Form Tie Hole Waterproofing: Plugs, Rings & Connectors Explained

Editor’s Note: This post, originally published on August 14, 2024, has been thoroughly revised and updated to ensure accuracy and comprehensiveness.

Removable formwork tie systems can leave spacer openings or penetrations through concrete walls. Where these details are exposed to groundwater or retained water, they may require a purpose-designed sealing arrangement.

This is particularly important for below-ground and water-retaining structures, where groundwater or hydrostatic pressure can force moisture through untreated form tie holes. Over time, water ingress can contribute to concrete deterioration, reinforcement corrosion and increased maintenance costs if appropriate waterproofing measures are not specified.

Selecting the right form tie waterproofing system is essential for helping limit water ingress through compatible formwork details. Depending on the form tie system, project specification and construction method, this may involve Form Tie Plugs, Form Tie Rings & Connectors, or other waterproofing solutions integrated into the concrete structure.

For a broader guide, the Waterproofing Concrete Foundations: A Comprehensive Guide for Building Professionals article explains how water ingress can be addressed through construction joints, penetrations, cracks and below-ground concrete surfaces.

Why Form Tie Holes Require Waterproofing

After concrete has cured and formwork is removed, untreated form tie penetrations can provide a potential pathway for water through a concrete wall.

Formwork spacer openings and embedded tie details can create through-wall water paths where they are exposed to groundwater, retained water or other moisture. Their treatment should be determined by the formwork system, exposure conditions and project specification.

Effective waterproofing helps minimise this risk by sealing the penetration and reducing potential pathways for water ingress.

Form tie waterproofing may be particularly important for structures subject to conditions or requirements such as:

• Groundwater and hydrostatic pressure
• Below-ground construction
• Water-retaining structures
• Aggressive environmental conditions
• Long-term durability requirements

Because every project uses different form tie systems and construction methods, selecting the correct waterproofing solution depends on the type of tie system, penetration geometry and project specification.

Form Tie Waterproofing Solutions

Danterr offers two complementary solutions designed to help waterproof compatible form tie penetrations. While both aim to reduce water ingress, they are used at different stages of construction and suit different form tie systems.

Understanding how each solution works makes it easier to specify the most appropriate waterproofing method before installation.

Form Tie Plugs

Form Tie Plugs provide a purpose-designed method for sealing compatible formwork spacer openings that could otherwise create a through-wall water path. After the removable components are taken out, the plug is inserted into the spacer and driven into position.

The supplied technical information describes the plug as water-swellable and states that no additional finishing or after-treatment is required. Product size and compatibility must be confirmed against the spacer system and current technical documentation.

Form Tie Plugs provide a practical waterproofing solution for compatible removable form tie systems, helping reduce water ingress through completed spacer openings.

Form Tie Rings & Connectors

Form Tie Rings & Connectors form part of the waterproofing arrangement around compatible embedded formwork spacer and tie assemblies. The connector is positioned against the tie rod and secured with the sealing component before concrete placement.

Once embedded, the hydrophilic sealing component responds to water exposure to help limit water migration along the spacer and tie detail. These components perform a different role from the Form Tie Plug, which is used to close the compatible spacer opening.

Form Tie Rings & Connectors provide an integrated waterproofing solution for compatible form tie systems where sealing is incorporated during concrete placement.

Form Tie Plugs vs Form Tie Rings & Connectors

Although both solutions are designed to help waterproof form tie penetrations, they perform different roles within the waterproofing system. The appropriate solution depends on the form tie system being used, when waterproofing is incorporated into the construction process and the project’s waterproofing requirements.

Where supported by the compatible formwork system, product documentation and project detail, Form Tie Rings & Connectors and Form Tie Plugs may perform different sealing roles within the same assembly. Compatibility should be confirmed before specifying both products together.

Where Is Form Tie Waterproofing Used?

