Wednesday, June 1, 2011

Wall Construction Simplified

Walls are built as two primary components, they are the structure, and the finish materials.

Structure

The structure is used to house service utilities, provide support for the upper portions of the building, and as means of attachment for finish materials or insulation. They are constructed in two major divisions, interior walls, and exterior walls.

Interior wall structure is constructed in two primary categories, load bearing, and non-load bearing. Although not common, many homeowners opt to insulate the wall system to reduce sound transmission and lower heat loss in unused rooms.

Interior load-bearing walls are primarily constructed of 2" x 4" or 2" x 6" dimensioned lumber, with a two top plates, and one bottom plate, nailed to vertical members called "studs" spaced 16" apart. They are located over bearing beams, columns or footings, capable of supporting the loads that will be placed on them. Most often, load-bearing walls are installed perpendicular to, and as support for upper floor joists, ceiling joists or framed roof assemblies. Openings in load bearing walls are installed with headers, or small beams, supported on shorter studs, spanning the required height and width of the opening in the wall. Often cross bracing is required to prevent parallel deformation from external forces, and holds the building square.

Interior non-load bearing walls are installed in locations where the upper structural components do not rest or require support. They are built usually from single top and bottom plates, with studwork, often on 24" centers, nailed to them. Locations that this type of wall is used include walls parallel to joists, and in buildings with clear spanning truss's or manufactured/framed joist work. Openings in these walls generally do not require the use of structural headers or supports, but often do need diagonal bracing to prevent lateral movement.

Exterior walls always provide support for the upper structure, including floor and roof assemblies. They are always load-bearing, requiring diagonal supports or shear panels, and enough space for insulation. In Northern Ontario, these walls are generally constructed from 2"x6" material, but often double wall systems for added insulation are constructed. In the wall assemblies, windows and doors are installed to provide access to the building, as well as allowing for natural light or ventilation of the indoor environment. They are constructed from a framework of studs, usually 16" apart, nailed to a double top plate, and single bottom plate. Within the cavity, utility lines and insulation is placed.

The interior surface is treated with a vapor barrier, and finish, with the exterior surface having an air barrier and exterior finish or "siding" installed. Openings are framed with beams or lintels, supported on shorter studs, called "jacks", and nailed to the top and bottom plates. Although there are many configurations, builders utilize, for diagonal support, it is most often installed as shear panels, which are sheets of plywood or aspenite, nailed to the exterior of the walls framework. Other methods of diagonal support include wood or metal wind bracing which is a member placed diagonally from the bottom plate, through the studs, to the top plate.

Finish

There are two main areas on walls over which a finish will be applied, they include the interior exposed surface and the exterior exposed surface. The finish materials provide an esthetic surface, protect the utility lines, and reduce the transmission of sound and heat.

Interior exposed surfaces

Finishes applied to interior walls are very much the more important consideration to homeowners. This is the surface, which they will see each day, and must be visually appealing, yet, durable and require little maintenance. Of the multitude of finishes, we will discuss paneling, gypsum board, and interlocking wood.


Paneling is thin sheets of wood products, typically 4' x 8' in size, and come with a variety of finish textures, colors and patterns. It is manufactured for use in general locations, but some types can be installed in wet areas, like shower stalls and laundry rooms. It is easily put on, requiring no finish work other than trim and caulking, when required. Advantages to this type of finish is that it can be quickly installed and requires no maintenance or upkeep. One disadvantage is that the finishes are generally only available for a few years, so future repair, tends to require the complete replacement the damaged panel, and all adjacent panels, to ensure a match.

Gypsum board (often referred to by the trade name "drywall") is probably the most popularly installed interior finish. Gypsum board provides a smooth, flat surface finish, which is durable, can be altered by painting over to change its appearance, easily repaired and requires little maintenance. It is relatively cheap to install, but does tend to be a bit messy. This is due to the need for repetitive coats of a plaster based compound, required to fill in all the joints and penetrations located between the individual sheets, which need to be sanded down. It is a good sound and heat barrier, in that its smooth and light-colored surface easily reflects both sound waves, and radiates heat, back into the room.

Interlocking wood finishes, are very natural surface treatments. They are simply strips of wood, designed to interlock with each other. This type of finish, can be manufactured from oak, birch, maple, cedar, or most commonly, pine. Installers normally use small nails to fasten the individual slats, but often they will opt to glue the sections in place. This type of finish requires trim work to hide any exposed edges. Interlocking wood, is more expensive to install, both due to material costs, and higher labour time. It requires occasional sealing with shellacs, sealers, oils, or stains to maintain, and repair work is rather difficult. Finishes of this type, are most often installed in areas requiring less noise, like dens, living rooms or libraries.

Exterior Exposed Surfaces

Finishes applied to exterior exposed wall surfaces are an important consideration to homeowners. This is the surface, which the neighbors and passerby's will see, each day, and must be visually appealing, yet, durable and require little maintenance. Of the multitude of finishes, we will discuss paneling, vinyl or aluminum siding, brick, and interlocking wood.

Paneling is thin sheets of wood products, typically 4' x 8' in size, and comes with a variety of finish textures, colors and patterns. It is manufactured for use in exterior locations. It is easily installed, requiring no finish work other than trim and caulking. Advantages to this type of finish are that it can be quickly installed and require little maintenance or upkeep. One disadvantage is that the finishes are generally only available for a few years, so future repair tends to require the complete replacement the damaged panel, and all adjacent panels, to ensure a match.

Vinyl or aluminum siding is by far the most popular type of siding, installed in modern homes. It is a product manufactured by extruding, or pressing poly vinyl through a mould, or by stamping aluminum sheets into shape. It comes in a wide variety of colors and textures, as well as varying in width. It is fastened to the building with small, large-headed nails, which are left loose to allow for thermal expansion. This is a durable, maintenance free type of finish, with a very long life span. Because of this, and the fact that it is one of the cheaper sidings to install, it tends to be the siding of choice for builders. The only disadvantage to this type of siding is that they damage easily, and repairs are difficult, at best, to make.

The most durable and expensive, exterior finish, is the popular brick siding. Bricks are made from clay or cement, molded or extruded to form small 4" x 3-1/2" x 8" bricks (typically). They come in a variety of colors, and a variety of textures. Other types of brick siding can include rock or stone, cut to fit. Brick is installed by laying the units in a 1/2" bed of mortar, called a joint, and connected to the walls with brick ties. The mortar can be tinted to accent or match the brickwork. Brick siding is a very durable and maintenance free finish, requiring no maintenance or upkeep, while giving a very solid or stoic feel to the home. It is quite expensive to install but still remains a popular choice for modern buildings.

Interlocking wood finishes, are very natural surface treatments. They are simple strips of wood, designed to interlock with each other. This type of finish can be manufactured from pine, or more commonly, cedar. Installers use small-galvanized nails to fasten the individual slats. Interlocking wood requires trim work to hide any exposed edges, and caulking to seal the exterior penetrations. It is a moderately expensive finish to install, both due to material costs, and higher labour time. It requires occasional sealing with shellacs, sealers, oils, or stains to maintain, and repair work is rather difficult. Finishes of this type, are most often installed in cottages or rural building locations because of its natural look.








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