Background

As a structural design (engineering) consultant I rarely get to see fabrication and construction processes, this is because most designs are "standard designs" for manufacturers, so they could be built at any time. If I do get to see the end-product, it is typically illegal as-built-construction, which needs to be assessed to avoid demolition. So the only real access to fabrication and construction processes I have at the present are youtube videos of processes posted by manufacturers and builders around the world for promotional purposes. Such videos are not entirely suitable for work study and work measurement, but they do provide some insight.

South Australia Housing Crisis

At the beginning of the 1990's here in South Australia, average household occupancy was less than 3 persons per household and vehicle ownership at 2 vehicles per household. We had 2 vehicle assembly plants just before, giving a total capacity of 180,000 vehicles per year, this reduced to 1 assembly plant at 100,000 vehicles per year. On average had 1 person per household not yet coupled, with no car and no house. To couple up the population and reduce occupancy to 2 persons per household would require 1.5 times the housing stock, and land. The vehicle industry could provide these couples with private space in the form of a single vehicle in less than 3 years, assuming all production used for one purpose. In less than 5 years the couples would have 2 vehicles. The building industry was producing less than 10,000 dwellings each year. So they should have provided the couples with housing by the year 2015.

Here we are nearing 2025, and average household occupancy still less than 3 persons per household but not yet 2. The Adelaide metropolitan area has grown to the edge of rural towns, large areas of open space have disappeared under housing. We no longer have vehicle assembly plants, we have a housing crisis, and shortage of skilled labour in the building industry.

From my view there has always been a housing shortage and the building industry been unable to supply. The housing we have is not suitable, and is difficult to adapt. Most of the existing housing is single storey, 3 bedroom, brick veneer on timber frame, with concrete floor slab on ground. Large numbers of these houses are occupied by one to two persons, not by families.

Always Been Housing Shortage

Also when we experience bushfires, floods and tropical cyclones, it takes far too long to restore housing. Modular housing could be produced faster, and provide more adaptable buildings. However to be fully adaptable also need to be able to change the division of land: that is the division of land has to be more adaptable more rapidly. That is larger blocks with internal division into sites, sites which can vary at an instance.

Modular Production

However, there seems to be a problem with production. Both established and new players in the modular building space, do not appear able to produce more than around 4000 modules each year. Given that a building is largely empty space, and modules to be transportable have to comply with the dimensional constraints of vehicles, it should be possible to produce such modules as fast as or faster than vehicles. Also the largest shipping container manufacturer in the world produces 2 million containers in 11 factories, so an average of 181,818 containers per factory.

It has been suggested that the market isn't large enough, they need more volume on the demand side. That may be true, but again an average of 2 vehicles per household, so if building construction at rate of 10,000 then vehicle assembly plant only needs to be producing 20,000? The vehicle assembly plant is 5 times larger than needs to be, no wonder it closed down. Except the vehicle assembly plant was exporting, and also producing replacement vehicles. But cannot export buildings, and buildings last 50 years or more. But can export building materials, and vehicle sized building modules, also vast majority of building activity is renovating existing construction and renovations can be done using modules.

It should be possible to produce modules faster, and modules can be produced as flat pack kits. Can transport a lot more flat pack kits over seas than empty boxes. But then the box doesn't have to be empty, it can be filled with furniture and appliances, and so used as a storage container. Want to go over seas, then don't need to pack all possessions into a container ready for shipment, just pack the whole house up and ship the whole thing.

Global Housing Shortage

So there is a global housing shortage, and skilled workers don't necessarily have any desire to go live in a tent whilst building houses in a developing country. So moving skilled workers to where needed a potential problem. But if can transport the buildings then the workers and factory can be located any where. Cars are expensive, and houses more expensive. But why is the empty box more expensive than the complex machine? Excluding the cost of land: as who wants to own land which is merely space: it doesn't have natural water supply and doesn't produce food, and if government or community wants to put highway through the land or submerge below water then they will.