Form tie hole waterproofing is most important where concrete structures are exposed to groundwater, hydrostatic pressure or long-term moisture exposure. In these environments, untreated tie penetrations can become pathways for water ingress if they are not properly sealed.

Typical applications include:

• Basements – Below-ground basement walls may be exposed to groundwater and moisture, depending on site conditions. Waterproofing compatible form tie penetrations can help reduce potential leakage paths through the wall.
• Retaining Walls – Retaining walls may be exposed to groundwater and hydrostatic pressure depending on site and drainage conditions. Waterproofing form tie penetrations can contribute to the overall waterproofing strategy.
• Water Tanks and Water-Retaining Structures – Water tanks, reservoirs and treatment structures require careful detailing to control water leakage through concrete joints and penetrations. Sealing compatible form tie penetrations helps maintain the integrity of the waterproofing system.
• Tunnels and Underground Structures – Infrastructure such as tunnels, lift shafts and underground service corridors frequently encounter groundwater during their service life. Waterproofing form tie penetrations forms part of a broader waterproofing strategy.
• Civil Infrastructure – Bridges, culverts, pump stations and other civil concrete structures may require waterproofing of form tie penetrations where the concrete is exposed to groundwater, retained water or other moisture conditions.

Key Selection & Application Considerations

Selecting the appropriate form tie waterproofing solution begins with understanding the type of form tie system being used. Not every waterproofing product is compatible with every tie configuration, so product selection should always align with the project specification and manufacturer’s recommendations.

Before selecting a waterproofing solution, consider:

• Compatible form tie system – Confirm whether the project uses removable form ties or a system designed for Rings & Connectors.
• Penetration size and geometry – Ensure the waterproofing solution matches the dimensions and configuration of the form tie hole.
• Clean, prepared penetrations – Remove debris and contaminants before installation in accordance with the applicable installation instructions.
• Correct positioning – Install waterproofing components in accordance with the relevant product instructions and project specification.
• Identify all relevant penetrations – Review the formwork layout and waterproofing design so that form tie penetrations requiring treatment are addressed consistently.

Detailed installation procedures, compatibility information and technical requirements are available in the relevant Technical Data Sheets for Form Tie Plugs and Form Tie Rings & Connectors.

Choosing the Right Waterproofing Solution

Form tie hole waterproofing is one part of a broader concrete waterproofing strategy. Water can also enter through construction joints, pipe penetrations, cracks and below-ground concrete walls, so selecting the appropriate waterproofing method begins with identifying where the potential water ingress occurs.

The infographic below provides an overview of the major waterproofing solution categories used throughout concrete construction and shows where Form Tie Plugs and Form Tie Rings & Connectors fit within Danterr’s waterproofing solution range.

Conclusion

Form tie penetrations are one of several locations where water can enter a concrete structure. Selecting the appropriate waterproofing solution depends on the form tie system, penetration geometry, exposure conditions and project specification rather than a one-size-fits-all approach.

Where compatible removable form tie systems are used, Form Tie Plugs provide a practical method for sealing completed penetrations after formwork removal. For compatible systems that incorporate waterproofing during construction, Form Tie Rings & Connectors are part of the sealing arrangement around compatible embedded spacer and tie details.

As part of a broader waterproofing strategy, form tie waterproofing should be considered alongside construction joint waterstops, penetration sealing and other applicable waterproofing systems to address different potential water-ingress points.

If you’re planning a below-ground, water-retaining or civil infrastructure project, Danterr’s technical team can help you select the most appropriate waterproofing solution for your construction method and project requirements.

Find the Right Form Tie Waterproofing Solution

Whether you’re sealing removable form tie holes or specifying waterproofing for a compatible form tie system, Danterr offers technical guidance and purpose-designed waterproofing solutions for compatible concrete form tie systems.

Explore our range of Form Tie Plugs, Form Tie Rings & Connectors, and related waterproofing systems, or speak with our team to discuss the most suitable solution for your next project.

📞: 1800 262 383
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