Melencion shear wall system

Abstract

The Melencion Shear Wall Systems calls for the application of the Melencion Theory improving durability of shear walls to at least 100 years via: a. Spore barrier film preventing entry of new decay spores. b. Increase ventilation of the shear wall system by 1. Creation of an air chamber (dead air insulation) between the SBF-covered sheathing and the lap siding or external paneling with the use of 1 inch (25.4 mm) wooden spacers. 2. The use of micro-porous spore barrier film instead of moisture protective barrier film over the sheathing material. 3. The removal of the insulation stuffing (e.g. glass fibers) within the shear wall cavity. c. The dusting (inoculation) of inside the protected cavity (all wooden components) with spores of any commercially available antagonistic fungi prior to sealing with SBF.

Description

CROSS REFERENCE TO RELATED APPLICATIONS (IF ANY)

None

STATEMENT OF FEDERALLY SPONSORED RESEARCH/DEVELOPMENT (IF ANY)

Privately conceived.

REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISC AND INCORPORATION BY REFERENCE OF THE MATERIAL ON THE COMPACT DISC. THE TOTAL NUMBER OF COMPACT DISC INCLUDING DUPLICATES AND THE FILES ON EACH COMPACT DISC SHALL BE SPECIFIED

No sequence listing, table or a computer program submitted.

BACKGROUND OF THE INVENTION

The design of the Melencion Shear Wall Systems (MSWS) is based on the Melencion Theory On Mold-Decay Fungi Interactions In A Contained Environment on fungal interactions inside the shear wall, spore exclusion and unique designs tailored to increase shear wall aeration.

Melencion Theory On Mold-Decay Fungi Interactions In A Contained Environment

• • Decay fungi present in any wooden members of the shear wall (framing lumber, studs, oriented strand board, plywood, etc.) whether as hyphae, spores, chlamydospores and or any other resting fungal propagules that may have established or settled on the surface of the wood while green wood was processed into lumber, seasoned, stack in lumberyards; or in the case of sheathing panels (OSB, plywood or any other reconstructed wood (composites) during stacking, and construction in shear walls of houses, can never successfully grow and cause decay while antagonistic molds still grow on wood. To achieve longtime control of fungal decay, the entry of new fungal spores into the system must be prevented while the antagonistic effects of the molds are still working, which essentially incrementally sanitize the portion of wetted wooden members during repeated wetting and drying. Fungal spore exclusion can be done by sealing the entire system (over the OSB, gypsum board and the outside framing lumber) with a micro-porous film barrier (whose porosity should be no less than 70%, and pore diameter of not less than that of the average spore diameter of prevalent decay fungi (<6 microns) and thickness of 1 mm), prior to the installation of sidings or interior paneling. Adequate ventilation should be provided in both the inside cavity of the shear wall and the outside surface of the micro-porous film barrier.
  • N. B. Mold fungi do not cause decay in wood (Wood Handbook, 1999, Zabel and Morrell, 1992), except for some reduction in the impact strength of wood.

The Melencion Theory can be expressed into two main theorems:

Theorem 1

Decay fungi present in the lumber and sheathing materials can be controlled by antagonistic molds that are also present in the wood. By restricting the entry of new fungal spores into the shear wall cavity with the use of micro-porous spore barrier film (SBF) over the entire outer surface areas of the sheathing and the gypsum boards, decay progression and aggravation could be prevented (Inoculum Exclusion).

Theorem 2

Increasing the ventilation within the shearwall cavity and in-between the sheathing material and the outside paneling/sidings will help shorten the time for concentrated moisture to stay in places where leaking occur. Decay fungi would therefore have very little opportunity to propagate and do damage.

The areas of higher moisture will then easily give up water vapor into these micro-climates, aiding the rapid decrease of moisture content in water-compromised areas. Moisture will then further equilibrate into these specially provided micro-environments and into the wood boundaries. Shorter time for wood to have moisture content above 20% means that decay fungi would have no time to germinate or to reanimate their quiescent hyphae. After several repetitive water intrusions-rapid drying-and imperfect reanimation of fungi, would cause the decay fungi to die due to viability exhaustion.

