Before buying, you need to clearly understand how much space your future sofa will take. It has three measurement parameters: height, depth and, most importantly, width. It is measured along the widest part of the sofa - the armrests or the back. Do not forget that you need to take into account the size of the sofa, not only when folded, but also when unfolded.
If you choose a sofa in the living room, for relaxing and receiving guests, then the PPU model (made of polyurethane foam) is quite suitable for you. If your goal is a full-fledged option for a comfortable daily sleep, then it is better to choose a spring sofa with a convenient and durable transformation mechanism.
The upholstery of a sofa designed for a living room should be resistant to wear, as the furniture in this room will be used often. Here you should pay attention to the type and density of the fabric: they determine how quickly the material wears out and re-upholstery is required. The optimal density is considered to be 200g/m2 or more.
The basis is better to choose from steel: the cost of the sofa will be higher, but metal is the most durable material. The second place in terms of strength is occupied by a tree; but the most fragile base will be from chipboard, but it is also the most budgetary. The armrests are usually firmly attached to the main frame - they should neither move nor stagger.
The spring block is considered the most durable filler - it will last at least 10 years. In second place is polypropylene. Hollofiber also has a long service life - up to 8-10 years. If we are talking about a sofa for sleeping, then it is better to stay on a model with an independent type of springs.