Foundation for retaining wall 1.5m high made of large ashlar stones.

Hello KingSong

Wow, quite some big ones.
Of course, they can catch the slope if they are properly installed. That's exactly why I would create a proper foundation. And naturally connect it with the wall. Otherwise, frost, cold, and heat could gradually push the wall away by millimeters.

Steven

But the concrete blocks are actually 60cm x 60cm... I hope that the 1.80m height will be enough to support the slope with 1.60m behind it.

Hello KingSong

Do you want to retain a 160cm slope or are you intending to build tank traps? I have no idea what such a thing costs, but the costs for construction shouldn't be small either. In that case, a foundation is no longer decisive. If you build the same wall with concrete formwork blocks (50 x 30 x 25) and put a bit more weight into the foundation, you can save a lot of money.

Steven

This slope here needs to be intercepted:



On the one hand, part of the house stands on it (a total of 2.40m frost protection gravel, laid 80cm deep) and on the other hand, we simply do not like concrete formwork blocks at all. I also don't think formwork blocks can withstand this pressure in the long term. The concrete blocks have a certain aesthetic for us that fits well with the rest of the house. On the left (where the pavement is now), a carport is to be built that will then be supported on the blocks above.

And the blocks are not that expensive at all, a 180cm x 60cm x 60cm block costs me €75, in total we would be at €3,400 gross including delivery.

Hello KingSong

ok, then it makes sense.
The guys who will lay the stones must be professionals. I think they won’t start without a foundation. After all, they are liable.

Steven

Hello

another idea.
Excavate the foundation to size, add 20cm of RCL and compact. Then formwork up to the final height and fill with ready-mix concrete. That lasts forever. And should be much cheaper. Would be about 27m³ of ready-mix concrete.
Material does not cost significantly less than the stones. But the assembling could far exceed the formwork. Steven

That's exactly the question, should I do it myself or have it done.... I would have excavated 60cm deep, put in 40cm frost protection and compacted it well. Then 20cm of lean concrete on top and the blocks on that. I've also heard all kinds of other approaches from different companies and I'm unsure who is right now. It ranges from tilting the wall 3° towards the house for structural reasons to creating a complete strip foundation......

Oh, and I got a quote for complete formwork and pouring with concrete..... it would then be 4000.-€ more expensive than the blocks. Stacking them is the easiest part, you just have to lift them with the wheel loader and set them down.