Every through-wall formwork tie is a potential leak path. In basement walls, water tanks, swimming pools and reservoirs, groundwater migrates along the rod-to-concrete interface unless it is deliberately blocked. A tie rod water stop plate - a small square steel plate welded at the midpoint of the tie rod - is cast into the wall, forcing water to detour around the plate edge instead of traveling straight along the rod.
Why The Plate Sits At The Rod's Midpoint
The plate is welded on before assembly, so it ends up near the wall's mid-thickness. Centering maximizes concrete cover on both faces and keeps the seepage path symmetric. A plate welded off-center reduces cover on one side and becomes the weak point of the joint - verify position before every pour.
Selection: Material, Size And Weld
Three parameters decide performance. Material: Q235 hot-rolled carbon steel, yield strength ≥235 MPa, is the standard plate grade and matches common tie rod steel. Size: 50×50×3 mm and 60×60×3.5 mm plates suit most wall and rod combinations; other dimensions and hole diameters are made to drawing. Weld: a double-sided full weld locks the plate in position during the pour; intermittent welds can crack under vibration and leave gaps that channel water. The center hole must match the rod diameter exactly, because a loose hole lets grout and water pass. Plain steel is standard, with anti-rust oil or hot-dip galvanizing available for aggressive exposure.
Pair The Plate With A Complete System
A water stop plate performs best as part of a three-piece set: the plate itself, a wall-through bolt and a tapered rubber hose. The EPDM hose - pressure resistance 16–67 MPa, service temperature −40°C to +100°C - forms a clean tie hole, blocks grout loss around the rod, and is pulled out for reuse after stripping, leaving a regular recess for sealing.
Installation Sequence
- Order tie rods with plates double-welded at the midpoint; confirm the hole diameter.
- Insert the tapered hose and rod through the formwork panels; secure with wing nuts and tie plates.
- Verify each plate is centered in the wall thickness before concrete arrives.
- Pour in lifts, keeping poker vibrators away from the rods so welds are not disturbed.
- Strip the formwork, pull the hose, cut or grind the rod ends, and fill recesses with sealant to the project waterproofing specification.
Standards And Submittals
Formwork ties and anchorage are governed by ACI 347R, Guide to Formwork for Concrete; underground waterproofing follows the applicable project standard (for projects in China, GB 50108). Confirm sealing details with the engineer of record before the pour.
Shaanxi Flourish Industrial Co., Ltd. exports tie rod water stop plates, wall-through bolts and tapered rubber hoses as a complete watertight set, cut, punched and welded to your drawings. Every inquiry is answered within 24 hours, with a full quotation in one working day. Planning a basement, tank or reservoir pour? CONTACT US or Send Inquiry Now.