When I was in school, there were people who had a mortgage on a house in Adelaide, but were working and renting in Sydney or Melbourne. They couldn't sell their houses because there was a lack of employment in Adelaide. If just rented land, and houses were transportable, then could just move house to new location. When move to new locality typically stuck with the houses which exist, and these are not always suitable, and not always viable to make suitable. Land is wasted because unsuitable houses get built. If houses can be relocated, then houses which better suit can be moved in and out of neighbourhoods. Whilst modular houses can expand and contract as needed.

But first need to see if can produce faster. If take the 4000 units a year as a bench mark, the question is does this require 25 production lines to produce 100,000 units per year or is the process capable with out modification and the suppliers merely have low demand?

Also important to understand that whilst a vehicle assembly plant suggests that produces 1 vehicle every 4 minutes, 2 minutes or 16 seconds, this does not mean it takes such short amount of time to produce a vehicle. It likely takes around 2 to 4 weeks to fully assemble a vehicle, however if they are to flow from the line at the rate of 1 every 2 minutes, then no operation can take more then 2 minutes. So if have a 4 minute task on the line, the flow would be one every 4 minutes, it doesn't matter if other tasks take a few seconds, and it doesn't matter if the last task only takes a second, product cannot exit the line faster than 1 every 4 minutes. There will be waiting along the line.

The flow is similar to water in a pipe. It may take 2 weeks for water to flow along a pipe from the reservoir to your house, but once there it flows from the pipe at a rate of around 10 litres/minute. But it cannot do that until the pipe is full. The same is for the assembly line, once the line is full of partially assembled vehicles then completed vehicles can start to flow from the end of the line.

Need for Distributors

Another point of note is that the only reason vehicle manufacturers can sell near to their production quantity is because they have distributors around the country and around the world. Currently they do have a problem and there are large areas of land covered with vehicles which cannot sell or at least have not sold. The change over to electric vehicles is a partial problem, and existing product not being suitable for the remaining demand. With an average of 2 vehicles per household and 3 persons per household, it is unlikely that all 3 possible vehicles need to be oversized, fuel guzzling, 4 wheel drive, all terrain vehicles to travel 1km to 5km to local stores. I will hazard a guess that as electric becomes more viable, that there will be additional vehicles per household, and that they most likely will be electric bikes or trikes. Further more that smaller vehicles will be capable of being coupled to form larger vehicles. The vehicles will also be more adaptable, so that enclosed in winter and open in the summer. Electric vehicles have less constraint on shape and form compared to vehicles with internal combustion engines (ICE). Whilst battery packs and electric motors impose some constraints on form it is not as restrictive as the ICE and its supporting machinery. There is also the issue of autonomous robotic drones which can travel to the stores and retrieve goods on their own, these will occupy even less space. So private mechanised transport is going to change, and so existing manufacturers will have some transition problems as they transform their factories or choose not to change, and continue to supply for the reduced demand.

So there are problems with factories and substitute products. However, the problem with buildings is onsite versus offsite fabrication, and whether a box is empty or fully fitted out. The largest structures tend to be assembled from components made in a factory: large structures do not merely consist of buildings and bridges, there are also ships and aircraft and various other utility structures.

So need to get the small to medium sized buildings off-site. Identify the issues keeping the fabrication and construction on-site, and keeping buildings being anchored to the ground by methods which make it difficult to relocate the building.

So what timing can we expect for production of a building module?

Production Examples

Cold-formed Steel Framing

So here is a video which indicates that takes 30 minutes to assemble the panels of a tiny home onto a trailer, the framing produced by Dynamic Steel Frame.

Here's another showing more activity:

Whilst Dynamic Steel Frame are mostly cold-formed steel (CFS) building fabricators, they do have a few videos, of tiny homes, modules and pods. On a LinkedIn post they indicated a time of around 4 hours to roll form the steel framing and assemble the framing. So subtracting the 30 minute assembly time, the roll-forming of the sections and assembly of the panels takes around 3.5 hours. Check out their other videos and buildings here.

So CFS provides a relatively quick means of providing framing for a small module.

Timber Framing

Here are some examples of more complete construction of timber framed building, constructed on site.

The building is 14 ft x 28 ft (4.2m x 8.5m), so larger than a tiny home on wheels (THoW) which typically restricted to 2.5m wide. So this shed building is assembled and clad in one day.