This rapid distribution of moisture and the eventual drying of the water-compromised portions of the shear wall would subsequently be the main defense against decay fungi, especially when antagonistic molds can no longer grow in the wood substrate.

Although it is assumed that the incremental wetting-drying in the presence of antagonistic molds will sanitize the affected areas against decay fungi and that the entry of new inoculum is prevented by SBF, there are always possibilities of breaches in the SBF—nail punctures, edges of the film and near window frame-sheathing interface. When antagonistic molds are still capable of growing, entry of fungal spores through unavoidable leaks in the SBF is not a problem. Molds will sanitize the area as previously mentioned. When molds are no longer around, the importance of Theorem 2 will be more pronounced as the growth or no growth of the decay fungi is dependent if the wood is above 20% m.c.

All areas in the United States have equilibrium moisture contents of less than 20%. This means that if wood is prevented from direct or continuous wetting, it will dry to less than 20%. Hence, when shear wall members are compromised by water leaks (which are often intermittent, except due to busted pipes and direct hit from garden sprinklers), will easily dry to below 20% with the unique provisions of the Melencion Shear Wall System (MSWS).

Explanation of the Melencion Theory

Biological interaction between the decay fungi (spores, chiamydospores and other resting propagules) and molds are antagonistic in nature. In a contained environment, antagonistic molds will always dominate the decay fungi until such time that non-structural carbon will be exhausted in the cell cavities. Molds, like Trichoderma viridae, T. harzianum, Gliophyllum virens etc., will prevent any decay fungi from gaining foothold in green wood. Any basidiospores, mold and other fungal spores that lands on green lumber will generally prevented from germination or fungal growth due to the presence of prophylactic preservative treatments that are often applied to green lumber. Green lumber used as studs and framing material will eventually dry before any extensive fungal growth occurs (i.e. assuming the application of prophylactic treatment of green lumber). Oriented strand boards (OSB), on the other hand, may harbor molds due to occasional wetting while the shear wall are still under construction. Most of the fungal activities, whether decay fungi or molds, stop as wood's moisture content drops below the 20% threshold (above it, fungi will start to grow). The fungi will either produce chlamydospores in the case of basidiomycetes or sporolate in the case of molds. Fungal activity reactivates as soon as adequate water in wood (>20% m.c.) becomes available in the form of water ingress or moisture condensates.

The theory works by sealing the shear wall with a Spore Barrier Film (SBF), a micro-porous film barrier with pores not less than 6 micron and thickness of 1 mm. This SBF will be applied over the sheathing material (OSB or plywood) and over the gypsum board on the other side of the wall. In effect, the interaction of the initial decay fungi inoculum and the molds are isolated from further entry of other fungal inoculum.

Water ingress from rain is incremental and transitory in nature. It will only wet a small portion of the sheathing material, often times just under the window frame where the sheathing material including the water-barrier film and the siding interfaces with the window jam. This is due to leaks in the caulking material and the dimensional movement of wood. Moisture in the shear wall can also be in the form of condensates. As soon as water in wood becomes adequate enough, molds and decay fungi will start to germinate/rejuvenate. For prophylactic-treated lumber, this will happen after six months when preservative chemical efficacies start to fail. Sheathing materials, however, which are mostly untreated, will readily supports the growth of molds as soon as free water becomes available.

Incremental activation/Incremental sanitation

Rain water ingress into the shear wall near windows is generally small, not more than the average rainfall precipitation in that particular rain incident. This will only wet a small portion of the shear wall, causing molds to grow and sporolate in the wetted areas. The antagonistic action of the mold (e.g. Trichoderma viridae, T. harzianum, etc) will prevent the normal growth of decay fungi belonging to Basidiomycetes and some Ascomycetes. Decay fungi will likely be killed directly by the antagonistic molds or be forced to undergo constitution dormancy, as the prevailing biological environment is not favorable for its growth. Since only a small amount of water will intrude in the system and due to the unique modifications of the shear wall system to increase air circulation and evaporation (removal of fiber glass or other insulator often stuffed in the shear wall cavity, the provision of a spacer between the SBF-covered OSB, and the porous SBF), water in the affected areas will easily be equilibrated via evaporation into the atmosphere inside the cavity, diffusion into the adjacent dry areas of the board and the evaporation towards the outside of the SBF-covered OSB into the micro-atmosphere created by the spacer. Hence, the continuous growth of the molds and the decay fungi will be stopped for the time being. The ability of the molds to readily sporolate in a matter of days enables them to survive repetitive short-time wetting and drying and at the same time produces more spores to inoculate the entire cavity.

