US20040159065A1

US20040159065A1 - Retaining wall block

Info

Publication number: US20040159065A1
Application number: US10/779,200
Authority: US
Inventors: Andrew Burgess; William Henschler
Original assignee: Menard Inc
Current assignee: Menard Inc
Priority date: 2003-02-17
Filing date: 2004-02-13
Publication date: 2004-08-19

Abstract

A mortarless concrete block retaining wall is formed from special blocks arranged in set-back tiers and interlocked by a special post groove arrangement. Each block is trapezoidal in plan view with a pair of laterally spaced posts projecting from the top surface of the block. A groove on the bottom surface of the block fits over adjacent posts in the underlying tiers. The vertically adjacent tiers are laterally offset to interlock the tiers via the post/groove arrangement. The post/groove arrangement allows for blocks that are adjustable to interlock the tiers in a straight configuration or in varying degrees of convex and concave curved configurations.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims the benefit of provisional application Serial No. 60/448,028 filed Feb. 17, 2003.[0001]

FIELD OF THE INVENTION

This invention relates generally to masonry blocks which may be used in the construction of landscaping elements. More specifically, the invention relates to mortarless retaining wall blocks.

BACKGROUND OF THE INVENTION

Protection of natural and artificial structures, soil retention and increased land use are only a few reasons which motivate the use of landscape structures. When reliance on natural feature is not possible or practical, man often resorts to the use of artificial mechanisms such as retaining walls.

Many different materials may be used to construct retaining walls depending upon the given application. One common solution is the use of mortarless concrete blocks. Blocks used for these purposes include those disclosed by Hodel U.S. Pat. No. 5,161,918, Woolford U.S. Pat. No. 6,142,713, Risi et al, U.S. Pat. No. 4,490,075 and U.S. Des. Pat. No. 280,024 and Forsberg, U.S. Pat. No. 4,802,320 and U.S. Des. Pat. No. 296,007 among others. These blocks have typically been patterned and weighted so that they may be used to construct a wall which will stabilize the landscape by the shear weight of the blocks.

Mortarless concrete block retaining walls generally have the advantages that they are inexpensive, easy to construct with unskilled labor, have long life, and will adapt to ground subsidence which could crack a poured concrete or mortared wall. Conventional mortarless retaining walls used to hold earth embankments are typically made of poured concrete blocks, stone, concrete, and railroad ties.

To provide adequate strength, stability and long life, a retaining wall preferably is tilted somewhat into the embankment. These systems are often designed to “setback” at an angle to counter the pressure of the soil behind the wall. Setback is generally considered the distance which one course of a wall extends beyond the front of the next highest course of the same wall. Given blocks of the same proportion, setback may also be regarded as the distance which the back surface of a higher course of blocks extends backwards in relation to the back surface of the lower wall courses. In vertical structures such as retaining walls, stability is dependent upon the setback between courses and the weight of the blocks. It is an ideal to have a wall that has sufficient setback to allow for adequate pressure on the backfill and structural integrity of the retaining wall, while at the same time minimizing the setback for aesthetic and space considerations.

Despite the popularity of mortarless systems, many of the mortarless methods are outdated and complex involving the use of separate metal clips, or pins to secure the courses to one another. This is costly and making curved walls with these blocks and clips is difficult and requires considerable skill. For example, to make a wall with an outside curvature (that is, outwardly convex) certain ears that are required for a straight wall must be carefully and precisely knocked off.

Several attempts have been made to provide a mortarless retaining wall block that maximizes the advantages discussed above while allowing for the construction of curved walls. For example, U.S. Pat. No. 5,294,216 to Sievert discloses a masonry block comprising a block body having an irregular trapezoidal shape and comprising a front surface and a back surface, an upper surface and a lower surface, and first and second sidewalls. The block however, further includes a flange extending downward from the rear surface of the block in order to form a locking surface and further requires the use of an anchoring matrix. The flange limits the amount of curvature allowed in the wall and is prone to cracking and chipping. U.S. Pat. No. 6,142,216 to Woolford et al. discloses a similar retaining wall block to that disclosed in Sievert having a generally planar upper surface, a generally planar lower surface and a flange extending off the lower surface.

