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The Modular Housing
System of US SYSTEMS presents a radical new approach to housing
construction offering new freedom and capability for the home
owner and a new economic model for the housing market. Here we
will compare MHS to conventional housing, illuminating the key
advantages of this new construction system.
Contrary to popular
belief, the wooden stud or, as it's sometimes called, the 'platform'
framing system commonly used in contemporary housing is a rather
recent invention which had its origins in a building technique
called'balloon' framing which appeared in the US Midwest in the
1830s and was popularized by early Do-It-Yourself carpentry and
construction books and magazines. Up until that time the predominate
framing system for housing construction was the post and beam
system which had been in use for thousands of years and which
has its variants in every culture and civilization in the world.
Stud framing method was developed primarily as a means to save
labor and materials, trading the use of skilled carpentry with
nail-less joinery for quick and easy nailed construction and
large heavy pieces of lumber for smaller lighter pieces that
were easier for one person to handle, easier to transport, and
which allowed the lumber companies to get a larger percentage
of usable lumber out of a given tree with less waste.
Stud frame construction
did not start to become ubiquitous for American housing until
the 1920s-1930s with the import of the 'garden city' concept
from Europe, the growth in automobile use, and the subsequent
growing demand for housing outside of urban areas where, for
fire safety, masonry had become the predominate construction
material. The labor saving, reduced skill virtues of this technique
and its use of cheap small piece lumber appealed to builders
-especially the mass housing developers that emerged during the
post-WWII housing crisis. They faced problems of a need for rapid
large volume construction and a steadily declining quality and
rising cost of wood. This building technique offered a means
to build quickly with what used to be considered quite inferior
grade lumber, this virtue aided by the adoption of composite
wood products which made what was formerly lumber production
waste into a usable product.
Over time this trend
to make nominally durable structure from materials of steadily
declining quality has evolved into an increasing dependence on
the products of organic chemistry. The diagonal dovetail board
cladding of early 'balloon' framed structures was replaced by
adhesive bonded plywood which now is itself being replaced by
Oriented Strand Board made of even cheaper wood and cellulose
fiber scrap bound together with more adhesives. The early wood
lath supported hand plastered interior wall covering, with its
often intricate molded plaster details, was replaced by a laminate
of paper and gypsum called 'plaster board' or 'sheet rock' and
is now giving way to various forms of paper composite board.
The humble 2x4 is now being replaced by laminate lumber made
of glued wood strips and wood trusses made of OSB and thin laminate
wood pieces. And most recently the whole stud frame system is
starting to be replaced by Structural Insulated Panels -a sandwich
of OSB and styrofoam. All-in-all, there really isn't much that
one could call 'traditional' about this conventional building
method. It became the standard simply because it was fast and
cheap, and nothing more. And if the current materials trends
hold true, it looks like stud frame construction will ultimately
evolve into a system where houses are nothing more than various
forms of composite paper held together by and wrapped in plastic.
Stud frame construction
is based on the concept of a stressed skin structure where the
frame and its cladding combine to function as a whole load-bearing
system. It's quite similar in nature to the monocoque structures
of aircraft, affording a high strength-to-weight ratio but at
a cost of a high number of individually fragile components -as
anyone who has built model airplanes knows well. In the original
'balloon' framing system the stressed skin structure would be
fashioned to span all stories of a home and be unified by a cladding
of dove-tail joined planking in a diagonal pattern. In the more
contemporary 'platform' system each floor is framed independently
and clad in plywood or Oriented Strand Board creating a system
of stacked single-story boxes. Altogether, this is an adequately
strong and efficient system with great initial design flexibility
but it imposes severe limitations on performance and later adaptation.
Structural Insulated
Panels represent the latest innovation in this building technology
and may eventually replace stud framing while remaining essentially
the same building system. Composed of a sandwich of semi-rigid
foam insulation and Oriented Strand Board with an edge frame
of conventional stud lumber, they function as stressed skin structures
in the same way as the stud frame but eliminate all the assembly
of intermediate studs and offer the further bonus of built-in
insulation. One simply erects the panels in the same places one
would build a stud frame and nail them together at their edges.
