Building a timber frame house: the key is…

Timber frame houses are no longer an exotic phenomenon in Lithuania. Quite many people live in this type of houses and do enjoy living in them. However, we still happen to meet some who are not very satisfied with the timber frame houses. This is the result of poor construction knowledge and inadequate economy during the construction process. It’s good to have an economizing approach, but you need to know where to save and where not.

Since there have been many articles written about timber frame house building techniques and basically they are all good, if builders know what they are doing, so there is no point in writing about yet another technology that is either very traditional and not interesting, or that would break the rules, lead to debates, but basically would be good. In this article, we would mainly like to list common mistakes made in construction of timber frame houses and how to avoid them.

House architecture and structure

One of the biggest advantages of a frame house is its highly flexible and fast construction. In low rise building construction, using wooden structures, it is possible to build the most pretentious houses from any decoration materials available on the market. Planning to build a traditional single-storey house, sheathed with wood panelling, any man, after searching the Internet and reading this article, would fine it quite easy to build a good timber frame house without making many mistakes. But often we do not want to live in simple houses with a standard finish, thus resulting in unventilated facades, to install which correctly requires a lot of knowledge and experience. We also want houses of more sophisticated and complex construction, which require a constructor. For construction of more complex structures, or higher than single-storey timber frame house a constructor is necessary and that’s where you shouldn’t be saving. It is very common in Lithuania when timber frame houses are observed to have a too faint, squeaking and cracking ceiling or a curved roof and this diminishes the image of timber frame houses and the cause of this is economizing and poor skills.

It is very popular in Lithuania to use the decorative plaster and clinker bricks for wall finish, and if this type of finish is chosen for the timber frame house, most often the façade will be made unventilated. And if it’s installed on wet construction or humidity can get inside the structure from inside the house, there is a very high probability for mold or fungus to develop in the structure. To have this type of finish for the timber frame house, it is necessary to consult an expert before starting the construction. A number of timber frame houses have been built in Lithuania with this type of finish, however many with technological requirements being ignored, which does not add to the popularity of timber frame houses.

Timber

It seems logical that if you are building a house for yourself, you want to use the best materials, and particularly those that support the house. The house is supported by the structures made of wood. A large proportion of timber frame houses in Lithuania have been built from wet and non-calibrated wood; it is bad, but this is so. It’s even worse that building a house from the wood which has not been dried out and calibrated, it must be impregnated with all kinds of “green” agents thus making construction of a house more complex. These two elements constitute that difference, which would have been paid if buying already good and proper timber. Dried and calibrated timber is no food to insects, unless they had already been there before it dried, while mold and fungus does not develop in timber, if the house architecture is well planned. Good timber, if it is not exposed to weathering, requires no impregnation. So, it’s really not worth saving on basic building material.

Thermal insulation

Mineral wool is the most commonly used material for thermal insulation of timber frame houses. There are also other ways of insulation, but they are not that popular and usually more expensive, so we shall not be discussing them.

Mineral wool is classified into stone and glass wool. Their differences are very small, so it’s not worth analysing them in more depth. Much more important is their practical application in construction and the myth associated with their “subsidence”.

First of all, the basic components of mineral wools are durable natural materials – glass and stone. They haven’t changed for centuries. The wool binders account for about three percent of their composition, and are usually made from formaldehyde adhesives, the same glue, which is used to make furniture, constructional panels, carpets etc. The oldest known items glued with this type of adhesives are the Soviet furniture, which are now more difficult to dismantle, if they did were not affected by moisture, so this binder is also a very durable material. If mineral wools are not subjected to moisture or other kind of atmospheric variations, over time their structure does not change, and they do not “subside”. The mineral wool used in the well-designed structure of timber frame house elements is not exposed to direct atmospheric effects, so it cannot “subside”. The myth regarding “subsidence” of wool is a result of ignorance and excessive economizing by people. Even now, for example, you would sometimes see that the roof trusses are constructed in larger increments than necessary. Wool widths usually range from 565 mm to 610 mm, so the spacing between structural elements cannot exceed 600 mm. In other cases, mineral wool boards are cut, there remain many scraps, which are then inserted into the structure, and it is impossible to position them correctly. This results in the so called “subsidence”. It is essential that the mineral wool is protected against atmospheric variations and when placed in the structure it is compressed on all sides. With this done, the wool “subsidence” is impossible.

Tightness

 The idea of building tightness is still new in Lithuania. Only now, with the mandatory approach towards homes rated class A in energy efficiency adopted, builders and people begin to understand what is tightness and why it’s needed for the house. House tightness requirements and measurements would give enough material to write a separate article, but we will try to describe the idea in brief.

Generally speaking, a windy day may result in pressure differences between the outside and the inside of the house, causing the air penetrate the premises. In order to build a warm house, it is our duty “to plug” all the holes to prevent the cold air from entering inside the house. Mineral wools are wind-permeable, it is therefore necessary to attach different films and panels on house elements. The joints of all panels and films are glued with specially adapted adhesive tapes. After gluing, the tightness test can be performed to the check the house tightness.

Very few houses in Lithuania do meet the energy class requirements on tightness, because it’s a relatively new thing overlooked by many. Tightness is equally important for all types of houses, but the timber frame house walls are insulated with mineral wool, so this is particularly relevant to them. Poorly sealed houses absolutely do not store heat on windy days, so greatly increasing heating costs. We should not exclude timber frame houses either, because the houses of all types in Lithuania are very poorly constructed with regard to tightness. When building a house, pay a lot of attention to tightness, because it will directly affect the heating costs.

So in order to build a warm and strong timber frame building, what you need to pay attention to most, include: house structure, its insulation and tightness. This is logical, and nothing new is written here.

© 2015 Karkasa. All Rights Reserved.