Building a rather large wall by side of the road

[mattylad]

Thinking about it, as it's been suggested that it may get a lot of wind, perhaps lots of holes in it might help

 

[^woody^]

If that wall collapses, there will be fatalities no doubt about it. The fact that it has been built without PP is the fundamental factor here.

That's contradictory. Planning permission will not consider nor depend on whether the wall is safe or not, so can't be a fundamental factor to your concerns.

 

[Bluey62]

Going by the bricks the new wall is circa 1.4 m high built on top of an old 2 m high wall. Does the original wall have any foundations? As it is a garden wall and going by the age it would not have been subject to the regulations of housebuilding so its possible that it has little or no foundations.
I would not go anywhere near it until a survey on the supporting wall by a structural engineer is done.

 

[KayCee14]

Going by the bricks the new wall is circa 1.4 m high built on top of an old 2 m high wall. Does the original wall have any foundations? As it is a garden wall and going by the age it would not have been subject to the regulations of housebuilding so its possible that it has little or no foundations.
I would not go anywhere near it until a survey on the supporting wall by a structural engineer is done.

And this is my point in case.

 

[^woody^]

Going by the bricks the new wall is circa 1.4 m high built on top of an old 2 m high wall. Does the original wall have any foundations? As it is a garden wall and going by the age it would not have been subject to the regulations of housebuilding so its possible that it has little or no foundations.
I would not go anywhere near it until a survey on the supporting wall by a structural engineer is done.

The foundations that have kept the existing wall up for so long, will be adequate for keeping up the additional bit of wall too.

 

[KayCee14]

The foundations that have kept the existing wall up for so long, will be adequate for keeping up the additional bit of wall too.

would the existing foundations have accommodated for that monstrosity to have been built on top of it? I wonder if a structural assessment has been carried out on it.

 

[^woody^]

would the existing foundations have accommodated for that monstrosity to have been built on top of it? I wonder if a structural assessment has been carried out on it.

Foundations don't work on a basis that they need to be incrementally deeper as a wall goes higher

 

[RonnyRaygun]

would the existing foundations have accommodated for that monstrosity to have been built on top of it? I wonder if a structural assessment has been carried out on it.

Already answered that - see below:

OK
Well, obviously we can see that the house is considerably higher than the street, and if you look at the snapshot below, we can see from the steps that ground level directly outside the house is somewhere near the top of the wall.

Looking at the wall between the steps and the front garden, this would imply that garden level nearest to the wall in question is pretty much at (former) top of wall level (probably a couple of hundred millimetres down, I'd guess).

So the wall is a retaining wall and is already retaining a good couple of metres of soil and potential surcharge load.

There are a few issues in that respect with building another 1.5m or so of wall on top of it (and potentially it looks like they might be thinking about some timber panelling between the pillars, which would raise the new structure to 1.8m above existing).
That's quite a lot of wind load on a 9" wall, but they have, at least, also put in some 215x330mm piers, which do help stiffen the structure, as does the curve.
Anyway, making a few assumptions with regard to the wind load (shouldn't be too high in South East London) and flexural strength, I reckon the new portion of the wall, at least, is probably OK.

The other question is the affect the additional dead load and wind load is having on the existing retaining wall. We don't know if the wall is masonry or concrete, gravity, or reinforced. Assuming that the wall has no toe (as it would have to protrude into highways owned land) then any additional dead load will be over the heel (but closer to the front of it). Are the new piers built off the existing wall (assuming it is 330mm thick, or it thickens to 330mm not too far down)? You would hope they are built off the wall itself, but we don't know. Either way, the additional dead load will add forces that will likely contribute to overturning, bearing, and sliding forces, as will the additional wind load.

Definitely a wall that should have had SE input, with trial pits to check the existing wall structure and a design carried out to determine capacity with regard to the additional loads created.

Obviously, none of us know if that is the case. Those are my thoughts anyway...

The truth is that the additional loads from the wall above will have minimal impact - the wall has been stable for 90 years or so I'd guess so clearly the foundations are suitable for what was there. The new wall will have some (likely negative) effects on the foundations though - Without an assessment there is no way of knowing for sure, but also, what can be proved by calculation is often not what can be observed to have worked historically.

 

[Harry Bloomfield]

The new wall will have some (likely negative) effects on the foundations though - Without an assessment there is no way of knowing for sure, but also, what can be proved by calculation is often not what can be observed to have worked historically.

Exactly, look what happened at Pisa. They never turn a bungalow into two story building without assessing the foundations first. Tall buildings have deep foundations.

 

[^woody^]

Tall buildings have deep foundations.

The ground conditions determines the foundation depth, not the building height. Every. Single. Time.

 

[RonnyRaygun]

Exactly, look what happened at Pisa. They never turn a bungalow into two story building without assessing the foundations first. Tall buildings have deep foundations.

The ground conditions determines the foundation depth, not the building height. Every. Single. Time.

Agreed. It's usually not possible to put very tall, slender buildings on shallow foundations due to the huge areas required and the risk of uplift, but making a trench a metre or so deeper does nothing to help with load carrying capacity, unless they end up in a stronger substrate.

 

[Mobo_14]

The builders put that wall up in a day, trust me even I was amazed at their speed.

must’ve been awfully quick to throw that up in a day….I think you might be telling porkie pies

 

[KayCee14]

must’ve been awfully quick to throw that up in a day….I think you might be telling porkie pies

Trust me. There were five or so of them working on it. Nonetheless that’s beside the point isn’t it. I have posted this on a community forum and the local councillor has taken it upon himself to speak to planning. I will let you all know the outcome.

 

[Bluey62]

On a plus side if it rain's heavy enough for long enough, or rains and freezes it may just be enough to compromise the older wall and if that goes possibly the house will go with it. Problem solved

 

[jacko555]

I have posted this on a community forum and the local councillor has taken it upon himself to speak to planning

But it's permitted development. As noted earlier by the ground level by the stairs.
Neighbours eh?