The current designs of pinless, mortarless masonry blocks generally fail to resolve problems such as the ability to construct walls which follow the natural contour of the landscape in a radial or serpentine pattern. Previous blocks also have failed to provide a system to stabilize the stacked course without complex pinning or strapping fixtures. Reliance on such complex fixtures often discourages the use of retaining wall systems by the every day homeowner. Commercial landscapers generally avoid complex retaining wall systems as the time and expense involved in constructing these systems is not supportable given the price at which landscaping services are sold.

As can be seen, the present state of the art of forming masonry blocks as well as the design and use of these blocks to build structure has definite shortcomings.

SUMMARY OF THE INVENTION

In view of the foregoing, it is a primary object of the invention to provide a mortarless retaining wall which is inexpensive, easy to construct with unskilled labor, having adjacent tiers permanently interlocked in a predetermined set-back relationship, in a straight configuration, or in a wide range of optional convex and concave curved configurations. The present inventive locking function provided by the inventive post and groove combination is highly advantageous to those systems disclosed in the Sievert, Woolford, and other patents.

In particular, the object of this invention is to provide a special concrete block with integral stubs or posts and grooves for interlocking a plurality of such blocks when arranged side by side in successive set-back tiers to thereby provide an improved, mortarless retaining wall.

Consistent with the foregoing objects and in accordance with the present invention, there is provided a composite masonry block comprising a block body having a front surface and a substantially parallel back surface, an upper surface and a lower surface, two intermediary walls, and two sidewalls. The intermediary walls extend from the block front surface towards the block back surface at an angle less than ninety degrees in relationship to the block front surface. The sidewall adjoins the intermediary wall and lies between the intermediary wall and the block back surface. The block of the present invention also comprises two posts or stubs projecting upwardly from the upper surface and a groove that extends side-to-side in the bottom surface of the block. The posts are fitted to be inserted inside the groove when the blocks are stacked upon one another in successive courses.

In accordance with a further aspect of the present invention there are provided landscaping structures such as retaining walls comprising a plurality of courses, each of the courses comprising a plurality of the composite masonry blocks of the present invention.

