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GUIDE TO LOG CONSTRUCTION

GUIDE TO LOG CONSTRUCTION

I choose a log building

For many of us, a log sauna, log granary or log cabin is one of the greatest investments in our life. The design and construction process has many stages that need to be taken into account when planning the log building of your dreams. Below, you can learn more about log construction, choices of materials, healthy indoor air and a smaller carbon footprint. Timber is the most rapidly-growing construction material both for leisure buildings and permanent residences. At Salvos, we have chosen to focus on log buildings, and maybe it could be your choice, too?

WHAT ARE ‘LOGS’?

Logs are made of timber, usually pine or spruce. Of the two wood types, spruce is more popular as it can be treated with light-coloured glazing. When using pine, the red hue of the wood will push to the surface and treated timber will soon turn light red. However, spruce and pine do not have any other substantial differences, and both are excellent for log construction.

Timber is the most traditional building material in Finland. In Finland, there are log buildings that are hundreds of years old and still in great condition to this day. When treated right, log buildings last for generations.

 

 

TIMBER’S GEOGRAPHICAL QUALITIES

There is significant variation in the quality timber, the raw material for logs. In the Southern part of Finland, trees grow up to 2.5 times faster than at the level of Kainuu in Northeastern Finland. Southern wood is porous, while northern wood has tighter grains. However, wood should not be harvested too far north, as the wood may twist and turn, which causes challenges for log construction. It is easy to imagine that a twisting Lapland pine is more difficult to work with than a firm Kainuu spruce. It is also natural that southern wood is cheaper than northern wood, but skimping on wood quality may turn out more expensive than you thought. The wood used by Salvos is harvested in Kainuu, which is also the location of our log production plant.

MASSIVE LOGS OR LAMINATED LOGS?

Planed rounds logs are the most common type of industrial logs. There are two types of planed round logs: One type is made of massive wood, while the other is made of two or more separate pieces glued together, depending on its thickness. The glued logs are called laminated logs. Laminated logs are the most common type particularly used in larger buildings. Massive logs are best for smaller log buildings, such as outdoor saunas, granaries and storage buildings.

Laminated logs have significantly better thermal properties than massive logs. Both types of logs are suitable for all-year use and extreme variations in temperature.

SETTLING OF A LOG BUILDING

Logs tend to settle over time. New log buildings settle as the logs dry and become denser. Settling also occurs as the joints become denser. Settling needs to be taken into account when designing a log building since the building needs space for settling. We leave extra space above windows and doors, and window and door frames are attached to supports which allows for settling. The supports also bind the logs vertically. If interior walls are made of other materials, the walls also need to have extra allowance for settling so that the weight of the other structures does not fall on the wall. Planning for settling is the most important matter in log construction.
When the log layers are built, the logs are attached to each other with wooden pins. Each log is bound to the log below it, and, this way, to the entire structure up to the last log. When the log frame has been assembled, threaded rods are installed into the walls. The threaded rods need to be tightened at regular intervals during the first year so that the logs settle evenly in all parts of the building.

PLACEMENT AND FOUNDATION OF A LOG BUILDING

The best location for a log building is the highest spot in the plot so that rainwater flows naturally away from the building. Buildings that have lasted on the same plot for hundreds of years have always been built on the highest spot. Other locations can be suitable for log buildings, but in this case, you should reserve more funds for earthworks and rainwater control.

When the foundation has been done correctly, it will be safe to build on. Preparatory foundation works, such as earthworks and the installation of drain pipes, rainwater pipes, and inspection wells, must always be performed by a qualified professional. Soil is compressed layer by layer to withstand the weight of the building, after which the actual foundation works begin with the installation of frost insulations, bases, and pillars. When preparatory foundation works and foundations have been done with care, the building will stand straight and its windows and door will work right.

