As you may pick up from the previous thread i live in cheltenham. I had been doing some planting work near my parental home in Surrey. The clients needed a landscaper to do the longer bits of work - fencing, driving machines etc. I suggested someone i had worked with before and they went ahead and worked with him.
The clients asked this contractor to build a dry stonewall to create a flatter area of lawn. The wall was built in June of last year.
This wall collapsed on Monday after the heavy April rain. The contractor is now saying that the rain was exceptional and the wall needed some drainage which he did not allow for at the time as he could not build the wall to account for the high volumes of rain that we had... He says he will fix it, which will take a week, but wants some money towards the cost of it as these are exceptional circumstances. The client has taken the opposite opinion.
What are your thoughts? Is it the contractors responsibility to fix the wall....and how should things proceed?
I attached a picture of the wall standing and on the floor.
I am obviously involved, being the introducer.
If the wall is higher than 90cm was not a structural engineer involved?
this guy local to us knows about dry stone walls
it looks like a classic example of how not to build a wall!
it looks like, rather building a wall, the soil bank was just faced, in which case it would almost certainly collapse (lacking structural integrity)
Looking at the 2 photos, the 'standing one' looks to have a mighty bulge and already moving. Not sure at what stage that picture was taken, but looking at the trees, I would guess last year - not long after completion.
I am not a structural engineer, but it would appear that the wall is too high for the job it is trying to do. Also, being a dry wall, the stones are just placed on top of each other and are directly against the soil they are retaining, which I would think means that any weight/movement is passed directly into the unsecured stones, edging them out until they become unstable. Heavy rain or not I wouldnt have expected it to have lasted too long and the ground settled.
Rebuilding it in 2 tiers may be a better option - with drainage of course! I think the 'end profile' should be a lot wider at the bottom and tapering to give strength.
Remain professional but you may need to be very firm. The guy who built it has to suck up all the costs or re-building and i would insist on a specification to be followed.
Lets be realistic if he wasn;t an aquaintence you would probably say the work was cowboy-ish as it was down-right dangerous. From his excuses he clearly knew what he should have done (i.e. drainage) but chose not to because it was easier/less work.
I know its an alarmist thing people always say when walls collapse but it is true not the less that He should count himself lucky a child wasn't playing under it.
It looks to be only a single "skin" or thickness of stones as-well, at that height that is totally unsuitable to hold back any amount of weight, let alone as a dry stone wall. I have helped repair a 2m Dry stone retaining wall on a river bank (Not a paying job i might add - I was a volunteer) and this wall was about 2m Thick, built in a variation of what could loosely be called "flemish bond" with lots of lenghtways though stones to bind the wall together.
I was told by the gentleman overseeing the project that it was 75% dependent on its own Mass/weight to hold back the earth bank, and 25% on the interlock between the stones. Based on this alone, the above wall would fail come what may given its height and very loose single skin structure. The net should provide you with more detailed info on dry stone walls.
As for the contractor who built it - if it failed, for whatever reason, this soon after he built it, he should shoulder the cost of re-building and do it properly this time - The cilent can't be reasonably expected to foot a bill to rebuild the wall unless their was something done by them or someone instructed by them, to the ground near the wall.
many years ago i did a lot of proper dry stoning and that is not it in the picture. that is just a facing off on a big bank of earth, it was bound to fall in a few years anyway. A dry stone wall of that height would be a good 3/4ft wide at base if free standing let alone holding back tons of earth.
Imagine if this guy was responsible for the dry stone walling in Yorkshire Dales and surrounds - there wouldn't be many walls left standing let alone 100 yrs plus
Many thanks all you wonderful people. Please keep the comments coming.
The more considered responses the better.
Given the height of the wall and the weight of soil to be retained, would it not be a better idea to use gabion baskets with retaining pins and concrete anchor blocks. It may seem over kill but given the site conditions it would be belt and braces. Additional water drainage in the form of a 6 or 8" pipe at the base and aggregate backfill with a landscape fabric divider would be more than advisable if this is the result of rainfall. Just a few thoughts.
As to who pays for it, well i guess it depends on who specified the original installation??
Echo most of the comments regarding the wall there should have been a retaining wall built as the amount of soil leaning against it would be too much, regardless of the amount of rainfall no seep holes would have allowed drainage from the soil as there is just too much weight behind it, what happens next soil will need to be dug back, allowing a retaining wall to be built or cubes as suggested by James , the depth needed for foundations will be dictated by how far down you need to go before hitting the "hard" unfortunate but whoever constructed the wall should have known better!
For this ammount of made up soil the wall deffinately needs to be double skinned built on a concrete foundation.
9" blocks filled with concrete and thread bar throughout. Facing wall then built on front of the blockwork.
Adequate drainage also a must!!!!