PU Injection Grout

PU injection is one of the suitable waterproofing methods for some water leaking issues such as roof cracks and balcony leakage. We apply chemical pressure to the defect areas. When the PU touches base with water, the chemical reacts and expands to seal the cracks. It is one of the preferred methods if you do not want to hack on the water leaking floors. You only need to drill some holes on the wall and apply PU injection in the holes. For more details, refer to the below steps.

How it is performed

Unlike flexible cementitious waterproofing, this PU injection method uses high-pressure injection technique. The chemical liquid travels through the foundation walls. Then, it solidifies when it mixed with water. Thus, it will prevent water from leaking into the cracks. 

Normally, we will drill holes on the affected water leaking walls, before applying PU injection waterproofing. The hydro liquid form of polyurethane is able to flow into cracks, hence permanently sealing the cracks. 

This non-toxic chemical will not freeze and is more flexible as compared to cement. It sets quickly; making it an ideal product to use especially when filling large cracks.


The advantage of PU injection is that it’s cheaper compared to other waterproofing methods. Besides that, it saves a lot more time due to its quick to dry chemicals. Last but not least, it requires a less clean up and less disturbance (do not need to hack).

However, do avoid injecting PU chemicals into expansion joints or cracks that are subject to movements. This is because the gel will disperse under tension/compression, which will damage the seal.

The proper PU injection waterproofing requires training, skill, knowledge, and the right equipment. Hence it is wise to hire a professional waterproofing contractor to perform this technique. Although this method is not guaranteed to solve all leakage problems, if applied correctly, PU injection repairs are permanent.

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