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dansaleen_04
Concrete expansion joint

Hello everyone, this is my first post in this forum. I have somewhat of a big project this weekend and need some advice. I am pouring a 15' X 30' patio slab 4" thick along the back of my house. Between the house and the slab I will be installing a fiber expansion joint since the house is still brand new and it still needs to settle correctly. But not only am I pouring a slab, I am also pouring a 2 level concrete step on the slab going to the house. my question is, do I also install fiber expansion joint between the step and the house or not? And if so, any recommendations on how to install since the fiber board is only 4" tall and obviously the steps are going to be 18" tall in total. Anything would be greatly appreciated. Thanks everyone and anyone!

A. Spruce
Re: Concrete expansion joint

1 - Create a footing under the steps or you're going to have cracking of your slab due to the weight.
2 -If the steps will be touching wood, you have to have a sheetmetal barrier separating the two.
3 - You could do this in a monolithic pour, but this is not something for the average DIY'r, it would be better to pour one, then the other. If you pour the steps first, they will be independent of the slab, thus nearly eliminating any chance of later cracking. If you pour the slab first, you'll have a little easier time finishing without the steps in the way, but only minorly so.
4 - an expansion joint along the house would only serve to make the pour/finishing easier because it gives you a "form" to screed and finish to. Alternatively, you would set a form board several inches away from the house to use as a screed, once the screeding is done, pull the form board and sprinkle in concrete to fill the void. Again, not an average DIY'r move, so using the fiber X-joint along the house would be much easier for you. You can attach the material directly to the house. DO NOT bury or leave wood stakes, as this attracts termites that can infest the house.

dansaleen_04
Re: Concrete expansion joint
A. Spruce wrote:

1 - Create a footing under the steps or you're going to have cracking of your slab due to the weight.
2 -If the steps will be touching wood, you have to have a sheetmetal barrier separating the two.
3 - You could do this in a monolithic pour, but this is not something for the average DIY'r, it would be better to pour one, then the other. If you pour the steps first, they will be independent of the slab, thus nearly eliminating any chance of later cracking. If you pour the slab first, you'll have a little easier time finishing without the steps in the way, but only minorly so.
4 - an expansion joint along the house would only serve to make the pour/finishing easier because it gives you a "form" to screed and finish to. Alternatively, you would set a form board several inches away from the house to use as a screed, once the screeding is done, pull the form board and sprinkle in concrete to fill the void. Again, not an average DIY'r move, so using the fiber X-joint along the house would be much easier for you. You can attach the material directly to the house. DO NOT bury or leave wood stakes, as this attracts termites that can infest the house.

Hey spruce

Thanks for the response. I dont mean to be rude but I didn't understand really your 4 responses to my question. Maybe I need some more clarification Im dyslexic from time to time lol.
My question again, do I require an expansion joint between my concrete steps and the FOUNDATION of the house?
My foundation is concrete obviously, there is a 2x6 ledger for the original steps that were in place. the house is new so it is still settling. the steps will be pured along with the slab so in theory it is attached to the top of the slab. the slab is having expansion joint installed between itself and the house. So again, is an expansion joint required for the concrete steps to be poured against the house? And if so, the expansion joint is only 4 inches tall whereas the steps total height is 18", how do you install it?

again sorry, no disrespect or rudeness implied!

A. Spruce
Re: Concrete expansion joint

You will already have an expansion joint, simply because the house is "old" concrete and the patio is new. With no mechanical connection, the two are free to move independently of each other. As I said before, the only reason a felt expansion joint would be put against the house is so that you have something to screed and finish to. As for putting something between the steps and the house, again, the only reason this is necessary is if the concrete steps will be over siding or framing, then you only need to use a piece of sheet metal as a pest barrier.

If the 2x6 ledger is a wood member, I would remove it before pouring your concrete steps, again, not good to bury wood in concrete.

dansaleen_04
Re: Concrete expansion joint
A. Spruce wrote:

You will already have an expansion joint, simply because the house is "old" concrete and the patio is new. With no mechanical connection, the two are free to move independently of each other. As I said before, the only reason a felt expansion joint would be put against the house is so that you have something to screed and finish to. As for putting something between the steps and the house, again, the only reason this is necessary is if the concrete steps will be over siding or framing, then you only need to use a piece of sheet metal as a pest barrier.

If the 2x6 ledger is a wood member, I would remove it before pouring your concrete steps, again, not good to bury wood in concrete.

OK, the original steps that were in was poured up to the wood by the contractor. the house was built in march 2016. they had the concrete directly against the wood ledger. if I remove it, that would require me to also add siding and flashing to the sides of where the steps would be. But I get what your saying as far as pouring against it and not needing an expansion joint. Should I at least seal the edges with an caulk type sealer or leave it as is?

A. Spruce
Re: Concrete expansion joint

There is no need to seal the joint with anything. Just make sure the patio slopes away from the house, 1/4" per foot slop is typical and adequate.

The one thing with the ledger is that you want to make sure that you are not creating a leakage point, so if that means cutting it out and filling in with siding, that is the way to go. You only need to do this where the steps are located, you don't necessarily need to remove the entire ledger. The reason to remove it is that encapsulating it in concrete will promote rot, which you do not want to do.

HoustonRemodeler
Re: Concrete expansion joint

Or pour the patio without the stairs, then slap down a set of pre-formed ceement stairs which are hollow, lighter, cheaper, and easier than forming solid stairs.

dansaleen_04
Re: Concrete expansion joint
HoustonRemodeler wrote:

Or pour the patio without the stairs, then slap down a set of pre-formed ceement stairs which are hollow, lighter, cheaper, and easier than forming solid stairs.

LOL, if it werent because I already made my forms I would so do that in a heart beat lol. But then again wife wants everything done correctly so it is what it is now. Ill post pictures after everything is done this week end!

Mastercarpentry
Re: Concrete expansion joint

Yes you need the expansion joint fiber board between steps and house IF those stairs are going to have a physical connection with the slab or are going to pour along with it. That material provides both isolation and waterproofing. Joints in the material are simply butted together, but you can duct tape them if you want to. What I'd recommend is that you pour the slab flat, then after a few days pour the steps with a few layers of heavy poly in between (still using the expansion joint as before) so that if there's any separation movement, you can push the stairs towards the house more easily later on. Let the poly extend well past the stair forms to handle spillage and seepage. And the stair form needs to be held down until it cures as it will tend to float- you may have to get creative there. A few sacks of concrete atop spaced-off boards or a number of concrete blocks hung on the sides with wire will be enough for a few steps rise. I'd also recommend a 'toe-down' on the edges of he slab of about 6"-8" depth and 8"-12" width which will add both strength and stability.

Those stairs don't need to be solid, you can fill the non-exposed areas with anything non-organic which will not float and save some concrete- that can be a great place to dispose of rocks dug out during the slab excavation. Just leave a couple inches of concrete everywhere, double that thickness on the horizontal parts. Remember to bevel cut the riser forms so your trowel can reach all the way to the "L" between treads and risers.

After a month or so, you can go back and gouge out some of the expansion joint then caulk it for aesthetics. I'd do that at the top anyway for a little extra water-tightness.

Phil

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