Spruce house

Physical and mechanical properties of spruce

In forests spruce trees usually grow as single trunks with a small number of bottom brunches and absolutely straight. In these conditions a branchless part of the trunk can reach up to 25m with the total height of the tree amounting up to 60m; the diameter is between 0.4 and 1.2m, with the maximum of 2m. In open areas a spruce crown becomes more voluminous while the number of branches increases. Spruce wood is light white or yellow-white with a silk sheen, and there is no colour difference between sapwood and heartwood. Under the effect of light, spruce wood darkens and becomes yellowish-brown. Tree rings are easily distinguishable, and the colour of lighter early wood smoothly turns into darker late wood; the edges between growth rings are distinct. Like other softwood, spruce wood has noticeable resin canals and pockets that create a light dotted pattern in cross sections. This is the quality that a fir tree does not possess, which makes it possible to distinguish the two. Another difference lies in the position of branches on a tree trunk: fir branches are usually at a straight angle and leave round marks on the trunk, while spruce branches are at a narrow or wide angle and leave oval marks.

Building a spruce house

Finished spruce log shell

Comparing pine and spruce timber

Spruce wood is very soft and has an average density of 470 kg/m³ with 12-15% moisture content. Its density decreases and mechanical qualities worsen with an increase in tree ring width (and a subsequent decline of the late wood percentage). Consequently, only softwood with growth rings between 4 and 6mm (DIN 4074-1) is deemed suitable for construction. The mechanical properties of this wood are excellent for such a low density; that is why spruce wood is extensively used as a constructional and building material. Nevertheless, raw spruce is nondurable due to varied weather conditions, and also rots easily in direct contact with the ground. For exterior use, this wood needs to be chemically treated in a correct manner. At the same time, spruce possesses comparatively low saturation properties; its moisture content of more than 20% and related fungal infections hinder absorption. It is relatively easy to process and treat spruce wood by means of sawing, chipping, milling and other techniques; screw and nail joinery and adhesion do not cause any difficulties either, but trunks with exceeding number of branches, resin pockets and growth-related inner tension can change their shape after use. Painting, coating and staining also do not cause any trouble. Spruce log cabins are quite popular thanks to their properties.

In house construction spruce wood is widely used for ceiling and overlap beams as well as pole constructions as it supports horizontal loads well.

Non-rotting wood (excerpt from Johanna Paungger's book)

Non-rotting wood must be cut during the last two days in March with the moon on the wane in Pisces. These days do not come round every year. So people used to look out especially for them or else cut the wood on alternative days: New Year's Day, January 7, January 25, and from January 31 to February 2. Timber that is cut down on these six days will not rot or get woodworm.

Furthermore, wood that is cut at New Year or between January 31 and February 2 will become very hard as it ages. 

It could well be that the foundations of the magnificent "floating" buildings of Venice consist of such timber. If they had not been felled on the correct day, the splendid city would probably have sunk into the water once and for all by now. Restoring the foundations with wood of this sort would be the ideal solution, for its durability can be clearly seen from the age of the present timber. Any other solution (concrete, steel, etc.) is unsuitable in the long run. This is also the right kind of wood for landing jetties and tall buildings on pile foundations. 

Consult the reputable experts in the field - the North House company. Commission a turnkey spruce house project at an optimal price.