Modular homes

Call :  Tel 866-764-3466 

email – Info@Rohehomes.com

connect on FaceBook  –  click here

Modular and Prefabricated Housing:
Literature Scan of Ideas, Innovations, and Considerations to Improve Affordability, Efficiency, and Quality

(Source BC Housing)

Modular and prefabricated units are built on an assembly line in a plant and transported to the construction
site. Prefab or modular building systems can have advantages over traditional on-site construction:
• Site work can happen at the same time as units are being built in the plant;
• Units can be built when weather does not allow outdoor construction;
• Efficiencies and lean manufacturing principles realized on the assembly line can result in savings;
• Because units are built indoors and closely supervised they can be of higher quality.
However, there are also a variety of potential challenges with modular and prefabricated construction:
• Modular units and prefabricated systems may have to travel long distances to the site, which can be
costly or lead to damage, they are typically lifted off the truck and on to the foundation with a crane,
which can be expensive;
• On-site integration of units, systems or pods can be a challenge, and there can be scope gaps;
• If units or systems get damaged on route or deficiencies are noticed once the unit is on-site, it can be
ambiguous whether site labour or the plant is responsible for making the repairs;
• Modular units using standard designs may not work in all climates and mistakes in the design can be
repeated on the fast moving assembly line.
The purpose of this study is to identify ideas, practices, and innovations to overcome these challenges and
help maximize the potential benefits of modular and prefabricated construction for housing. This report
examines nine research questions:
1. Unit design and construction: What are practices in the modular and prefabricated design and
construction process to improve the time efficiencies and cost effectiveness?
2. Materials: What are the materials that can improve affordability, sustainability and performance?
3. Transportation: What are options for transporting modular and prefabricated housing units to
development sites to ensure the process is as time efficient and cost effective as possible?
4. Housing Form: What types of modular and prefabricated buildings are proving affordable, efficient and
durable? What innovations are being made?
5. On-site: What are the options for on-site integration of modular and prefabricated housing units at
development sites to ensure the process is as time efficient and cost effective as possible?
6. Emergency Lodging: What are lessons learned around using modular and prefabricated construction
for temporary housing for those displaced during a natural disaster?
7. BC Climatic Appropriateness: Are the best practices identified through this study appropriate for BC’s
climate and landscape?
8. Sustainability: What are best practices to maximize the environmental sustainability of prefabricated
and modular housing units during the construction phase and in terms of energy consumption once the
units are occupied?
This report provides an overview of what was identified in the literature. The report is only meant to provide
a summary of the literature. It is important to note that each project is unique and options covered in this
report will not work in all situations.
This information may be helpful to the residential modular and prefab construction industry as it provides a
scan of emerging ideas and some best practices. This report can also be used by housing organizations
who are considering the use of modular and prefab construction as background reading to inform
discussions with designers, site construction workers, and modular or prefabrication plants.

Modular and Prefabricated Housing Executive Summary
BC Housing, MHABC, REIBC 7
This report finds a variety of notable practices that are not just pushing the modular and prefabricated industries forward, but are in some cases offering new solutions compared with standard building construction methods. Projects in the US, the UK, Australia, France, Austria, Asia as well as Canada are pushing the boundaries on how quickly prefab and modular construction can be erected on-site, with some projects going up in days and other months. Projects in Canada, the UK and Australia are among those aiming to build the highest wood building using prefabricated, structural composite wood systems. The majority of the modular, prefab and manufactured projects noted in this report have significant sustainability and health considerations, which can add value to housing not just in terms of better mental and physical health outcomes but in terms of the financial paybacks embodied in low or no energy and water bills. Finally,  the current growth of the modular and manufactured industries has led to the potential for emergency shelters that have the opportunity to be developed into long term housing, if designed properly. Examples of ideas and practices to maximize the potential benefits of modular construction and prefab, as well as address some of the challenges include:

Unit Design and Construction
Project integration techniques such as use of BIM and inclusion of the on-site construction team in pre-planning stages can help prevent mistakes or integration issues;
Efficiencies may be realized on the assembly line through practices such as automation, twinning production lines, running 24 hour shifts, building modules from the inside out, and automating parts of the assembly line;
Tools that increased the chances of success on a modular or manufactured project – particularly larger, more complex projects, include: Modular Test Fit (MTF), Building Information Modeling (BIM), Computer Aided Design and Manufacturing (CAD-CAM), and Computer Numerical Control (CNC) in manufacturing. These are part of the integrated design and project delivery processes (IDP, IPD).

