? on proper install of wall in area subject to freeze - base preparation?

   / ? on proper install of wall in area subject to freeze - base preparation? #31  

dave1949

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Hope we didn't scare Jim away with project scope creep, well maybe landslide would be more accurate. :laughing:
 
   / ? on proper install of wall in area subject to freeze - base preparation?
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#32  
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jim_wilson

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Jim,

There are two types of shallow frost-protected foundation methods. One is for heated buildings, the other is for unheated. There are some differences in where all the foam boards are placed between the two. If you check out the links, you will find the two methods.

Revised Builder's Guide to Frost Protected Shallow Foundations (FPSFs)
At the above link, open the "Full Report" 752 KB pdf. On document page 17, there is a diagram for unheated showing foam below the foundation. The whole report is good reading and everything you need to know is there.

In either case, the foam is isolating the ground (with an ambient temperature of ~45*F) from the ambient air temps in winter. The foam does need to extend horizontally far enough to prevent the frost from reaching the part which is actually being protected--the foundation. There are charts for different regions which specify how far that horizontal foam apron extension needs to be, how thick, and how deep the foam is buried.

In common usage, a "frost wall" is something set deep enough to prevent heaving and usually consists of a footer poured in a trench that is as deep as the frost penetration in the area, and a poured or layed block wall that sets on the footer and rises above ground.

In your case, either poured or block walls will need some sort of lateral support. This could be ells at the ends, and tee(s) in the mid-section depending on the length of the wall. And, you need free space on the footer next to the wall to support the granite curbing.

The masonry walls can carry a lot of vertical weight, but they are fairly easy to push over from the sides. a strong wind can blow down a tall block wall that is not laterally supported, for example.

You can incorporate the lateral support ells and tees into a built-in seating bench, planter, outdoor grill, etc., etc., limited only by your imagination and budget. :laughing:

Thanks for posting that. I went back and read some of the section about frost walls and unheated buildings and realized I had forgotten that the ground below is warm(er) - than the air during the winter - so an insulation layer could still prevent the ground from freezing because of the warmer ground below.

I understand that just going down four feet or so - would give me frost heave protection for the wall. What I was looking for - was to see if there was some way of avoiding doing that and still having a relatively stable wall. This was why I asked the original question. I've seen stone walls just build on grade or on a bed laid only a foot or so deep, when curbstones are laid alongside roadways - the are laid in a 6 inch or so bed of cement - and they stay straight and level for decades - etc.

So what I was wondering was - is there some relatively simple way to lay these down and get the effect I'm looking for.

So after reading the frost wall info a little - I'm wondering if something like this might be sufficient to work:

wallwithfoam_zpsb24fc198.jpg
 
   / ? on proper install of wall in area subject to freeze - base preparation?
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jim_wilson

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Hope we didn't scare Jim away with project scope creep, well maybe landslide would be more accurate. :laughing:

Yes - project creep - just a little.

full_0207_f3_1.jpg
 
   / ? on proper install of wall in area subject to freeze - base preparation? #34  

dave1949

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Yes - project creep - just a little.

full_0207_f3_1.jpg

Good one! :laughing:

Granite curbstones are one layer deep, have more material buried than exposed, are trapped between paving on one side and dirt or sidewalks on the backside, usually with no more than about 1" above the backing material. I get what you are saying about curbs, but what you are thinking of is very different.

It's the top stone of the two that is the challenge: how to keep it straight. Your latest diagram in post #32 doesn't look too bad. The drainage and insulation look reasonable. The concrete coming to an acute angle behind the top stone is iffy maybe. The geotextile running through it is going to be a problem.

If you square that tip off, bring it up to half the height of the top stone, and position rebar vertically to tie the top to the base (cut holes for the rebar to pass through the geotextile), that could work IMO.
 
   / ? on proper install of wall in area subject to freeze - base preparation? #35  

Egon

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Refer to post #19. :thumbsup:

It's a retaining wall you are building. They have different design parameters than a plain wall.

You should have drainage at the bottom of the wall. (Lowers pore pressure) The wall should be set on a compacted granular/clay base. If underplaying material is prone to frost heave try and remove it. ( material that will allow capillary action for water)

Forget the insulation and geotextile. More cost than true benefit.

If in doubt get the opinion of a geotechnical engineer.

Again, Post 19 :thumbsup:
 
   / ? on proper install of wall in area subject to freeze - base preparation? #36  

dave1949

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Refer to post #19. :thumbsup:

It's a retaining wall you are building. They have different design parameters than a plain wall.

You should have drainage at the bottom of the wall. (Lowers pore pressure) The wall should be set on a compacted granular/clay base. If underplaying material is prone to frost heave try and remove it. ( material that will allow capillary action for water)

Forget the insulation and geotextile. More cost than true benefit.

If in doubt get the opinion of a geotechnical engineer.

Again, Post 19 :thumbsup:

Have you ever seen a retaining wall built by stacking one curbstone on top of another?
 
   / ? on proper install of wall in area subject to freeze - base preparation? #37  

Egon

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Have you ever seen a retaining wall built by stacking one curbstone on top of another?

Will cut granite stone, just plain granite boulders or flat slate stone count?:D
 
   / ? on proper install of wall in area subject to freeze - base preparation? #38  

dave1949

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Will cut granite stone, just plain granite boulders or flat slate stone count?:D

Ah, so Egon, you admit you have never seen this? :laughing: Sometimes what we have never seen has a reason behind it, and if curbstones were great retaining walls when stacked on edge, we may have seen that.

I could see old cut granite foundation stones being used, but they are as wide or wider than they are thick. It's the proportion of height to thickness that worries me with curbstones, and the joint between the lower and upper stones is a pivot point for forces coming from the retained side of the wall. There is more "pushing" surface than holding surface.

There wouldn't be much lost if Jim just stacks them and sees what happens for a couple years. If the top stone starts leaning, then he will need to rethink that. I was trying to come up with methods that would be 99% once and done.
 
   / ? on proper install of wall in area subject to freeze - base preparation? #39  

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How serious do you guys want to get? There is a real good federal publication on natural stone retaining walls:

http://www.google.com/url?sa=t&rct=...=i91xszQgPtZY9TcFGIXuXw&bvm=bv.46751780,d.cGE
First page is an ad, but the rest is the document.

:laughing:

Now this is certainly a lot more large scale than the OP is talking about, but it does show a lot of good practices and standards that can be incorporated into any wall. The primary one here is that you should have stones that are deeper than wide or tall. Obviously that is not in the cards for this wall given the raw materials at hand. There are 2 ways to approach this, IMHO:
1: Build a normal compacted wall base and backfill the wall with free draining stone and compact. Stack the curbs, with a slight batter angle (slope back into the hill). Hope for the best. Maybe some exterior rated construction adhesive between courses of stone.
2: Pour a concrete retaining wall and face it with these stones, purely decorative.

I suspect the risk of the wall in #1 overturning over time is high given the size/shape of the stones. It is quite low and not really a big risk issue, just an annoyance if it does, so there is not an huge disincentive to trying it, other than your time.
 
   / ? on proper install of wall in area subject to freeze - base preparation? #40  

Egon

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Without a doubt curbs stones do not make a good retaining wall but if that is what you have and the height is not great it may work. Getting the fencing material in there makes a world of difference.

Rock retaining walls are not all wide. There are some pretty narrow ones.:D
 
 
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