SIP panels offer higher strength-to-weight ratio than stud frame
structures and are very quick and easy to assemble but are far
more dependent on chemistry for their performance than anything
previous. Some have questioned their use as an exterior wall
system because of Oriented Strand Board's greater susceptibility
to moisture and the potential for deformation of the panels in
the event of moisture infiltration -though, of course, polymer
chemistry will probably arrive at some quick solution for that
too. It's a great labor savings innovation, but also one that
amplifies all the inherent limitations of the stud framing it
replaces by an order of magnitude!
The greatest limitation
of stud frame construction is its non-demountability-its inability
to be taken apart without destroying it in order to repair or
adapt its structure. With this system walls are the primary load-bearing
elements and their arrangement becomes critical to the structural
performance of the house. Once built, it becomes very difficult
to rearrange the layout of a stud frame home because of the impact
of such changes on structural integrity. Change too much and
the whole home comes down. Most home designs try to ameliorate
this limitation by putting the load bearing dependence primarily
on the exterior walls and a few select key interior walls which
are assumed to be less likely to need later changes. Innovations
in roof truss systems have expanded this capability, allowing
for larger clear roof spans with most of the roof load on the
perimeter walls alone. But room spans can still be very limited
with this system and when homes are expanded at their perimeter
it becomes impossible to remove those key load bearing walls
when they suddenly become intermediary walls without radical
modification of the roof and floor systems.
These limitations
on structure and its adaptation are reinforced by the reliance
on nailed connection and plywood and plaster board use. Using
nailed construction, the act of assembly itself permanently damages
the material it uses. Upon completion, the structure becomes
impossible to modify or repair without first performing some
form of surgical demolition causing possible additional damage
and producing much waste in the process-since the material is
damaged by its construction process and can't be reused. Very
little of the material is directly reusable in the event of renovation
or demolition. Most of it simply becomes trash when taken apart,
ultimately increasing the expense of repair and renovation. While
larger pieces of framing can withstand multiple re-nailing using
nails in different locations, you can only get away with this
a few times. Eventually the integrity of the wood is completely
lost and one is compelled to replace it altogether. We like to
pretend our homes are built to last forever but in reality they
all -if based on stud frame construction- have a built in obsolescence.
A point where, because of the nature of this building system,
they MUST reach a state of diminishing returns where the cost
of repair or renovation becomes higher than total replacement.
This inevitable condition tends to be hidden by the tendency
of labor and bureaucratic costs to inflate faster than the rate
of home deterioration, always keeping the cost of new home construction
slightly ahead of old home renovation and perpetuating the illusion
that homes appreciate with time. But ultimately this cannot be
sustained -especially when homes are relying more and more on
materials with less and less reusability, such as SIPs.
Because of these
limitations the use of stud frame construction has, in fact,
been quite limited. Though originally adopted by farmers to aid
in building agricultural structures with solitary labor, today
it is ONLY in common use for suburban housing. All other types
of buildings -industrial, municipal, commercial, urban mass housing-
generally rely on the true traditional technology of post and
beam construction, though these days they normally use steel
instead of wood. One would think that by now the limitations
of stud frame construction would have become so obvious that
its use for housing would be in decline. But the public seems
largely oblivious, tending to have a poor grasp of history and
being easily fooled into thinking that anything which has been
around for at least one generation has been a 'tradition' forever.
Thus this form of construction has become very ingrained into
the culture despite its obvious flaws. People simply have no
memory of what came before -and little understanding of what's
behind the plaster board and siding in the first place- and so
the methods and materials commonly used by the other classes
of construction are regarded as 'new' and 'unconventional' even
though their roots are thousands of years deep!
Let's now look at
MHS. With its reliance on factory fabricated modular aluminum
components using quick-connect assembly technology and standardized
dimensions, the Modular Housing System of US Systems presents
a radically different situation from that of stud frame construction.
But its virtues are rooted not in new technology but rather in
the practical advantages of traditional post and beam construction.
