Can I skip backer rod for thin concrete cracks?
When concrete cracks are too thin to squeeze a backer rod into, you can either cut the rod into thinner strips or skip it totally before applying Sikaflex. Leaving the crack as is makes people worry the concrete will collapse, prompting them to consider filling the gap with bricks or stones instead.
What the numbers show
Counted from the threads quoted below. How we count
- People have been saying this in most months since September 2026.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
Can I skip backer rod for thin concrete cracks?
- 1Skipping the backer rod entirely or cutting it into thinner strips to stuff into the cracks.Did this help you?
- 2Putting bricks or stones to fill the gapDid this help you?
- 3Testing drainage joints with a garden hose to locate leaksDid this help you?
- 4Unclogging and resealing joints in the underground drainage systemDid this help you?
- 5Building a small retaining wall to divert water away from the concreteDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“most of the cracks are so thin I won't even be able to fit squeeze the backer rods into the cracks. Should I still maybe cut up the backer rod into thinner strips to stuff into the cracks before applying the silkaflex on top, or is it okay to just skip the backer rods totally?”source ↗
“The concrete will collapse one day if I leave it as that?”source ↗
“What can I do to prevent the black cap back flow?”source ↗
“Thanks, I was thinking put bricks or stones to fill the gap. What do you think of that?”source ↗
Where this came up
People with this problem also raised
- 29How to fix concrete cracks near garage foundation
- 2How to fill a deep concrete void under a slab or wall
- 4How to fill a wide gap between garage floor and driveway
- 3Contractor poured concrete over basement floor access holes
- 2Will concrete in the backyard crack and look bad over time?
- 5Painted concrete basement floor keeps dusting and crumbling