Draft:Wooden house



Wooden houses are houses constructed primarily from wood. Many different types of wooden houses have been available for a long time, the main ones being:
 * House with pole/beam structure.
 * House made of solid plywood panels.
 * Wooden frame house.
 * Stacked solid wood house (planks, trunks or logs, wooden block).

Environmental aspects
Wood, like stone and brick, is a durable building material that allows wooden houses to last for decades or even longer. There are several hundred year old half-timbered houses in various parts of Europe (Germany, France, Norway, Switzerland, etc.) and Asia.

In addition to being recyclable and biodegradable (if it hasn't been painted or treated), wood is also a source of energy when burned.

Carbon dioxide emissions
The production of materials used in the construction of any home consumes energy, but more importantly, it releases pollution into the atmosphere, mainly in the form of CO2. The amount of CO2 produced varies depending on the materials used. Wood can reduce the amount of CO2 released into the atmosphere by half. In addition, wood has a significant CO2 storage capacity, which limits its release. However, when wood is destroyed (naturally or by combustion), all of the previously stored CO2 is released into the atmosphere.

Another environmental aspect of wood construction is the low amount of waste on site, as all off-cuts can be recycled or burned in a furnace.

Post-and-beam structure
The load-bearing structure of a wooden house is made up of posts and beams, generally in solid wood or glued laminated timber, rigidly joined together, providing great dimensional stability. These load-bearing elements include bay windows, which can be fixed in place without the need for intermediate joinery, non-load-bearing insulating masonry blocks (e.g. hemp concrete blocks), wall elements that can be timber-framed (as in the timber-framed house described below) or stacked with planks. Such walls serve as infill and have no load-bearing function. Although the construction can be done on site, it is much more precise and reliable when done in a workshop. This type of construction allows the creation of large spans, preserving large open spaces and very open facades. Its complexity usually limits it to high quality projects or to the south-facing facades of bioclimatic buildings.

Solid wood panel house
This type of construction is becoming increasingly popular in France. On the other hand, it is widespread in Austria, Germany, Belgium and Switzerland. The main manufacturers are: Schilliger, KLH, Finnforest, Binderholz, MHM, Biospeedhome, etc.

This construction technique is a combination of framing and solid wood systems: aesthetically, it offers the same attractive features of a timber-framed house (siding, plaster, painted or unpainted on the outside, with additional insulation, and with a wide range of possible finishes on the inside, including the natural wood look of the panels), with the performance of solid wood in terms of inertia. The use of solid panels optimizes the use of wood, giving it equivalent mechanical characteristics in all directions, eliminating warping and deformation due to ageing or humidity, and allowing architectural freedom.

It's widely accepted that solid panel construction is more resistant to seismic activity. Some panel houses are over six storeys high, and some are as high as ten storeys. Modern techniques allow factories to produce wall sections of great length (up to 24 m) and variable thickness (from 7.8 to 50 cm) by assembling wooden planks glued or nailed together in multiple criss-cross folds. This type of wood construction ensures great stability over time.

Glued panels can be used to build a house from floor to ceiling. The house can be built on a conventional concrete slab or on stilts, in which case the floor can also be made of panels. All walls built with this type of panel are load-bearing. Floors and roofs can also be built this way. Panels can also withstand large overhangs, allowing balconies to be built without joist support.

Wooden-frame house
The wooden-frame house is the construction technique that best adapts to most regional styles. As such, it's the most widely used. The walls of a wood-frame house are built on a structure of wooden beams spaced 40 or 60 cm apart (typically), with insulation between them. This construction technique also allows complete walls to be prefabricated in a factory, protected from the elements. The enclosure can be completed in a matter of days as there is no drying time. The current trend in home insulation is to add heavy insulation (such as wood fiber) to the outer perimeter of the frame. This improves insulation, provides better thermal phase shift for summer comfort, and eliminates any thermal bridging attributable to the wood frame. A wood-frame house can be expanded quickly and cost-effectively.

Exterior cladding serves as a shield against the elements. It's often made of cladding, which is wood planks that can be painted, treated or left natural. Wood (especially untreated wood) exposed to the sun and the elements will turn gray over time, but will not lose any of its mechanical properties. Exterior cladding can also be created using coatings, composite cladding, wood, cement, PVC, resin, etc.