Basidiomycetes present in the water-ingress area will be forced to undergo constitution dormancy due to the antagonistic effects of the molds. The next brief wetting period will have the same interaction. Molds will still dominate while basidiomycetes are forced to undergo repetitive constitution dormancy, without having any chance to produce chlamydospores due to the shortness of the wetting period and the presence of molds. This cycle is repeated until all the viability of the basidiomycetes in that particular area is exhausted, and hence they will eventually die. This area near the leak is now sanitized. Molds, on the other hand, dominate longer in short but repetitive wetting-and-drying cycle than they would if continuous water is present in wood. They will continue to exist until such time that the non-structural carbon in the wood is consumed.

The volume of Water intrusion may increase as building ages (due to increase in leaks as a result of progressive degradation of the caulking material, the corrosion of nails giving more water pathways, the repetitive dimensional changes in wood may loosen adhesive properties of the caulking material etc.). This will produce an ever widening area of mold-free surface due to the exhaustion of free nutrient in those areas that were the first to be colonized (as explained earlier). The area where molds grow normally follows a downward pattern as water flow follows gravity. The inner portion of this ever widening water-intruded shear wall member will become mold-free due to depletion of excess carbon nutrients. This will also opens the possibility of the entry of new aerial- or water-borne basidiospores that might infect those mold-free, yet water-challenged areas. In the Melencion Shear Wall System, however, decay fungi's chances of sustained growth are greatly minimized due to the incorporation of unique design that will improve the evaporation rate of moisture in the affected areas.

In Case of Leakage in Spore Barrier Film

Leakage in the spore barrier film (SBF) is inevitable during construction. This can be due to nail punctures, inadequate sealing between film strips, and construction mishandling. The corresponding risk for water leakage is low if the puncture is far from the high leakage zone (under window frames). Spore entry, however, is then possible. However, since these minor leakages in the system are not exposed to water ingress, whatever basidiospores that may land on the exposed wood will not germinate until the moisture content of the wood underlying the spore barrier leak reached 21%. In the case where the leak is exposed to moisture (direct water seepage due to leaks or due to condensates, the previously described antagonistic effects of molds will prevent the growth of decay fungi.

Should the moisture exposure in the said leaks happens when molds can no longer grow in that particular portion of the wood (due to nutrient depletion i.e. depletion of free carbon), the built-in unique design incorporated in the MSS will see to it that the compromised areas will dry as soon as possible, negating the chance of the new entrant basidiospores to grow and cause wood decay.

Micro-Environment in Between Studs

Studs equidistantly-spaced within the framing lumber of the shear wall create a micro-environment whose boundaries are in between studs, the sill and top framing lumber, and the oriented strand board (OSB) and gypsum boards. For a medium size house, this rectangular space provides enough micro-atmospheric environment that will help equilibrate any concentrated moisture quickly anywhere within the said boundaries, such as in areas where leaks are often observed like under window jams.

Glass fiber fillings are often stuffed in the aforementioned areas to increase the thermal conductivity of the shear wall. When water seeps through in any area within the stud-bounded confines, drying would become difficult and water will accumulate in the wood. Water molecules at the surface of wetted wood will tend to evaporate into the micro-atmosphere. Owing to the smaller air space present between glass fibers and wood, there would be less air space for the water molecules to evaporate. Evaporation of water molecules from the surface of the wood will immediately saturates those micro-atmospheric confines. Water diffusion within glass fibers is not possible, except in between fibers, where its water potential is not comparable to the cellulose fibers found in wood. In effect, moisture will tend to be confined in the area where the leak occurs. Diffusion and run over, however, are still possible downwards in the framing lumber and in the OSB.

