This project is imaginary, but still based on an actual situation.The physical context and regulations to integrate are real.A French architect is actually hired, having made her own proposal and being locally based.In fact this architect must now revise the building permit submission, the city hall has been unpredictably hostile to a first project, arguing of non-written regulations.My contribution as a relative of the owner is to sometime comment on the other architect’s project, graciously.On the side, it was interesting to develop an alternative to the official project, as a case study, a pilot illustrating how I would tackle the subject.This family of 5 leaves in a compact house by French standards, standing at the head of a long stretch of terrain. The house is separated from the garden with a couple of sheds. Those appendices are filled with a humongous quantity of items accumulated over the years. Historical stack of the family. The storage there does not suffice, more is outsourced at other people’s sheds and cellars, in the other cities.What the parents expect from demolishing the sheds is to access the garden from the house, and in the process extend the building to reach a 4 bedrooms housing unit.The house shows a blind wall on a main city center street, being accessible from a perpendicular alley with no other houses, just the school on the other side, and enclosed gardens further up.The alley is filled twice a day with a noisy cohort of kids going to duty.A first project proposal was a blending-in house equally divided between ground floor and first floor, connected downstairs to the existing part via a small corridor across a patio. Reasonable.The project got denied, too much occupancy on the upper floor. The city asked for no more than one new room above, and you can spread as much as you wish on the ground floor.The owners’ reaction was OK, what is it? a corridor around a patio?Correct, but why not find a way to arrange it that would still include their expectations and needs.– Open the garden in width as much as possible. The resulting narrow corridor would maximize storage on the street side.– Sunk in the parents’ aisle to keep 2 compulsory parking spaces above without losing a square meter of garden.– Get light in on the existing house side, provided with very few openings.– Change the upper floor layout to add the allowed additional room and access all bedrooms from just one staircase.The house looks into the garden through a maximized glazing surface, no columns in the way.All the mass and anchoring is accumulated on the wall protecting the house from the public space.There is no window on the street, they don’t want to be seen and there is nothing to see there anyway.The separation is a bark of a hollow tree. Repelling outside incursions of people and weather, through this repulsion actually establishing a physical contact; notably with the children teasing the building with nasty fingers on their way.On the inside it is a cavity, a deep functional stick to grip on and stock in reserves.On the outside and floors a layered concrete with various aggregate sizes, poured from a a robot, akin a geological story, didactic to the kids passing by each day.The inner layer is made in one same material for structure and panelling of the storage elements (Baubuche, german company Pollmeier). All can be precisely made ready for digital fabrication ahead and simulated + inspected against errors in 3-dimension, then cut and finished in Germany, then shipped to France.The building should be mounted very fast, the family has no alternative housing option during construction.That justifies the choice for dry assembly of prefabricated elements.