Timber is the only greenhouse effect gas neutral material. Felled when mature, timber stores carbon.
Taken from sustainably managed forests, it is a renewable material most of which is PEFC or FSC certified.
Its recycling chain is mature and controlled, making the recycling of its waste products possible to achieve zero losses.

In the forestry sector,
a timber species is generally a specific tree species or variety.
These species all have biological specificities and specific uses.

It all depends on the end product and its use, it also depends on its natural or added durability.
Some species are more suitable than others depending on their use.
For example, the species to use for patio decking will not be the same as for a facade.

The main purpose of finishes applied to timber products is to durably colour them.
Timber with no finish greys naturally due to the combined action of UVs (sun and moon) and bad weather, without altering the timber’s physical characteristics.
This natural appearance is therefore mitigated by the use of paint or saturator to optimise the aesthetic aspects over time.

We talk about treatments when processing timber that is not naturally durable, or when it includes sapwood, which is vulnerable to the risks inherent to timber:
Attacks by insects and fungi. Using a specific product applied using an autoclave, by spraying or by soaking, the
timber fibres benefit from a protective product. These products are regulated, controlled and CTB P+ certified. Protac guarantees the effectiveness
of its treatment for 10 years.

Cladding, or any other timber structure, can always be painted using a finishing product.

Nevertheless, the result will not be at its best and will not match a product coming out of an industrial application line.
Indeed, the Preserve cladding green or grey colour will inevitably show through the saturator.
Therefore it is preferable to choose to apply an opaque and more covering paint.
However, the treatment components will migrate from the timber to the paint surface, thereby altering the overall appearance.

Finally, manual application never achieves the quality of a factory application of which the quantity is consistent and permanently controlled,
where the application conditions are ideal for the best results and durability (for example, saturators must not be applied at temperatures that are
too high or too low and they require controlled humidity for at least 24h).

Yes, larch is one of what is called class 3 naturally durable species (except for the sapwood).

Usually, the term is shortened to “naturally durable”.
Each species has a field of application depending on its use class.
For example, in general the use class for timber facade cladding should be Class 3, whereas for a patio it should be Class 4. The use class is defined depending on the timber species and/or the treatment, it can be natural or added.
Without any treatment, larch is naturally durable class 3 except for the sapwood.

Sapwood is the “soft” part of the timber, it is vulnerable to attack by wood-boring insect larvae and xylophagous fungi. That part of the log therefore requires preventive treatment in order to be usable outdoors.
Even though larch is naturally durable, larch structures should be preferred in low humidity geographic zones, such as mountains or the South of France. All timber products without a finish will grey due to the combined action of UVs (sun and moon) and wet weather.

There are no direct answers to the question. This is because a ratio can’t be applied to the reality of a patio
or cladding project, even though its logic may be useful. The quantity of fixings depends on several factors. It depends on the species, the treatment, the thickness,
the support, the layout, the project shape and it must imperatively comply with applicable building regulations. Moreover, this type of indication engages liability,
as it is the equivalent of advice. Each project is unique and must be the subject of specific quantity surveying.