And another example by the same crew Atlas Backyard Sheds, this time 16ft x 40ft (4.8m x 12m), again larger than a THoW, and I believe completed in less than 1 day.

There is additional work required internally, but we have an indication that the shell for a building can be constructed in less than 1 day.

Container

Now here is an example of the assembly of a simple 16ft (4.8m) box from composite panels. The panels are the full size of the box, and now space is enclosed in less than 10 minutes. {Assuming video is real time.} The associated company appears to be a producer of the composite panels: HolyCore.

So if use full panels for each side then can significantly reduce time to assembly a box.

Caravans

Here is a caravaners tour of the Bailey caravan factory. In part 1, can see the composite panels which form the shell being shaped.

and in part 2, see the components assembled into the caravan. Also note it seems a relatively common practice to keep the walls and roof off, whilst fitting out the interior. This means do not have to work in a cramped or dark space.

Here's a video from Bailey themselves, from which we get it takes an average of 6 hours and 48 minutes to make a caravan and over 12,000 components for each caravan. The caravan being fabricated is indicated as the Bailey Phoenix+ 640, which has berths to sleep 4.

Here's a tour of Adria Mobile factory providing another view of the equipment available to improve production, this time motorhomes not just caravans.

Truck Bodies

Still another comparison is that of truck bodies, these are similar to light weight shipping containers, with all sides of the box being full size: not an assembly of smaller panels.

Manufactured Homes and/or Static Caravans

In the UK they have static caravans, whilst in the USA they have HUD specification manufactured homes. Here in Australia we just have transportable houses designed and built to the same code as housing. Though the tiny house movement has arrived to confuse issues, such buildings are considered caravans if on wheels, otherwise they are considered to be houses and have to comply with building code.

Here is an example of static caravan production by Swift:

And here is a tour of a manufactured home factory by Skyline Homes presented by Factory Home Expo Centers

Not much different than a site built home of light weight construction, here in Australia, except here we don't need to provide a permanent wheel chassis. In Australia we normally transport , relocatable or transportable houses on the back of a truck, it doesn't need its own wheel set. When it needs to be moved the building gets put on the back of another truck.

Here is the start of a series of videos on manufactured homes by Oakwood Homes Tulsa.

Then there is Boxabl who have built a massive factory, but still only down around 4000 units each year.

Prefabricated or Segmented Transportable

At the moment few manufacturers claiming to be modular are truly modular. The majority simply take a floor plan and divide into transportable segments and then set about designing and building each segment. For true modular, the floor plan is determined from the available modules. If the floor plan determines the modules then have segmental transportable not modular. As long as Boxable does not customise its floor plans and buildings, then it is modular.

An example of prefabricated, with walls having appearance of brick, by TopHat Homes. It isn't necessary to loose the appearance of brick, nor is it necessary to have the appearance with all the disadvantages of brittle bricks. Important here in South Australia, where mostly have brick veneer and large footings to minimise cracking due to soil heave. With masonry panels can have the decoration without the expense.

An example of robotic production for walls, by Autovol, the question is why don't they have a more continuous production of the walls, compared to the wall segments?

Here is something which appears to be modular, as long as the modules do not change from project to project, then can consider them to be true modular, otherwise they are just prefabricating transportable segments.

Some History

A Nissan Hut isn't entirely prefabricated but it is a simple kit to assemble.

Early prefab steel house:

and mail order kit homes:

and post war reconstruction in the UK:

And some historical background to prefabricated:

Prefabricated the Way Forward

I believe that prefabricated will be the way forward. There has always been a housing shortage, the current crisis is not so much locally generated, but generated by migration. People have legs, they are not plants, they are meant to be mobile. The problem is when they settle, put down roots and stay.

There was an idea to allow migration to create pressure for housing to keep the building industry going. The consequence, average household occupancy did not reduce to 2 persons per household it stayed close to 3 persons. So we covered roughly 1.5 the area of land to get additional houses and we need to do so again, and talking about immigration to provide the labour force. But same problem exists across the industrialised world. So where would the skilled labour come from, and when they arrive where will they live? Competition in the labour market, and attracting skills away from one place to another, doesn't solve the problem.

