How to attach two tarps: Glue? Sew? Tape?

[tallsteve]

I have two 6'8"x20' pieces of poly tarp that I want to join into a 6'8"x40'-ish tarp. What's the best way to make that seam?

This is for the wall of a custom tent I'm making. It'll be backed by vertical poles spaced less than 4' apart (one of them right behind the seam) and by diagonal cables, so I'm not paranoid about blowouts. Justifiably concerned, sure, but not paranoid. There has to be a good way to do this, because manufacturers make big tarps by joining narrower strips.

[lemur]

if water is not a concern: grommets

[Elliot]

Is it absolutely necessary that this wall be one single big tarp? Two smaller ones are much easier to handle.

[The CO]

Circus seam.

On one mating edge of one tarp (a), place grommets every 12".

On matching edge of other tarp (b), fold back 9" to create a double flap. Place grommets matching the 12" placement on other tarp.

Take 1/4" rope, cut into 30-32" long pieces. Tie into a loop running 12.5" from loop end to knot.

Match grommets on tarp a to grommets to tarp b with tarp a end between the two flaps of tarp b. Starting at one end, feed a rope loop thru grommets in b/a/b order. The second rope goes thru wnd grommet set same direction, then thru the loop of the previous rope. Follow that pattern to the end and tie the last with a stopper knot.. It creates a waterproof seam, while keeping the convenience of 2 smaller tarps.

I'll see if I have photos on the home computer.

[International Incident]

Agrees with CO.
That's what my Dad does. Sounds a little like work but pretty easy.

[MikieCGY]

Zip ties are your friend.. triple zip tie every loop together once zip tied together, add DUCT TAPE to "seal it up" and voila..

one big tarp

[Elliot]

Oh... and if you need to install grommets, they are available -- and the tool to install them -- in many hardware stores, and even the dreaded W*Mart.

[Trishntek]

If you match up your grommets, you can simply take a 3/8" dia X 3/4" long hex bolt and nut with a washer and bolt the together. You could even add a rubber washer to water proof it.

[tallsteve]

So there's a strong consensus that grommets are the way to go, with varying opinions as to how to join the grommetted pieces. I like the the bolting idea for its simplicity, though I'll probably also leave a Z-flap on one side just to keep my options open.

Thank you all!

[JStep]

D: weld.


A heat gun works.

[Bob]

Staple the two to one 1x4, take two wraps, batten off with another 1x4 screwed onto the first 1x4. No glue, no sewing, no tape. Could use clinched nails if you had to.

[falk]

I like CO's idea the best. I thought I had sketches around, but can't find them.

For my own dome, I wound up sewing 2"-wide velcro to the edges of the tarps. That worked incredibly well.

Duct tape = bad idea. The stickum gets soft in the hot sun and the whole thing falls apart. Nuts & bolts would work, but OM's circus lacing would be easier.

[The CO]

I have an a-frame structure 12' tall, 22' wide, 24' long, that has been to the playa twice. All made from uniform stock tarps that we circus seamed to fit the frame. We will have to repair a few things on it for this year, number 3 for it.

The circus seam is worth the prep time beforehand; the ratio of time spent manufacturing compared to how well it holds up is very worthwhile.

Still trying to find sketches/photos.

[Doohickey550]

I have an a-frame structure 12' tall, 22' wide, 24' long, that has been to the playa twice. All made from uniform stock tarps that we circus seamed to fit the frame. We will have to repair a few things on it for this year, number 3 for it.

The circus seam is worth the prep time beforehand; the ratio of time spent manufacturing compared to how well it holds up is very worthwhile.

Still trying to find sketches/photos.

Hey CO or anyone else who has done this circus seam stitching,

Any way you can put up a diagram or something of how it's done? I'm having trouble following the directions provided. Or do you know of an online resource where I can find a diagram? I googled it but nothing came up.

Thanks.

[mablewill]

In my place, we just tie rope in each corner...






.

[FIGJAM]

I just seamed a tarp with this and it will fail someplace else before that seam fails.

https://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=HPIC,HPIC:2011-50,HPIC:en&q=hh-66

[adamrice]

I've used HH-66 (and its equivalent, Weldon 66). I think they'd work if you get a good bond, but I agree that at this size, handling two tarps is preferable to handling one. Wish I knew about that circus seam a few years ago when I was working on my shade structure.

[robbidobbs]

Ah come on CO. Gonzo and I are dying to know what a circus seam is.

We were just

[robbidobbs]

Ah come on CO. Gonzo and I are dying to know what a circus seam is.

We were just going to suggest epoxy, but that's just a DOE secret.

[Bob]

Still don't have a decent picture of it in my mind, but I hope placing grommets on a fold also involves some reinforcing webbing tape. But it's only a week in the desert, and you're working with cheap materials. Keep it simple until you have a good reason to get complicated.

[TomServo]

I connected two large tarps with Nashua duct tape from Home Despot. I did this a couple weeks BEFORE taking it up to the playa, and it held up with no problem, through wind and heat. I overlapped the tarps about 3-4 inches, duct taped both sides...a few strips perpendicular to the seam and about 4 overlapping strips the length of the seam.

[Anarquistador]

Trying to get my head around your description of a "circus seam", CO, I can't quite picture it and I couldn't find anything on Google. Do you need a double row of grommets on Tarp B, so that each rope loop is "pinching" Tarp A between two layers of Tarp B? That's the only way I can imagine you would end up with a seam that is somewhat waterproof.
Also, how far from the edge would you position the grommets?

[melodiousdirge]

HH-66 won't work on poly tarps to the best of my knowledge - if it does I apologize, but it's a very specific adhesive designed for vinyl. Polyethylene is very adhesive repellent. The best way to put a seam in it is either sewing or some other mechanical means, or else heat seaming with an iron (quite easy in my experience, but YMMV).

If you're going to go grommets - might I suggest spray gluing a strip along the edge, or folding the edge over and ironing first to make sure there is enough meat for the grommet to hang on.

If it were me I'd strongly consider actually doing a circus seam (this is actually a sewing term - I can't picture what CO was suggesting either, though it sounds like he knows his stuff), but instead of sewing, punching grommets through both tarps after you fold the edges together. No messing with bolts or zap straps or bungee balls (moop).

If it were me, and I needed a strong seam in a poly tarp that's likely what I'd do. Something like this, only with grommets, instead of sewing:



(Image is not mine - Stolen from a backpacking site)