Technical details for comfortable and safe wooden chairs

A good chair is not just about design, color or the wood used. It's about comfort and relaxation. When we buy wooden chairs, we won't choose the ones that look great unless we're comfortable, unless we don't feel like we're slipping, our legs are dangling or the edge of the seat is sagging. Design is very important, but without clear manufacturing rules, the chair remains a decorative object without demonstrating its usefulness. This is why not just anyone can make chairs. Few factories make both body furniture and chairs. Wooden chairs are usually made in factories where that's all they do, and other factories buy them in white and finish them together with the table and other bodies so that the whole piece of furniture has the same look. Let's see how chairs should be made to give us the comfort we want.

General considerations

The stool has been around since ancient times, but at that time it was not considered an ordinary piece of furniture, but it was an object that showed rank. It was the one on which kings and emperors, high priests sat, it symbolized power (the throne of the kingdom). The others used chests, benches, stumps or other improvisations. From the 16th century onwards, chairs began to become common items of furniture, but they were not available to everyone. No longer the prerogative of kings, they could also be found in the homes of the privileged classes, adorned and decorated according to their own style. styles of the time. Simpler versions were available in inns, taverns and other meeting places.

The style of chairs has come through different periods, reflecting the opulence or austerity of the times as much as other pieces of furniture. As well as appearance and decorative elements, the sizes have changed over time. Because they have always been in line with the average human size, which has also changed over time. 200-300 years ago, people were not so tall, but they were more robust, more robust, and you can see that in the chairs of those times. They were shorter, but with wider seats and backs. The legs, though delicately shaped (cabriole) or finished with specific decorations (ball in claws, lion paws) were strong and sturdy to support the weight.

The seats are now designed so that a person of 1.78 m (considered average height) can sit comfortably. This is, of course, a chair for an adult. When it comes to children, seat sizes are different depending on the age group (more on this below). But let's see what it means to sit comfortably in a chair.

wooden chairs — Louis XVI chair
photo source: archiexpo.fr

What it means to be comfortable

First we should first define what is comfortable. Because we don't all mean the same thing by 'comfortable', and we need to find a middle line that satisfies everyone. And the general wishes are:

to sit and get up without difficulty
the soles of the feet should rest naturally on the floor and the knees should not be pushed upwards but should form an angle of 90-100º in as normal a position as possible
to sit comfortably and securely on the seat, without slipping
The seat should not be too deep so that the edge of the seat pushes into the calf. This forces us to come to the edge which leads to an uncomfortable position.
the seat should not be too narrow either, as it becomes unstable and gives a feeling of insecurity
The backrest should be slightly inclined backwards from vertical so as not to impose a rigid posture. The angle should not be very steep because we don't feel comfortable even if we are very flat back.
If the chair has arms, our arms should rest loosely on them without our shoulders being pushed up. Bear in mind that such chairs only go slightly under the table.
the height of the seat should be in line with the height of the table so that you can sit at the table without feeling that the table is on your lap or in your chest
one of the rules that is less and less followed is that the backrest should end below the line of the shoulder blades. However, there are many who prefer high backrests and find them very comfortable (I am one of them). This is why designers and manufacturers are increasingly breaking this rule.

Dimensions of an ordinary dining chair

Now that we've seen what comfortable means, let's look at the dimensions of a chair we use to sit at the table. And while we're on the subject of the table, you should know that it can't be just any table either. The height, the space necessary for one person not to disturb and not to be disturbed by the person next to him, the length, the width are standardized dimensions that we have to take into account when ordering a table. We've talked about them on other occasions, but Călin from Solid oak, in the March 2018 issue of Wooden Magazine (you will still you can subscribe for 2018 and receive the March and September issues).

The seat should be 46-52 cm above the ground. The perfect shape is slightly trapezoidal, with the long side in front. The difference between the two parallel sides is 5-8 cm (2.5-4 cm on each side). This shape leaves enough room for the legs and allows the elbows to rest naturally on the arms of the chair. The seat width is between 40 and 52 cm and the depth between 38 and 46 cm. To avoid the sensation of slipping, it is customary, especially in the case of chairs without cushions (not upholstered), to tilt the seat from front to back by 5-8º from the horizontal. This is not recommended for office chairs. In this case a straight seat facilitates the forward leaning required for office work.

Spăthe tar has a height of 40-52 cm for elegant chairs and 30-40 cm for ordinary chairs. The rule that the backrest should stop at the line of the shoulder blades is no longer complied with in the case of the former. The inclination of the backrest in relation to the vertical is up to 5º for elegant chairs and up to 15º for relaxing, all-day chairs. However, as the angle increases, the inclination of the seat should also be increased so that there is always an angle of 90-100º between them. At the joint between the seat and the backrest there should be a gap or, in the case of molded seats, a curve should be made to give more space. This is necessary in order to have space when sitting down and not feel pressure on the lower back.

Arms The chair should be positioned so that our arms rest naturally, without feeling our shoulders rise. This means they should be 18-23 cm from the seat, 20 cm long and 5 cm wide. The distance between them is about 48 cm.

What type of wood to use in chair construction

The chair is a piece of furniture subject to very strong forces. It not only has to support people's weight, but also to withstand countless sitting and standing up, different forces when the chair is tipped backwards or forwards with only 2 feet on the ground. These are all tests that a prototype chair must pass before it can go into production.

That's why hard, durable wood is used for chairs. The most commonly used wood is fag is also very good for manufacturing curved elements (steam bending or using high-frequency currents). But chairs are also made from oak, frasin, but also by resinous.

Several types of wood can be used in the construction of a chair. However, care should be taken not to make high-stress joints between hardwood and softwood, and the legs should always be hardwood. Softwood can be used for the arms or parts of the backrest that are less stressed.

Different types of chairs

The above recommendations are for ordinary, adult, table chairs. But there are many other types of chairs, each with their own standards and rules of construction.

Child seats

While for adults an average height is sufficient to determine seat sizes for generations, for adults an average height is child seats things are not as simple as they used to be. Children are constantly growing and the seat has to be adapted to their size. That is why an average height was chosen for each age group, and the height of the seat in relation to the ground was determined accordingly. The other dimensions were calculated proportionally to match the seat height.

between 1 and 4 years the seat height is between 25 and 30 cm
between 5 and 7 years the seat height is between 30 and 36 cm
between 8 and 10 years the seat height is between 33 and 43 cm
between 11 and 13 years the seat height is between 38 and 46 cm

There are also differences with armchairs, bar stools and rocking chairs. To give you an idea, I'll stop at bar stools, which look very similar to regular bar stools, the difference being the height.

High bar stools

Bar stool it should be chosen so that it is 25-38 cm below the bar counter. As the height of a bar is 100-115 cm, this results in a seat height from the floor of about 72-76 cm, which is considered standard for a bar stool. The backrest height is between 26 and 36 cm, the seat width between 38 and 46 cm and the depth between 30 and 40 cm. If the bar stool has a round seat, the diameter should be between 40 and 43 cm for the most comfortable seating. At 50 cm below the seat, there should be wooden bars attached to the seat legs or a metal bar at the base of the bar so that the legs can be supported for comfort.

This type of stool is not only used at the bar but also when there is a kitchen island used for breakfast or as a bar. Such islands are built 90 cm high and the seating is lower than bar seating (61 - 66 cm).