Construction Method to Reinforce Masonry Walls with Wood

Abstract

This disclosure relates to masonry construction of residential houses using prefabricated masonry panels or blocks, such as Autoclaved Aerated Concrete (AAC) panels or Concrete Masonry Units (CMU). Unlike existing masonry construction methods, this masonry structure is reinforced by common wood studs as join keys. All wood studs are individually strap-tied directly to the foundation and horizontally bound together to form a network of cells enclosing masonry blocks throughout the entire building. Considerations are given to prevent wood studs absorbing moisture from masonry material.

Description

REFERENCES

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OTHER PUBLICATIONS

• 101. Zhe Qu. et al., Seismic Damage of Masonry Infilled Timber Houses in the 2013 M7.0 Lushan Earthquake in China, Earthquake Spectra August 2015, Vol. 31, No. 3 (August 2015) pp. 1859-1874 (http://earthquakespectra.org/doi/abs/10.1193/012914EQS023T)
• 102. Anna Brignola. et al., Experimental Evaluation of the In-Plane Stiffness of Timber Diaphragms, Earthquake Spectra November 2012, Vol. 28, No. 4 (November 2012) pp. 1687-1709 (http://earthquakespectra.org/doi/abs/10.1193/1.4000088)
• 103. Hu Shiping, The Earthquake-Resistant Properties of Chinese Traditional Architecture, Earthquake Spectra August 1991, Vol. 7, No. 3 (August 1991) pp. 355-389 (http://earthquakespectra.org/doi/abs/10.1193/1.1585633)
• 104. Andreea DUTU. et al., Components interaction in timber framed masonry structures subjected to lateral forces, Journal of Civil Engineering Research 2012, Vol. 13 No. 1 (http://www.jourlib.org/paper/2944338#.Vk-fav6FOz1)
• 105. Joa{tilde over ( )}o Azevedo. et al., Seismic Behavior of Blocky Masonry Structures, Earthquake Spectra May 2000, Vol. 16, No. 2 (May 2000) pp. 337-365 (http://earthquakespectra.org/doi/abs/10.1193/1.1586116)

BACKGROUND OF THE INVENTION

Field of Invention

This subject disclosure relates to house construction with prefabricated masonry building blocks reinforced by common wood studs instead of metal.

Discussion of Prior Art

There are generally two types of masonry constructions, using blocks, such as Cement Masonry Unit (CMU), and using panels, such as Autoclaved Aerated Concrete (AAC) panels.

The challenge in block construction is how to reinforce it. A lot of practice and inventions exist [U.S. Pat. Nos. 5,881,524, 6,629,393, 8,297,021, 8,893,450, 9,133,619, 9,267,260]. They all use various forms of metal, such as rebar, prefabricated plate or brackets, or threaded rods and bolts. Metals are either prefabricated into masonry blocks or buried among block seams during. Their construction costs are high due to the high material cost, need of skilled worker, long building duration, and inflexibility to customize or extend.

Prefabricated wall panels are generally more efficient to use than blocks. They mostly have special peripherals and embedded metal couplings hardware designed to structurally interface and bind with adjacent panels [U.S. Pat. Nos. 4,219,978, 4,343,125, 5,033,248, 6,955,016, 7,958,687, 9,068,581, 9,097,000, 9,234,349]. They are hard to cut on site for customization if ever allowed. So, they are ideal only for large buildings with fewer variations, such as factories or warehouses. They are generally more expensive too because, in part, the panel manufacturer has monopoly on all the building materials and process.

Other type of panels are on-site cut-able plain panels. Examples are AAC panels from Hebel Inc (http://www.hebel-usa.com) and AerCon AAC (http://www.aerconaac.com/). Those plain panels, such as AAC panels are structurally bound together by applying special straps, nails and corrugated nails, and with special mortar or glues. Panels are tied down by foundation straps, or metal tracks precision-mounted on foundation. Special masonry nails are directly applied into the panels for binding. But unlike nails in wood, nails into such panels are subject to loosening due to micro movements or temperature fluctuation. Nails also cause local stress to the panel.