INDOOR AIR IN A LOG BUILDING

Log buildings have excellent indoor air and even temperatures. The buildings are cool in the summer and warm in the winter. Timber naturally binds and gives out moisture, which is why it is ideal for buildings with highly varying temperature and humidity levels. In log buildings, indoor humidity is more even than in other types of buildings, which contributes to your well-being in all seasons. There is significantly less dust and bacteria inside a log building than in any other kind of building.
Studies show that residents of log buildings find the indoor air in their building better than in other buildings.

VENTILATION IN A LOG BUILDING

In Finland, temperature and humidity levels vary fluctuate wildly, which is a common challenge in their construction of new buildings. Buildings coated with plastic are too dense, which is why moisture will condensate in the structures if ventilation is not ideal. This leads to poor air quality, which causes issues and health problems. People with illnesses related to air quality have often visited Salvos model buildings, and some of them have decided to purchase a log building of their own.

Gravity ventilation is traditionally used in log buildings. In the case of a three-season cabin, gravity ventilation is the most popular option as mechanical ventilation is not required by regulations. Gravity ventilation is implemented with air valves. Each room has a supply air valve and exhaust air valve.

Studies show that indoor air in log buildings is the safest and most carefree option.

ENERGY CONSERVATION WITH LOG BUILDING

A log building with a timber frame base can withstand winter conditions without maintenance heating if the building is only used from spring to autumn. This is made possible by the unique Salvos timber frame base, selected materials and technical solutions. Buildings are not insulated with wool, which absorbs moisture; instead, the insulation is made of extruded polystyrene. Airy base floor and roof ensure that the structures remain healthy throughout the year. The cabin will always greet you with a fresh scent of wood. Salvos water engineering has been developed with energy conservation in mind. Our salesperson will help you design a full solution that suits your needs. Depending on the size of the building, heating savings can amount to hundreds of euros per year.

A SUSTAINABLE ALTERNATIVE

Using timber in construction is an environmentally-friendly action in itself. The production of logs also produces wood chips as its by-product, which can be used as fuel. This is why log manufacturing produces more energy than it uses. Logs and other wooden materials bind approximately 2 kilograms of carbon dioxide per one kilogram of grown wood. Timber is a renewable and completely natural construction material.

Salvos’ centralised logistics reduce greenhouse gas emissions in various construction stages. Large masses are delivered directly from the contracted plant to the Salvos production plant where products are installed or compiled for assembly. Our products are delivered to customers in a single batch.

CORNER SOLUTIONS

Salvos offers three standard corner solutions.

Traditional cross corner: The most common corner model used in log buildings. The logs protrude 150 mm outside the outer walls. Cross corners are extremely leak-proof in terms of wind and heat.

Dovetail: An impressive and stylish corner model. The model is ancient, but also fits modern styles perfectly. The manufacturing of dovetail corners is difficult, but with our solid expertise and determined research and development, we have been able to develop a wind-proof and heat-preserving corner model, of which we are extremely
proud.

Short corner: A short cross corner is encased in vertical shuttering. The short corner is also suitable for locations where the area plans do not allow for protruding logs.

MATERIAL CHOICES FOR A LOG BUILDING

As for roofing materials, felt roofing is the most common one. Felt is excellent for log buildings thanks to its silence. You should always choose external sills with drips for your felt roofing. In the installation of felt, the most common mistake is bending the felt and nailing it to the fascia. As the sun heats the felt and cold weather cools it the felt will crack where it has been bent and nailed – and you may soon have roof repairs in your hands.

For insulating the base floor and the roof, we favour extruded polystyrene (Finnfoam) which does not absorb moisture. You may be familiar with the unpleasant smell of an old cabin. The smell is caused by woollen insulation which has absorbed moisture. With polystyrene, smell is not an issue.

 

A LOG BUILDING IS A SAFE CHOICE

As in all construction, the best option for log construction is to assemble the building indoors, protected from weather. Digitally optimised humidity will ensure that the structures are fully dry. Both move-in ready log buildings and weather-protected or package deliveries are packed indoors in our production plant. This ensures that our buildings and construction materials are always delivered dry and clean.

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