MHS is essentially a traditional post and beam system using a
simple rectilinear space frame geometry and a bolted rather than
nailed method of assembly. It overcomes the limitations of using
large heavy specially crafted lumber -the limitations which compelled
the invention of stud framing- through the use of a light weight
low cost recyclable material -aluminum- and precision engineered
mass produced modular components. It is a system which offers
us the best of both worlds; the flexibility, simplicity, and
strength of traditional post and beam structures with the labor
savings and efficient economics of industrial production. It
is the closest we have so far come to the ideal of a plug-in
architecture.
MHS consists of
a system of extruded aluminum profile posts and beams similar
in nature to those of T-slot framing commonly employed in industrial
automation. These are assembled in simple box frames using a
concealed bolt-lock clamp which leaves the structure with a clean
appearance. This is supplemented by a bolt-in-place diagonal
corner brace for multi-story structures which is normally concealed
within wall panels. The cladding system uses either Structural
Insulated Panels or most any combination of other panel materials
which slide into the special grooves of the framing profiles.
The panels contribute little to no addition to structural performance
so their composition is not critical, all loads being born solely
by the post and beams as with traditional post and beam construction.
These panels may be pre-finished, composed of materials that
need no finishing, or can optionally be finished by conventional
house siding, surface mount veneer board, and painted plaster
board sheathing. The profile slots also readily accommodate modular
window panels or composite panel
walls can be framed to accommodate more conventional windows
of any shape. Roofing, supported by a simple roof truss and extruded
profile solid web truss rafters, can be either conventional or,
more practically, metal panel roofing. Flooring uses the same
extruded solid web truss pieces as joists
and can employ any conventional flooring material. Additionally,
the joists will also accommodate a clever suspended panel ceiling
system. Foundation systems can be conventional curtain or slab
foundations or piling foundations typical of many post and beam
structures.
The greatest feature of MHS is its demountability -precisely
the feature that stud frame construction is lacking. With MHS
one can freely and quickly disassemble, repair or modify, and
reassemble structures without causing any damage to the components
and materials using little more than a few hand tools. Combined
with the virtues of a modular space frame geometry, this affords
the system a flexibility, capability, and economy impossible
with stud frame construction. The MHS building is a truly immortal
structure -not because its basic materials are more resilient
but because all its components can be forever replaced as they
wear out and its form can be forever adapted to any use or need.
Our ancestors knew
what they were doing when they first adopted post and beam construction.
Before industrialization, people had to make most of the things
they needed with their own hands and all such work competed for
time with the more important priorities of producing food, caring
for family, and preparing for seasonal changes. So people were
frugal with their time and labor. They built things to last,
and in those days that didn't mean futilely trying to defy nature
by making things impervious to wear and damage. It meant making
sure whatever you made could be repaired, reused, adapted, and
recycled perpetually. The post and beam framing system achieved
this capability through its demountability and modularity. By
being able to be readily taken apart, any individual component
could be replaced on demand without effecting the rest of the
structure. By using a space frame where the loads were borne
by the frame alone, weatherproof enclosure materials could be
easily replaced as they wore out and the structure adapted and
expanded on demand, since no walls were actually permanent. If
you needed more room, you added more to the grid of the frame.
If the roles of some rooms changed, you could readily remove
or add walls to change the space for its new use. If you needed
larger clear-span rooms, you increased the length of beams and
posts around those rooms -though this had the caveat of increasing
their mass greatly as well when using wood. If situations forced
you to move, the whole building could be readily taken apart
and rebuilt somewhere else, conserving your labor investment
in its fabrication. And in the worst case situation where your
house suffered too much damage to be saved or became completely
obsolete, all its surviving components could be readily salvaged
and directly reused in another structure. Indeed, many of the
new wooden post and beam homes built today -for sake of their
rustic style- use lumber salvaged from buildings more than a
hundred years old!
