Author Topic: Another concrete question: DIY stairs and landing  (Read 773 times)

dragoncar

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Another concrete question: DIY stairs and landing
« on: September 26, 2018, 12:03:08 AM »
I've read through the other concrete threads, and I think this warrants a new post.

I'm planning to widen a concrete staircase and landing, 3ft originally, adding 2ft.  I'm going to veneer it afterwards with 3cm pavers.

My original plan was 6in 3/4 crushed rock plus 6 in concrete on top, 1/2 in rebar, with 6 in minimum throat on the steps.  I was going to dowel into the existing staircase and landing with epoxy.  This is all based on rudimentary online investigation.

After digging out the area, I see that the existing staircase and landing, which are totally solid, no cracks, look like half-assed 6-in on grade (meaning 3-5 in actual concrete, 6in throat on the stairs).  This is clay soil and I was originally worried about movement.

Given that concrete isn't particularly more expensive than crushed rock, should I just go ahead and pour 8-12 in of concrete?  Cost isn't really the issues ($1-200 more in concrete), I want to do a solid job.  We are talking about half a yard of concrete, which may increase to 1-2 yards depending on how crazy we go.  The short load fee almost covers the extra concrete.

Should I still dowel?  I read that doweling such a thin slab could cause spalling.  If I do dowel, should I drill 3/4 inch holes and epoxy #5 rebar (5/8in)?  Another suggestion I saw was to dig under existing concrete and pour a lip underneath.

I do not want to demo the existing staircase, just trust me on that.

Major issues I see are the clay soil and veneer.  I don't want the veneer cracking where the two slabs meet.  I could cut control joints into the meeting point, but it would look a bit wonky.  Necessary?

In sum, here are my questions:

1) Should I lay down crushed rock or pour double thick on grade?
2) Should I dowel into existing concrete, and if so what specs (rebar, drill, depth)
3) Should I cut control joints into the veneer despite the cosmetic effect?

lthenderson

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Re: Another concrete question: DIY stairs and landing
« Reply #1 on: September 26, 2018, 06:45:33 AM »
I can't really follow what you are trying to do but I have poured a lot of concrete and from what I understand you are trying to do, it sounds like a ton of work. It also sounds like if not done right, there could be numerous points of failure in the future that could cause problems. I'm guessing it would be lots of money ahead just buying another set of precast concrete steps from a local supplier and have them deliver and set it in place. We have a place here in town that makes all kinds of precast things from septic systems to steps where you specify the height and pick from several precast widths.

Fishindude

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Re: Another concrete question: DIY stairs and landing
« Reply #2 on: September 26, 2018, 10:20:55 AM »
Not what you want to hear, but  ...... Pinned and doweled together or not, you are going to get slight movement and cracking where the new and the old join which may lead to deterioration of the pavers you plan to veneer over the top.   I would seriously consider complete removal and replacement.

dragoncar

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Re: Another concrete question: DIY stairs and landing
« Reply #3 on: September 26, 2018, 01:19:39 PM »
Not what you want to hear, but  ...... Pinned and doweled together or not, you are going to get slight movement and cracking where the new and the old join which may lead to deterioration of the pavers you plan to veneer over the top.   I would seriously consider complete removal and replacement.

Eh like I said demo is not happening.  Whatís the best way to do this given the constraints we have?

lthenderson

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Re: Another concrete question: DIY stairs and landing
« Reply #4 on: September 27, 2018, 06:39:18 AM »
Not what you want to hear, but  ...... Pinned and doweled together or not, you are going to get slight movement and cracking where the new and the old join which may lead to deterioration of the pavers you plan to veneer over the top.   I would seriously consider complete removal and replacement.

Eh like I said demo is not happening.  Whatís the best way to do this given the constraints we have?

Hire someone to haul the old steps away and dispose of them. There really aren't any good shortcuts in this case.

Car Jack

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Re: Another concrete question: DIY stairs and landing
« Reply #5 on: September 27, 2018, 07:57:14 AM »
You're only going down 6 inches?  We're actually replacing wooden stairs with granite made on location.  Speaking with the mason, they're going down 3 to 4 FEET, putting in crushed stone then a concrete pad re enforced with rebar, then building the stairs on top of that.  6 inches ain't gonna cut it unless you live somewhere that has a slab of granite at the 6 inch point.

dragoncar

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Re: Another concrete question: DIY stairs and landing
« Reply #6 on: September 27, 2018, 11:22:10 AM »
You're only going down 6 inches?  We're actually replacing wooden stairs with granite made on location.  Speaking with the mason, they're going down 3 to 4 FEET, putting in crushed stone then a concrete pad re enforced with rebar, then building the stairs on top of that.  6 inches ain't gonna cut it unless you live somewhere that has a slab of granite at the 6 inch point.

