METRIC CONSTRUCTION MODULES, ARCHITECTURAL INFORMATION, MULTI-FAMILY BUILDING CONSTRUCTION

METRIC CONSTRUCTION MODULES

-Although all codes and standards now use metric measurements as the official numbers, most low rise residential construction today is still built following imperial measurements.

-Soft changes involve the use of existing physical sizes now specified in metric measurement

-Hard changes involve the establishment of metric standards.

-Another hard change involves the dimensions of sheet products.

ARCHITECTURAL INFORMATION - Site Plan

-A well designed site sustains its value and is less likely to become obsolete as design standards increase or change.

-The following are considerations of a good site plan:

• Siting of the building: The siting of the structure should relate with the design and grouping of the surrounding buildings, abiding by set-backs and other building bylaws.

• Visual aspects: The building should be sited to preserve privacy of ground floor residential windows and ensure the overlooking of upper windows is minimized. Natural lighting should not be impaired by other buildings.

• Orientation: The siting of the building should take advantage of pleasant views and consider sun, wind, and snow drifting.

• Access: Routes for public access should be convenient without creating a nuisance or detracting from the living environment of the site.

• Physical characteristics: Attention should be given to the topography of the site, particularly its drainage, soil, and natural features. These physical characteristics may affect the form and cost of the site development.

-The blending of building and site design is fundamental to good architectural practice

ARCHITECTURAL INFORMATION - Building Plan

-a drawing of the intended arrangement of rooms and zones within a building

-The first consideration in judging building design is its suitability to meet present and future space requirements at a marketable price

-a building plan that is designed to meet the most typical requirements of the market will get the maximum price

-A good residential plan will have the layout of the sleeping, working, and living zones arranged in relationship to one anothe

-These areas are connected with traffic zones, which allow passage from one zone to another without passing through a third zone.

-This traffic zone should be of a minimum area and designed to reduce foot traffic at any one place.

-A building design should be in harmony with the neighbourhood style in light of social factors, aesthetic characteristics, climate conditions, and local trends.

MULTI-FAMILY BUILDING CONSTRUCTION

-Building design and construction is governed by the applicable building bylaw or code.

-The four top-level objectives of the National Building Code or BC Building Code are:

1. Structural safety

2. Public health (sanitary conditions)

3. Accessibility

4. Fire and structural protection of buildings

-For multi-family buildings, the principal limitations as to height and size of building are governed by local zoning and planning regulations.

-The National Building Code regulates the construction requirements of apartment buildings by indicating the type of fire protection required for buildings based on building area, number of stories, and the number of streets that the building faces.

-Heavy timber construction is an older form of construction that was used to address fire protection.

Materials Used

-In Canada, most of these standards are set by Canadian Standards Association (CSA Group) or the Underwriters Laboratories of Canada (ULC).

-some material standards are established by agreement within an industry

-another reference for materials use are product evaluations by the Canadian Construction Materials Centre (CCMC), which offers a national evaluation service for all types of innovative construction materials, products, systems, and services

Multi-Family Dwelling Substructures

-The foundation (the lowest part of a building or structure, serving as support for the building or structure as a whole and typically placed below ground level) for any building is the most important element on which the building sits

-The materials used in foundations can consist of everything from pressure-treated wood to stone to concrete

-Geotechnical engineers must analyze the soil conditions on the property where the building is situated because the bearing capacity varies considerably according to soil type.

-Virtually all foundations are built with reinforced concrete

-Retrofitting or repairing older substandard foundations can be done to bring them up to current standards.

-Common types of foundations include concrete wall, concrete block, preserved wood, pillar and post, and concrete slab.

-The builder must excavate to a depth where the soil is undisturbed, thus ensuring that the footing can evenly distribute the weight to solid bearing soil.

-Moisture management is one of the greatest challenges with foundations.

-Drain tile and drain rock are placed around the outside of the foundation to ensure proper drainage of water away from the foundation

- In most cases, the drain pipe terminates on a sump (a large concrete cylinder), which has an inspection lid. From here, the storm water can be directed to a municipal storm system.

-Damproofing (the black coating applied to foundation walls) is not the same as waterproofing

- It is applied to seal minor capillary pores in the concrete that would otherwise suck in ground moisture.

-Moisture protection membranes and boards are increasingly used in new construction

-In most urban areas, water collection is performed by a double system. A solid pipe collects rain water from roof downspouts, while a perforated pipe collects ground water from around the house

Knowing the level of the underground water table

- to keep any basement areas under the building dry.

-Most buildings have underground parking and service areas, which are part of the foundation.

-Making use of the space below grade requires that the site have a low water table.

-A high water table is why buildings in areas such as Richmond and Delta do not have any basements, and the entire structure is built above ground.

-a risk with any building is soil subsidence (i.e., downward shift) or settlement of the foundation, which may result in corresponding deformation and failure of superstructure elements.

-High humidity and moisture in foundations is a concern because it may also affect building services in multi-family buildings.

-Although parking is typically placed in the basement, so are building utility areas, electric and communications controls, and mechanical and plumbing systems. These can all be affected by moisture.

-Moisture movement through the foundation can also be the major source of moisture throughout the building itself, especially the lower levels of the building.

-In foundation areas that are also used for services and parking, good indoor air quality must be maintained.

-This typically means continuous ventilation of parking areas to remove contaminants, with motion and gas sensors to increase airflows when increased levels of contaminants are noted.

Multi-Family Dwelling Superstructures

-The superstructure of a house is built upon the foundation to form the walls, floors, and roof of the building.

