KNOWLEDGE · CONSTRUCTION AND EXPANSION JOINTS

Drilling and injecting construction joints

First establish the joint position and water path. Then select access, the packer installation zone and points that show filling progress.

Assessment Procedure and options Selection and next step

EXPLORE THE METHOD

Wall–slab joint: from assessment to reinstatement

See the full cross-section and three access options. Access above the floor layer, through a thick floor layer and local exposure are alternatives. After selecting an option, the illustrations guide you through preparation, injection observation and two reinstatement methods, including one with an injection hose.

Slab joint with three wall types: concrete, brick and stone. Water may migrate through the junction between different materials.

01 · Assessment

Assess the joint and water path

First establish which elements form the leaking connection. The foundation slab, wall and additional floor layer have different functions. Moisture visible near the floor does not yet identify where injection material must be delivered.

The three wall materials shown are substrate options. Select the hole path, packer installation and sealing material for the actual cross-section, water and movement in the joint. Subsequent illustrations first show access without exposure, followed by a separate option with local breakout.

Distinguish the floor layer from the structural slab.
Establish whether leakage comes from the joint or another layer.

Material selection for the joint →

An angled hole from the wall face intersects the joint above the foundation slab; the additional floor layer remains in place.

02 · Access without breakout

Option A: access above a thin floor layer

Where geometry permits, the hole starts above the floor layer and intersects the target joint deeper within the wall. Starting height, angle and length together follow from wall thickness and fissure position.

WALL means wall thickness, FLOOR the additional floor layer, FOUNDATION PLATE the foundation slab, ANGLE the angle and DRILL the drilling length. DRILLING HEIGHT means the hole starting height above the top surface of the floor layer. The 50% label is an assumption of the option shown; joint intersection must be confirmed on site.

Measure the actual cross-section.
Account for reinforcement and service locations.

Calculate access to the joint →

Material injected into the joint appears at the next point.

03 · Access without breakout

Check option A with an injection trial

The trial point must show whether the completed hole actually communicates with the joint. Observe uptake, pressure and where material appears rather than drawing conclusions from drill bit length alone.

Communication to an adjacent packer confirms a connection, but not complete filling of the entire fissure. Lack of communication requires checking access, clear passage and migration paths; it does not itself justify breaking out the floor.

Observe more than one point.
Do not equate communication with watertightness acceptance.

Application trial →

A thicker floor layer changes the drilling start; the packer installation zone must lie in suitable wall material.

04 · Access without breakout

Option B: access through a thick floor layer

If the floor layer obscures the required starting height, the option shown takes the hole through this additional layer to the wall and joint. Floor layer thickness must not be replaced by foundation slab thickness.

DISTANCE means offset from the face, and PACKER DISTANCE the packer installation reach. The packer sleeve must seal the hole in sound substrate and leave clear access to the fissure. Installation solely in a weak floor layer may be insufficient.

Check access and actual packer length.
Identify layers beneath the floor.

Select packer length →

A packer delivers material through the thick floor layer to the wall–slab joint; an adjacent point is observed.

05 · Access without breakout

Check option B before extending the works

After installation, check that the assembly remains tight around the packer and directs material to the assessed zone. Material appearing beneath the floor may indicate a path different from the target joint.

If the trial confirms access and controlled injection, the floor can remain. Decide on local exposure only after assessing the cross-section, face tightness and cause of the unsuccessful trial.

Compare observations with the planned cross-section.
Record discharge locations and consumption.

Pressure and observation →

Cutting the additional floor layer defines the boundary for local joint exposure.

06 · Exposing the joint

Option C: mark and cut the exposure strip

This option starts only when exposure is needed to prepare or seal the leaking zone. Cutting defines the demolition edge and limits uncontrolled floor breakage.

Set the extent and depth according to the identified layers. The drawing does not authorise cutting the structural slab, reinforcement or hidden services.

Confirm which layer is flooring and which is structural.
Mark only the necessary working strip.

Local floor removal exposes the connection at the wall base.

07 · Exposing the joint

Remove the marked strip and inspect the joint

Removing the marked strip allows inspection of the joint face, loose fragments and inflow locations. This verifies the earlier assessment; it is more than simply making room for tools.

Clean the exposed detail and check that the revealed geometry matches the plan. Changes in layers or fissure position require adjustment of subsequent access.

Do not damage reinforcement.
Update the plan after exposure.

After exposing the floor, angled holes lead from the wall face to the identified connection.

08 · Hole preparation

Set out and drill holes to the joint

The holes must intersect the joint in the planned zone. Maintain consistent geometry while adapting it to actual changes in thickness and connection path.

Drilling start distance, angle and length are interdependent. Changing one dimension may move the hole end beyond the target, so the angle reading alone is insufficient.