Buildings can be produced in a factory, they can be made as flat packs or used as boxes filled with packaged household contents. So ship can transport more houses than cars.

So buildings can be produced in a factory, the buildings can then be transported over seas, to the locations the migrants are coming from. The migrants cannot be coming from the industrialised world, as they all have the same problem. So if the trades migrate, they increase the shortage at their point of origin, and reduce it at their destination: but over all the shortage remains. If migrants come from the developing countries, then those countries loose the resources they need to develop.

Houses are no longer made from local materials, all materials used are transported relatively large distances using mechanised transport. So unless making adobe bricks on site, and have a nearby woods the materials are going to be transported to site.

In the industrialised nations fertility rate is less than the 2.1 required for replacement. This is potentially good, as should not want further growth of our cities, drawing resources from ever more distant locations to feed an ever increasing population. So migration could be constrained to balancing a need for replacement. However in some situations, shrinking the cities back to previous size may be preferable, in which case halt migration altogether, allow the city to shrink, demolish the buildings and reclaim the open space.

Other issue is why do people migrate. Typically its some improvement in lifestyle and economic gain, in which case it suggests a need to modify something at the point of origin to encourage people to stay. For the developing and undeveloped countries the shortfall is the supply of food, clothing and shelter, and provision of education and health care. Furthermore migration is occurring in these countries from rural areas into cities. So whilst population maybe created in the rural areas it is flowing into the cities.

As people who remain in the rural areas age, there comes a time when there is a problem getting people to live and work in the rural areas. People are needed in the rural areas to to produce food, fibre and fuel. Living conditions in the rural towns needs to be improved and that largely requires improvements in the logistics of supplying the rural regions.

Rural towns don't necessarily need permanent facilities. Mining towns need to be mobile, even if there for a hundred years. Towns thus can move around in remote regions, and so can various service centres. If a town and its services are mobile, then it can adjust its location relative to other more residential towns. A service town may start out closer to one rural community than others, then it adjusts its location so that it is equal distances from many rural communities. Also people don't have to travel to service centres, the service providers can travel to the customers. So the services themselves are mobile.

It is not necessary for all buildings to be permanently anchored to the ground, and certainly not our residences if we need to relocate for continued employment. Established buildings are a problem as they seldom meet current needs. Consider from an alternative perspective your need is for a mini moke and the only vehicle available is a Mack truck. Similarly if need a small apartment, and only house available is a large multi-bedroom house with large gardens. Not only is the available house over sized there is a lot of work keeping the house and gardens maintained. The available product is unsuitable.

Another point is that caravan sites provide utility poles or boxes. There is no reason why residential sites do not provide like wise for housing. All services come into the site and need meter boxes, these can all be collected in the one place and sometimes are. A utility service box can be provided at the front of the site, and underground service access channel provided to reach the building. The service channel remains accessible. It is not an earth covered trench with a drive way over it. The whole system is then designed so that the building can be readily connected and disconnected from the services.

Also note that caravans can be fully self-contained, and do not require a permanent connection to services. They do need to dispose of waste and replenish resources. This is important as cities are stretching beyond their available infrastructure, so caravan technology is a viable solution in the short term. Also there is no point building additional infrastructure if population spike is temporary.

So majority of houses are 3 bedroom, and average household occupancy is less than 3 persons. Therefore each existing site is potentially designed for 4 persons, comprising of 2 adults and 2 children. There is no apparent need to release more land as residential, rather a need to modify a large number of existing dwellings to better suit the needs of sole occupancy or two person occupancy. To keep people in their neighbourhoods and using the existing infrastructure.

The main functional rooms in a house are kitchen, bathroom and laundry and these can be shared resources. All other rooms are largely empty space. Also minimum site area in a caravan park is 100 sq.m, or 10m x 10m, it used to be 81 sq.m or 9m x 9m. On such a block it is possible to place a 6m x 6m sole occupancy unit, which may be equally suitable for a couple.

So houses on large residential allotments with 100 sq.m to spare have the potential to provide ancillary accommodation. This has the potential to double the number of dwellings, reducing household occupancy to approximately 1.5 persons per dwelling. Also in first instance a module 2.4m x 6m or 2.4m x 4.8m is likely to be adequate, thus a smaller site would be suitable.

