Blog Archives

Tracer Test

Posted by on 14/ 11/ 15

Tracer tests involve the injection of an inert solution, or tracer, into an existing flow field via a borehole or a well. Tracer tests are often desirable because they are passive-type tests and do not place unnatural stress conditions on the flow system.

The dilution rate of the tracer at the injection well or its time of travel to another well can be used to calculate the water velocity and ultimately the permeability. Detection of the tracer, or concentration measurements, can be made by either manual or probe sampling. Commonly used tracers are radioisotopes, salt solutions and fluorescent dyes.

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WALLS AND PARTITIONS

Posted by on 14/ 11/ 15

The key to economical wall and parti­tion construction is preplanning to eliminate unnecessary materials and labor. Carpenters usually find extra material is needed here and there to accommodate doors and windows.

They may also follow traditional training by adding studs where partitions intersect exterior walls, blocking at mid-height of walls, double studs and headers at openings in nonbearing walls, and similar practices. Each of these excessive material uses is avoidable through proper attention in the planning stage. They add significantly’to cost without benefit to the home buyer.

Cost savings will be greatest when the overall out-to-out dimensions of the house and the location of wall openings coincide with a module of 2 feet...

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WOOD FRAME FLOORS

Posted by on 14/ 11/ 15

Most wood frame floors utilize nominal 2-inch thick joists placed on a center­bearing beam and covered with sheath­ing. Floor trusses have recently become more popular and post-and – beam crawl space floors have been in use in some areas for years.

Floor design is based on a number of factors, such as:

• Design load

• Lumber species, size, and grade

• Clear span between supports

• Floor sheathing materials and thickness

• Fastening techniques

Utilization of full span capacity of lumber joists can often save between 6 and 8 percent of joist framing costs.

If allowable spans for joists presently used exceed the spans shown on the floor plan by 1 foot or more, impor­tant savings may be realized by changing either the joist grade, spacing, or size.

Built-up wood girders are usuall...

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Concrete

Posted by on 14/ 11/ 15

Introduction

Concrete is widely used in residential con­struction for footings, stem walls, and exposed basement flooring, as a subfloor for slab-on – grade construction, and as a finished floor material. Concrete consists of cement (usually Portland cement), water, and sand and other aggregates.

Once cured, concrete becomes an inert product and is not usually associated with toxic exposure, although there may be some more subtle health effects. (Refer to the essay by George Swanson to learn more about these effects and about products that can be sub­stituted for Portland cement.) Certain com­mon construction practices can make con­crete harmful to human health and should be avoided. These practices are discussed in the following sections.

Components of Concrete

Cement

Cement is the “g...

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Installation, in a Nutshell

Posted by on 14/ 11/ 15

Today, most doors, windows, and skylights are preassembled in factories and delivered preframed, which makes installation much easier. Basically, you screw or nail the unit’s squared frame to a rough opening (RO). If the opening is in an exterior wall, weatherproof it first-wrap, flash, and caulk. Rough openings are typically Уг in. to 1 in. wider and taller than the outside dimension of the door or window frame being installed.

However, rough openings are rarely square or perfectly sized, so you need to insert shims (thin, tapered pieces of wood) between the square frame and the out-of-square open­ing. Shimming takes patience. But if you install shims well, doors, windows, and skylights will operate freely, without bind­ing...

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Plan Components

Posted by on 14/ 11/ 15

Typical highway construction plans are made up of several individual components. The paragraphs that follow will present a brief discussion of various types of plan sheets that make up a set. Except for major projects, seldom will all of the compo­nents be required in a plan. However, when required, they are usually placed in the order discussed.

The title sheet is the first in the set and contains a brief description of the project and indication of its length. It displays the title of the project in large, bold letters...

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FRAMING

Posted by on 14/ 11/ 15

There are many ways to frame walls, but it is always good to follow an organized sequence. This 16-step sequence has been developed over years of framing. Following these steps will help you and your crew work efficiently and eliminate errors. It will also ensure consistency from framer to framer. For example, if you have to leave a wall in the middle of framing it to go to another task, another framer can easily pick up where you left off and proceed without having to check every nail to see what you have done.

Keep in mind, walls must be square, plumb, and level. Measure accurately, cut straight, and nail tight.

Rake walls (sometimes referred to as gable end walls) typically start at the height of the standard wall and go up to the ridge of the roof...

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Meeting Code

Posted by on 14/ 11/ 15

I should be clear that, despite the absurdities in their codebooks, our local housing officials are not necessarily absurd people. This is important to re­member if you are about to seek their approval for a project. Building codes are made at the national level, but they are adopted, tailored and enforced at the local level. View your housing department as the helpful resource it wants to be, not as an adversary. Once your local officials are politely informed about the actual consequences of the codes they have been touting, the codes are likely to change. Be sure to provide plenty of evidence about the merits of smaller houses, including documentation of projects similar to the one you intend to build...

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Computer-Aided Design and Drafting (CADD)

Posted by on 14/ 11/ 15

As an example of the use of CADD files and design software, the Ohio Department of Transportation (ODOT) has stated that this is the preferred method of preparing plans. ODOT has adopted MicroStation and GEOPAK as its standard drafting and design software (Ref. 8). (Note: The preferences mentioned here are those used by ODOT and are cited here only as an example. This is not intended to be an endorsement by the authors. Other agencies use a variety of similar programs.) The standards refer­enced in the ODOT manual have been developed and tested using the software versions listed on the web site www. dot. state. oh. us/cadd/GPKStandards. For a more detailed explanation and background of the use of CADD in ODOT plan development, the reader may view the CADD Manual at www. dot. state. oh...

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Site Clearing

Posted by on 14/ 11/ 15

Although it is more convenient for a contrac­tor to build on a site without obstacles such as trees, native vegetation, and boulders, some but not all contractors will go to great lengths to preserve as much natural vegetation and as many other landscape features as possible. Do not assume that the preservation of your site will be a priority of the same magnitude for a contractor as it will be for you. To clarify your desires and the contractual obligations of the contractor in this regard, you can formalize site preservation intentions by stating them as part of your contract.

Here is an example of site specifications created for the purpose of preserving the nat­ural features of the site and preventing pest in­festations as a result of the clearing process.

It is the owner s intentio...

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