VOLUME 19, NUMBER 1

TIPS FOR SUCCESSFUL HOME OWNERSHIP

When you select the lumber for you new home, always use the highest grade you can afford. The performance of the lumber will usually pay for itself. When selecting a grade, the lower the number, the higher the quality. In other words, number 1 grade is better than number 3 grade.

In This Issue

WHY CAN’T WE BUILD A PERFECT HOUSE?

WOOD IS MATERIAL OF CHOICE

IT’S ORGANIC!

IT SHRINKS!

IT IS NOT HOMOGENOUS

For More Information

Call our local office or visit our Web site at:

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WHY CAN’T WE BUILD A PERFECT HOUSE?

This is the second part of a continuing YOUR HOME series that looks at the various challenges faced during the life of any home. Many people expect a perfect home, whether buying a brand new or a “used” home. With that expectation, they will be disappointed. There simply is no such thing as a perfect house.

To start with, what is perfect? To each owner and builder, that probably means something different. Is being precisely square, level, and plumb perfect? Are smooth, uniform, unblemished finishes perfect? Is an expected service life of 100 years perfect? Is a virtually maintenance-free exterior perfect? If any of these criteria define a perfect house for you, then you will be disappointed.

We suspect that Mother Nature and Mother Earth get a good laugh at our futile efforts to build the perfect house. There are probably endless reasons why building the perfect house is an impossible goal. We believe the following to be the most fundamental:

1. We build our houses on the ground! Mother Earth (the ground) is unpredictable.

2. We build most of our houses with wood. Wood is organic. Mother Nature did not design wood to be a predictable, reliable building material. It is dimensionally unstable and changes shape as it ages and as temperature and humidity change. In this issue, we explore this topic in more detail.

3. We use human beings to build our houses! Human beings are not perfect. Further, there seem to be fewer and fewer skilled human beings available to help build houses.

4. We build our houses outside! That’s the worst practice of all!! The same Mother Nature that gives us imperfect wood with which to build our houses then throws unpredictable weather at us while we build.

In this issue, we’ll look at the effect of building our homes with wood.

Ever since man began to build his own shelter and stepped out of the world of cave dwelling, wood has been an important part of those structures. For the log cabins of our earliest settlers and the tepees of American Indians, wood was an essential part of construction. Even in the centuries-old stone buildings of Europe, wood was still an important part of the roof structures and, often, the floors.

In certain climates, alternatives have evolved, but none have endured to the point of replacing wood as the material of choice. Each has clear disadvantages and are very dependent on certain environments for durability. These include the adobe and straw bale structures of the Southwest and the igloos of northern Alaska and Antarctica.

Throughout various parts of the world, there are certainly other variations but the one most common material that repeats itself over and over through different cultures and different centuries is wood.

Its attractiveness lies in its availability, relative light weight (as compared to metals and stone) making it easier to work with, and the relatively simple tools required to prepare it for use (cut and shape it) as well as assembling it into a structure (nailing and screwing).

Wood comes in many different forms, species and ratings. This article is not intended to provide an understanding of the choices of wood in construction, either now or in the past. Instead, the article attempts to explain why the use of wood in the majority of our homes prevents us from building the perfect house.

As noted above, any such discussion must first define what is meant by perfect. In our experience, in today’s world, perfect means, among other things, without visual flaws. In an average home, that means no cracks, no blemishes in flat painted surfaces, no separations in the joints between separate pieces of wood trim, doors that open and close smoothly from season to season, etc. For each homeowner the definition of a perfect home is likely to be different.

Wood is Material of Choice

Wood continues to be the material of choice for most residential construction. During the last decade there have been some new wood-based products introduced that generally fall under the heading of engineered lumber. TJI, Trus-Joist, glu-lam and micro-lam are examples of product names of material in this category. Waferboard and Aspenite and similar “plywood substitutes” can be considered engineered lumber or structural composition board. The big difference between conventional timber framing components and engineered lumber is the fact that engineered lumber is processed by using smaller pieces of lumber and gluing them together to create a larger usable timber framing member or construction component.

It’s Organic

Standard timber, while it continues to be one of the most economical materials to use, is easy to work with, light weight and generally readily available, has one significant flaw as it relates to building the perfect home.

It is organic!

Mother Nature, in her vast gardens and forests throughout the world, grows trees. The growth of those trees is affected by weather variations from season to season, severe weather events (hurricanes, floods, etc.), and geographic influences. The quality of any tree to be converted to useful construction lumber is also dependent on the type of tree and its age. As is to be expected in a free enterprise, market-driven economy, those trees that produce the best construction lumber are also typically the most expensive. Unfortunately, the framing that is not visible once the home is complete is one area where savings is often targeted. Thus, lower quality lumber is often used for framing.

In addition, since it is an organic material, wood is not dimensionally stable.

What is wood? When it is still a tree (a large plant, to botanists), wood is a growing, living entity, primarily xylem. According to Webster’s, xylem is a complex tissue in the vascular system of higher plants that consists of vessels, tracheids or both usually together with wood fibers and parenchyma cells, which functions chiefly in conduction of water and dissolved minerals and also for support and food storage. Xylem constitutes the woody element of a tree. If you are wondering, parenchyma cells, again, according to Webster’s, are a tissue of higher plants that consists of thin walled photosynthetic or storage cells. Add to that mix some cellulose, which forms the walls of the cells. Cellulose, by the way, is a type of glucose (sugar). And to complete the mix, add water. Just as a healthy living human body is mostly water, a healthy living spruce tree, for example, is about 50 percent water. Wow, and you thought wood was, well, just a piece of wood.

It Shrinks!

As long as all of the normal functions of life in an organic entity such as a tree are active and healthy, the water is an important part of maintaining that health. As soon as the tree is cut down, it dies as an organic entity and the cellular structure and dependence on water take on significantly different characteristics. Most importantly, the water no longer serves a function and the systems that were dependent on the water become inactive. Without an ongoing source and use for the water, it dries out, and the moisture content (percent of the DRY weight of the wood that is water) begins to decrease.

The timber industry has established that 19% moisture content is an acceptable level for a piece of lumber to be used in construction. This is referred to as surface-dry or kiln-dried lumber. In most timber industries, drying lumber in kilns is no longer common. The term, however, has survived. There is also a standard in some forestry organizations that dictates that a piece of lumber sold for construction purposes must be at 15% moisture content or less. In other words, when that piece of lumber arrives on the construction site, there is still some water in it.

Over the first few years after that piece of lumber is used in your home, the wood will shrink. As the moisture leaves the wood, the cellular structure must shrink to compensate for the absence of that water.

Eventually, it will reach equilibrium with its ambient conditions which will vary according to the climate, part of the country, how the home is occupied, other available sources of moisture, etc., etc. Typically, that piece of lumber will reach equilibrium with its surrounding conditions at somewhere between 8 and 12% moisture content. Thus, there will have been a change in moisture content between how it arrived on the site and where it finally reaches equilibrium. Sometimes, the moisture content will even go up temporarily depending on how the material is handled on the site and whether it is exposed to rain, high humidity, etc. For this reason, better contractors will often bring finished lumber into the house and allow it to sit there for several weeks or months so that it reaches equilibrium with the surrounding conditions before it is cut and put in place. This is the best technique for getting the best results from a wood floor or quality wood trim, for example.

It is Not Homogenous

There is yet another reason why wood is not dimensionally stable. It is not a uniform, homogenous material. The grain structure (those faint lines you see in a piece of wood which represent the layers of wood that have developed through the years of growth) will vary from season to season. Also, for various reasons, imperfections will develop, such as knots and pitch pockets (accumulation of sap in certain spots within the wood). These imperfections contribute to the dimensional instability of a piece of wood. They also contribute to the reasons why wood will twist, warp and/or split after it has been put in a home. As it dries out, the influence of each of these imperfections will take on different levels of significance within that piece of wood.

Wood will continue to be an important part of residential construction well into the foreseeable future. Wood continues to be a material that provides a sense of quality and feel in a home. While we have many composite products that are replacing such things as wood trim, cabinetry, and doors, the homes people dream about still have a lot of wood. Framing, of course, will remain predominantly wood, all of which is, in our opinion, as it should be. It is simply important to realize that as long as we do use wood, it will be impossible to produce a perfect home. Along with the various other reasons noted in this series of essays, the use of wood simply makes it impossible to meet the standards of perfect often considered by many homeowners today.

Is there an answer to this apparent dilemma? Yes, to maintain a reasonable level of expectation for the homes that we build.

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