Manufactured Housing in the NorthTechnical Series 94-215
Building in a northern or remote region is a challenging and difficult endeavour. The further north and more remote the site, the more challenging and difficult it becomes.
Manufactured housing systems offer significant benefits in remote and northern regions, given conditions such as:
To lessen the impact of these factors and to facilitate and hasten installation and finishing, companies, agencies or contractors building in the North often use various forms of manufactured (prefabricated) building components.
Building components or structures can be manufactured to various levels of completeness. The simplest level is pre-cutting, basic preparation and coding or marking of the materials that go into a structure. The manufacturing process can also involve increased levels of component assembly, from truss and panel assemblies, through to completion of full sections of dwelling units, such as sectional or modular housing or mobile homes.
The level of manufacturing that is appropriate for a particular situation or location is highly influenced by the factors outlined above. Determining the most cost-effective approach requires an economic analysis that will include the availability of equipment and material, labour and transportation costs.
A typical prefabricated wood-frame system for northern use consists of stud-framed wall sections. These have insulation installed and protected with exterior grade plywood sheathing or siding on the outside, and plywood, fibreboard or other sheathing material on the inside, but without the final interior cladding. Hand holes at the sides of each panel allow the wall sections to be bolted together. The floor may be precut beams supporting stressed-skin plywood panels or conventional construction with precut joists and sheathing. Precut roof trusses or prefabricated box beams are used to support site-applied roof and ceiling cladding. Much of the work of applying interior finish is done on the site, so careful on-site supervision is required.
Stressed-Skin Panel Systems
Stressed-skin designs use light, strong sheet materials as structural skins which are bonded to stabilizing webs to form an enclosed panel. The panels act as groups of I-beams or H-columns. The framed stressed-skin panel offers high rigidity and a strength-to-weight ratio which can only be surpassed by the structural sandwich type of stressed-skin design.
Structural Sandwich Systems
Structural sandwich panel design represents a further advance from the framed stressed-skin concept. The structural skins are bonded over their full area to a light core sandwiched between them. The core acts both as the stabilizing web and as insulation. True stressed-skin action is achieved over the whole panel and the structural sandwich allows the highest possible strength/weight ratio with given materials. Skins may be of plywood, hardboard, wood-cement board or metal; honeycomb or plastic foam is normally used as core material.
Prefabricated Modules, Sectional Units, and Mobile Homes
Modular building entails factory production of the largest and most complete section of the house that the transportation route and system will allow. This maximizes productivity, minimizes on-site labour, and reduces the need for skilled labour. Freedom of design is somewhat limited, and because modules are bulky and hard to handle, they usually cost more to transport. However, the high factory content allows better quality control. Given careful handling, the better modular units, designed for the North, can allow excellent, permanent housing to be quickly installed in any accessible northern area. Modular units can be shipped by suitable road, or by sea to a port with suitable off-loading facilities.
Because of the stresses imposed during transportation, the rigidity of a modular unit must exceed its on-site requirements. However, it is easy to make the whole unit into a rigid box by using either a stressed-skin or monocoque (similar to unit-body automobile design) structure.
The rigid box also simplifies foundation design. The number of support points for a dwelling is usually dictated by the span of the structure, not the loading capacity of the support. When units are made rigid in order to survive transportation, it is possible to support the structure on three or four rather than a dozen points. This has several advantages:
When considering any type of prefabrication for the North, transportation of the components or units is one of the more restrictive considerations. The transportation requirement will affect the weight, size, materials, finish, and strength of the units or components, and obviously the cost.
Things to consider when transporting components or units to remote and northern regions include the following.
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