MOISTURE CONTROL

Wood is a 1) _____ material, which means it naturally absorbs and releases water to balance its internal moisture content with the surrounding environment. The moisture content of wood is measured by the 2) _____ of water as a percentage of the oven-dry weight of the wood fiber. The key to controlling decay is to control moisture. Once decay fungi are established, the minimum moisture content for decay to propagate is 22 to 24 percent, so building experts 3) _____ 19 percent as the maximum safe moisture content for untreated wood in service. Water by itself does not 4) _____ the wood, but rather, wood with consistently high moisture content enables fungal organisms to grow.

The 5) _____ objective when addressing moisture loads is 6)_____ water from entering the building envelope in the first place, and to balance the moisture content within the building itself. Moisture control by means of accepted design and construction details is a simple and practical method of 7) _____ a wood-frame building against decay. Finally, for applications with a high risk of staying 8) _____, designers should specify durable materials such as naturally decay-resistant species or wood that’s been treated with preservatives. Cladding, shingles, sill plates and exposed timbers or 9) _____ beams are examples of potential 10) _____ for treated wood.

10 Fill in the gaps with derivatives of the words in capitals:

To avoid decay and termite 1) _____, it is important to separate 2) _____ wood from the ground and other sources of moisture. These separations are required by many 3) _____ codes and are considered necessary to maintain wood elements in permanent structures at a safe moisture content for decay 4) _____. When it is not possible to separate wood from the sources of moisture, 5) _____ often rely on preservative-treated wood. Wood can be treated with a preservative that improves service life under severe conditions without 6) _____ its basic characteristics. It can also be pressure-impregnated with fire-retardant chemicals that improve its performance in a fire. Wood does not deteriorate just because it gets wet. When wood breaks down, it is because an organism is eating it as food. Preservatives work by making the food source inedible to these organisms. 7) _____ preservative-treated wood can have 5 to 10 times the service life of untreated wood. Preserved wood is used most often for railroad ties, utility poles, marine piles, decks, fences and other outdoor applications. Various 8) _____ methods and types of chemicals are available, depending on the attributes required in the particular 9) _____ and the level of protection needed. There are two basic methods of treating: with and without 10) _____. Non-pressure methods are the application of preservative by brushing, spraying or dipping the piece to be treated. Deeper, more thorough penetration is achieved by driving the preservative into the wood cells with pressure. Various combinations of pressure and vacuum are used to force adequate levels of chemical into the wood.

INFEST TREAT BUILD PROTECT DESIGN ALTER PROPER TREAT APPLY PRESS

11 Fill in the gaps in the following passage with a suitable preposition given below:

between of(x3) into for in with to

Under microscopic investigation, softwoods show only one type 1) _____ cell which varies 2) _____ size 3) _____ the rapid growth 4) _____ spring and early summer (early wood) and the slow growth 5) _____ the late summer and autumn (late wood). These cells perform the food- and water-conducting functions and give strength 6) _____ the tree. Hardwoods, however, have a more complex cell structure 7) _____ large cells 8) _____ the conducting functions and smaller cells providing the mechanical support. They can be divided 9) _____ two distinct groups: diffuse-porous hardwoods and ring-porous hardwoods.

Softwood – Scots Pine	Diffuse-porous hardwood – Birch	Ring-porous hardwood – Oak
Figure 5.2 Cell Structure

 

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1. Деревянные части здания. 2. Рельеф. 3. Кирпич. 4. Электророзетка. 5. Выключатель. 6. Водопроводчик. 7. Оконная рама. 8. Сосна. 9. Герметичный. 10. Желобок. 11. Петля дверная, оконная. 12. Ручка дверная, оконная.

13 Look at the text, separate the words to make sense: