Stone Retaining Wall Failure

Tuckpoint it, and it will be able to get old again. Soft mortar is okay, but stone can withstand hard mortar too. A good mix might be 1part masonary cement, 1 part portland cement and 4 parts sand (the sharper the better).

Seems like good advice. Especially if the wall is leaning back a bit. (We usually put a "batter" on retaining walls to keep the center of gravity as far back as possible).

But if the wall is leaning forward, it might be a different story.

It really depends on how far gone the wall is. You could post pictures.

I repaired a wall today where the homeowner expected that I would have to tear a big chunk of it apart. I ended up removing about 6 stones, cleaned up put them back and a tiny bit of recapping and a little pointing. Lots of old walls are in great shape and a few hours of superficial work does wonders.

i agree with you completely when you say that a lot (most) broken or out of adjustment articles can and should be fixed and adjusted so they are usefull again and not a waste of space. whether its a retaining wall or a tube circuit the processes that we as a society have grown used to are not that complex and they should not be that difficult to achieve yet we are still not comfortable.... where is the answer to this next step

look here, see the references to retaining walls and dead men, etc,

Dead man search

Retaining walls and dead man anchors

You should tell us where you are located.

i.e. frost has its effects on retaining walls and consequently it will determine specific remedies.

Vince

I would make sure it doesnt have termites and then patch the holes with

matching mortar.

I'm sorry, could yew repeat that?

CaptMoosie, you paint the problem with a such a broad brush. Could you possiblly slow down, take a little more time, and give us somewhat greater detail; so as to more specifically let us know actually what the options are.

Now how the heck in the world am I to do that with just a simple description by the OP that contains no in-depth information and data, sketches, plans or the prerequisite pics of the existing conditions so as to make any informed detailed analysis, followed later with some general recommendations with appropriate initial options. Additionally, ideally an Engineer should conduct visual site observations and take preliminary measurements IF warranted. In my opinion, a whole lot of questions as posed by others and myself, first need to be answer first by the OP before that can happen. Subsequent questions and answers may be needed, not usually an option.

I just him/her an overview as well as some options for starters, so that he/she can begin to think about ramifications and possible solutions.

What to do concerning the wall will ultimately be up to the OP, and not any of the Forum membership...all we legally can do is make suggestions, not design the darn thing from hundreds or thousands of miles away, let alone from an Internet connection.

Not trying to be argumentative by any means shape or form, just stating the realities of the situation.

Please have great day!

my my that took to long to write, and unfortunately too long as well! LOL

Sorry about producing a novel of sorts!

Thank you for the detailed discussion. it is very informative and exhaustive. I always enjoy and learn from your posts. Keep it up and don't let anybody stop you. A jewler will know the value of a jewel to a layman it is just a stone.

First a little levity this morning as the coffee slowly takes effect...

You're very welcome Guest. I enjoyed writing the post....a heck of a lot of fun and much better than going outside to remove accumulated snow and ice off of the roof and PV solar panels with a DIY snow rake when the air temps were well south of 0 F...actually (-)11 F last night (cobbed together yesterday with bits and pieces laying about in my garage and metal shop/workshop.....it works great and doesn't damage the PV panels! hehehehe saved over a $125 too!!! ). Now they're saying we are going to get another 24-inches ++++ Tuesday from a Nor'easter. What again more or the White Chit??? LOL Ohhhhhhhhhhh myyyyy where to put it all?

Back to the wall issue:

One thing I should have mentioned about the segmental concrete block wall systems is that in a lot of cases you do not need to install the small diameter PVC weep tubes through the wall. The groundwater will seep out of the block joints, thereby eliminating the need for drainage works. Just place a minimum of a 12-inch deep by 12-inch wide bed of washed rounded river stone backfill at the base of the wall rear. this layer of stone should be enveloped with a filter fabric cloth such as Mirafi 140N or similar fabric. In cases where you have higher walls and/or constant ground water seepage you're going t need to install the weeps spaced @ 24-inches o/c horizontally + install a perforated PVC underdrain pipes (perf's down) inside that gravel pack behind the wall....just make sure to slope the pipe at a minimum grade of 0.25% and daylight it at the end of the wall (if a short length of wall), or if necessary, actually punching through the base of the wall (by using a PVC 90 degree elbow) at intermediate locations. Try to limit the runs to 20 linear feet on each drain run. the minimum pipe diameter I'd use would be 4-inch SDR-35 to prevent siltation problems from occurring. Of course larger height walls and year round ground water seepage will dictate more engineered drainage systems and most be evaluated on a case=by-case basis. The key here is to remove the presence of ground water behind the wall and it's loading influence acting against the wall in addition to the lateral soil loading force.

That should do for now....more food for thought.

You're very welcome Guest, and thank you for the words of encouragement! I like that proverb that you posted. May I have your permission to use it sometime?

You have been reading to much Tolstoy

LOL Icarus....a good one!

Moose

This is a safety issue, patching and "playing" cannot be made. If part of it collapses on your child its bad enough, wait till it collapses on someone else's!!!

Dig out wall from behind when its a fairly dry season for at least two meters. Remove wall completely and build a new wall following proper advice or get a company and a 20 year guarantee to have it made.......

I would hire a small digger and do it myself, but that is just me (Tightwad Scot!!), because its also a lot of fun, provided you have an idea what to do and have worked with stone and cement before....

If the base of the new wall foundations are made properly deep and very wide, (may I suggest 1.5 meters deep and at least a meter wide at the base). More is better) using the stone from the old wall and plenty of rebar, sloping back as someone else mentioned. The base should be at least a meter wide (more is better) and the wall should gradually reduce in thickness as it rises. thick rebar should be used from the bottom to the top, tied together horizontally every 40 cms or so with more rebar....

Drain holes with proper sieves/filters at intervals is a good idea where high rainfalls can be expected....

Face the result with some nice looking stone or brick to give it pleasing appearance. Use steel nets and cement to first stabilize the face before adding the brick. Even outside tiles could be good if you like such stuff......

I live in a house and garden on mostly bedrock, with at most a meter of earth above, when needed we dig down and build on the bedrock (very hard basalt), with many fixings into the rock. But you have to make sure that any water that gathers on the rock is not fully obstructed, a porous pipe with a fleece filter is often used, which is what I did to my hose on the uphill side.....then backfill.....

Build it far stronger than you ever think it will ever need to be.....really "over-do-it"

Many houses here had to have an explosives expert to make room for the cellar!!Or build "high"......which the council does not really like.....

Drill 1/2" holes 24" O.C. IN THE MORTAR AT BASE TO LET THE WATER DRAIN OUT. AND PUT IN A CONCRETE SWAIL AT THE TOP OF THE WALL TO KEEP THE SURFACE WATER FROM POOLING AGAINST THE TOP OF THE WALL

Why some pics of the wall. That would help with communication.

Yeah, pictures were necessary from the start. By the time we are finished it will be poured alloyed steel with piles into the bedrock and with buttresses inside and out.

The remedy depends on the condition of the wall, what is underneath it, what is behind it and where it is.

Just ask a local mason or 3 to give you quotes and remediation suggestions. do not be surprised if opinions and quotes differ widely. Another person who you can ask is your local bylaw officer. That is really important if you want to tear it down and rebuild. Because I have heard of cases where a person tears down, rebuilds, gets fined and has to tear it down again.

5 ft is close to the height where engineers get called in. (5 ft 10 here).

The biggest batter I have ever put on a wall is 20% (required). Masons do not like to do more than 5% because it is harder to reach in with heavy rocks. Another thing is that many curved walls are stronger and the center of gravity is back further. But your mason might want to do straight walls because it is easier and faster.

The wall is not leaning and it is sound. I will get some pictures.

Hello again Guest,

Yes, please post some photographs before anyone else comments. By the sounds of it things may not be so bad as originally thought resulting in a lot of knee-jerk reactions around here. LOL

Okay, I think we as a whole should wait until we get the pics, therefore we should also reserve further comments. I do believe that I have an inkling of what's happening to your wall and am presently thinking about a possible solution to fix your problems...I just require verification first. The more pictures that you provide the better (within reason of course). Thanks!

Please have a nice evening.

PS: would be nice to know where you are located to determine weather conditions and how they could possibly affect the wall.

If it leans in the direction that the earth is, that is good, provided its not cracked....