MHS improves upon
these original virtues by taking advantage of modern materials
and industrial parts fabrication. Traditional post and beam structures
required a high level of skill to craft their key components
which tended to be large and difficult for a single person to
handle. This is what compelled the old tradition of community
barn raising, the components of these wide span structures being
far too heavy for any individual farmer to handle alone. By using
much lighter and stronger aluminum profiles fabricated by mass
production, MHS eliminates the skill overhead associated with
fabricating lumber post and beam components and brings the mass
of components suitable for a useful range of frame spans down
to a level where an individual can easily handle them. Like it's
lumber predecessor, MHS still requires an increase in the length
and mass of its beams as it increases in span. But because aluminum
offers a higher strength-to-weight ratio than lumber it doesn't
increase in required mass as fast as lumber does as required
spans increase. Thus a fairly modest profile size of 6.75"
is sufficient for a very wide range of spans. When the limits
of this component scale are reached, the system can readily switch
to the use of trusses made out of the same components, switching
to a type of structural member with an even higher strength-to-weight
ratio but also with a greater volume.
Another limitation
of the traditional post and beam system which MHS resolves is
the limited demountability in cladding and partition walls. In
the past it was generally very difficult to achieve a weatherproof
barrier from materials which were not monolithic in nature. Thus
while the frame system of post and beam buildings was readily
modular and remountable, the materials filling in the space between
the frame members for walls often had to employ a compromise.
Walls might be based on more 'plastic' materials like clay, cob
(a mixture of clay-rich earth like adobe), wattle & daub
(mixture of cob-like materials applied to a light grid of thin
crossed wood strips coated in plaster) or might use siding attached
with nails -even though that did damage the major frame pieces.
These materials were not truly remountable but they could be
very easily removed and were potentially recyclable. More remountable
walls appeared in the traditional construction of Japan. They
also relied heavily on their own kind of waddle & daub (though
made with bamboo lathe) but complimented this with decorated
paper and veneer wood panels, heavy wood planks, and paper shade
screens which fit into shallow grooves carved into the post and
beam frame. This was generally poorly suited to exterior walls,
however, because they were so lightly and loosely attached and
was more commonly employed for interiors. The Japanese also developed
modular panel flooring in the form of tatami mats -an innovation
that never found its equivalent in the west until the invention
of raised floor panel systems for computer rooms!
MHS solves the wall
fabrication issue using SIPs and other panel materials which
slide into the paired grooves of the frame profiles. This affords
the ready demountability of the Japanese light partition panels
while allowing the use of more resilient materials like sheet
metal or ceramic with weatherproof gasketing along the exterior
faces. The result is a hollow wall system like that of stud frame
construction, able to accommodate insulation, utilities runs,
and built-in fixtures but with none of the disadvantages of stud
frame construction. This also allows for the use of pre-finished
materials or materials that need no finishing, since the walls
are mechanically fastened. One can use virtually anything one
might want for a wall surface; conventional plaster coated sheet
rock, solid wood planking, veneer board, metals, cloth, plastic,
Panelized masonry materials (gypsum plank, ferro-cement panel,
corrugated clay panel), or just about anything else one could
imagine. The MHS frame will even serve adequately as a window
frame allowing for the direct integration of window panels.
And if this isn't
powerful enough, this method of panel integration offers the
option to physically integrate whole pieces of furniture or appliances
fashioned into this panel shape. Photovoltaic and thermal solar
panels, flat panel TVs and home entertainment systems, computer
systems, plumbing fixtures, lighting fixtures, HVAC systems,
shelves and cabinets, 'Murphy' beds and folding tables, art objects,
and more can all be designed to integrate directly into this
frame system just like the many industrial components which integrate
with T-slot framing systems. To facilitate this kind of integration,
the MHS profiles will also integrate with a smaller scale version
of the same kind of profile originally developed by US Systems
for store display framing. This system can be used to fashion
many kinds of furniture and appliance enclosures and will plug
right into the larger MHS frame structures. This capability to
integrate so many kinds of materials and equipment creates the
potential for a vast third-party marketplace of products to plug-into
MHS housing -much like the innumerable peripherals and software
which are made for personal computers.
