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How to apply epoxy to garage floor expansion joints?

Hi there, I’m starting a project to epoxy my garage floor, my garage is made up of 4 concrete slabs with a large dent between them, I’m assuming this is to allow the concrete to expand? Do I need to patch this before applying the epoxy? If I patch it does it compromise the concrete because it can no longer expand? And if I do need to patch it what is the best product? It’s quite a wide crack so want to ensure I’m using the correct product.

also we have already etched the concrete so Hoping I won’t need to watch again over the patching?

help!

thanks

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EricL

Hello @arielsturdy

The instructions for the Epoxy set does recommend that any cracks be filled in before applying the garage coating. I suggest using a hard drying filler such as Earl's 500g Concremate Expanding Cement.

The other option of course is to leave the cracks as they are and just make sure to saturate the cracks with the epoxy paint. Once the epoxy hardens and cures, you can then use a flexible filler such as Gripset Betta 1L Concrete Crack Filler to cover the top of the crack. Because it is a flexible filler, I don't recommend painting over it.

I wouldn't worry when filling the cracks on your cement slabs. They run much deeper and are there to absorb any movement from the slabs, hence you see cracks on the control joints. Should any large-scale movements happen those control cracks will work just fine even with the filler in them.

Here is a handy step-by-step guide: How to apply epoxy to a garage floor

Here are some amazing garage floor projects shared by our Workshop members:

Epoxy concrete floor for large shed by @CSParnell
Epoxy garage floor transformation by @maknilsin
Epoxy on newly built house garage by @An_kn.

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

Eric

arielsturdy

Thanks so much @EricL @this is really helpful. I’ll get patching! I actually went to my local Bunnings last night and they recommended concrete bog, is that ok to use or is the product you recommended better/easier to use?

thanks

Ariel

MitchellMc

Hi @arielsturdy,

@EricL will be back on the site after the weekend, and I trust he'll add to the discussion if needed.

I thought I'd add that if you fill these dents and if there is any movement in the slabs, there is a high chance that the filler will crack, and any paint over it will likely follow suit. There's obviously been some movement already, as there are cracks seen in your expansion joints. I suggest filling the cracks within the expansion joint itself and painting over as is. Personally, I wouldn't be filling the dent up so it is flush with the surrounding surface.

The concrete bog is not a flexible filler, so it wouldn't be something I'd recommend over an expansion joint. Quite a few products have been recommended to you, and it's starting to get a little confusing. I'd suggest that the manufacturer of the epoxy paint would not recommend you paint over flexible expansion joints. The paint is designed for solid concrete surfaces. Given the expansion joints already have a flexible filler between them, I would be filling the cracks in them with a flexible filler like Sikaflex 11FC. You'll then be able to make the decision if you'd like to paint over the expansion joint, bearing in mind that the paint could crack in those locations due to it being over a moving expansion joint.

Bear in mind that if you fill the dents, you'll need to do an incredible amount of sanding and blending to make them seamless before painting, otherwise you're going to see your filling job through the paint. It will then most likely crack in the near future. I believe the finish will be much neater if you leave the dents and paint over them.

Please let me know if you have any questions.

Mitchell

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