These, and other, aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

A clear conception of the advantages and features constituting the present invention, and of the construction and operation of typical mechanisms provided with the present invention, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings accompanying and forming a part of this specification, wherein like reference numerals designate the same elements in the several views, and in which: [0016]
FIG. 1 is a front perspective view of a preferred embodiment of the retaining wall block in accordance with the present invention; [0017]
FIG. 2 is a top plan view of the retaining wall block shown in FIG. 1; [0018]
FIG. 3 is a bottom plan view of the retaining wall block shown in FIG. 1; [0019]
FIG. 4 is a left side elevational view of the retaining wall block shown in FIG. 1; [0020]
FIG. 5 is a rear elevational view of the retaining wall block shown in FIG. 1; [0021]
FIG. 6 is a front elevational view of the retaining wall block shown in FIG. 1; [0022]
FIG. 7 is a partially cut away perspective view of a retaining wall constructed with the preferred embodiment of the retaining wall block of the present invention; [0023]
FIG. 8 is a cut away view of the wall shown in FIG. 7; [0024]
FIG. 9 is a partially cut away perspective view of a retaining wall having a serpentine pattern constructed with the preferred embodiment of the retaining wall block of the present invention; [0025]
FIG. 10 is a partially cut away perspective view of a retaining wall having a serpentine pattern constructed with the preferred embodiment of the retaining wall block of the present invention; [0026]
FIG. 11 is a fragmentary top view of the wall shown in FIG. 7; [0027]
FIG. 12 is a fragmentary top view of the wall shown in FIG. 9; and [0028]
FIG. 13 is a fragmentary top view of the wall shown in FIG. 10.[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In describing the preferred embodiments of the invention which are illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific terms so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word “connected” or terms similar thereto are often used. Such terms are not limited to direct connection but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art. Furthermore, certain dimensions of the block are given to help illustrate the preferred embodiment, however, the inventive concept could be applied to numerous varying dimensions and the inventive concept includes such variations. [0030]
Accordingly, the present invention provides a retaining wall block, and structures resulting from this block. The present invention provides a mortarless interlocking masonry block which may be used to construct any number of structures having a variety of patterns. [0031]
Retaining Wall Block [0032]
Referring to the drawings wherein like numerals represent like parts throughout several views, a [0033] retaining wall block 1 is generally shown in FIGS. 1-6. The first aspect of the present invention is a retaining wall block having an irregular hexagonal shaped block body 2.
[0034] Block 1 is a unitary member preferably of high density concrete. The block body 2 generally comprises a front surface 3 and a back surface 5 which are substantially parallel to each other. In the preferred embodiment, the front surface is about 8 and two thirds inches long and the back surface is about 9 inches long. The front 3 and back 5 surfaces are separated by a distance comprising the depth of the block. In the preferred embodiment, the depth of the block 1 is about eight inches, however the design and inventive concept is applicable to an infinite number of dimensions. The block 1 also has a generally smooth upper 7 and lower surface 9 separated by a distance comprising the height of the block 1. In the preferred embodiment, the height of the block 1 is about four inches.
The [0035] block 1 further has first 15 a and second 15 b intermediary walls adjacent to the side edges of the front surface 3. In the preferred embodiment, the intermediary walls are about 2.2 inches long. As shown in FIG. 2, the intermediary walls 15 a, 15 b extend from the block front surface 3 towards the back surface 5 at an angle, alpha, which is less than ninety degrees in relationship to the block front surface 3. In the preferred embodiment, alpha is about 40 degrees. The block also has first 11 a and second 11 b sidewalls separated by a distance comprising the width of the block. In the preferred embodiment, the width of the block measured from the juncture points 27 a, 27 b is about twelve inches although numerous dimensions are envisioned. The sidewalls 11 a, 11 b adjoin the block upper 7 and lower 9 surfaces. The sidewalls 11 a, 11 b further adjoin and lie between the intermediary walls 15 a, 15 b and the block back surface 5. Preferably, the sidewalls 11 a, 11 b converge towards each other as these surfaces move towards the back surface 5 of the block 1. As illustrated in FIG. 2, the angle, beta, between the sidewall and the back surface preferably ranges in magnitude from about 30 degrees to about 60 degrees in relation to the block back surface. The block has two juncture points 27 a, 27 b where the side walls 11 a, 11 b adjoin the intermediary walls 15 a, 15 b.
