Static structures (e.g. – buildings) – Wall – ceiling – floor – or roof designed for ventilation or...
Reexamination Certificate
2001-04-13
2002-12-17
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Wall, ceiling, floor, or roof designed for ventilation or...
C052S293300
Reexamination Certificate
active
06494006
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to the field of straw bale construction and more specifically to a vent that is incorporated into the wall joinery system between the bottom of a straw bale wall and the top of its' foundation to allow condensation from within the wall to be removed.
Straw bale construction is a technique for building structures that greatly reduces and in some instances can even eliminate the use of lumber by forming walls out of stacked straw bales. The resurgence of straw bale construction has introduced current knowledge about modern materials and construction analysis to create structures that are especially durable and energy efficient when compared to both traditional lumber and non-lumber built structures. For example, modem straw bale construction features steel rebar that is driven through the straw bales that form the walls in order to provide strength, rather than more traditional materials such as bamboo or lumber. In addition, cables can be wrapped from the foundation to the roof-plate to form an exoskeleton. Modern straw bale construction also takes advantage of computer simulation and other techniques presently adapted to building construction to optimize designs for improved energy efficiency, for example.
The greatest strengths of straw bale construction are the fact that it is using a waste product as a building material and that wall structures having insulation values from r50-r60 are possible. These two factors make this construction medium an extremely promising component for addressing the global energy situation. However, there are several places where this technique needs refinements.
One involves the most vulnerable point of straw bale construction, namely moisture that tends. to collect in the lower outside corner of the wall. Therefore, the need exists for a vent system incorporated into the wall joinery system between the bales and the foundation in order to increase the longevity of straw bale wall systems. When kept dry, bales have been shown to last in excess of 100 years.
Straw bale construction combines well with other building technologies like greenhouses and cob for thermal mass. As a result, structures that combine the advantages of several natural building techniques are facilitated by straw bale—allowing designs of maximum diversity, efficiency, and comfort.
These four advantages make straw bale special with respect to the following environmental considerations: 1) Reduced lumber consumption, 2) Increased thermal efficiency, 3) Use of a waste product as a building material, and 4) Adaptability to other building technologies. Clearly, a system that would increase the longevity of straw bale wall systems would further advance these environmental factors.
As shown in
FIG. 1
, straw bale structures typically include a cement foundation
10
and a wall
12
disposed thereon. The wall
12
is built of a plurality of straw bales
14
held in place by a plurality of steel rebar
16
. The rebar
16
between a first row
18
of straw bales
14
and the foundation
10
is set in the foundation
10
while the cement is still wet. Thereafter, the first row
18
of straw bales
14
is set in place such that each bale
14
is impaled onto rebar
16
protruding from the foundation
10
.
FIG. 1
includes a partial cut-away section to show several rebar
16
set into the foundation
10
and protruding up into a straw bale
14
. A new set of rebar
16
is then driven into the first row
18
of bales
14
such that approximately half of the length of each rebar
16
protrudes out of the bales
14
. A next row of bales
14
is then impaled on the rebar
16
and the process is repeated. It will be apparent to one skilled in the art that this technique can be varied in many ways including the offset of the bales
14
from one row to the next as well as in terms of the number of rebar
16
used per bale
14
, the particular arrangement of rebar
16
, and how that arrangement is offset between adjacent rows of bales
14
.
As shown in
FIG. 2
a typical straw bale wall
12
includes both an interior siding
20
and an exterior siding
22
. The interior siding
20
is commonly formed of plaster and is provided to prevent straw and straw dust from contaminating the interior of the structure, to provide a preferred surface for painting and anchoring fixtures, and to improve the insulation value of the wall
12
. The exterior siding
22
is commonly formed of stucco and is provided to prevent the bales
14
from degrading due to sun, rain, and wind, to provide a preferred surface for painting and anchoring fixtures, and to improve the insulation value of the wall
12
. An interfacial layer (not shown) is provided on both sides of the wall
12
to improve the adherence of sidings
20
,
22
. Interfacial layer
24
is commonly chicken wire.
Straw bale walls
12
have proven to be strong and durable, and have excellent insulating properties. However, it has also been found that warm, moist air from within the structure can penetrate the plaster of the interior siding
20
. This can cause condensation
23
to form on an interior surface
24
of the exterior siding
22
. The condensation
23
then tends to drip down the interior surface
24
and pool at the bottom along the foundation
10
, as shown in
FIG. 2
, and can cause the straw to rot.
Accordingly, what is desired is a venting system that can be interposed between the wall
12
and the foundation
10
to collect moisture and to vent it back into the interior of the structure without significantly increasing building costs and without significantly diminishing the insulation value of the wall
12
.
SUMMARY OF THE INVENTION
According to an embodiment of the present invention, a straw bale wall vent box comprises a lower member, a substantially planar top member, and a plurality of rebar disposed through the top member and the bottom side of the lower member. The lower member includes substantially parallel first and second sides, an exterior side, and an optional bottom side. The top member is substantially planar and includes a plurality of apertures, and can further include a stucco screed on an exterior end and a plaster screed on an interior end. The top member is disposed above and substantially parallel to the bottom side of the lower member, and is joined to a top edge of the exterior side of the lower member. The plurality of rebar is disposed through the top member and the bottom side of the lower member. This structure is advantageous as the apertures allow moisture from the straw bales to enter the vent box from which it can then vent into the air space above the foundation. The rebar serves to transfer the load from the top member to the foundation.
It will be appreciated that although the embodiments described herein and shown in the drawings all include stucco and plaster screeds, these are not critical elements to the invention and in some simple embodiments they are excluded. One of skill in the art will readily see how the invention can be constructed and used without screeds, or with only an exterior or interior screed.
The lower member can further include a drainage floor sloping downwardly from the exterior side, the rebar being disposed through the drainage floor. In those embodiments that include a drainage floor the bottom side is optional. The lower member can also include a trim piece substantially parallel to the exterior side and extending from the bottom side towards the plaster screed. The trim piece in some embodiments joins the plaster screed. In some embodiments the drainage floor joins the trim piece along its top edge, and in other embodiments along a line beneath and substantially parallel to the top edge. The drainage floor is advantageous to guide moisture towards the interior side of the vent box. In those embodiments in which the drainage floor joins the trim piece along its top edge, moisture can drain out of the vent box. In those embodiments in which the drainage floor joins the trim piece beneath the top edge, the moistur
Friedman Carl D.
Perkins Coie LLP
Slack Naoko
Sun-RG
LandOfFree
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