Parts of a sofa: What are they and how do they influence its quality?

The sofa is one of the most important pieces of furniture in a house, where we can relax and get comfortable after a long day. But have you ever wondered what the parts of a sofa are and what determines whether it is more or less comfortable?

As we will see below, both outdoor sofas and indoor sofas are made up of different parts that determine the quality, comfort and appearance of the sofa.

In this post, we explain what a sofa looks like on the inside so that you have a clear idea of everything that influences its quality when choosing a good piece of furniture for your garden or living room.

What are the main parts of a sofa?

The first thing you should know is that each part of a sofa directly influences its durability, resistance and comfort. Below, we tell you what the parts of a sofa are called and what each of them is used for:

Structure or frame: the most important part of a sofa

The structure of a sofa, also called the frame, is the most important part of the sofa, as it acts as the skeleton on which the rest of the furniture is built. It is the part of the sofa that supports all the weight and determines both its strength and durability.

In fact, a good sofa frame will ensure that the furniture does not deform over time and can withstand daily use without problems. However, in order to assess the quality of the frame, it is necessary to look primarily at the materials used.

Frame materials

The most common materials used in the manufacture of a sofa frame include:

• Solid wood: this is the strongest and most durable option, but it is also often the most expensive. Woods such as oak, beech, pine or walnut are used, which offer a solid structure that can last for decades without losing its shape.
• Plywood: is made of several layers of pressed wood and, although it is not as solid as solid wood, it still offers good strength for a cheaper price.
• Chipboard: the cheapest option, but also the least durable. It can weaken or warp over time, especially if the sofa is exposed to moisture. It is used in low-end sofas and is not recommended if you are looking for a sofa that will last for many years.
• Metal: used in some modern sofas or futon-type structures. It offers great strength and lightness, and is also an excellent choice for outdoor sofas due to its high resistance to humidity.

Suspension: the secret of comfort and durability.

Another of the components of a sofa that most influences its quality is the suspension, which refers to the system that supports the weight and distributes the pressure evenly. This part sits on top of the frame and prevents the seat from sagging over time.

There are several suspension systems, of which two are the most important:

• Zigzag springs: used in the internal structure of a high and medium range sofa, due to its balance between comfort and resistance. It consists of a series of S-shaped springs that are fixed to the structure of the furniture by means of staples or screws, allowing a uniform distribution of weight.
• Straps: these are a very common option in mid-range and low-end sofas. They are rubber or elastic nylon bands that criss-cross the base of the sofa and are fixed to the structure, and can offer greater or lesser resistance depending on their quality.

Frame cover: the invisible layer that makes the difference

Above the frame and suspension, but before the upholstery, the frame cover is placed, whose main function is to soften the shapes of the structure and provide stability to the upholstery.

For this part of the sofa, materials such as are commonly used:

• Low density foam, to give a more uniform base before the upholstery.
• Silicone fibre, to soften the lines of the sofa.
• Reinforcing fabrics, to avoid friction between the upholstery and the structure.

Seats and backrest: the heart of comfort

The seat and backrest are the components of a sofa that most influence its comfort. Both are made using an upholstery that can be composed of different materials, as we will see below.

The seat is the surface you sit on and its level of firmness or softness depends on the type of foam or padding used, as well as the suspension system we have already discussed. As for the filling, it can be composed of polyurethane foam, silicone fibre, viscoelastic, down or a combination of these materials.

The backrest is the part where you rest your back, and can be made up of a single cushion for the whole piece or independent cushions. In addition, the backrest can be high, offering greater support for the head or neck, or low. Like the seat, the backrest is made with a padding that can be made of different materials.

Upholstery materials

Let’s take a look at how the filling materials influence the comfort of the sofa:

• Polyurethane foam: this is the most commonly used filling in sofas thanks to its strength and resilience. Its density can vary, offering from firmer seating to softer options. High density foams (more than 30 kg/m³) guarantee greater durability and prevent the sofa from deforming over time.
• Down: This is a natural and traditional filling, composed of bird feathers. Nowadays, it is often used in high-end sofas, due to the softness and comfort it provides. However, it requires frequent maintenance, as it tends to cushion with use.
• Silicone fibre: this is a synthetic material that imitates the softness of down, but with greater resistance and less maintenance, as well as being hypoallergenic.
• Viscoelastic: a modern filling that adapts to the shape of the body and slowly returns to its original state. It provides an enveloping sensation and relieves pressure at contact points, making it a perfect alternative if you are looking for an ergonomic and comfortable sofa.