Yeah but you have a deep frost line and I have none

dragoncar

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Re: Another concrete question: DIY stairs and landing
« Reply #7 on: September 27, 2018, 11:25:07 AM »
Not what you want to hear, but  ...... Pinned and doweled together or not, you are going to get slight movement and cracking where the new and the old join which may lead to deterioration of the pavers you plan to veneer over the top.   I would seriously consider complete removal and replacement.

Eh like I said demo is not happening.  Whatís the best way to do this given the constraints we have?

Hire someone to haul the old steps away and dispose of them. There really aren't any good shortcuts in this case.

Guys seriously, the old stairs are not going anywhere.  This is happening.  All I want are answers to the questions I posed.  I appreciate your outside the box thinking, but in this case you need to color within the lines.  Since nobody has answered those questions, Iím going to assume nobody here actually knows.

Fishindude

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Re: Another concrete question: DIY stairs and landing
« Reply #8 on: September 27, 2018, 01:24:14 PM »
So you are asking advice on how to best jerry rig something?
Proceed with your plan and see what happens.   Make sure it's sitting on a good base, bottom of concrete needs to be below frost line (if applicable), pin the heck out of it to the existing stairs, reinforce the new steps with rebar, apply a little bonding agent where new concrete butts against old prior to pouring, and use a good concrete mix.

Hope it works, but I think you will have some movement at the joint.
You could cover the tread surface with wood or fake deck board plank that will span over the joint and still remain in one piece even if things move around a little.  I'm about certain that tile or pavers laid over this will crack at the joint eventually.

dragoncar

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Re: Another concrete question: DIY stairs and landing
« Reply #9 on: September 27, 2018, 01:42:23 PM »
So you are asking advice on how to best jerry rig something?
Proceed with your plan and see what happens.   Make sure it's sitting on a good base, bottom of concrete needs to be below frost line (if applicable), pin the heck out of it to the existing stairs, reinforce the new steps with rebar, apply a little bonding agent where new concrete butts against old prior to pouring, and use a good concrete mix.

Hope it works, but I think you will have some movement at the joint.
You could cover the tread surface with wood or fake deck board plank that will span over the joint and still remain in one piece even if things move around a little.  I'm about certain that tile or pavers laid over this will crack at the joint eventually.

Yes Iím asking three specific questions above, and would like answers within the constraints provided.  If you are sure it will move at the joint, then see question #3, cutting control joints into pavers.  In that case itís less pretty but nothing will crack.  Thereís also the option of crack isolation membrane.

This isnít a game where you just come and criticize my plan without offering any specific knowledge.  There are better and worse ways to do things even when the underlying plan isnít optimal.  Iíve said it three times, the existing stairs arenít going anywhere.  I shouldnít have to justify that decision, so just trust me that it would be an engineering and logistical nightmare.  I have also purchased the materials for this project.  So simply telling me not to do it is completely unhelpful. 

I put it to you, armchair concrete experts.  I believe you if you think my project is doomed to fail, but show me your expertise and answer my questions three. 

lthenderson

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Re: Another concrete question: DIY stairs and landing
« Reply #10 on: September 28, 2018, 07:01:38 AM »
I have read lots of Fishindude's advice over the years and it has always been spot on. He and I are both telling you that your solution is doomed in failure and yet you keep asking us how best to do it.  Some of the reasons: Pinning concrete to existing concrete horizontally is generally not a good idea especially over an unstable sub-base. First off, you can't seal the joint from future moisture so the rebar begins to rust immediately. In a decade, you no longer have a pinned joint anymore. You said you have no frostline but if it ever freezes and their is moisture in the crack, it will essentially jack the two slabs apart or spall off chunks.  Also, concrete poured right next to other concrete can catch as one slabs moves and not the other causing all sorts of interesting problems. My garage floor was poured that way and when it heaved and caught on the house slab, it buckled as much as a foot in places. When I bought the house and repoured the floor, I put an isolation barrier in and the problem went away. The only way I would pour concrete right next to other concrete is to have a very stable, well draining base and put in an isolation joint.

Veneers on top of horizontal concrete never last too long. Mortar cracks, concrete moves and cracks and you are thinking about cutting an expansion joint between the two slabs. Anyplace moisture can get under the veneer layer opens it up to freezing and popping off the veneer. I don't know where you live and how often you get freezing weather so it is hard for me to advise you on your chances of this happening. But clay also expands and shrinks with moisture changes.

So to answer question 3, yes, I would cut an expansion joint where the two slabs meet which then opens you up to a whole host of future problems from rusted rebar, water getting down in the joint to expand the cracks with a freeze or hydrating the clay and expanding it as well causing it to heave. But at least you reduce the chances of cracking your veneer.