The interior walls are usually made of drywall, providing a wide range of finishing options (paint, wallpaper, etc.).

Insulation
A common argument in favor of a wooden house is that for the same insulation quality as a masonry construction, the wall of a wooden house is 40% thinner, which means a significant additional square footage in case of urban planning restrictions and resale. In practice, the advantages of wooden construction include the possibility of building a much better insulated building than a masonry one. The additional cost is limited as a percentage of the total construction cost and remains minimal in relation to the expected energy savings. In addition, since a wooden house is not designed in the same way as a masonry house, there is a high probability that the architecture and surface areas will be different. As a result, the gain in surface area is no longer significant.

However, the thermal resistance of the materials used in the construction of wood-frame houses is different from that of traditional houses. The thickness of different materials for the same thermal resistance (0.50 m2 °C W-1) is as follows: The amount of space saved will depend on the type of construction and the type of material used.
 * Solid concrete: 88 cm
 * Hollow block: 52 cm
 * Pisé: 39 cm
 * Solid brick: 28 cm
 * Softwood: 7.5 cm
 * Hemp concrete: 6.5 cm
 * Cork, cellulose panels, mineral wool: 2 cm

Prefabrication
One of the advantages of wooden-frame construction is that the wall panels can be manufactured in a shop in a dry, safe environment. Once the walls are complete, they are loaded onto a semi-trailer and erected on site using a boom or crane. As a result, the walls can be up in a matter of days, leaving only the floors and framing to be installed. This method of construction requires forethought, good supply management, millimeter precision and synchronization with other trades, but it also guarantees that the wood has not been exposed to the elements for several weeks (unlike erecting the walls on the slab). More advanced stages of prefabrication include the prefabrication of floors and frames in the workshop. A frame, for example, takes the form of boxes that are assembled on site by crane.

Stacked solid wood house and wooden masonry
Often referred to as chalets, they feature solid wood walls constructed by stacking planks (rectangular finish), logs (smooth finish) or timbers (rustic finish). Wooden masonry includes the use of solid wood breezeblocks. These are stacked using the masonry technique. This technique makes it possible to create any architectural style and encourages self-building and the construction of solid wooden houses with a minimum of tools.

Modern techniques now make it possible to assemble wooden chalets from pre-cut logs in kit form. Log thicknesses generally range from 28 to 60 mm, depending on the manufacturer and product range. Installation is step-by-step and requires little carpentry or framing knowledge.

Lack of inertia
Despite its thickness, solid wood has what is known as light inertia. This makes it a popular wood construction technique in North America and the mountainous regions of Europe. On the other hand, wood is an average insulator (with a lambda coefficient of 0.12) compared to materials specifically designed for this purpose (0.04 on average for rock wool, wood fiber, cellulose or hemp). To obtain an insulation coefficient comparable to that of a wood-frame wall, it is essential to add a layer of insulation, ideally from the outside, to take advantage of the inertia of solid wood inside the building. The exterior insulation can then be lined with thick boards to restore the "chalet" feel. This eliminates the need for interior insulation.

The modern concept of stacked solid wood construction offers significant thermal gains due to the design of the building walls themselves: single logs with insulation from the outside (to avoid thermal bridges, sources of major heat loss), or double logs with insulation (whose thickness can vary according to location and needs).

The most commonly used species for this type of construction are larch, spruce, red cedar, Scots pine and Douglas fir. Modern wooden houses generally offer very reliable insulation thanks to a system of double planks with insulation in between. For example, instead of 120 mm of wood, there are two 60 mm planks with an 80 mm layer of insulation between them.

Importance of timing of harvest and drying
The tree must be cut in the drier months, when the tree is at rest and the sap circulates very slowly, making it less prone to warping, splitting, and decay.

Natural drying, which can take up to a year, gives the wood great strength and durability. This means wood must be sheltered from the elements, yet stored in the open air to ensure good air circulation and avoid the accumulation of moisture and the proliferation of fungi and other parasites. Then it must be stored in a dry warehouse before being processed.

Factory-produced lumber is not always cut in the right season. It is also cut in spring and summer, and kiln-dried to produce lumber that, while less expensive to buy, is of poorer quality and will need to be further treated.