In summary, all the existing masonry constructions practices and inventions rely on metal connectors, one way or the other, to achieve structural support to mitigate the brittle character of masonry.

This disclosure uses wood studs, instead of metal, in masonry construction. It provides a solution to couple together two materials of different characters and takes advantage of both materials and lower the overall construction cost.

SUMMARY OF THE INVENTION

Objective Overview

Masonry houses resist to fire, water and moisture, which are especially critical in the light of recent frequent flooding and forest fires. Other advantages are its durability, low maintenance, insect resistance, acoustic break, and environment friendliness.

The disadvantages of masonry houses, comparing with wood frame house, are the high construction cost, especially in US, where timber products are inexpensive and wood stud houses are easier to meet stricter earthquake building codes.

This disclosure is a masonry construction method that combines wood structure into masonry construction to take advantages of both materials, lower the overall construction cost, and still meet the earthquake-proof requirement in US.

The scope of the disclosure relates to AAC and CMU construction and including a profile shape design of the masonry blocks. We will not distinguish the terms panels and blocks in the rest of this discussion unless being called out in the context. They both have the same profile shape vary only in height.

In this method, walls are built in stack bound pattern. Each stack column can be a stack of CMU blocks, AAC blocks, or one AAC panel. Each column is joined on its sides by wood stud as keys with adjacent columns. The blocks have distinct vertical grooves at sides to receive the wood keys. All keys are strap-tied directly and individually to the foundation and extended upward to the upper floor to increase the integrity of the structure vertically between floor levels.

All stud keys are further horizontally connected by bands of metals or wood studs, which acting like the hoops on a wine barrel, to hold the house together at various elevated levels. The one on top of the wall is called top rail, which serves as the tie-down anchor for the roof or upper floor level wall.

Other house elements, such as windows, doors, floor joists, lintels, stairs, and even stud walls, can easily anchor to the wood stud keys with typical wood connections.

The entire construction is still masonry dominant but with wood keys embedded inside the masonry blocks. The wood keys and the masonry blocks are bound together by soft-based construction glue, which also combined with waterproof sealant or membrane as moisture barrier to prevent the wood key from absorbing water masonry blocks and to allow wood natural expansion.

Floor and roof construction are same as walls, varying only in extra enforcement for the additional weight bearing needs.

Advantages—A Structurally Stable Hybrid Combination

The proposed method is a type of hybrid of wood and masonry construction. Timber framed brick house used in the history of multiple cultures around the world also combined the two materials. The historic practice has been proven an effective structure to stand for earthquakes. Studies also did on such structure [Ref. 101, 102, 103, 104, and 105].

Advantages—A Simpler Construction

Other panel installations require special construction crew, and some level of special equipment and hardware. CMU block laying also requires highly skilled masonry workers and rebar workers. Both requires special training. Therefore, both are more expensive and far less available than carpenters and requires strict scheduling.

The proposed method, combining wood with blocks, is still mostly traditional framing carpentry type of work. In case of CMU for example, workers still lay stack bound blocks, but enforcement is by carpentry. All hardware materials and tools are currently available on market. So, the proposed method is very much like that for the traditional framing carpentry work with less on-site coordination as needed for traditional masonry project. Inspection can be done after all framing completed.

Advantages—Easy to Customize and Extend

Single-family houses often have a lot of variations in shape, especially interior partition walls and façade. Other panel construction is hard to customize because panels can't be easily cut to fit on-site if ever possible. This makes prefabricated panels practically unpopular for single-family house construction.

CMU construction typically using running bound laying patterns. Block cut to fit at turns or T's are often the most time-consuming work.

In both cases, it is difficult to customize for any variations or integrate with any interior features, especially those built with wood.