Verify intersection on a trial section.
Check depth and direction.

Construction joint drilling geometry →

A chase at the wall base prepares the substrate for a fillet.

09 · Face preparation

Prepare the area for face sealing

The prepared chase must support the face seal and provide adhesion. Remove weak fragments and contamination that could cause debonding during injection.

Chase extent follows the planned detail. Do not deepen it without structural assessment or use it to conceal evidence of another inflow path.

Retain sound substrate.
Do not damage hole edges.

A mortar fillet seals the joint face between wall and slab.

10 · Face preparation

Form a fillet to restrict discharge

The fillet limits injection material escaping onto the surface and helps direct it into the connection. Check substrate preparation and CrackOn.5 application conditions in the product data sheet.

The main seal forms inside the joint. A new fillet alone does not confirm fissure filling, and its role in subsequent reinstatement must be defined before work.

Retain access to injection points.
Check seal continuity.

CrackOn.5 — application conditions →

Flushing removes dust from the hole before packer installation.

11 · Hole preparation

Clean the holes and confirm clear passage

Dust and drill cuttings hinder packer installation and material access to the joint. The stage shown includes hole flushing; the medium and preparation method must suit the selected material and substrate.

Distinguish hole cleaning from pump flushing. Introducing water into the line carrying a water-reactive resin may start the reaction inside the equipment.

Check that drill cuttings have been removed.
Match preparation to the injection material.

Cleaning the delivery system →

Packers in the completed holes lead to the joint behind the fillet.

12 · Injection

Install packers in sound substrate

Select the packer for actual hole diameter, layer thicknesses and sleeve sealing location. The packer must remain stable, and incorrect installation must not block its injection path.

The drawing shows geometric access to the joint. Dimension labels do not define the wall's permissible pressure or the force for tightening every packer model.

Check connection tightness.
Retain the ability to observe adjacent points.

Steel packers →

Yellow material reaches the joint; an adjacent point allows communication to be observed.

13 · Injection

Start injection and observe communication

Start on a trial section and observe uptake, pressure and discharges together. Material should remain in the assessed zone rather than disappear uncontrolled into voids beneath the floor.

Material appearing at the next point is a sign of spreading. Record the observation and adapt further injection to material working time and structural behaviour.

Monitor the fillet and surface.
Do not increase pressure merely to force communication.

Interpreting pressure and flow →

Injection has moved to the next packer while the further section of the joint remains under observation.

14 · Injection

Move to subsequent points

Continue according to the established sequence and observations so far. Changing points does not remove the need to monitor the previously injected zone, since material may return or open another escape path.

Compare material quantity and response at successive points. A marked difference may result from joint non-uniformity, a void, substrate change or blockage and requires investigation.

Keep records for every point.
Also observe previous sections.

Material appears on the fillet surface instead of remaining solely inside the joint.

15 · Monitoring during work

Check uncontrolled seepage

This illustration shows possible behaviour during work, not a desired stage of every injection. Surface discharge requires assessment of whether the face seal retains material and whether injection reaches the correct zone.

Stop or adjust injection according to observations. Do not treat visible resin outside as proof of effective connection filling.

Identify the discharge location and cause.
Check the seal and migration path.

Returning to a previously injected point tops up a zone requiring further filling.

16 · Top-up and acceptance

Consider re-injection within the material's working time

Re-injection can top up areas where the trial and observation showed further injection was needed. Its feasibility depends on the point remaining clear and the actual material condition.

“While fresh” does not specify one common time for all resins. Base the decision on product instructions, temperature and material behaviour; do not try to force a cured blockage through with higher pressure.

Confirm clear passage.
Do not exceed material and assembly operating conditions.

Pump preparation and cleaning →

The exposed strip beside the wall is filled with stone aggregate or expanded clay.

17 · Reinstatement alternatives

Finish A: a strip with access for inspection

The finish shown may allow easy re-exposure of the repaired location. It is a functional option for a suitably designed zone, not an additional sealing material.

Backfill does not replace acceptance of the completed injection. Select the solution for room use, access and floor reinstatement requirements.

Verify watertightness before covering.
Establish the subsequent inspection method.

The cross-section shows water moving beneath the additional floor layer beside the repaired joint.

18 · Top-up and acceptance

Distinguish water beneath the floor from joint leakage

Water visible in the inspection strip may come from layers beneath the floor even though the wall–slab connection itself is sealed. Compare the location of moisture with the path of individual layers.

Distinguishing these paths helps assess the repair and plan further investigation. Do not automatically treat every new damp mark as proof of missing material in the joint.

Observe where the water comes from.
Assess the joint and floor layers separately.

