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

[Carl_NH]

Jim

The pins to loop the chain link around, then backfill with some stone/mortar around the chain link then the pins also hold the top block from kicking out at the bottom.

Also makes it easier to align the blocks with the pin.

 

[BuilderML]

I don't think you'll like seeing the pins and chain link on the face of a finished wall. :2cents:

 

[jim_wilson]

I don't think you'll like seeing the pins and chain link on the face of a finished wall. :2cents:

Yeahhhh - I was thinking the same thing. One of the reasons I got the granite blocks is because they can be stacked and made to look like a nice tightly stacked wall - like you'd see on the side of a expensive building or something like that.

 

[Carl_NH]

Guys,

I agree it would not be the prettiest wall on the block.

One more suggestion I think was mentioned before is to build a false wall and face it with the granite.

Like 1/2" PT plywood 16" high with 2x4 every 4' driven/dug into the base with dead men tying it back into the bank? Would take 3 sheets of PT plywood and a few PT 2x4s - not terribly $$.

 

[dave1949]

Guys,

I agree it would not be the prettiest wall on the block.

One more suggestion I think was mentioned before is to build a false wall and face it with the granite.

Like 1/2" PT plywood 16" high with 2x4 every 4' driven/dug into the base with dead men tying it back into the bank? Would take 3 sheets of PT plywood and a few PT 2x4s - not terribly $$.

If you pour a concrete frost wall on a footer, then face that with the curbing, that would be the most permanent and strongest solution.

You would need to start on the footer with concrete blocks, the solid kind, then as you come above grade switch to the granite. The footer could use the frost-protected techniques to shorten the wall - if you can use the backside of the wall area, sounds like that is close to the property line. If not, then use a deep footer and taller frost wall.

This also opens up some design possibilities like interlacing the curbing with another colored stone or brick. Or, putting a cap stone across the top of the curbing and concrete. More work, more money, but it does open up some nice possibilities and longevity that you may appreciate in the long run.

 

[jim_wilson]

If you pour a concrete frost wall on a footer, then face that with the curbing, that would be the most permanent and strongest solution.

You would need to start on the footer with concrete blocks, the solid kind, then as you come above grade switch to the granite. The footer could use the frost-protected techniques to shorten the wall - if you can use the backside of the wall area, sounds like that is close to the property line. If not, then use a deep footer and taller frost wall.

This also opens up some design possibilities like interlacing the curbing with another colored stone or brick. Or, putting a cap stone across the top of the curbing and concrete. More work, more money, but it does open up some nice possibilities and longevity that you may appreciate in the long run.

That's pretty much what I was thinking of doing - except I keep hearing "frost wall" used - and I'm not sure how any sort of insulation in a retaining wall is going to make any difference - since there's no heated environment anywhere around the structure that the insulation will be holding the heat in for. My understanding of frost walls is that they only work when they're backing up a heated building.

On this retaining wall - it's going to be sitting 75 feet from the nearest structure - the ground is going to freeze all around it and I'm not sure I understand how a frost wall is going to change that.

 

[dave1949]

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:

 

[dstig1]

You are mixing terms a bit. A "frost wall" generally just means a proper footing and wall that goes down to the typical footing depth in your area. Around here that requires 4'. Down south it can be almost nothing. It has nothing to do with insulation, unless you start talking about a shallow frost protected footing, like I posted earlier (and another Dave just posted above - great Dave minds think alike! )

 

[dave1949]

You are mixing terms a bit. A "frost wall" generally just means a proper footing and wall that goes down to the typical footing depth in your area. Around here that requires 4'. Down south it can be almost nothing. It has nothing to do with insulation, unless you start talking about a shallow frost protected footing, like I posted earlier (and another Dave just posted above - great Dave minds think alike! )

I think that is the confusion point--frost wall combined with frost protected. I guess technically, a shallow frost-protected wall or foundation is still a frost wall, it's just that the insulation artificially reduces the frost penetration depth.

So, in an area with normal frost depth of 4', an insulation frost-protected wall could be only 2' deep, for example, but it still functions as a frost wall.

There are a lot Dave's around, it was a very popular early baby boomer name.

 

[Rustyiron]

I've been told that an inch of foam equals a foot of (ground) cover. This is related to Dave1949's comment about the ambient ground temps and a lesser actual wall depth to avoid heaving. The whole burried foam thinking is to keep the heat "in the ground" and away from the (possible) 0 deg or less air temps. Heat allways seeks cold. I have seen insulation work in a well line over ledge (bedrock) that could not be installed below frost & was going to be plowed...... no snow cover, also a great insulator.

 

[dave1949]

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

 

[jim_wilson]

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:

 

[jim_wilson]

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.

 

[dave1949]

Yes - project creep - just a little.

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.

 

[Egon]

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:

 

[dave1949]

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?

 

[Egon]

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?

 

[dave1949]

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

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.

 

[dstig1]

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.

 

[Egon]

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.