Revisions log for Answer #464
This is the answer to the question How to make the terrace higher by 15 cm? Use piles?
Revision 1
Thin tiles (up to 2 cm) laid in rubble will sooner or later shift or tilt; if tiles, more likely on a solid foundation – with possible risk of freezing/joint damage.
Supports on piles also require a water table (drainage) underneath.
In the end, we settled on natural stone (100 x 50 x 4), with a fired surface and laid on gravel. The slabs weigh 60 kg, lie sturdy and secure (and can be lifted again). A little more expensive (but not by much), but easier/cheaper to lay.
Very nice to walk on, only minimal algae in the spring and those get scrubbed off with hot water and wiped dry. It doesn't get too hot in the summer, etc.
Our terrace is also elevated (you can see another 20-50 cm), but the retaining wall was very expensive:
A strip foundation, formwork stones with concrete, facing bricks in the front in the tone of the house, a curtain wall slab of the same natural stone (with a rain gutter), a slot gutter "hidden" inside in front of the curtain slab, into which the back water is diverted along the slope of the terrace.
A simpler solution: planting stone as edge support (or formwork stones).