A hose is fixed in the exposed strip beside the existing wall, with accessible ends brought out.

19 · Reinstatement alternatives

Finish B: prepare a hose before reinstatement

When reinstating the floor, a hose can be planned as access for future injection. The scene shown concerns reconstruction after local breakout, not the first casting of a new wall.

Before covering, establish the section layout, fixing and access to both ends. The hose does not replace the completed repair or remove the need to assess watertightness before reinstatement.

Record section positions.
Protect and label feed lines.

Hoses in a reinstated joint →

After reinstating the floor strip, accessible hose ends remain beside the wall.

20 · Reinstatement alternatives

Reinstate the floor while preserving access

After checking installation, reinstate the layer according to the selected detail. Protect lines against crushing and movement, and leave connection points accessible and clearly labelled.

A first future injection and reuse of an already filled hose are different situations. Re-injection depends on the system, material and how the previous work was completed; the presence of hose ends alone does not ensure it.

Check access after reinstatement.
Include the section map in the documentation.

Material selection for the hose →

The joint beneath a wall may be hidden

At a construction joint, the wall and slab were built at different stages. Water may travel along this connection and emerge only at the edge of an additional floor layer. Before setting out boreholes, establish the cross-section: wall thickness, joint level, floor layer thickness and foundation slab position. Also check existing waterstops, hoses and previous repairs.

Distinguish a construction joint from an expansion joint intended to move. A similar leakage line does not mean the same joint function. At the junction of old masonry and a new slab, additionally identify mortar joints, uneven substrate and possible voids. See the assessment of such a joint in Piotr Kobus's case study.

Two access methods, one target zone

With moderate floor thickness, entry through the wall may intersect the joint without drilling through the finish layer. With a thick floor layer, consider entry through it leading onward to the correct zone. Passing the bit beneath the visible edge is insufficient: it must reach the identified connection plane.

When entering through the floor layer, the packer expansion sleeve should lie in sound wall material beyond that layer, according to the access geometry. Select body length and sleeve zone accordingly. Overall borehole length is not packer length. The construction joint drilling calculator organises the geometry, while the first holes verify it on site.

When should the joint face be exposed?

If a trial shows communication between points and injection can be controlled, the floor need not be removed merely to see the joint line. Expose a local strip when the concealed leaking face needs cleaning and sealing and the retained floor prevents those operations.

After identifying the layers, mark the area for cutting and removing the additional floor. Drill holes, prepare and clean the fillet area, then form the specified CrackOn.5 seal. Clean holes according to the material method; for water-reactive resins, flushing may also reveal communication. Install packer bodies before resin appears in the holes.

The trial must explain the flow path

Material appears at the next point

This confirms communication. Check that the path corresponds to the joint zone and continue filling according to established criteria. The first trace of resin alone does not confirm the entire cross-section.

Discharge at the fillet, without onward communication

Check seal tightness, hole intersection and spacing. Resin may take an easier path towards the surface; increasing pressure does not automatically resolve this cause.

Pressure rise without uptake

Check assembly passage, borehole and sleeve position. The hole may miss the joint or the joint may be locally discontinuous. Stop injection and identify the cause.

High uptake beyond the planned section

Look for a void or connection to another zone. A shorter section, an additional observation point or a changed reaction time may be needed before continuing.

Inject in sections and allow time for inspection

Treat initial spacing as a hypothesis for the trial. In the existing option, half the wall thickness is the starting point, but actual communication and substrate determine the subsequent layout. Do not repeat the grid if the first points miss the zone or material bypasses the intended section.

Increase the setting gradually while observing uptake, communication and the joint face. After material passes through, close the specified points according to the assembly instructions. Carry out any re-injection within the material working window and under control; setting resin should not be forced using pressure alone. Explore pressure and observation principles.

Watertightness and access after repair

Inspect the entire section, including ends and adjacent water migration locations. Record the injection procedure and water conditions during inspection. Moisture between the floor layer and slab may originate from a path other than the repaired joint.

Match floor reinstatement to its use. A removable strip filling may facilitate later inspection; during floor reinstatement, you can plan an injection hose for future intervention. Installation requires correct positioning and accessible ends; it does not itself prove the completed repair is watertight.

RESINBAU SELECTION

Calculate what you know

CALCULATORConstruction joint drilling →

Determine hole entry, angle and length from the actual cross-section.

CALCULATORMaterial quantities →

Separate the assessed volume from the allowance; adjust assumptions based on the trial.

Next step

Plan sections and ends before reinstating layers.

Check actual diameter and sealing zone.

Discuss your project conditions

Prepare a cross-section, a description of water and movement, and results of previous trials. ResinBau helps select the material and application method.

Discuss your project / technical selection ↗