-There are many different structural methods of construction, including post and beam, masonry, and platform framing.

-platform framing is the most common residential construction method

-The joists for the first floor are leveled on top of plates that will rest either on the foundation wall or a pony wall (a wall of partial height)

-Where openings exist, beams are laminated or prefabricated in accordance with the engineered specifications.

-When the joists and beams are all installed, the floor deck, which is usually plywood or oriented strand, is secured to the top of the joists.

-On this platform, the walls (interior and exterior) are built and stood in place.

-The same process is repeated if there is a second floor.

-Over the frame, there must be sheathing to tie the studs together to form a rigid wall unit.

-The buildup (components included) in exterior walls varies according to structural method used, but always includes some form of protection for the house structure, maintenance of the internal environment of the house, and interior finish.

Four principal construction types for multi-family developments

• Wood stud frame

• Steel studs and concrete topping

• Concrete framing

• Masonry walls and wood floors

Superstructure Terminology

• Joist: a horizontal framing member used to support a floor

• Stud: the vertical framing member used to construct walls

• Beam: laminated, built-up lumber or steel used to support vertical loads in the absence of a vertical wall under the load

• Column: a solid or built-up post under a beam or point load

• Header: the supporting structure over an interior opening

• Lintel: the supporting structure over an exterior opening

• Truss: an engineered, prefabricated roof or floor support structure

• Rafter: the structural member that supports the roof deck

• Ceiling joist: the structural member that supports the ceiling finish

• Sheathing: the plywood or dimensional lumber that covers the walls under the siding

• Plate: the horizontal lumber that the studs rest on at the bottom and the top of all framed walls

• Engineered wood products: include the full range of new wood products such as wood-I joists, paralam and micro-lam beams, and finger jointed studs

Wood Stud Frame

- least costly

-The principal differences between single and multi-family wood-frame construction is space separation and the methods for heating, ventilation, and air conditioning (HVAC)

-Space separation means the walls and floors dividing the units from each other and from the common space, largely for fire protection, normally provided by gypsum board covering to the ceiling and walls

-Framing consists of plywood sheathing on joists spanning between wood stud bearing walls → provide lateral resistance.

-A common problem with wood frame construction is shrinkage of the wood framing as the wood dries out

-can be mitigated by the use of engineered wood products, such as manufactured truss joists and beams made from wood products (e.g., Parallam).

-Stud walls for external walls of upper floors in one- or two-storey apartments may be of 2" × 4" studs.

-The National Building Code includes Span Tables for wood joist rafters and beams

• The allowable spans are measured from the face or edge of support.

• In the case of a sloping roof framing member (rafters, etc.), the spans are expressed in terms of the horizontal distance between supports rather than the length of the sloping member.

• Snow loads are also expressed in terms of the horizontal projection of the sloping roof.

• Seismic design requirements are taken into account.

Steel Frame

-was commonly used in the past

-The floors are constructed from metal decking with concrete topping spanning between load bearing metal stud walls.

-The lateral resistance is provided by cast-in-place concrete walls, which are usually located at the elevator core and the stair shafts

-non-combustible, there are none of the shrinkage problems inherent with wood construction, and the fire resistance can be provided by drywall for the floors and walls.

-Unprotected steel frame is the preferred type of construction for economy and speed.

Masonry and Timber

-Masonry and wood buildings have exterior load-bearing masonry walls and protected wood frame interior construction

-Staircase and corridor walls are often of block and, in some instances, reinforced concrete spandrels are incorporated

-older construction style

-less common with the more stringent fire bylaws.

Concrete Framing

-most common type of construction today for mid- to high-rise multi-family buildings.

-an be altered on the fly to accommodate design changes and decisions during construction

-Building and fire codes typically require a two-hour fire rating for floors and columns – concrete will give this rating without any additional protection for most applications.

-several building systems choices for reinforced concrete construction:

• Flat plate: most common

• Flat slab

• One-way or two-way joist

-simple to form, simple to reinforce with straight bar column mats, and simple to finish.

Weather Barriers

-The building envelope must be designed to be weather resistant.

-Moisture in any form must be repelled by the envelope and led away from the building using proper drainage techniques.

1. Siding: usually wood, vinyl, stucco, hardboard, or fibre cement

2. thin layer of water-resistant tar paper or house wrap, below the siding, attached to the outside of the sheathing and structural components (The exterior sheathing beneath this layer can consist of plywood, oriented strand board (OSB), waferboard, or exterior gypsum board.)

-insulation, vapour and air barriers, drywall, and paints make up the final layers of a typical wall.

Air and Vapour Barriers

-In cool climates as are found Canada, air and vapour barriers protect the structural components of the building envelope from water produced inside the home.

-If the warm, moist air in the home finds an access point into the wall and roof assembly, the concern is that the moisture vapour it holds will condense as the air cools on its way outwards.

-The exact placement of these barriers within the building assembly will depend on the climate and choice of building assembly combination.

-Products are considered air impermeable when they have an air leakage rate of below 0.021 litres per second per metres squared when tested at a pressure of 75 pascals

-polyethylene housewrap, plywood sheathing, cement board, and aluminium foil.

-Other types of vapour barriers include speciality paints, treated paper, Kraft paper, aluminium foils, or black polyethylene

-Low Volatile Organic Compound (VOC), non-toxic vapour barrier products are available to minimize the negative effects of off-gassing on the home’s indoor air quality.

-The air barrier must be continuous, but less precision is required of the vapour barrier connectivity.