At present one feature
of MHS limits the flexibility inherent in the rest of its building
system, and it's something which also troubled builders in pre-industrial
times. The one thing it cannot, at this time, realize with the
same modularity and demountability as the rest of its system
is its roofing. This is because we have yet to realize a fully
weatherproof roofing system which can be freely changed in area
using modular remountable units.
There are two sides to this problem which tend to work against
each other. On the one side is roof cladding -the material which
makes the roof waterproof. Modular roofing materials exist in
the form of shingles and tiles. Though uncommon in shingles,
tiles are readily remountable and reusable and so one could use
them to fashion a modular roofing system that can be changed
on demand to suit changing roof areas. But tiles and shingles
only work with a sloped roof. They rely on the force of gravity
to insure that water sheds off them in one direction. On the
other side we have roof shape. Sloped roofs are difficult to
modularize because as you increase the area under a roof you
must simultaneously increase the length of the rafters and beams
supporting the roof. The flat roof solves this problem. Its rafters
remain the same length no matter how you increase the area. You
just add more of them. But roofing tiles won't work for a flat
roof! Most flat roof construction relies on some form of monolithic
material; membranes of plastic or asphalt sometimes called 'composite'
roofing or layers of continuous concrete.
The closest we can
come to a solution is a set of compromises. One can make modular
sloped roof units and repeat them as the area of the structure
increases. This way the individual roof structures don't have
to be changed. One just adds on more of them for the newly added
sections. But there are practical limits to this. Roofs valleys
-the points where opposing descending roof slopes meet in the
center- tend to be leak-prone and can get complicated if you
try to mix roof sections of different sizes. The other option
is to use a flat roof and a kind of roof panel which is modular
in one direction and monolithic in other. Raised seam metal roofing
is the prime example of this. This kind of roofing consists of
long panels of sheet metal -or sandwiches of sheet metal and
foam insulation- which are joined along their sides by raised
seams. Water sheds off the panels only in parallel to their seams,
since they create a channel. It's as if you made a roof tile
that was very long and overlapped on its sides. Such roofing
is readily expandable in the direction perpendicular to its seams.
But it can't expand in the direction parallel to its seams unless
-just like the old fashioned roof tiles- there's a slope in the
roof that allows them to overlap. Of course, this is just as
much a problem for stud frame structures as for post and beam
structures. We just don't have, as yet, a roofing technology
that lets us freely expand a roof in all directions while using
modular parts. But a solution may come if people finally clue-in
to the virtue of plug-in architecture and start applying some
modern engineering to it. For the time being, MHS offers the
option to use either of these compromise approaches, or one can
just settle for a more conventional sloped or flat roof in shingle,
tile, metal panel, or composite.
In conclusion, we
can see that with MHS we have a building system vastly superior
to the stud frame construction common to contemporary housing.
It restores and greatly improves upon the virtues of the traditional
post and beam construction system and so simplifies the process
of construction that it becomes quite practical for most anyone
to assemble their home on demand in a very short time. It has
the potential to be a true plug-in architecture that anyone can
use -and not just for housing but for an infinite diversity of
applications. With a modular structural system offering ready
demountability we not only have infinite flexibility but indefinite
repairability and the option of transportability. Not only can
the home be eternal, we can pack it ALL up and take it with us
wherever we go! We don't have to go into great debt to buy more
house than we need in anticipation of what we might need in the
future. We can change our house to meet our needs on demand.
And with the freedom to take our whole home with us when we move
just like it was a piece of furniture we don't need the crutch
of bank financing to make the value of our home fungible. And
we don't have to fear losing the value of our home investment
if there are differences in market values one place to another.
We can think about things like saving for a home by literally
stockpiling its parts or letting our children take a portion
of the family home away with them when they are old enough to
leave and live on their own. With a healthy industry based on
this kind of building technology in place, we can also expect
the appearance of a large after-market for used components. This
would be a practical solution to the problem of low-income housing
and possibly an answer to the problem of hopelessness as well
-though, of course, having a place to build a home is just as
important as having the stuff to build it out of.
Eric Hunting
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