[Matt Kulp]

John,
You are exactly right about the settling. What should happen on every foundation less then 5 years old, you should dig all the way down to the bottom of the footer of the house or as far as it takes to find virgin fill and then bring up with compacted stone.

[neversatisfiedj]

Yeah well sometimes getting a jumping jack in there at the lasts 2 risers in not going to happen. I just use a 10x10 hand tamper and use my all to wet and pack the heck out of it. I definately could use a nice stair seminar. I missed one at MAHTS , could not go because of the ice storm MD had. I also need more experiance with soil conditions. I have to change my contract for overdigs . Great discussion guys !

Josh

[neversatisfiedj]

When going to the footer of the house, use modified stone or clean drain stone ?

Josh

[Matt Kulp]

Always modified, that is the only way your are going to get proper compaction. Drain stone would open up a whole can of possible water issues for the basement.

[Stonehenge]

But which would be less expensive - digging down 8-10' and building back up in compacted 2-3" lifts of stone, or putting some rebar into the foundation and pouring a 4" thick slab slightly bigger than the step area? In my opinion, digging that far down, no matter what you do in compacting that stone, you'll now have a vertical slip plane of sorts where stone and native soils meet. There might be uneven compaction issues there, or even settling (think of the way the soils around an excavation where a trench box was used end up being uneven relative to the surrounding grade). So if the soils would require that kind of excavation, I'd lean toward a slab for a pedestal. It'll be cheaper and likely more sturdy in the long run.

We don't pour slabs all the time (not even some of the time), but we've done it enough that I value it's use in given circumstances. I know there are at least a few others here that do the same.

Josh - the power you put into a hand tamper can't match even the smallest gas-powered compaction equipment. You're better off using the rammer/jumping jack to prep any area near a foundation. We just started using one a couple years ago and have been very happy with how well it can compact the clay soils in our area.

My $.02, anyway.

[johnkeegan]

I just came from a customer's house where the front concrete stoop was literally rocking like a see saw. It didn't do it until after 6-7 years in the house. I'll have to jackhammer it out and see what's up.
I've also seen recently where "sinkholes" have suddenly developed after 5-7 years in customer's yards, with the ground dropping 2-3 feet. Undoubtedly stumps or debris was buried and now it was finally giving way. Trouble is these may be lurking under a patio (happened to me once) or retaining wall (also happened once). In both instances the rest of the areas of the patio or wall stayed perfectly true and one small area dropped after a few years. In both cases, these sinkholes began appearing throughout the yards, so it was obvious what was ocurring.
Installing pavers or stone around pools also presents the same "Russian Roulette" risk. Have you ever watched the guys who install pools do their backfilling. I don't think they know what the phrase "installing in lifts" means.
And then they want you to do an installation where you're just going to remove 6" of fill and replace it with base material and tamp that 6". What about the 7 FEET of loose material under it? My neighbor had the fill under the poured concrete area adjacent to the pool drop 18" , with the concrete collapsing. Plus water got in there and floated the liner.Pool company refused to do anything because it was 3 years after it was installed.
....BOTTOM LINE IS BEWARE.

[cutntrim]

I'm building wrap around steps up to a landing in a backyard right now and have been weighing my options (and costs) between just having each step sit atop compacted granular A, or using a modified pedestal method. The reason I say "modified" is that it's too expensive to completely fill in the center of the steps with block. Permacon Celtik 90mm isn't cheap. But, I'm planning to set one block under each riser and then compacted gravel underneath. I only have the base course completed so far, but I dug down 24" and have the bottom course of block buried, so I hope that'll add to stability. Although I used a plate compactor for the base layer of gravel, I was going to just use my own muscle power and a 10"x10" tamp for the rest of the layers. Now I'm wondering if I should try a jumping jack or re-rent the 15" compactor.

[Squizzy Taylor]

Originally posted by neversatisfiedj
When going to the footer of the house, use modified stone or clean drain stone ?

Josh

I have to ask somewhere; It must just be a terminology thing but...

What the hell is "modified" stone???

[Matt Kulp]

Originally posted by Stonehenge
But which would be less expensive - digging down 8-10' and building back up in compacted 2-3" lifts of stone, or putting some rebar into the foundation and pouring a 4" thick slab slightly bigger than the step area? In my opinion, digging that far down, no matter what you do in compacting that stone, you'll now have a vertical slip plane of sorts where stone and native soils meet. There might be uneven compaction issues there, or even settling (think of the way the soils around an excavation where a trench box was used end up being uneven relative to the surrounding grade). So if the soils would require that kind of excavation, I'd lean toward a slab for a pedestal. It'll be cheaper and likely more sturdy in the long run.