Utility installation requires cutting channels in the masonry walls, either AAC or CMU walls. Existing AAC panel constructions use AAC panel for both walls and floors, which make utility installation even more challenging. Therefore, utility contractors will charge a premium for a masonry house job not to mention a lot of them cannot do such jobs.

This proposed method exposes wood keys at joins to makes customization, integration, and utility installation much easier.

In summary, the disclosed is a masonry house construction method using common wood studs as reinforcement. The method takes advantages of both materials. The method reduces the overall construction cost. It is faster to build and more flexible to integration with common wood components. The result is equally strong to stand against earthquakes. A house built with this method will be more resistant to fire and flood; the house will be more environment-friendly, more energy-saving, and more comfortable to live in.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. The overview of the masonry construction method using wood stud as join keys.

FIG. 2-1. The front horizontal view from inside the house showing wall components.

FIG. 2-2. Top sectional view showing how wall panel blocks are joined together by wood stud keys.

FIG. 2-3. Top cutaway detail view of panel joint from FIG. 2-2 showing gaps around the wood stud key.

(Drawings from PPA do not contribute and are omitted here.)

FIG. 2-7. Wood floor joists connecting with panel blocks.

FIG. 2-8. Side Sectional of FIG. 2-7 with sample dimensions.

(Drawings from PPA do not contribute and are omitted here.)

FIG. 5-1. Wall panels and wood header/beam integration.

FIG. 5-2. Wall and wood roof truss joint.

(Drawings from PPA do not contribute and are omitted here.)

FIG. 6. AAC roof panel mounting detail.

DETAILED DESCRIPTION OF THE INVENTION

The proposed is a construction method to build with prefabricated masonry building blocks. The method reinforces the structure with conventional wood studs instead of rebar-reinforced cement. The wood studs form a skeleton that encloses and holds the masonry blocks around their entire perimeter. Each studs of the skeleton are directly tied down to the foundation as seismic enforcement. The method leverage conventional carpentry skills to keep the overall building cost low.

Hold Down to the Rails

FIG. 1 is a 3D overview of the design. An array of Ω shape steel rails (2), made from metal, such as construction rebar, are embodied into the poured concrete foundation (1). The exposed parts of rail (2) along the foundation wall run in parallel with the foundation (1) throughout the entire foundation wall. They are positioned right under the edge of the prefabricated masonry panel blocks (5) so that the wood stud keys (4) can tied to it directly using metal strap-ties (3). An example of strap (3) is Simpson Strong-Ties.

In FIG. 1, straps (3) tie the studs (4) to the foundation (1) while straps (3a) tie the top rail (6) to the studs (4). So, blocks (5) are entirely under the hold-down enclosure. Straps (3b) tie the roof truss or the second-floor wall to the top rail (6). Straps (3), (3a), and (3b) are all nailed or bolted to the studs (4) using conventional carpentry method.

In FIG. 1, strap (3) are threaded through under rail (2). It is easier to work with rail (2) than conventional anchor bolts and hold downs straps. It will not slip or break. It is also flexible to use. Multiple strap ties can share one rail in all directions, like tying two boats on one cleat. Strap (3a) and strap (3b) both are secured on one top rail (6).

In FIG. 1, rails (2) are the anchors of the entire house throughout. They are cheaper, easier to work with, and stronger than conventional hold-down ties with the help of masonry blocks enclosing them. Top rail (6) serves the same anchoring role to the second floor as rail (2) to the first floor.

Top rail (6) runs throughout the house wall perimeter on top of panel (5) to form a horizontal bound. Rebar used for rail (6) is welded together. Studs (4) can extend beyond the rail (6) from the first floor into second floor (not shown in the drawing). The extension of studs (4) will increase the binding across floor levels.

In FIG. 1, the bottom of block (5) has a groove to receive rail (2). For AAC construction, the groove can be carved out on-site. For CMU construction, the groove can be a knockout tab. During construction, a block (5) will sit onto foundation (1) surface, with moisture barrier and mortar cement (not shown in drawing) applied in between.