Referring now to FIGS. 3 and 4, the [0036] lower surface 9 of the block 1 has a groove 19 of given depth “h” and width “w” that extends from the first side wall 11 a to the second sidewall 11 b at a location slightly forward of the longitudinal middle of the block 1. In the preferred embodiment, the center of the groove is about 3.5 inches from the front surface 3 of the block 1. Furthermore, in the preferred embodiment h is about 0.5 inches and w is about 2.25 inches however the design and inventive concept is applicable to an infinite number of dimensions. The upper surface 7 of the block 1 further comprises two horizontally aligned circular posts or stubs 21 a, 21 b projecting upwardly from the upper surface 7 in the longitudinal middle of the block. Preferably, the center of the posts 21 a, 21 b exists about four inches from the front surface 3 and rear surface 5 of the block 1. In the preferred embodiment, the centers of the posts 21 a, 21 b are spaced about five inches apart. The posts 21 a, 21 b have a given height “h” and width “w.” Preferably h′ is about 0.375 inches and w′ is about 2 inches at its widest point. As illustrated by the preferred embodiment, the posts 21 a, 21 b have rounded edges 77 at the top, but a squared edge is envisioned as well. The rounded edge 77 allows for ease of manipulation of blocks 1 as they are being aligned in their post/groove arrangement.
It is not compulsory that the [0037] posts 21 a, 21 b be circular or of the given dimensions, even though this is preferred. However, it is compulsory that the posts 21 a, 21 b have a height “h” equal to or smaller than the depth “h” of the groove 19. It is also compulsory that the posts 21 a, 21 b have a width “w” which is substantially equal to or slightly smaller than the width “w” of the groove 19. As will be described in further detail below, the groove 19 is designed to fit over the posts 21 a, 21 b when the blocks are stacked in courses. This interlocking feature of the groove 19 and posts 21 a, 21 b creates greater stability in the finished retaining wall.
Generally, the [0038] block 1 may vary in shape and dimension in accordance with the present invention. Distinctive of the present invention is the ability to use the block 1 seen in FIGS. 1-6 to construct either straight or serpentine mortarless retaining walls. Accordingly, the block 1 of the present invention preferably has an irregular hexagonal shape having parallel front 3 and back surfaces 5. The necessarily irregular nature of the hexagonal block 1 of the present invention comes from the varying lengths of the block's intermediary walls 15 a, 15 b, sidewalls 11 a, 11 b, front 3 and back 5 surfaces.
Referring again to FIGS. [0039] 1-5, the block body 2 generally has eight surfaces. The front surface 3 generally faces outward from the structure and has a roughened appearance to enhance the blocks aesthetic appeal although a smooth surface or other decorative face is envisioned. The back surface 5 of the block 1 generally lies parallel to the front surface 3 and is generally smooth in appearance. The upper surface 7 generally lies parallel to the bottom surface 9. Both the upper 7 and lower 9 surfaces are also generally smooth in appearance.
The block [0040] intermediary wall 15 a, 15 b surfaces have a series of ridges or grooves 18. This generally ridged appearance also enhances the blocks 1 aesthetic appeal. The ridges are comprised of a series of peaks 78 and valleys 79. In the preferred embodiment the peaks are spaced about 0.250 inches apart. The block 1 sidewall surfaces 11 a, 11 b lie across the width of the block. As shown in FIGS. 7, 9, and 10, the interaction between the sidewalls 11 a, 11 b and intermediary walls 15 a, 15 b of the block body 2 of the present invention allow for the construction of straight structures (FIG. 7) or serpentine structures including outside radius turns (FIGS. 9,10).
The inventive block can be used to construct a [0041] straight wall 31. An aligned straight wall can be constructed by aligning the adjacent juncture points 27 a, 27 b of the same wall course, (see 27 a, 27 b FIG. 7). Optionally, the same embodiment of the block of the present invention allows the construction of aligned serpentine structures as seen in FIGS. 9, 10, 12 and 13. In the serpentine wall, the block sidewalls 11 a, 11 b align with adjoining sidewalls in the same course, (see 11 a, 11 b FIG. 10).
As can be seen in FIG. 8, the blocks of each successive course will setback from blocks from the course below. This is a result of the offset between the [0042] posts 21 a, 21 b and groove 19. As noted above, the center of the posts 21 a, 21 b are located about 4 inches from the front surface of the block. Alternatively, the center of the groove 19, is located 3.5 inches from the front surface of the block. Therefore, each successive course will have a setback of about 0.5 inches. Generally, each successive course of blocks should setback far enough to maintain the stability of the soil 35 behind the wall. This preferred setback range provides minimal setback, (for aesthetic value) while ensuring stability of the soil behind the wall.