The other culprit that causes ingress water to be trapped inside the shear wall is the moisture protective barrier film often placed over the OSB. Since the moisture protective barrier is often breached at its edges, like at the window jam-OSB interface, ingress water will diffuse inside the OSB between the OSB-moisture protective barrier films.

Due to this faulty design (incorporation of glass fibers and moisture protective barrier film), ingress water will now remain in the wood near the leakage area longer, saturating wood beyond the 20% moisture content threshold, giving the decay fungi the environment ideal for germination and growth. During wet seasons, especially in the West Coast, daily water intrusion (although may be less than the monthly average precipitation of 8 inches), will cause ingress water to overrun the water-soaked OSB and into the still dry portion of the board. In effect, an ever widening water-soaked OSB will be created whenever rain brought water ingress inside the wall, especially during intermittent rains.

Prevented from evaporating into the inside microclimate by the stuffed glass fibers and from the outside by the moisture film barrier (which now turns into water trap, from the standpoint of water going out of the wall), water will remain in the OSB for a long time and will provide the right environment for decaying fungi like Basidiomycetes to colonize the whole water-compromised area leading to shear wall decay. This threshold environment capable of supporting decay is 20% wood moisture content and according to Viitanen (n.d.), an optimum relative humidity between 90-95% RH and at temperature ranges of 10-40° C.

Exceptions/Limitations

1. Continuous wetting due to busted pipes or intermittent wetting due to garden sprinklers (splashing of water at the bottom of the shear wall or direct water hit) may cause eventual shear wall decay by decay fungi as soon as the molds can no longer thrived in wet wood due to nutrient depletion. Remedy for this condition is to set the range of the garden sprinkler one foot away from the wall.

2. Fungi that grow outside the shear wall system and extend their hyphae (as mycelial fans, or rhizomorphs) towards and into the shear wall cavity can wreck havoc to even to the Melencion Shear Wall System (MSWS) and will cause decay. This is due to the fact that these fungi (Meruliporia incrassata and Serpula lacrymans) bring their own water into the shear wall, negating the antagonistic effect of molds, the spore exclusion of the spore barrier film (SBF) and the increased aeration (the fungi get its water requirement outside of the shear wall). The only remedy in this situation is to clean the areas near the building from wood debris that may serve as the launching substrate for these fungi.

In cases where spores of these fungi are already present in the wood before the application of SBF, subsequent wetting of the shear wall will not produce any substantial growth of these fungi as explained by the Melencion Theory and due to the fact that no adequate water source is available for these fungi to grow. In cases where possible intermittent wetting is unnoticed like those described in Exception 1, these fungi may thrive hence the need for vigilance and immediate actions.

3. When fungi are already inside the wood as in the case of heart rot and root rot like the white rot fungi (e.g. Heterobasidium annosum) that infect and kill trees, subsequent wetting above 20% m.c. will cause them to regenerate and will be abated only when moisture will drop below the said wood moisture threshold. Mold fungi will have no effect on them as molds only thrive on wood surfaces. Incorporated designs to improve shear wall aeration may help shorten the time when wood is moisture saturated, thereby shortening the time for the embedded fungi to do damage on the wood. Subsequent rewetting-drying will eventually cause the failure of the framing lumber in question and to the adjacent sheathing material.

BRIEF SUMMARY OF THE INVENTION

Melencion Shear Wall System aims to control the decay in shear wall through the application of Melencion Theory On Mold-Decay Fungi Interactions In A Contained Environment that calls for the control decay fungi initially present in wood from lumberyards and during construction with a) the use of equally present antagonistic molds (ab initio) in the wood components of the shear walls (with the possibility of supplanting it with antagonistic mold spores through dusting prior to sealing), b) spore exclusion with the use of porous film barrier (porosity of not less than 70%, and pore diameter of not less than 6 micron, thickness, 1 mm) that covers the entire shear wall system i.e. over the gypsum board and the OSB or other sheathing panels and, c) increase ventilation of the shear wall (please see attached drawings for specific designs).