Also modules can be made to match existing, by demolishing part of existing and salvaging the bricks, then cutting those bricks into tiles, and make wall panels using the tiles. For example if only cut the bricks in half then can cover twice the surface area. The bricks are 110mm thick if cut into 10mm thick tiles, then get 11 tiles from each brick, so even more surface area covered. Other materials are required for the wall assembly, but over all for a given thickness of wall, the wall has better performance.

Existing dwellings have the potential to be transformed by modules. Remove the roof and add modules to turn from single storey to two storey. Or demolish part of the house and replace with a two storey modular segment. However have to have true modular. The buyer has to know what the module costs, and that it will be delivered and installed in a short time frame and that there are no additional hidden costs.

From another perspective houses are declared to be our most expensive purchase, but it seems the suppliers go out of their way to make them so. A module the size of a car, is mostly empty space, and should cost less in materials and labour than that of the car. The most involved spaces are kitchens, bathrooms and laundries: these need plumbing, wiring, various fixtures and cupboards, and surfaces tiling. But again they are not as involved as the components of a mechanised vehicle. So where is the cost and what is the production delay?

Production

So from the above videos it seems one team can produce and empty shell in 1 day. So given 250 productive days in a year that one team has the potential to build 250 units per year. However, with CFS framing two frames can be built each day, increasing to 500 units per year, but these lack cladding. With the wooden shed, there were 6 workers, The basic tasks comprise of:

Floor Assembly
Wall Assembly
External Wall Cladding
Windows and Doors
Roof Assembly
External Roof Cladding

To a certain extent only need one person per task, but assuming need an assistant with each task, then need two people per task. If all tasks in parallel that would increase to a need for 12 people, though the assistants could move between tasks as needed if not required all the time. Staying with 6 people, split into 3 teams of 2, and adjust tasks into:

Floor Assembly
Wall Assembly
Roof Assembly

In this scenario, doors and windows, and wall cladding are part of the wall assembly, whilst roof cladding is part of the roof assembly.

Assume floor and roof stages of equal length, and a 480 minute day. Whilst wall stage longer than either floor and roof stage. So total time T=x + 2x + x = 4x, therefore x=T/4=480/4=120 minutes. So have stages:

Floor Assembly : 120 min.
Wall Assembly : 2*120 = 240 min.
Roof Assembly: 120 min.

So now can conclude can build 4 floor frames each day, and 4 roof assemblies each day, but only 2 lots of wall framing. So in a year, 2 workers have the potential to complete 1000 floor frames. If modular then the floor frames have a fixed width, but possibly varying lengths. So assume 4 frames are each 12m long, then they build 4*12=48m of framing in 480 minutes, or at the rate of 0.1m/minute or 10 minutes/metre.

So if work is staged in such manner then have a problem, as roofer cannot install roof until walls are built, and wall framer cannot install walls until floor built. However framing can be assembled at the same time as the floor is assembled. Assume this accounts for half the wall assembly time. So when the floor assembly is finished the walls are ready to install. To do this then require at least 4 work stations not 3, in a factory, if moving around sites then a different matter. If moving between sites then the floor framers just move to the next empty site, but if in a factory with a fixed number of work stations then they will get held up, as they will move between available work stations faster than buildings are complete. Or if work is moving between work stations, then it will not flow, as the work will back up at the slow station.

So whilst making wall framing in parallel with floor assembly saves some time, and drops total time from 480 to 360 minutes, this is not sustained unless have another two workers: 2 workers for wall frame assembly and 2 workers for installation. Otherwise whilst walls are being installed another floor frame is built, but there are no walls ready to install on it. whilst the wall frames are being assembled another floor is competed. So with 6 workers, it takes 360 minutes to complete the first building, and then 240 minutes there after. With 8 workers it takes 360 minutes to complete the first building and then 120 minutes there after. With 6 workers there is a delay waiting for wall assembly to install. So once the production line is flowing then producing buildings at the rate of 1 every 120 minutes. So in a 480 minute day that is 4 buildings per day and 1000 buildings per year. From 8 people in a factory compared to 6 people on site. Depending on building and equipment used then one person can make the delivery. Though chances are one person cannot make more than 1 delivery per day depending on how far the destination is located.