Papa bear

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Re: Another concrete question: DIY stairs and landing
« Reply #11 on: October 02, 2018, 08:22:18 AM »
So you are asking advice on how to best jerry rig something?
Proceed with your plan and see what happens.   Make sure it's sitting on a good base, bottom of concrete needs to be below frost line (if applicable), pin the heck out of it to the existing stairs, reinforce the new steps with rebar, apply a little bonding agent where new concrete butts against old prior to pouring, and use a good concrete mix.

Hope it works, but I think you will have some movement at the joint.
You could cover the tread surface with wood or fake deck board plank that will span over the joint and still remain in one piece even if things move around a little.  I'm about certain that tile or pavers laid over this will crack at the joint eventually.

Yes I’m asking three specific questions above, and would like answers within the constraints provided.  If you are sure it will move at the joint, then see question #3, cutting control joints into pavers.  In that case it’s less pretty but nothing will crack.  There’s also the option of crack isolation membrane.

This isn’t a game where you just come and criticize my plan without offering any specific knowledge.  There are better and worse ways to do things even when the underlying plan isn’t optimal.  I’ve said it three times, the existing stairs aren’t going anywhere.  I shouldn’t have to justify that decision, so just trust me that it would be an engineering and logistical nightmare.  I have also purchased the materials for this project.  So simply telling me not to do it is completely unhelpful. 

I put it to you, armchair concrete experts.  I believe you if you think my project is doomed to fail, but show me your expertise and answer my questions three.
Yeah, not sure why you are blasting him on advice. Fishindude is always spot on from the construction side.  and if paddedhat we’re still posting here, I’m sure he’d say the same.

But go ahead, put lipstick on the pig, and deal with the issues with a poor job in a few years. 

Jon Bon

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Re: Another concrete question: DIY stairs and landing
« Reply #12 on: October 02, 2018, 11:33:13 AM »
Pictures might help.

dragoncar

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Re: Another concrete question: DIY stairs and landing
« Reply #13 on: October 02, 2018, 08:44:17 PM »
So you are asking advice on how to best jerry rig something?
Proceed with your plan and see what happens.   Make sure it's sitting on a good base, bottom of concrete needs to be below frost line (if applicable), pin the heck out of it to the existing stairs, reinforce the new steps with rebar, apply a little bonding agent where new concrete butts against old prior to pouring, and use a good concrete mix.

Hope it works, but I think you will have some movement at the joint.
You could cover the tread surface with wood or fake deck board plank that will span over the joint and still remain in one piece even if things move around a little.  I'm about certain that tile or pavers laid over this will crack at the joint eventually.

Yes Iím asking three specific questions above, and would like answers within the constraints provided.  If you are sure it will move at the joint, then see question #3, cutting control joints into pavers.  In that case itís less pretty but nothing will crack.  Thereís also the option of crack isolation membrane.

This isnít a game where you just come and criticize my plan without offering any specific knowledge.  There are better and worse ways to do things even when the underlying plan isnít optimal.  Iíve said it three times, the existing stairs arenít going anywhere.  I shouldnít have to justify that decision, so just trust me that it would be an engineering and logistical nightmare.  I have also purchased the materials for this project.  So simply telling me not to do it is completely unhelpful. 

I put it to you, armchair concrete experts.  I believe you if you think my project is doomed to fail, but show me your expertise and answer my questions three.
Yeah, not sure why you are blasting him on advice. Fishindude is always spot on from the construction side.  and if paddedhat weíre still posting here, Iím sure heíd say the same.

But go ahead, put lipstick on the pig, and deal with the issues with a poor job in a few years.

I'm not blasting anyone, I'm simply asking specific questions and getting generic naysaying in return.  Note that fishindude and lthenderson actually disagree.  One says to dowel the hell out of it and the other says don't dowel.  Neither actually answers my question as to dowel dimensions, base thickness, or controls.

Despite the fact that I asked about cutting controls into veneer, I get complaints that veneer will crack where slabs meet.  Well it won't if there's no bridge over the meeting point, so that's a roundabout way of saying yes, cut a control into the veneer.

There are veneer installations in my neighborhood that have been in place 10, 20, and even 30 years so it's a very common practice and I don't agree that a veneer will inevitably fail.  We don't have a freeze thaw cycle so maybe that helps.

Bottom line is you can help me install the materials I have in the best way possible or just naysay.  It's actually a common problem on this site where someone asks how they can reduce spending on such and such and they get answers like "you don't need such and such".  How can I get better gas mileage through hypermiling?  Actually a car is bad for the environment just sell it.  Thanks, super helpful.






BDWW

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Re: Another concrete question: DIY stairs and landing
« Reply #14 on: October 05, 2018, 12:47:54 PM »
It's hard to say with seeing it, I'm imagining a short stoop?

I would completely decouple the sides. If it's how I'm picturing it in my head, I would use a piece of marine plywood between them. Make sure you have a good layer of gravel underneath for drainage. Then I would use a decoupling membrane for setting the pavers on top of them.

Not saying it's right, but that's probably how I would do it.