walls up; others rely on the inner pulling them taut. A bathtub floor that sags in the middle of one side is a bathtub floor with a low point, which is exactly where water will find you.

What this means when you're choosing

  • Height of the wall, with 4 inches and up being reassuring
  • Whether the sides are tensioned or left to slump
  • Taped floor seams, which should be standard but sometimes aren't on budget tents

The common mistake

Ignoring how well it is tensioned

A tall bathtub floor that sags flat at the corners is doing nothing, because the seam ends up on the ground anyway. Look for corner tension points or small guy loops that hold the walls up, and use them.

Common questions

How high should a bathtub floor be?

Three inches is workable and four to six is comfortable. What matters more is that the walls stay tensioned, since a saggy corner creates a low point regardless of the stated height.

Does a bathtub floor replace a footprint?

No, they solve different problems. The bathtub floor keeps water out; the footprint stops the floor being abraded and punctured from below.

Where this comes up

Guides on Tom's Hiking where bathtub floor changes which product is right for you.

More in shelters

Freestanding tent

A freestanding tent holds its shape on its own poles without needing stakes to stand up. You can pitch it on rock or a wooden platform, pick it up to move it, and shake it out, none of which a staked shelter allows.

Trekking-pole tent

A trekking-pole tent uses the poles you're already carrying as its structure, so it ships without a pole set. That removes a pound or more from the pack, and requires stakes and taut guylines to stand up at all.

Vestibule

A vestibule is the covered space between a tent's inner door and its fly, outside the sleeping area but under shelter. It's where boots, packs and wet gear live, and where you can cook in bad weather if you're careful.

Footprint

A footprint is a shaped sheet of fabric that goes under a tent to protect the floor from abrasion and punctures. It's almost always sold separately, and a piece of polycryo or Tyvek does the same job for a fraction of the weight and cost.

Trail weight

Trail weight, sometimes called minimum weight, counts only a tent's essential parts: inner, fly and poles. Packed weight counts everything in the box, including stakes, guylines, stuff sacks and instructions. The gap is usually several ounces.

Gathered-end hammock

A gathered-end hammock is a flat rectangle of ripstop nylon bunched to a single point at each end and hung from two trees. It is the standard camping design, and it only lies flat if you sleep diagonally across it rather than down the middle.

Structural ridgeline

A structural ridgeline is a fixed length of cord tied between a hammock's two gathered ends. Because it cannot stretch, it holds the hammock at one repeatable amount of sag no matter how far apart the trees are, so the bed feels the same at every campsite.

Double-wall tent

A double-wall tent is built as two separate layers: an inner body, usually largely mesh, and a waterproof rainfly over it. Condensation collects on the underside of the fly instead of on the surface you and your bag are touching.

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