So this is just a simple exercise without any real process data. However, it indicates that can change a system from 250/6= 41.6 buildings/worker each year to 1000/8= 125 buildings/worker each year. That is approximately 3 times the output, for 8/6=1.33 increase in workers. Or from another perspective we do not need more workers. Taking note that I deliberately made the intermediate task of wall framing take longer to create a delay. We can already assemble prefabricated wall frames and roof trusses on site so already have people producing these things. The problem is with the on site tasks, and many of these tasks can be taken off site.

Also workers don't have to get bored in a factory, they can follow an instance of the product down the production line, and then loop around again. This way they are involved in construction of an entire building, and using a multitude of skills.

Consider a larger building which takes longer. So this time all 3 stages take 1 day, and making use of prefabricated components. Each stage involves 2 people, so total of 6 people, and takes 3 days to produce one dwelling. But after completion of each stage the workers can move on to next project, this is what they typically do anyway, or at least some of the subcontractors do. So one team can make 250 floor frames each year. During the first year, the wall assembly and roof assembly people are behind, they finish the 250th building in the second year of operation. The question is can these 6 people produce more simply by changing their schedule? Based on the data the answer is likely no.

Also note that whilst it takes 3 days to produce a building, production is not limited to 250/3=83 buildings each year. Each building takes 3 days, but buildings are completed at the rate of 1 every day, after the first building is complete. In the time it takes to construct a building, 3 floor assemblies are produced, and 2 wall assemblies are installed, and 1 roof assembly installed. So on day 4, the second roof assembly is installed and a second building is complete, on day 5 the third roof assembly is installed and the third building is complete, and so on, a building is completed each day.

In the first case had 6 people on site building one building, and the assumption was these people are not fully occupied with construction. Therefore the people were either waiting or occupied with some task not directly related to the building shell. So the assessment was making them fully occupied on the building shell. If they were waiting to work then the waiting has been eliminated. If working on other tasks then those still need doing, but that also means time for the building shell is less than assumed, and therefore the shell can be built faster.

Tiny Houses

To improve on the 3 days the task needs breaking down into smaller stages. It is noted that tiny house builders are indicating 4 to 12 weeks to supply. Now that seems acceptable if they have a list of existing orders to complete. So as a time frame its acceptable, as a production duration it does not seem acceptable.

So a closer look at production stages:

Floor Assembly
Wall Assembly
Roof Assembly
External Roof Cladding
Electrical Systems (1st)
Plumbing Systems (1st)
External Wall Cladding
Internal Wall Linings
Internal Ceiling Linings
Electrical Systems (2nd)
Plumbing Systems (2nd)
Windows and Doors
Internal Decoration
Bathroom Fitout
Kitchen Fitout
Quality Checks

As only considering a small building, and there is no concrete to wait 28 days to cure, expect most of the tasks can be completed in less than 1 day. So at a maximum 16 days. With 16 buildings on the production line, then buildings would be completed at the rate of one every day. But already indicated that 5 of those activities can be completed in one day, leaving 16-5=11 activities, so total of 12 days of production. Still need 16 buildings on the line, and still only flow at the rate of one each day.

The problem, they only start building when get an order. So it takes 12 work days, which is short of 3 calendar weeks. Or if stay with 16 work days, then short of 4 calendar weeks. So unlike cars the buildings are not being produced to fill distributors show rooms. Or put another way there is no supermarket like supply of dwellings.

Supermarket for Houses

As the most expensive purchase in a persons live, it may not seem appropriate to buy a house from a supermarket. But it appears to be the most expensive item, because go out of the way to make it the most expensive item. A dwelling largely comprises the following spaces:

Kitchen
Bathroom
Laundry
Dining
Lounge
Living/Family room
Bedroom

The kitchen, bathroom and laundry are the main functional rooms, and not used all the time, so they can be shared amongst others. For many the main purpose of a dwelling is somewhere to sleep, which gives rise to the Japanese capsule hotels. Also in a sole occupancy dwelling, the lounge, dining, and living and sleeping areas are all shared space. In a caravan space is shared between the various functions depending on time of day. For some people all these extra rooms are a waste of space, and a waste of time keeping clean.

