Thread: Zip Strip Concrete Joints

I inspected a new house that had four uneven cracks in the garage floor. The builder said that the cracks were okay because he used zip strips for the expansion joints. It told him that if zip strips joints are done properly you end up with a even groove in the concrete. What has been you guys experience with the zip joints? Are these cracks typical?

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www.superiorprofiles.com/PDF/Zip_Instructions.pdf

According to the installation instructions, the installer is supposed to float over the top of the zip strip once the top T part has been removed. That very thin coat of concrete will crack and follow the zip strip within a week. I believe minor variation in the crack as shown in your photo will occur.

Here is the site I sent to the builder for reference. Note it says the top is to be removed after the concrete has setup.

BoMetals Zip Joint: Two Piece Joint Inducer | concrete and masonry accessories: waterstop, flatwork keyway, control joint

James,

I have been involved in many slabs using zip strips. The picture you posted is typical of the results. It's fine.

Darren...thanks for the input. This is in the garage. In the driveway they used trowled joints and they are perfect and look great. I don't see how and why this jagged joint is better than a method that leaves a uniform joint. It's like a different contractor did the garage floor vs the one that did the driveway.

Originally Posted by James Duffin

Darren...thanks for the input. This is in the garage. In the driveway they used trowled joints and they are perfect and look great. I don't see how and why this jagged joint is better than a method that leaves a uniform joint. It's like a different contractor did the garage floor vs the one that did the driveway.

The zip strips or pow (point of weakness) strips are put in when the concrete is poured and the control joints your seeing in the driveway are more than likely cut in. I personally don't care for the jagged edge they leave either, but they are effective. This method just saves time of the contractor coming back to cut in the control joints.

Thanks door guy...

The ones in the driveway are troweled/tooled in but I went across the street to a house with just the house slab poured and they had sawn in the joints in the house slab.....they were perfect too. You could still see the red caulk lines they used as a guide. Same builder doing both houses.

My point is that the builder used three methods for the control joints and two of them left a clean line that could be caulked if desired and one method that left a jagged surface crack that can not be caulked and made look like it should. Hopefully my client can get the builder to put an epoxy coating on the garage floor to hide the cracks.

Originally Posted by James Duffin

Thanks door guy...

The ones in the driveway are troweled/tooled in but I went across the street to a house with just the house slab poured and they had sawn in the joints in the house slab.....they were perfect too. You could still see the red caulk lines they used as a guide. Same builder doing both houses.

My point is that the builder used three methods for the control joints and two of them left a clean line that could be caulked if desired and one method that left a jagged surface crack that can not be caulked and made look like it should. Hopefully my client can get the builder to put an epoxy coating on the garage floor to hide the cracks.

Hand grooved joints take the most time. I think they look the best. However they also easily fill up with dirt and debri. Saw cuts stay fairly clean looking, even if they are full. I think zip strips are ok to use on a basement floor when floor covering will conceal them. Just my opinion.

Never use red chaulk, never comes off...

Epoxy won't cover the cracks unless they are filled first, they will just telescope through.

Originally Posted by Door Guy

Hand grooved joints take the most time. I think they look the best. However they also easily fill up with dirt and debri. Saw cuts stay fairly clean looking, even if they are full. I think zip strips are ok to use on a basement floor when floor covering will conceal them. Just my opinion.

Never use red chaulk, never comes off...

Epoxy won't cover the cracks unless they are filled first, they will just telescope through.

I agree with everything you said. My client is a realtor I sometimes do work for so I should be able to follow up and see what happens.

The joints look typical. The strips (the product I have used is called Speed-E-Joint) leave a beautiful job if they are installed correctly. If they are installed a bit too deep, the crack will become more jagged. I find that the crack is much less noticeable than if they are cut in. The plastic strips are a pain in the neck to get nice and straight in a big floor though.