A built-in sofa isn’t bought: it’s built. And it almost never turns out right the first time if you don’t plan the order of the steps. Here is the actual sequence we follow on site, with the points where things usually go wrong.
Step 1: fix the opening before ordering anything
The most common mistake is ordering the sofa using the measurements from the blueprint rather than those of the actual opening. Hollow brick partition walls get plastered, and that centimeter and a half per side doesn’t appear on the blueprints. Measure with the plaster in place and allow 1 cm per side so the piece goes in without knocks.
A specific case: in a renovation of a 1960s apartment, the opening between pillars was 2.10 m on the blueprint, but after the drywall lining it dropped to 2.03 m. The 2.05 m prefabricated sofa didn’t fit. Solution: a built-in sofa with a 2 m frame and custom upholstery.
Step 2: choose the construction system
Option A: wooden frame with masonry legs
Pine or beech structure, crosspieces every 40-50 cm, and masonry legs clad in mortar or plaster. It’s the most integrated solution in full renovations where the sofa is part of a continuous bench.
Option B: masonry base and loose cushions
A plinth of brick or concrete block is raised and finished with moisture-resistant board. The cushions go separately. Advantage: they can be renewed without touching the masonry. Drawback: it’s heavy and doesn’t move, conditioning the layout forever.
According to technical documentation from foam manufacturers, for seats in daily use a density of 35-40 kg/m³ is advisable for the base cushion and a top layer of 25-30 kg/m³ for comfort. Below 30 kg/m³ the seat flattens within months.
Step 3: sort out ventilation and access
A built-in sofa closed on all four sides accumulates moisture. Always leave a ventilated cavity in the base with discreet grilles or a removable front. On ground floors or with a slab in contact with the ground, this is not optional.
This doesn’t work in basements without mechanical ventilation: the wood of the frame ends up swelling even if it’s treated.
Step 4: upholstery and finishing
The upholsterer needs the frame already fixed to the floor or, at the very least, with the anchors in place. Upholstering before screwing to the wall forces you to take it apart. The masonry finishes (plaster, mortar, bead) go after the upholstery, protecting the fabric with plastic.
Fabrics: outdoor types such as acrylic or polypropylene withstand cleaning with water on site better than a velvet or a linen. If the sofa is next to a window with direct sun, an untreated cotton fades within a season.
Step 5: final check
- Seat at 40-43 cm from the floor (standard living room ergonomics).
- Seat depth between 55 and 60 cm; more than 65 cm forces you to lie down, not sit.
- Backrest height no less than 35 cm above the seat for lumbar support.
- Anchoring to the wall in seismic zones or with small children.
What this system doesn’t solve
It’s not a good idea in rentals or in apartments where you plan to move: dismantling it means construction work. It’s also not worth it if you’re looking for an occasional sofa bed; the mechanism requires clearances that masonry doesn’t allow. And I don’t recommend it in renovations with a tight budget: between masonry, carpentry and upholstery it usually exceeds the cost of a conventional custom sofa, even if the result is more durable.
Before starting, consult the project architect or quantity surveyor: the opening dimensions and the slab loads (a built-in sofa with a brick base can weigh around 150-200 kg) must be reflected in the project.