FIG. 1 shows how rails (2) serve as the anchor of the building. The same connection also applies to the traditional wood stick buildings, where each load-bearing stud is tied down to rails (2) with strap (3) (not shown) in the same way as shown in FIG. 1.

FIG. 2-1 is a front horizontal view from inside the house showing how wall blocks (5) are secured between foundation (1) and top rail (6) stud (4) and straps (3) and 3a). Spacers (7) raise rail (6) so that straps (3b) can thread through under rail (6).

The dashed line in FIG. 2-1 represents a soft strip (2-1-1), such as rubber band, wrapped around the stud (4) every foot or two to create a gap between block (5) and the stud (4). Strip (2-1-1) can also be foam tapes or pad to keep a gap in between, which is important to keep moisture away from entering the wood stud key (4).

Connect Panels by Wood Stud Keys

Blocks (5) carry the dead load of the house and studs (4) carry the shake forces during earthquake and wind. However, wood and masonry materials have different properties. One important consideration of this design is to integrate the two and prevent wood stud key (4) from absorbing moisture from cement. The proposed solution utilize gaps between the two to absorb force spikes on wood and to block moisture penetration into wood.

FIG. 2-2 is a top sectional view of the join. A groove at the side of block (5) has two uneven shoulders. The exterior side has higher shoulder (called primary shoulder) that yields a smaller gap (9), which is filled by construction glue or caulking toward at the end of construction phase. The interior side has a much lower shoulder (called secondary shoulder) that exposes most of the wood stud (4) in gap (8).

Gap (8) renders space for nailing straps to the studs during framing. It also makes inspection easy. Gap (8) can also be the channel for utility routing. Importantly, Gap (8) is the moisture escape route to keep the stud (4) dry. During finish, the cover of gap (8) must be breathable, like wood or drywall.

FIG. 2-3 is the detail of FIG. 2-2 to show how gaps are made. The groove is tapered in toward the bottom to leave side gaps (12) on both side of stud (4). The corners at the bottom are rounded or slightly raised to retain gap (10) at the bottom. Gaps (10) ensure the minimum contact between the stud (4) and blocks (5).

Gaps (10) and (12) are filled with soft based waterproofing construction sealant or glue during construction, optionally, with sheet of waterproofing membrane. Therefore, Gaps (10) and (12), with the waterproof agent, shield moisture from the stud (4).

FIG. 2-3 also shows toenails (11) applied to enhance the binding between stud (4) and block (5). Toenails (11) are applied at an interval along the stud (4). In case of CMU, said toenail (11) is in fact a metal plate going into the seam of block (5) stack and nailed to the stud (4).

In FIG. 2-2, the lower shoulder, could be reduced to 0-height relying only on toenail (11) to secure the stud (4). Optionally, add-on wedges are used in gap (8) to help secure the stud (4) (not shown in the drawing.)

At a 90-degree corner turn, the groove shown in FIG. 2-2 will not be on the ends, but on the inside of the turn. The adjacent block will join to that groove to form the 90-degree turn. (not shown in drawings.)

Wood Floor in Platform Frame Construction

Building code specifies maximum spacing between wood floor joists (<16″ in US). If the width of block (5) is the same as the maximum spacing, all joists (41) will line up to and secure to the studs (4) with nailing or strap-ties.

When the width of block (5) is wider than the joist spacing, FIG. 2-7 and FIG. 2-8 show how wood floor joists (41) integrate in the design. In this case, some joists (41) are off from studs (4) and run into block (5). A vertical groove (42) is needed at the bottom of the block (5) to receive joist (41) and hold it upright. Groove (42) can be either pre-molded into panel (5) or cut on site.

FIG. 2-8 includes some sample dimensions for the 8″-thick block (5) to demonstrate feasibility of the profile with masonry materials. In other words, block (5) will not be too thin to break off easily.

All joists (41) sit on foundation (1) with required waterproof application and are secured to rails (2) by strap ties (not shown in the drawing).

