What to expect
| Typical duration | Repair 1–3 weeks · new engineered wall 3–8 weeks |
|---|---|
| Cost band | Figures live in the cost index |
| Permit required | Above roughly 1.5 m retained height, and in protected settlements |
| Seasonal constraint | Best done before the winter rains, not after a failure |
Why they fail here
The island is terraced from top to bottom because it had to be — agriculture on volcanic slopes needs level ground and windbreaks. Much of that terracing is centuries old, built dry, and it works because a dry stone wall drains through itself.
Modern rebuilds fail because they do not. Someone rebuilds a collapsed section in blockwork or concrete, renders it for neatness, and produces a watertight dam holding back saturated ground. The first serious winter builds pressure behind it and it bulges, then it goes.
The lesson is inverted from what people expect: the traditional dry wall was not primitive, it was drained. The improvement was the mistake.
What a repair that lasts includes
- Establish why it moved. Water, undermining, surcharge from something built above, or simple age. A repair that does not answer this repeats.
- Free-draining backfill behind the full height of the wall, not just a token layer at the base.
- Weep holes through the face at regular centres, kept clear.
- A perforated drain at the base, taken to somewhere it can actually discharge — a drain to nowhere is decoration.
- Surface water routing above the wall, so rain is intercepted before it saturates the retained ground.
- Correct batter — the face leaning into the slope — which is how traditional walls stay up without reinforcement.
- Where the height or the surcharge warrants it, an engineered design with reinforcement.
When it stops being landscaping
Above roughly 1.5 m of retained height, or where there is a surcharge above — a building, a driveway, a pool — a retaining wall is a structure. It needs an engineer's design and it needs a permit.
Traditional dry stone — ξερολιθιά
Rebuilding in traditional dry stone is a genuine skill and it is the right answer in a lot of places: in designated settlements where the appearance is controlled, on agricultural terracing, and anywhere the wall needs to drain through itself.
It is not cheaper than blockwork. It is slower, it needs someone who can actually do it, and the stone has to be sourced or reclaimed. What it gives you is a wall that drains, moves slightly without cracking, matches its surroundings, and does not need approval arguments in a protected settlement.
Where a wall is part rebuilt in stone and part in concrete behind, we detail the junction so the two do not fight — which is the usual failure of a half-hearted restoration.
Terracing for a new build
On a sloping plot the terracing comes before the house, and it should be designed with the house rather than after it. Three things get decided together: where the level platforms sit, where the water goes, and whether the excavated material can be reused as fill behind the walls.
That last point matters more than it sounds. Spoil reused on site is spoil nobody carries off the island, and on an access-restricted plot it is frequently the largest single saving available. See excavation and earthworks.
Questions people actually ask
My terrace wall is bulging. Do I need to rebuild it?
Not necessarily. Sometimes a bulge is stable and old, and the right answer is drainage plus monitoring. Sometimes it is progressive. The difference matters and it is worth a look before spending — but a wall that has moved recently, or that has a building above it, should be seen quickly.
Can I just render over it to tidy it up?
That is the worst available option. Rendering seals the face and stops the wall draining through itself, which is often what was keeping it standing. It also hides the movement so you no longer know whether it is getting worse.
Do I need a permit for a garden wall?
Below about 1.5 m of retained height and outside a protected settlement, usually not. Above that, or with anything surcharging it, or in a designated settlement, yes. Ask before building — retrospective legalisation is far more expensive.
How long does a dry stone wall last?
Correctly built, generations — there is plenty of evidence of that on the island. What kills them is undermining from below, water concentrated by something built above, or a well-meaning repair in cement that stops them draining.
Can you match existing stone?
Usually, by reclaiming from the collapsed section and sourcing locally to make up. In a designated settlement matching is not just aesthetic — it is part of the approval.