I'm going to have a wall approximately 3 metres [9 feet] high built using boulders. As it's over 1 metre high, it will required to be properly 'engineered'. Doesn't need any lean back, tie-ins or much allowance for drainage weep holes ! Another type of retaining wall which I've looked at is 'ConCrib' - which uses concrete 'sleepers' [for want of a better description]. These do use tie-ins/tie-backs into the soil and require a lean back of nearly 1 metre for each three metres in height!

Capt Moosie suggests 4 inch SDR pipe to assist in drainage.

Here in Aus we have 'socked' ag [agricultural] pipe approx 4 inch diameter which comes in various length rolls. Best laid on a bed of 'blue metal' aggregate which itself has been put on a bed of sharp sand.

As for his little critters in the treated pine slabs..try a Jack Russell terrier - great 'ratters'

Additionally, check the rebar. If it's started to rust badly get it out. That alone creates major problems.

Hello PhilD, I think I know what you're describing to us. Here in the States we call it "Crib Wall" for cribbage. As far as I know it's use started here in the late 1940's and is still being installed around here sporadically as it's old tech and has been pretty much sub-planted by newer type precast concrete wall systems.

Basically a row of interconnected boxes are arranged along the wall baseline. Each side of the box is comprised of a precast concrete section that resembles a wheel stop or curb stop usually found in parking lots and parking garages. They are slightly notched top and bottom at each end and are stacked like Lincoln Logs. the inside of the crib box is filled with compacted well draining gravel...ditto with the backfill that is usually wrapped with a filter fabric. The underdrain system is installed in almost the same exact manner as I had previously discussed. the slope or lean back of the wall that you refer to is commonly called the "batter", and is standard practice with gravity-type retaining walls and is used to overcome the 'overturning moment and sliding forces acting on the wall from the soil mass (and water if present). If is the type of wall that you're describing then it'd be most likely acceptable to construct for a wall height of 3 meters (roughly 10 feet). Some factors to consider are the type of soil and it's unit weight, allowable soil bearing pressure, back slope conditions and gradient if any, groundwater conditions to name a few.

If your Ag pipe is a coiled ( like a Slinky), perforated black HDPE tubing, then I know what you have there. It's pretty much universally found around the globe. I presume the "sock" is actually an adhered filter fabric? if so, you have a great product there Phil! I've spec'ed many a wall that included that type of drain pipe....economical and very easy to install. I highly recommend it!

Err, don't know what blue metal is! Must be an Aussie rock? Please send a pic of it or a Link as I'm completely curious as to what it is. Blue Shale perhaps?

Yeah, No wukkas mate! I'll have to get a Jack Russell to keep company with my Border collies and show them a trick or two. I'm sure the Border Collies would reciprocate as well! LOL I really had thought that our Corgi would have been up to the task of running off the Chipmunks and the Godzillion rabbits around here (bumper crop this last spring and summer), but he's such a Mama's boy it isn't funny...totally babied and useless. Anyhow, something needs to break loose here as I'm tired of sitting around all day plinking off the Chippies with the pellet rifle, and there's too many of them to count and quickly replaced by a new generation. I have to get rid of them because they, like the gray squirrels (aka "Tree Rats"), chew through the electrical wiring insulation if they get inside the house, which is a dangerous condition to say the least. Anyhow, I like the Jackies....cute little dogs, super smart, and a fighter to boot, just like me that don't back down for Chit....must be my old Rangers training leaking out lately. **GRINZ**

Hope you weren't in that flood mess down there.

Phil, please sent pics of your wall when it's being constructed!

Ta!

It probably needs more lean back than a retaining wall with mortar. You mean the walls where huge rocks are placed by machine?

We got big rains about 8 years ago in October and these are the walls that moved.

(Only the fresh ones to be fair) There is a "window of time" before the fill settles completely where the retained fill can get waterlogged.

And some of them moved a lot!

I realise this is not a dry stone wall, but perhaps this observation of a DSW may be of general interest.

I have DSW's that were capped with concrete in the past.

As the wall settled over the years, the cap and the wall separated, thus removing the weight helping to tie the wall together.

This then leads to movement of the lower layers eventually resulting in collapse.

Perhaps the capping here has had a similar but slighter effect.