Environmental Engineering Reference
In-Depth Information
D. Construction characteristics
Residential buildings vary enormously in their construction characteristics,
including size, design, building materials used, substructure, cladding, use
of insulation, quality of construction, and site conditions. They vary in size
from simple shanties, to nice single- and multifamily homes, to palatial
mansions. They vary in design from the simple rectangular boxes of manu-
factured houses, to the diversity of home designs of middle-income individ-
uals, to the more complex and architecturally inspiring homes of the Victo-
rian era and the present.
All residential buildings have similar construction requirements. They
include a substructure, sidewalls, flooring, windows, roofing, attic and crawl-
space ventilation, plumbing, electrical wiring, attic and wall insulation
(depending on climate), and roof and site drainage. They also include interior
furnishings such as storage cabinets, closets, and finished wall and floor
surfaces. These reflect construction practices that depend on regional climate,
site characteristics, design preferences, and availability of construction mate-
rials. They also reflect evolving builder and homeowner preferences and new
amenities in the marketplace. Construction characteristics are much influ-
enced by cost, the most important factor in residential building construction.
1.
Substructures
Most residential buildings rest on a substructure that supports their weight
and anchors them to the ground. There are three common types of substruc-
ture: slab-on-grade, crawlspace, and basement. Some residences have com-
binations of these.
House substructures reflect regional preferences (in general, basements
are preferred in the northeastern U.S.); contractor preferences (assuming
equal costs, some contractors prefer to build houses on crawlspaces, while
others prefer slab-on-grade); soil characteristics (poorly drained clay soils
are unsuitable for basements); and cost and construction time (this is a
major contributor to the increasing construction of slab-on-grade, single-
family dwellings).
Substructure type often has significant effects on building IAQ/IE prob-
lems. Houses with basements or slab-on-grade tend to have higher radon
levels (given the same soil radon-emitting potential). Basements tend to have
problems with water penetration and excess humidity, factors that contribute
to mold infestation and attendant exposure and health risks. Such health
risks may also exist in dwellings with crawlspace or slab-on-grade substruc-
tures when constructed on poorly drained sites (as is often the case).
2.
Roofing
Roofs are constructed to protect building interiors from rain, snow, and wind.
They are designed to intercept rain and snow and carry their waters from
the roof edges to the ground, either directly or through guttering. Climatic
factors determine the nature of roof construction and the use of guttering.
