How to fill gaps under pavers?

[jackle]

Hello!

I would appreciate any advice on filling a newly formed gap that’s formed underneath our outdoor pavers. Pieces of concrete (and other stuff?) have just come off and look like they might keep falling off.

 

[MitchellMc]

Welcome to the Bunnings Workshop community @jackle. It's great to have you join us, and many thanks for your question about filling under pavers.

It appears that cement-based grout has been used to fill this gap. However, due to the expansion of the pavers and timber, the grouting has failed. You might like to remove the remaining grout and replace it with a flexible polyurethane filler such as Sikaflex 11FC. This flexible filler would be much suited at dealing with the stress and movement of pavers over timber.

Please let me know if you have any questions.

Mitchell
 

[jackle]

Thanks @MitchellMc!

The remaining grout to the right is still quite set. Should I still try to remove it and break it apart with something like a chisel and mallet? Also, the timber below is a long board that is no more than 2 inches thick. Beyond that, the pavers are sitting on the cement-based grout. Is Sikaflex still the right product for this?

[MitchellMc]

The grout to the right has already delaminated from the tile, as seen by the gap @jackle. So, I'd be inclined to try to remove it with a chisel before it just falls out. Remember your PPE, including safety glasses, a face mask and gloves.

Sikaflex would still be suitable as it likely has the best properties of the available options.

Mitchell 

[jackle]

Thanks @MitchellMc. I made an attempt at filling the gap after removing the remaining loose grout. I’m not very strong to begin with but applying even a little bit of filler was very time consuming with the caulking gun.

Is there an appropriate expanding foam available that I could use to expedite the process?

[EricL]

Hello @jackle 

I don't advise using self-expanding foam as it does not provide an adequate seal. 

In regards to the slow flow of the filler, I suggest checking the tip of the tube making sure that opening is wide open. Next, I propose cutting the opening of the nozzle bigger to allow better flow.

If you still experience difficulty, please check the date of the silicone you purchased as it might be that the product has gone off.

Please keep us updated with your progress, we look forward to seeing the gap filled and repaired.

If you have any other questions we can help with, please let us know.

Eric