Sturdy benches in Oak, Elm and Ash.

Here I describe the different characteristics of a bench such as size, placement, type of wood, full or split board, rib bench, live-edge, leg models, surface treatment etc.

Plank bench:
The seat on these consists of 1-3 strong planks. Full seat board or split is mostly a matter of taste. Split seat board is always when the seat board is made of "full plank" i.e. I have used the entire width of the tree from bark to bark. Then you have to saw off the core in the middle (otherwise it will crack). Full seat board is often made of "half plank" i.e. only half the tree has been used. You can also use split boards of heartwood for outdoor benches.
The thickness of all the wood under the bench top i.e. the leg frame, is usually 30-35mm. I have a couple of different designs on the leg frame, see the pictures under "model of the legs" below.
The bench itself (i.e. what you sit on) is usually between 30-45mm and its appearance is usually determined by the wood it is made of.
Rib bench:
These consist of many small ribs that are about 30x30mm. A bench without a backrest has about 13 ribs and with a back there are about 26 ribs. The small ribs allow you to shape the bench to your body so they are very comfortable. Unfortunately, it takes a lot of work to make them.
Size:
The length depends on where it will stand - measure. It is better to take it a little too small than too large. I can in principle make benches up to 3-4m long but 50-150cm is most common. A nice and adequate size for 2 people that can also accommodate 3 with a little crowding is about 120cm wide. In a smaller hall, 80-100cm can fit well. The depth is usually between 20-35cm.
Location: indoor-outdoor:
Outdoor = exposed to rain and sun. A tough environment for wood, especially if it is outside all year round. It is best to place the bench in a cool but dry space during the winter.
Semi-indoor/outdoor: Built-in conservatories fall into this category. This is also a tough environment. It does not rain here but can be very damp in winter and very dry in summer.
Indoor = not exposed to moisture/wetness and an even temperature.
I only make outdoor benches in heartwood oak because it is the only thing that lasts in the long run. On indoor benches there is also sapwood and other types of wood such as elm and ash. I also prefer to treat outdoor benches with Sioo so that you do not have to re-oil every year.
Heartwood/Sapwood: The bark is on the outside. Inside it lies what is called sapwood. These are mainly the parts of the tree that are alive. Inside these lies the heartwood. It is often darker and more resistant to rot. I only make outdoor furniture in heartwood oak, which is the most resistant to rot among Swedish wood species.
Wood species:
I usually use oak, elm or ash. For outdoor use only heartwood oak. Elm is often a little darker, warmer and rustier in color than oak. Ash is usually much lighter, sometimes as white as birch. However, the heartwood of ash is often brownish.
Straight edges or "live"-edge:
When one or both sides of the seat board follow the shape of the tree, I have only removed the bark and left the sapwood. This is called "live-edge". Live-edge is less suitable for outdoor benches.
Model on legs:
I have several models on legs, for example:

model: "styrsö", "ww1", "ww2", "eas"
Surface treatment:
I try to stick to 2 treatments:
  Sioo:
If it is going to be outdoors, I usually treat it with a preparation that makes the bench quickly turn silver-gray, much like wood turns if it is left outside for a long time. Then the bench becomes fairly maintenance-free. You can have Sioo both indoors and outdoors, but it is as an outdoor treatment that it comes into its own. You get a bench that is silver-gray and maintenance-free for 8-12 years (except that you may have to wash it).
  Linseed oil/Osmo oil.
If the bench is going to be indoors, I oil it so that the wood's pattern appears. Linseed oil gives oak in particular a rich color tone and highlights the pattern and grain. Osmo oil is more neutral but also more durable. I often apply 1 coat of linseed oil (for the color) and then 1-2 coats of Osmo for durability.
For both, it is easy to touch up if there is damage.