We don't pour slabs all the time (not even some of the time), but we've done it enough that I value it's use in given circumstances. I know there are at least a few others here that do the same.

I agree that the slab approach would be more cost effective for a step system, but what if you have to go across the whole foundation for a patio system. I think there would be a point where stone would make sense for the budget. We have always done the overdig method and "ram" up lifts, but usually we are constructing along the whole foundation surrounding the steps and the whole area needed attention. Good discussion! I have never given the slab approach much thought.

[Matt Kulp]

Originally posted by Squizzy Taylor
I have to ask somewhere; It must just be a terminology thing but...

What the hell is "modified" stone???

Squizzy,
Modified stone is just another term for aggregate with fines. Some call it road base, crush and run, etc...

[Squizzy Taylor]

Originally posted by Matt Kulp
Squizzy,
Modified stone is just another term for aggregate with fines. Some call it road base, crush and run, etc...

Road Base...got it...thanks.

[Raj Venugopal]

some very interesting points here.

Great discussion...there always seems to be a real appetite around here for discussing techniques for steps, ponds and pools.

On our most recent jobsite we excavated a few feet down and built up with a combination of geotex, geogrid and 3/4"- crushed rock, not to mention compaction , etc...
Raj

[PSUscaper]

I'm with stonehenge on this one completely. In fact, I thought I had this topic up before in the past. The thought of digging down to virgin soil and then compacting stone up in lifts just seems silly.

I just can't see how you are going to get compaction in a 6x4' hole 5 ft deep that isn't going to settle somewhere.

I'd like to see a actual time and cost comparison of buiding a foundation up with block vs. compacted stone. I'd bet it would be surprising. Plus it would make a very good 'real world' test for Stonehenge to run, as I'm sure he has nothing better to do!

I hate to say it, but I firmly believe the SRW industry is brainwashing us into thinking up this stuff of building up 4 ft with compacted stone. It just seems rediculous.

Why, why, are we all so afraid to mix some mortar up? I use to be, but am starting to see the light at the end of the tunnel.

I have a prediction. (maybe we can get it posted somewhere to see how it turns out). Over the next ten years, we are all going to be blocking up are stair foundations or pouring footings. And why, well first of all, we going to find out that its just as much trouble to build it up with stone and get mediocre LONG term results (meaning 10-20 years, which, quite frankly, we don't see yet as we only starting building stairs in the last 10 years out of SRWs) as it would be to install a footer. Second, and yes, I KNOW it is going to happen, municipalities are going to grow 'wise' to the crap that is going on and make us. I know a few inspectors out there who are NOT happy with what they are seeing. If they are failing houses because the sticker on the smoke detector isn't peeled off, then you really think they aren't going to have a problem with the front stairs being built on a pile of gravel?

The thing is, the stairs I often replace, though they are falling apart, have been there for 30-40 years! All things considered, they did pretty darn well. Now, we are building on compacted stone and expect the same results????

I could be wrong, but isn't the reason people put footings in 50 years ago was because they knew nothing else worked. Its like were going backwards in time, and SRW manufactures are running the time machine.

[johnkeegan]

Why, why, are we all so afraid to mix some mortar up?

...Guilty as charged.
I admit that there are alot of instances where I need to learn to be more of a mason and less of a "landscaper." I wish I could find someplace to give seminars or courses on some of this. Yes, I could learn by trial and error but I rather just learn how to do things the right way first. I even spoke to a large local stone quarry supplier and suggested they offer such courses (fireplaces, steps, veneering etc.) to increase the use of their products. They, of course, said, "That's a great idea, we'll look into it..." And that was the end of it.
Winter time would be a great time to attack these issues with some seminars/courses.

[Matt Kulp]

PSU,

You have valid points for the slab under a set of stairs and I agree that it makes sense, more so then stone only. My only problem is that unless it is a front entrance to a house, 9 times out of 10 we are going to go across the entire foundation for an attached patio. To me, it would make more sense in this situation to use stone.

I don't agree that you can't get proper compaction from using stone only, if done with the right equipment, you will not have issues.

Obviously everyone is talking about tying the slab under the steps into the foundation via rebar to existing foundation, correct? If you would just lay a slab and not tie into a frost bearing footer, then you would have more movement then if you used just stone. I hope there is no one just pouring a slab on stone and hoping it will not move.