Materials
Composite wood materials (engineered and manufactured wood-based products such as engineered joists, beams, and wall and floor system) can offer increased strength, as well as faster building times and lower carbon emissions; Despite being combustible, heavy timber and panelized wood products can be designed to have good fire performance, due to the char layer that forms to protect remaining wood from fire; Panelized building systems can lead to faster construction time, increased thermal and structural performance and lowered labour costs; however, some panels may have challenges around increased capital costs, sound performance, off-gassing, the need for specialized trades, and special procedures
to ensure joints are sealed appropriately;
Using the structural properties of mass timber systems can provide reliable, affordable, high
performance buildings on an accelerated schedule and have potential for mid- and high-rise;
Laminated veneer lumber (LVL) can be used in wood curtain wall instead of the conventional
mullions, reducing the environmental footprint of the building and supporting local economies;
Steel framed modules can provide increased durability and have been used in recent projects with
non-standard modules (i.e. all modules were not identical);
Agricultural and landscaping materials, such as modular green roofs and green wall panels, are
being used to offer lower greenhouse gas emissions and improved indoor air quality;
Recycled-content and reused materials are being used in modular and prefab products to increase
its sustainability; challenges include off-gassing and ensuring materials are non-toxic;
New materials are emerging that meet rigorous health, sustainability and durability standards such as
BuiltGreen, LEED and the Living Building Challenge;
Shipping containers have been used as student residences, offices, hotels, malls, affordable housing,
shelters, and emergency lodging.
Modular and Prefabricated Housing Executive Summary
BC Housing, MHABC, REIBC 8
Transportation
Air bag lift systems can be used where CSA Z-240.10.1 foundations are approved in the place of
expensive cranes;
Barges can be used to transport multiple units at a time to coastal areas, to save time and money;
Space saving structures such as prefab panels, stackable or folding modules, can be more
efficient to transport by truck.
Housing Form
Modular units can be combined side-by-side or top and bottom to create larger or more units or to
extend existing buildings;
In taller, steel-framed modular projects, after roughly ten floors of modular, there is a need for a
concrete or steel core to act as structural support against wind, seismic and other loads. In taller mass
timber projects, structural support cores (housing utilities, elevator and stairs) can be created with
hybrid systems including wood, steel and concrete, or concrete and steel;
Modular and prefabricated construction has been used for six-storey and high rise multi-unit
buildings, dormitories or work camps, micro units, and flex housing.
On-site Assembly
3D designs and pilot modules can help ensure alignment of mechanical, plumbing, electrical
connections between modules;
Documenting covered connections through digital pictures or bar code scans can help inspectors
find hidden elements and on-site labour do connections without damage to the unit.
Emergency Lodging
Lightweight yet sturdy materials mean cranes may not be necessary;
Foldable, stackable, or panelized units can be stored for immediate use after disaster and can be
reused (following other disasters) if properly stored;
Hinged walls and simple locking systems allow for fast assembly without skilled labour;
Units should have hook ups that are compatible with transportable electrical/mechanical units;
If units are not in storage, pre-existing agreements with private manufactures to prioritize emergency
lodging units can speed delivery after disaster;
Built in solar hot water or solar electrical panels can offer affordable, on-site services;
Walls should be built with thermal materials to protect residents from extreme weather, as there will
likely be little opportunity to install insulation once on-site;
Moveable partitions as walls allow floor plans to be repurposed depending on the household
composition of displaced residents or other space needs at the site;
Using some modular units to create common indoor space (e.g. for day care, classrooms, or
recreational areas) in transitional housing can help create a sense of community;
Pre-testing unit designs before a disaster strikes can help ensure units are comfortable;
If permanent housing construction takes longer than anticipated, units can be adjustable so that they
can be connected through exterior openings to create larger units;
Temporary shelter is ideally built of durable materials and built to meet code requirements so that it
can offer an option for permanent housing.
BC Climatic Appropriateness
Multiple new innovative materials and systems such as panelized wall and floor systems, heat
recovery systems, in-floor heating, and high performing windows and doors for all climates
provide a wide variety of choices of high performance modular and prefab buildings for all BC climates.
Modular and Prefabricated Housing Executive Summary
BC Housing, MHABC, REIBC 9
Sustainability: Not Just Efficiency
Sustainable modular and prefabricated buildings can include solar ready, Passive House designs,
built-in renewable energy, socially and ecologically sustainable materials, water harvesting and
water reuse such as embedded rainwater harvesting, greywater and water reuse systems as well
as built-in composting toilets, innovative energy systems and super insulated envelopes.
Below is a summary of some ideas, practices, and innovations referenced in this report, which potentially
address challenges and maximize benefits of modular construction. Beside each idea, practice, and
innovation is an icon or icons to suggest how the idea, practice, or innovation might help optimize modular
construction (e.g. improve affordability, timelines or efficiency, sustainability, or quality). The legend in the
centre of the graphic below defines each icon. This graphic is not a comprehensive overview, but rather just
suggestions about how the idea, practice, or innovation might contribute to optimizing modular construction