Renovating a stone house: Costs range from €40,000 to €100,000

Renovating a stone house: €40,000 just for the roof

Is it worth buying a half-ruined stone house and investing heavily to make it habitable? It depends on one very specific thing: the roof. If the roof needs replacing – and in most of these cases, it does – the bill starts at €40,000 before touching a single internal wall. The range quoted by those who have gone through such a renovation goes from €30,000-€40,000 for a decent fix-up to €100,000 for a complete job with a contractor and permits. Demolishing it, paradoxically, doesn't reduce the cost at all.

How much does it cost to renovate a stone house, item by item

The first figure mentioned in any serious conversation about these properties is a warning, not a quote: fixing a stone house costs more than building a new one. Some people state this unequivocally after experiencing it firsthand. Without luxuries, just to make it look good, the most common estimate to make it habitable is around €100,000, assuming everything is contracted and the relevant permits are processed.

The calculation changes if the owner contributes their own labor. With personal work, the quoted budgets drop to the range of €40,000-€50,000, and even then, some consider that estimate optimistic. The difference between these figures isn't in the materials; it's in the labor.

The roof eats up almost half the budget

Beneath the tiles lies a structure that is almost never salvageable. Replacing a roof involves a perimeter reinforced concrete tie beam, sheeting, structure, and a new roof covering, plus rebuilding the chimney. For a house the size of the one in the photos, the most detailed breakdown places just this item at €40,000. Another direct experience, in rural Galicia, puts the roof cost at €36,000.

And doing it yourself? It can reduce the cost, but not miraculously: €25,000 is the realistic minimum considered if you handle the work yourself. The most affordable option for a decent roof is €100 per square meter. Below that, it's wise to be suspicious.

Cleaning the walls: €5,000 per wall

Here's the detail that surprises many. Old stone isn't left as is: it needs to be cleaned with a pressure washer or sandblaster and the joints refilled with a water-repellent mortar that mimics the original mud. This work costs €5,000 per wall. With four facades, that's €20,000 that no one had factored in.

The good news is structural. The guasonry walls, 70-80 centimeters thick, won't come down even with a crane. They appear straight, the stone seems of good quality, and they can withstand anything. The bad news: any new opening – a window, for example – requires temporary support while it's dismantled, and it doesn't always pay off.

Renovating or demolishing: the calculation that doesn't add up

The urge to demolish and start from scratch appears whenever you see a house like this. And it's almost always a bad idea. Those walls are the asset; it's everything inside that needs work. Replacing wooden joists with concrete slabs is cheap compared to building new walls, and insulation is handled internally with rock wool and plasterboard, leaving the stone exposed externally with a lime render. Those who have done it assure that creating doors and windows where none existed before is perfectly possible.

The question that truly decides the project isn't technical. It's this: if the villagers haven't bought it, it must be because no one wants it.

The urban planning report and dampness, the two surprises not included in the budget

Before signing anything, it's advisable to go to the town hall and request the urban planning report (ficha urbanística). A house in a protected area is not the same as one in a rural settlement, nor is a renovation the same as a rehabilitation. In many old town centers, there are also minimum surface area requirements that turn what seemed simple into an administrative labyrinth.

The second surprise is water. If there's a basement or a wall below ground level, dampness is tackled from the outside with a perimeter drainage system or an asphalt membrane, and this item significantly increases the cost. Fortunately, not all stone houses have damp issues: some have experienced zero dampness after a rainy December, with dry pine splinters on the floor.

The numbers are clear. What no spreadsheet can explain is why, knowing all this, some people still sign. The heart balances accounts that the calculator rejects.