He pointed out that one of the most common things people fail to take into account is the minimum height of a terrace. A terrace is usually not level with the ground, but at least 25 cm above it. This is due both to the decking itself, which is already 28 mm thick, and to the beams, posts or supports to which the decking is attached. If the terrace is to be recessed into the ground, drainage must be considered separately. “It is definitely easier to build a terrace on top of the ground,” Kams noted.

According to the expert, another common issue is that people sometimes have unrealistic expectations of a terrace. “A terrace is not a living room. It will never be as smooth, clean and free of cracks as a living-room floor. A terrace is still an outdoor area. If a child walks barefoot on the terrace and gets a splinter, unfortunately that is simply part of normal life,” Kams explained.

Planning time pays off

According to the expert, building a terrace should begin with thorough planning. “There is no need to rush the planning stage, because the time spent on it will pay off later. It gives you a chance to think through what kind of terrace you actually want,” Kams said.

For example, the first thing to consider is how the terrace will be used: whether for sunbathing or having dinner with friends, whether there should be a place for grilling or a separate area for children to play. In addition to its purpose, the size and location of the terrace should also be considered, including whether it should be built on the northern or southern side of the house.

“If you want to drink your morning coffee on the terrace, you should build it where the sun rises in summer, because in winter the sun rises in a different place. If you want to sunbathe, the terrace should preferably face east or south. If you want to grill with friends in the evening, it is worth considering the direction of the evening sun,” Kams explained.

He also recommends thinking through how people will move around on the terrace and physically walking around the planned location to better imagine the overall solution. It is also important to consider what kind of furniture will be used and how it will fit on the terrace.

Building regulations must also be taken into account

According to the Puumarket expert, planning should also take building regulations into account, because broadly speaking, a terrace can be built in two ways: under the open sky or under a roof. “As a rule, terraces are built under the open sky. If the terrace is less than 1 metre above the ground, it generally does not fall under the restrictions set out in the legislation. A terrace higher than that, however, becomes a structure and requires a building notice,” Kams explained.

According to him, a roofed terrace larger than 20 m² becomes a separate building and may require both a building permit and a building notice. In that case, the permitted building coverage of the plot must also be taken into account. “If the terrace has a roof or is higher than 1 metre, it is included in the calculation of the total built-up area of the plot. Lower terraces are not included,” he added.

Once the purpose, dimensions and location have been decided, the choice of materials must be considered. “The choice of material is sometimes what people regret later. This most often concerns larch, which is stronger and harder, but also more difficult to fasten and tends to curl up at the edges or develop sharp fibres,” the Puumarket expert explained.

Scots pine is used most often

The most common material for building home terraces is Scots pine. The sapwood of pine absorbs preservatives well, which means it can be treated deeply using vacuum-pressure impregnation. “To protect against biological decay, the wood is impregnated with a water-based wood preservative according to the NTR standard commonly used in the Nordic countries, class AB, or the European standard class UC3, which is also internationally referred to as H3. The NTR AB impregnation process used in the Nordic countries is slightly longer, the solution is stronger and therefore the wood becomes even more durable,” the expert said.

Thermally modified pine, or thermopine, as well as thermally modified spruce and ash are also used for terraces. The latter mostly originates from South America, but is processed in Estonia. There are also newer composite materials on the market, essentially wood-plastic composites containing around 60% wood, 30% plastic and 10% other components. Larch is mainly used for public projects that are subject to heavier use.

“Terraces in Estonia are exposed to very challenging weather conditions, with alternating rain, snow and sunshine. These cause the wood to swell and dry out, which in turn leads to cracks. It is therefore important to understand that a terrace will not last forever under these conditions,” Kams explained.

A well-built pine terrace has a lifespan of around 15–20 years, and a larch terrace roughly the same. Thermopine lasts around 20 years. Composite material, on the other hand, is still so new that its lifespan cannot yet be stated with certainty.

Moisture is wood’s greatest enemy

Moisture is important when it comes to the durability of wood. In Estonia, the moisture content of outdoor wood kept under cover is around 18%. However, wood exposed to the open sky can reach and remain above 23% moisture for long periods. This usually happens in the second half of the year. As a result, favourable conditions are created for the development of wood-decaying fungal growth.

For composite materials, the main enemy is UV radiation, which makes the material brittle over time. A composite terrace built on the southern side can also become unexpectedly hot in direct sunlight.

Scots pine is also the most budget-friendly option and usually comes from Estonia or neighbouring countries. For example, an 18 m² terrace costs around 800 euros including screws and other necessary materials. A larch terrace of the same size is around 50% more expensive, while a terrace made of plastic composite or thermally modified wood is around 2.5 times more expensive.

“At Puumarket, we have created a calculator that allows anyone to estimate the approximate cost based on the size of the terrace and the chosen material. It is a useful tool for budget planning,” the expert added.