How to join bamboo barrier without leaving a gap

How do you join two pieces of bamboo barrier?

Overlap the two ends at least 12 in, with both smooth faces toward the bamboo. Then clamp the overlap with the stainless connecting kit: two 1.5 in stainless straps plus hardware, one kit per joint.

The joint has to be tight because a rhizome that reaches the barrier often turns and runs along it. At a loose joint, it can push between the two sheets and come out on the other side.

Why 12 in of overlap and not 2 or 3 in?

Some guides clamp only a 2 or 3 in overlap, since a longer one may let a rhizome slip between the sheets. Our rule is at least 12 in, clamped tight, with no soil between the sheets.

Can I use tape, glue or caulk instead of the kit?

No. Tape is not a seal, and our joining method calls for no tape, glue, caulk or sealant in the joint. HDPE is slick, and most adhesives don't bond to it well.

There is one kit for each depth: 24, 30 and 36 in. Kit prices are on the Bamboo Shield product page.

How many joints will my barrier have?

A joint is any place where two ends meet. Count your pieces, then use the rule for your layout:

• Straight line (two open ends, including an L or U shape): joints = pieces − 1.
• Closed loop (all the way around a grove or bed): joints = pieces. A loop made from one piece still has one joint, where its ends meet.

A bend or corner in one piece is not a joint. A cut you make on site is. You need one kit per joint.

Fewer joints is better. Each one adds 1 ft of barrier, a kit and one more spot to check. So if the run fits in one piece, order one piece.

A 130 ft loop at 24 in needs 130 + 1 = 131 ft, so one 135 ft cut and one kit. Two cuts, such as 70 and 65 ft, use the same 135 ft but make two joints and need two kits.

How much extra barrier does a joint add to my order?

Add 12 in (1 ft) for each joint, then round up to the next 5 ft. Each cut is at least 20 ft, in 5 ft steps. The longest piece is 175 ft at 24 in, 100 ft at 30 in and 70 ft at 36 in.

For loops and odd shapes, see how much bamboo barrier you need. For ordering more than one cut, and for kit prices, see how cut-to-length ordering works.

Where should the joints go?

You choose where joints land through your cut lengths and where you start laying the barrier.

• On a straight stretch. The two sheets lie flat against each other there, so the clamp can press them tight. Keep joints off corners and tight curves.
• Where you can dig down to it later. Not under a patio, path, deck, shed or wall.
• For a loop in one piece, start and finish at an easy-to-reach spot. That is where the joint will be.
• Marked. Before you backfill, measure each joint from something fixed, like a house corner or fence post, and take a photo.

Worked example: placing the joint on a 150 ft line

You need a 150 ft line of 30 in barrier along one side of a yard.

1. 150 ft is over the 100 ft longest piece at 30 in. So you need two pieces and one joint.
2. 150 + 1 = 151 ft. In 5 ft steps, the two cuts add up to 155 ft.
3. Pick the split to place the joint. With 80 ft and 75 ft cuts, the joint sits about 80 ft from the start. With 100 ft and 55 ft, it sits about 100 ft in.
4. Add one 30 in kit. The 4 ft left over can run past the ends of the line.

The "How much do I need?" calculator on the product page splits long runs into equal cuts. Here it shows 2 × 80 ft = 160 ft. Any cuts that cover the line plus 12 in per joint will work.

How do I make the joint, step by step?

These steps fit into the full install in the Bamboo Shield install manual. Call 811 before you dig. Read the kit's instructions too, and check the tools they call for against the manual's tool list.

1. Open up the trench at the joint. Dig to the trench depth (barrier depth − 2 in: 22, 28 or 34 in). At the joint, widen it on both sides and past each end of the overlap. You need to reach both faces from top to bottom. A trencher cut is too narrow for that, so use a spade.
2. Set the first piece. Smooth face toward the bamboo, top tilted slightly outward, 2 in above the finished soil.
3. Overlap the second piece at least 12 in. Measure it. Set it the same way, with the same tilt.
4. Line up the edges. Both tops stand 2 in above the finished soil. Both bottoms sit on the trench floor.
5. Clean the overlap. Brush soil off the faces that touch, so nothing sits between the sheets.
6. Clamp it. Have a helper hold the sheets together. Fit the kit's two straps and hardware as its instructions show, so the overlap is held tight from top to bottom.
7. Check it. The overlap is still 12 in or more, the sheets are tight together, and both pieces show a 2 in lip.
8. Mark the spot, then backfill. Firm the soil as you go, so the joint keeps its line, tilt and lip.

For why the lip and trench depths matter, see how deep bamboo rhizomes grow.

Common mistakes at joints

• Butting the ends or guessing the overlap. Butted ends leave a seam for a rhizome to find. Measure 12 in or more.
• Tape, glue or caulk alone. None of them is a seal.
• Soil caught in the overlap. It holds the sheets apart.
• A trench too narrow at the joint. You can't reach both faces to fit the hardware.
• Flipping one piece. Both smooth faces go toward the bamboo.
• Uneven tops. If one piece sits low, its lip gets buried and a rhizome can cross it unseen.
• The wrong kit for the depth. Each kit fits one depth. Order the kit that matches your barrier.
• Counting a loop like a straight line. Two pieces in a loop make two joints, not one. That is one more foot and one more kit.

How do I check a joint later?

Once or twice a year, walk the outside of the barrier line and cut any rhizome that crosses the lip. Check the joints first, and keep mulch and soil off the 2 in lip.

If shoots come up just outside a joint, dig down on the outside of it. Cut the rhizome, and check that the overlap is still clamped tight.

Does this work for Sidewalk Shield, Grass Barrier and Pier Protector?

Sidewalk Shield: yes. Overlap 12 in and clamp with the stainless connecting kit, one per joint. The 18 in depth has its own 18 in kit.

The layout differs. Sidewalk Shield runs straight along the paving edge, vertical by default, with the top edge ½ to 1 in above finished grade. A lean of about 10°, top edge toward the tree, is optional where there is room. If the project plan or city detail differs, follow the plan. See the tree root barrier install manual.

Grass Barrier: no. It uses its own kit: two pre-drilled 200 mil HDPE clamps with 316 stainless hardware, one per joint. Overlap the ends a little inside the clamps; it makes the joint easier to line up, and you don't need to order extra length for it. See the grass barrier install manual.

Pier Protector: no. Piling wrap goes around one pile at a time. Tack one edge with 3 to 4 nails, pull the sheet tight around the pile, overlap the ends 6 in, then nail the seam every 3 to 6 in. See the dock piling wrap install manual.

FAQ

How many connecting kits do I need?

One per joint, in the depth that matches your barrier: 24, 30 or 36 in. A straight line needs one kit fewer than it has pieces, and a closed loop needs one kit per piece. A loop made from a single piece still needs one kit, where its two ends meet.

Is a longer overlap better than 12 in?

12 in is the minimum, and more is fine, as long as you add the extra length to your order. Length doesn't replace the clamp, because an unclamped overlap leaves space between the sheets for a rhizome to follow. Clamp every joint with one connecting kit, whatever the overlap.

Can I add onto a barrier that is already in the ground?

Yes, as long as the new piece is the same depth. Call 811 before you dig. Dig out the old end to its bottom edge, and brush the soil off its last 12 in or more. Overlap the new piece at least 12 in, smooth face toward the bamboo and tops level, then clamp it and backfill.

What if I cut the barrier on site?

Treat the cut as a new joint. Overlap the ends at least 12 in, brush out any soil between them and clamp them with a kit for that depth. Each new joint uses 1 ft of barrier and one more kit, so check that you still have enough length.