The FPT Guide to Modular Housing
The property industry is refabricating architecture through prefabrication
If you search for 'Modular Housing' on Google, you will see that this is a VERY popular and newsworthy subject at the moment. Here is an overview of what you need to know when it comes to this type of modern construction.
Let's start with the lingo…
First things first, let's start with the lingo! These terms do not mean the same thing. Read the differences here:
Offsite construction consists of the planning, designing, fabricating, and assembling of building components at a location other than their final installation point, or outside of the construction field. Prefabrication and modular construction both fall under the offsite construction umbrella.
Prefabrication refers to the creation of building components at a factory or manufacturing site, before they are assembled onsite. From a single prefabricated window system to an intricate prefabricated building module, almost all contemporary buildings integrate prefabrication to a degree.
Modular construction is a type of prefabrication where building components are constructed in box-like modules and then transported to the building site for final assembly.
Kit houses or kit homes are a form of self-build home that are constructed from series of prefabricated components that can be purchased from a supplier and then assembled on site to create a completed house.
Other Useful Keywords:
Design for Manufacture and Assembly (DfMA) is a design approach that focuses on ease of manufacture and efficiency of assembly.
CrossWall Construction is a modern method where load bearing walls provide the primary vertical support and lateral stability for precast floors.
Volumetric construction relates to modules constructed in a factory that are installed on site to form a cellular system.
Hybrid construction – Hybrids usually combine panel and modular prefabrication systems to construct a whole building
Unitised Whole Buildings – Whole buildings are standardized building units prefabricated to the highest degree of finish as compared to components, panels, modules, and hybrids.
Components – Number of elements used to build these structures
Panels -2D planer elements used to build floors, walls and roofs etc.
Modules – Modules are made in complete 3D boxlike (volumetric) sections, multi section units, and stack-on units
In short, what is a Modular Home?
A modular home is one that is built indoors in a factory-like setting. The finished products are covered and transported to their new locations, where they are assembled by a builder. A modular home is not a mobile home; it is simply a home that is built off-site, as opposed to on-site. These homes are often called factory-built, system-built or prefab (short for prefabricated) homes. Off-site locations may be permanent manufacturing facilities, or 'flying factories', that is, temporary facilities that operate for the duration of a project and then 'fly' to a new location to service another project.
How do modular homes differ from houses built on-site?
Because modular homes are built indoors, they can be completed in a matter of a few weeks, as opposed to months. They don't see the typical on-site delays caused predominantly by the weather. Modular homes must conform to specific rules, guidelines and building codes that often surpass those of traditional on-site homes.
What about planning permission?
A question asked repeatedly is whether or not planning permission and building regulations still apply to modular buildings. The answer is yes.
Modular homes have no design limitations
You can create any style of modular home you wish, whether you want a traditional center-hall colonial or a Mediterranean. You can add any style of window or architectural detail that you desire. Nearly all host plans can be turned into modular homes, which means you can create your dream home. Modular homes offer hundreds of personalized features that include (but are not limited to) ceramic floors, solid-surface countertops, various cabinet styles and wood species, exterior finishes, plumbing fixtures, etc.
How are they assembled?
A factory-built home starts out as sections that have been built in a climate-controlled area. The finished sections are transported to the building site and then assembled with cranes. Once planning permission is secured from the local authority, groundworks can begin on-site. Skilled tradespeople will dig foundations and liaise with utilities providers to ensure that all services connections are in place so that the final structure can be easily dropped into place.
The construction works normally begin at the same time in a specialist factory, where the building is assembled ready to be installed on-site. The final step in the process is dropping the finished building into place and connecting the utilities. Exterior cladding (which starts in the factory) is finished off on-site, as is plastering and painting. Modular homes cannot be moved after they have been placed and set on their foundations.
Are they much cheaper?
Prefab homes can typically save you quite a bit of money. Because they are constructed in a factory, they can be built fairly quickly — in a matter of weeks, as opposed to months — because there are no weather delays. Furthermore, all inspections are performed at the factory during each phase of construction by a third-party inspector, and are completed before the homes are transported to their permanent locations.