In its most preferred mode, the [0043] block 1 of the present invention is suitable for both commercial and residential use by landscapers as well as homeowners for use in building landscape structures
Block Structures [0044]
The [0045] composite masonry block 1 of the present invention may be used to build any number of landscape structures. Examples of the structures which may be constructed with the block of the present invention are seen in FIGS. 7-10. As can be seen in FIG. 7, the composite masonry block 1 of the present invention may be used to build a retaining wall 31 using individual courses 33 to construct to any desired height. The blocks 1 may be stacked in an even pattern or an offset pattern depending on the intended application.
Generally, construction of a structure such as a retaining [0046] wall 31 may be undertaken by first defining a trench (not shown) area beneath the plane of the ground 35 in which to deposit the first course 37 of blocks 1. The first course 37 of blocks 1 is then laid into the trench. As can be seen in FIGS. 11-13, successive courses 33 of blocks are then stacked on top of preceding courses while backfilling the wall 31 with soil. As best illustrated in FIGS. 11-13, successive courses of blocks 1 are stacked in a manner such that the groove 19 fits over the posts 21 a, 21 b of the underlying blocks 1. This arrangement is repeated throughout the courses until a desired height is reached. As stability is dependent upon weight and minimal setback, the minimal setback provided by the blocks 1 of the present invention assists in further stabilizing even lighter weight blocks. This minimal setback adds to the stability of smaller size blocks by slowing the horizontal movement backward of the wall through the addition of successive courses. In the preferred embodiment, the blocks weigh about twenty-five pounds. Due to this weight, the block structures are most stable at a height of up to about thirty six inches. However, by increasing the weight of the blocks stable walls can be constructed over thirty-six inches, and such blocks and structures are envisioned as part of the present invention. Clearly, the inventive concept could be applied to numerous varying weights and dimensions and the inventive concept includes such variations.
Still referring to FIGS. [0047] 11-13, fragmentary top views of two courses of a wall are shown. FIG. 11 illustrates the post/groove arrangement of two courses in a straight wall. As illustrated, the stacked courses are typically laterally offset such that the groove of one block 1 in an upper course fits over one post 21 a of one block in a lower course, and another post of an adjacent block 21 b in the lower course. FIGS. 12 and 13 illustrate the post/groove arrangement of two courses in a curved and serpentine wall. These illustrations demonstrate a key advantage of the post/groove arrangement of the present invention. Because the groove 19 is continuous with the width of the block, several different angles between adjacent blocks and courses can be accommodated while maintaining the post/groove interlocking arrangement of successive courses. Furthermore this can be accomplished without the use of pins or straps.
Another benefit of the [0048] blocks 1 of the present invention is the combination intermediary wall 15 a, 15 b and sidewall 11 a, 11 b. While the intermediary walls 11 a, 11 b have an angle of less than 90 degrees in relationship to the front surface of the block 3, the block sidewalls 11 a, 11 b converge or angle towards each other as the sidewall moves towards the back surface 5 of the block. The converging block sidewalls 11 a, 11 b allow the blocks 1 to be set in a range of angles relative to adjacent blocks of the same course, FIG. 9.
When a straight wall is desired, FIG. 7, the [0049] blocks 1 of the present invention allow for the placement of the blocks flush against each others juncture points 27 a, 27 b. As can be seen in FIG. 7, block juncture points 27 a and 27 b of two adjacent blocks are flush against one another while the adjacent sidewalls 11 a, 11 b are spaced apart. In contrast, if a more highly angled serpentine wall is desired, the blocks 1 of the present invention allow for the placement of the blocks with the sidewalls 11 a, 11 b flush against each other. (FIG. 10). In both instances, there is the desired tight block placement.
The above discussion, examples, and embodiments illustrate the current understanding of the invention. Certain dimensions of the block were given to help illustrate the preferred embodiment, however, the inventive concept could be applied to numerous varying dimensions and the inventive concept includes such variations. Since many variations of the invention can be made without departing from the spirit and scope of the invention, the invention resides wholly in the claims hereafter appended. [0050]