Providing people with private space to sleep and/or relax is easier than providing with an entire house. Providing shared facilities for washing and meals is also easier than providing to everyone. It is also possible to build a house such that the wet areas are a separate module to the rest of the house. The wet area module can remain on site, attached to services, whilst the rest of the building relocates as needed by the occupants. So a residential site has to be developed but it doesn't have to have an entire house on it.

If consider modular housing then most modules would be empty space, with wet area modules the only ones which require any significant fitout. So a wet area module may take 16 days, but the empty modules expect to take less, as the tasks would be reduced to:

Floor Assembly
Wall Assembly
Roof Assembly
External Roof Cladding
Electrical Systems (1st)
External Wall Cladding
Internal Wall Linings
Internal Ceiling Linings
Electrical Systems (2nd)
Windows and Doors
Internal Decoration
Quality Checks

So 12 days, or 12-5=7, so total of 8 days assuming shell only takes 1 day. So could produce shells which are taken aside and then modified into wet area modules, except that plumbing needs to be provided in the walls, floor and/or ceiling space, therefore really needs doing before a module is fully lined. So wet area modules likely better produced completely on separate production lines. If make fully modular then, kitchens, bathrooms and laundries made as separate modules, which can be assembled into larger more complete wet area modules.

So expect modules produced in large quantities and available mail order or from local show room. Is there a market? Not sure about current statistics but state of housing report, indicated that at any time some 5% of houses get a bathroom, kitchen renovation, or some outdoor renovation such as a deck or verandah, each year. Also some 5% of houses have inadequate number of bedrooms for the occupants.

So one issue there, is that real estate agents need to encourage people to move into more appropriate neighbourhoods and dwellings. Beyond that then have to modify the building that stuck with. Though with a lot of effort and reinforcement could lift the building off the site and relocate. The problem is a place to relocate to, and preparing the site. A true relocatable or transportable building can be located to a warehouse or a storage yard, the site doesn't require preparation if building in storage.

So consider a bathroom extension. Want to add an extra metre to the bathroom and refit it out. If it is close to boundary fence, then probably cannot do it in the first place, as there are fire safety issues and access to space between building and boundary fence. So expect have space for the extension and maintaining the boundary offset.

A module can take two forms. One option is it merely provides the 1m extension, the other is it replaces the entire bathroom. To replace the entire bathroom the module has to slide in horizontally or vertically. To slide in horizontally there needs to be adequate space besides the bathroom location. To slide in vertically the roof needs removing. So option 1 which only provides the extension is likely the simpler option. Also if module has its own floor then it will likely raise the floor level of the bathroom above the rest of the house, when really want wet areas below. So if have a concrete slab, will likely have to cut the slab out, which may have to do to modify the plumbing in any case. Alternatively the module needs to be constructed without a floor, and possibly without walls: in which case what is the module?

Whilst don't want to waste materials and wall thickness, double stud walls are typically installed to provide acoustic and vibrational isolation between rooms. So a module could just be a floor with fixtures on it and it uses existing walls, or it could come with its own walls. A floor could be removed and just have walls to the module if it is otherwise braced during transport and handling, with fixtures hanging from the walls.

If the house has timber floors then removing and replacing with module floor would be easier. Also if house already light weight construction or transportable than extending with modules is easier.

So the issue is to look at how house needs to be extended and modified and compare to modification using stock standard off-the-shelf modules. So masonry houses are the main issue, however most houses are brick veneer, and the existing bricks can be removed and cut into tiles and then replaced covering a greater area. The timber frame is also relatively easy to modify within certain limits.

So modules are useful if we can see how to use them and achieve our objectives.

This article is jumping around topics so will leave as is for now, and discuss other issues in separate posts.

Disclaimer:

I don't work for nor do I get sponsored by any suppliers I may mention. Nor is my mentioning a supplier a recommendation of their goods and services. Use the information at own risk.

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Revisions:

[31/12/2024] : Original

[1/1/2025] : Added Headings, some rewrite, and some extension

Pages

Tuesday, 31 December 2024

Comparing Production Times