The invention also requires the supplemental dusting of the wooden members of the shear wall with spores of any commercially available antagonistic fungi like Trichoderma viridae, T. harzianum etc. prior to sealing of the system with the spore barrier film. Furthermore, sill should be treated with Alkaline Copper Quat (ACQ), or other newer wood preservatives, the loading of which should be similar to wood intended for ground contact (precautionary measure for frequent wetting of shear wall base due to garden sprinkler system).

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING (IF ANY)

Please see attached drawing. The designated numbers indicate the key component of the Melencion Shearwall System.

DETAILED DESCRIPTION OF THE INVENTION

The Melencion Shear Wall System (MSWS) is a new system of shear wall construction based on the Melencion Theory On Mold-Decay Fungi Interactions In A Contained Environment that assures great improvement of shear wall durability to at least a minimum of 100 years or better. It is based on the observation on how decay fungi and mold interacts in a confined portion of the shear wall, provided that efficient aeration of the confined area is maintained with the use of 25.4 mm (1″) spacers over the sheathing material (as opposed to no spacers at all of the current shear wall construction code) and the removal of any fibro-thermal insulators often stuffed in the shear wall cavities in the current shear wall designs. The entry of new decay spores into the shear wall system is prevented by the use of a spore barrier film (70% porosity, not less than 6 micron pore diameter, and not less than 1 mm thick) over the sheathing material, the gypsum board and the side ends of the framing lumber. Dusting (inoculation) of spores from any commercially available antagonistic fungi like Trichoderma viridae, T. harzianum, G. virens etc. or any other antagonistic molds in all the wooden components inside the shear wall cavity prior to sealing with SBF is recommended.

Unique Modifications of MSWS to Improve Shear Wall Aeration and Their Advantages

• • 1. The provision of micro-atmosphere inside the shear wall cavity by the removal of the glass fiber stuffing currently used in the prevalent shear wall designs. This will improve the inside evaporation rate in case of water intrusion thereby reducing the equilibrium time required between the water-saturated areas where water ingress occurs and the dry portion of the sheathing and framing material. The lesser time wood remains water-saturated would mean reduction of the possibility of growth of decay fungi in the water-saturated areas.
  • 2. The creation of an air barrier and micro-atmosphere between the SBF-covered sheathing material and the lap siding helps increase the evaporation rate in cases where water-intrusion occurs in the sheathing material.
  • 3. The provision of air space between the sheathing and the lap siding will prevent the formation of condensates at the surface of the spore barrier film and its eventual seepage into the sheathing material. This will help maintain the sheathing material dry and free from fungal attack.
  • 4. The creation of two air spaces mentioned (within the shear wall and SBF-lap siding cavities) will also serve as dead-air insulating barrier in the Melencion Shear Wall System (MSWS), compensating the loss of thermal insulation due to removal of the fiber glass stuffed in the shear wall cavity.
  • 5. The use of micro-porous spore barrier film (SBF) in lieu of the usual vapor barriers (like Tyvac or tar paper) will greatly improve the evaporation rate of the entire sheathing surface area. The risk of water intrusion through the pores of SBF as opposed to the water-tight films currently in use is greatly outweighed by the increase porosity of the entire sheathing surfaces. While water-resistant films help minimize the entry of water into the sheathing material, it also serve as a water-trap in cases where water penetrates inside the shear wall cavity though below-window frame leaks.

Porous SBF-covered sheathing material provides better evaporation rates than water-resistant-film-covered sheathing. Hence, in the event of water intrusion inside the shear wall cavity, water will be evaporated from the affected sheathing material into the air cavity that exist right next to the lap siding.

Claims

1. The use of the Melencion Shear Wall System will insure that the durability of existing shear wall system to at least 100 years or better provided that strict compliance with the specific design principles called for in the invention are met and no continuous water leakage exist (as in the case of busted water pipes, leaks in bathroom floors and intermittent wetting from garden sprinklers).