Armrests: the stylish parts of a sofa

The armrests influence the aesthetics of the sofa, but also its functionality and level of comfort.

They usually have a solid wood interior, although in some designs the armrests are made entirely of exposed wood, giving them a rustic but less comfortable style. Normally, the armrests are padded with high-density foam and synthetic fibre, which provide a soft feeling when resting.

Depending on its design, this part of a sofa can provide different things:

• Wide, padded armrests: ideal for those looking for more comfort, they are usually filled with foam or fibre and can even serve as additional seating.
• Narrow and straight armrests: they give a more modern and stylish look to the sofa and are perfect for small spaces as they take up less space without sacrificing functionality.
• Curved or scrolled armrests: give a classic and elegant look, typical of Chesterfield style sofas. They are usually well padded and provide a cosy feel.
• Low or almost non-existent armrests: common in contemporary or modular sofas, they allow greater freedom of movement and can make the sofa visually lighter.

Legs: the base that defines stability

The legs are the parts of a sofa that act as a support, keeping the furniture above the floor and facilitating the cleaning and ventilation of the base. Made of wood, metal or plastic, their design can vary depending on the style of the sofa:

• High legs: ideal for modern and minimalist sofas, they add lightness to the furniture and make it easier to clean underneath.
• Low or almost invisible legs: give a more robust appearance to the sofa and reduce the height of the seat, creating a cosier feel.
• Turned legs: common on elegant sofas, they are usually made of solid wood with detailed finishes.
• Legs with castors: ideal for moving the sofa with ease, they are common on light, English-style sofas.
• Legs integrated into the frame: some sofas do not have visible legs because they are part of the structure, giving a feeling of greater stability but complicating cleaning underneath the furniture.

Upholstery: the visible face of the sofa

Upholstery is one of the parts of a sofa that most influences its style, aesthetics and texture. But beyond its appearance, the upholstery also affects the comfort, resistance and maintenance of the furniture.

The choice of material will depend on the intended use of the sofa, the environment in which it will be located and the ease of cleaning that is sought, the most common being:

• Fabric: it can be made of cotton, linen, polyester or a mixture of fibres. It is the most commonly used material in sofas because of its variety of colours, textures and patterns, as well as providing a pleasant feel. Some fabrics, such as polyester, can be treated to better withstand outdoor conditions, making them ideal for garden sofas.
• Natural leather: is an elegant and sophisticated material, widely used in office environments. It is available in matt or glossy finishes, depending on the treatment applied, but requires hydration to prevent it from cracking over time.
• Leatherette or synthetic leather: an inexpensive alternative to natural leather, which is also easier to clean and maintain. However, it can wear over time and is less breathable than real leather.
• Microfibre: made from synthetic fibres, it is resistant to wear and stains, and is also very pleasant to the touch.
• Velvet: a luxurious material with a very soft feel, which also has a shiny appearance when exposed to light. However, if you are looking to clean your sofa quickly and easily, this may not be the best option for you, as velvet is a very delicate material that is prone to marking with use.

Cushions: the final decorative touch

The final component of a sofa’s structure is the cushions, which not only provide extra comfort but are also a key decorative element. With them, you can transform the style of the sofa according to the season or give it a cosier, more personalised feel.

Just like the seats and backrest, they can have different types of padding that influence both the comfort they provide and their maintenance. Traditionally, down cushions were the most common, but nowadays cushions made of silicone fibre and polyurethane foam are very common.

We can also find different cushions according to their function:

• Back cushions: those that are part of the sofa and provide support for the back.
• Decorative cushions: not essential to the structure of the sofa, but add colour and style.
• Lumbar cushions: designed to provide extra support for the back area, often used on sofas with low or very soft backrests.
• Auxiliary or lounging cushions: larger and softer, perfect for supporting the head or arms.

Now that you know what a sofa looks like on the inside, you are ready to choose the model that best suits your needs. And if you need us to help you choose an indoor or outdoor sofa, don’t hesitate to contact us, at Home Zentrum we will be happy to help you!