Masonry Wall and Wood Integration

The proposed design makes it easy to join wood building components with masonry building by anchoring on wood key studs (4).

FIG. 5-1 shows how to install a wood header (5-1-1), which is sit on a column of shorter trimmer block (5-1-2) and secured to stud (4). Top rail (6) is immediately above the header (5-1-1). Extra straps (3a) secure the header (5-1-1) to rail (6). The bottom of a trimmer key (5-1-3) is secured by a horizontal strap (5-1-4) anchored on the neighboring rail (2), and by a regular strap (3) to the rail (2) directly under it (not repeated in the drawing). The top of the trimmer key (5-1-3) connects to the header (5-1-1) in the typical wood-to-wood connection.

The header beam can also be made of rebar-reinforcement masonry lintel (not shown in drawings), which is considered as a wider block (5), with the same profile at each end to connect to studs (5).

Wall and Roof Connection

FIG. 5-2 shows how a wood roof truss (5-2-1) is secured by strap-tying to the rail (6). Trusses (5-2-1) sit on the risers (5-2-2) and tied-down by strap (3b).

FIG. 6 shows how wall made of block (5) join with roof panels (22), which are often full-length AAC panels. Roof join key stud (6-1-1) is the same as stud (4) for walls is tied to rail (6) by strap (6-1-2) and ridge rail (6-1-3) by strap (6-1-4).

Installation Process

Starting from a corner, a column of block (5) is set. Then, the stud (4) is attached to the column with applied glue, padding, and membrane. Strap (3) is nailed to stud (4) looping over rail (2). Then, repeat the step on the next column of blocks.

Once the first level wall is completed, install wood floor joists (41) resting on foundation (1) in gap (8) or in groove (41). Then, secure them to the rail (2), or to rail (6) for higher floors.

Next, add the top rail (6) and secure to it with all studs (4) with strap (3a), followed by installing roof or upper floor.

Interior wood stud walls are anchored to studs (4) in gap (8). Utility lines can also be routed in gap (8). Every structure connection subject to inspection is exposed through gap (8).

Finally, gaps (8) and gaps (9) are covered during finish work.

Claims

1. A tie-down method in house construction that anchors an entire building to an array of Ω-shaped metal rails, which are embedded in the foundation concrete during pouring with the upper portion exposed as rings on the foundation top surface, and further comprising a method that ties the wood studs of walls and floor joists of the building directly to the exposed part of metal rails using metal connecting straps and their required nails and bolts.

2. The method in claim 1 wherein said Ω-shaped rails are made from construction steel rebar.

3. A masonry wall construction method that reinforces stack-bound masonry blocks with wood studs as join keys, and further comprising: a. a method that connects common wood building components, such as wood stud walls, windows, doors, lintels, floor joists, etc., to said masonry wall by anchoring on said wood stud keys, andb. a horizontal band or the roof wall band, named the top rail in drawings, that is made of either steel rebar or wood studs connected by metal straps, and circulates said house wall structure and straps together said stud keys and hence said blocks.

4. The method in claim 3 wherein said masonry block has four sides: exterior, interior, left and right side, and two surfaces, top and bottom surface, and the block shape further comprising, a. a vertical concave groove in at least one of the four side to receive, enclose, and interlock with said stud keys in claim 3, andb. said concave groove that secures said stud key between its two shoulders, a primary shoulder and a secondary shoulder, where the secondary shoulder is lower than the primary shoulder exposing said stud key at one side of the joint, andc. said concave groove that is tapered-in toward the bottom and has rounded corners or bumps at the bottom to retain gaps between said blocks and said keys in claim 3, andd. a mean to keep said wood stud keys dry by filling the said gaps on the primary shoulder side with moisture-barrier material, and by keeping the gap on the secondary shoulder side either open to air flow or covered with only breathable materials to allow moisture in said keys vaporizing.

5. The method in claim 3 wherein said masonry blocks are aerated autoclaved concrete panels or blocks.