Modular home facts
Modular homes appraise the same as their on-site built counterparts do; they do not depreciate in value.
Modular homes can be built on crawl spaces and basements.
Modular homes are considered a form of green building.
Home loans for modular homes are the same as site-built homes.
Insurance premiums for modular homes are the same as site-built homes.
Taxes on modular homes are the same as site-built homes.
Modular homes can be built to withstand 175-mph winds.
Modular homes can be built for accessible living and designed for future conveniences.
Benefits of Modular Housing
They don't require any timber to be used, and they are created using recyclable material, meaning that once they come to the end of their functional life, they can be recycled and used again.
They 'can' look like real houses
Modular buildings don't have to look 'fake', and there are plenty of options that can help the modular build fit in seamlessly with any traditional buildings nearby. Whether it's cladding or roofing material, there are options that are available to make a modular building look 'traditional'.
Specialists in this field
Off-site construction may be key to allowing a construction industry facing skills shortages to grow. Off-site specialists have a permanent and highly skilled workforce, and a robust, long-established supply chain reducing the reliance on subcontracted labour.
Health and Safety
Construction in a controlled factory environment also has the advantage of being more predictable and safer.
Space is not an issue
Modular construction does have the ability to reduce timescales and may introduce economies of scale but it does not have to result in little boxes that all look the same. Architects can use modular construction to overcome the constraints of tight space requirements of inner cities whilst creating quality, inspirational design.
Save time and money
It is said that the manufacturing of the homes in warehouse conditions, unaffected by the delays caused by weather and a varied labouring workforce, can save as much as six months.
Keep the local residents happy
In addition to being quicker to build, factory built modular homes can result in significantly less disruption to local residents – with evidence already showing 60% fewer trucks coming to sites and 90% less waste.
Everyone is in on it!
Even Hotel chains are getting in on the action! Marriott recently opened the first modular hotel! https://news.marriott.com/2017/05/marriott-international-expands-modular-construction-initiative/
Google's parent company Alphabet recently invested $30 million on housing for Silicon Valley Employees https://www.cnbc.com/2017/06/14/google-spending-30-million-on-housing-for-silicon-valley-employees.html
Japanese retailer Muji recently launched their very own MujiHuts! https://www.dwell.com/collection/muji-hut-launches-with-3-new-tiny-prefab-homes-76f808c4
Barriers to Modular Housing
1. Availability of Sites & Large Deposits
The biggest stumbling blocks are availability of sites at realistic prices, lack of funding to enable developers to build, and the large deposits required by first time buyers.
2. Factory Set-up Costs
Modular construction requires a huge up-front investment in developing a factory.
3. Flexibility in Design
Offsite construction requires a highly detailed design at an early stage. The downside is that this reduces the ability to influence the design as it progresses and if you want flexibility in the design or space planning where the programme permits, it may still be cheaper to build traditionally.
4. Location and Local Labour
One of the criticisms is that modular construction may be carried off site in distant locations which isn't particularly sustainable, nor does it utilise local labour.
Cost and scale are one of the constraints of modular construction, repetitive design enables economies of scale but buyers don't all want to live in uniform buildings.
Some argue that offsite construction is inflexible, expensive and results in ugly, identikit buildings.
7. Shipping and Delays
Potential that suppliers are not UK based. If so, there will be issues around shipping risk, marine cargo insurance and apportionment of the risk of delay arising from shipping or marine casualty.
Transportation restrictions due to module size and weight
A high level of detailed project management / coordination required for these builds
10. Lack of knowledge
Overall lack of general knowledge on this type of construction and preconceived ideas from the history of prefabricated construction
The FUTURE of Off Site Construction!
For the future, there is need to improve assurance of stakeholders by making known to the public performance data of existing prefabricated architecture; only then can prefabricated and conventional architecture be juxtaposed and quantified. Further, reducing costs through mass customization, promotions, and policies will be an important factor to widen the commercialization of prefab. The rising population means that we will have to consider modular housing globally. The ageing population is another thing to consider.
Modular housing is an incredible solution to tackle the global homelessness issue.
New York's Framlab are tackling the city's rough sleeping issues with these modular pods which attatch to existing buildings!