Claims

We claim:

1. A composite masonry block comprising:

a) a block body, said block body comprising a front surface and a back surface, said front surface and said back surface being substantially parallel to each other and separated by a distance comprising the depth of the block, an upper surface and a lower surface, said upper surface and said lower surface being substantially parallel to each other and separated by a distance comprising the height of the block, two intermediary walls extending from the block front surface towards the block back surface at an angle less than ninety degrees in relationship to the block front surface, and two sidewalls adjoining the intermediary walls and the block back surface;

b) a groove that extends sidewall-to-sidewall in the bottom surface of the block; and

c) two posts projecting upwardly from the upper surface of the block body, wherein said posts are fitted to be inserted inside the groove when the blocks are stacked upon one another in successive courses.

2. The composite block of claim 1, wherein said front surface of said block is roughened for aesthetic appeal.

3. The composite block of claim 1, wherein said posts are circular.

4. The composite block of claim 3, wherein said posts have rounded edges.

5. The composite block of claim 1, wherein said intermediary walls are grooved.

6. A retaining wall comprising:

a) a lower tier of blocks arranged side by side;

b) an upper tier of blocks arranged side by side and located on top of the lower tier of blocks;

c) each of said blocks having a body with front, back, top, bottom, side and intermediary surfaces;

d) each of the block bodies in the lower tier having two posts in the top surface of the body, and each of the block bodies in the upper tier having a groove in the bottom surface thereof, extending the width of the block and configured to receive the posts; and

e) the posts and grooves interlocking the block bodies in the upper tier with the block bodies in the lower tier.

7. The retaining wall of claim 6, wherein the tiers of blocks are interlocked in a laterally offset relationship.

8. The retaining wall according to claim 6, wherein the groove in the block bodies in the upper and lower tiers are in the same positions relative to the front, rear and side surfaces of the bodies.

9. The retaining wall according to claim 6, wherein the posts in each block body comprises a pair of laterally spaced vertically extending posts, each post set forward an equal distance from the back surface, and set inwardly equal distances from the side surfaces.

10. The retaining wall according to claim 6, wherein each block body comprises:

a) top and bottom horizontal surfaces;

b) front and back generally parallel surfaces, the front surface being substantially roughened relative to the other surfaces and being substantially wider than the back surface;

c) grooved intermediary walls extending diagonally from said front surface; and

d) straight side surfaces extending diagonally between said intermediary walls and back surface.

11. The retaining wall according to claim 6, wherein each block body comprises a generally trapezoidal shape in plan view, with the front surface wider than the back surface, and the two side surfaces extending diagonally therebetween.

12. The retaining wall according to claim 6, further comprising a central roughened face portion flanked by relatively smooth grooved, comer surfaces connecting each end of the front surface to a corresponding one of the side surfaces.

13. The retaining wall according to claim 6, wherein the body has a generally trapezoidal shape in plan view with the front surface wider than the rear surface and the side surfaces diagonally disposed enabling the tiers to be curved.

14. A retaining wall block suitable for use in forming a mortarless retaining wall, said block comprising:

a) a pair of substantially parallel and planar upper and lower faces;

b) a front face joining the upper and lower faces, which is substantially perpendicular to the upper and lower faces;

c) a rear face which is substantially perpendicular to the upper and lower faces;

d) a pair of intermediary faces joining the front face and a side face the intermediary side faces being substantially perpendicular to the upper and lower faces;

e) a pair of side faces joining the intermediary side faces and rear faces, the side faces being substantially perpendicular to the upper and lower faces, and including rearwardly converging portions, wherein a line drawn on the upper face through the points where the rearwardly converging portions begin is substantially parallel to a line drawn through the points where the side faces join the rear face;

f) two laterally spaced posts extending upwardly from the upper face; and

g) a groove extending the width of the lower face, configured to fit over the posts.

15. The block of claim 13, wherein the front face of the block is substantially planar.

16. The block of claim 13,, wherein the front face of the block is nonplanar.

17. The block of claim 13, wherein the front face of the block is roughened.

18. The block of claim 13 wherein each intermediary side face intersects the front face at an angle of less than 90 degrees.

19. The block of claim 13 wherein the rearwardly converging side face portions each intersect the rear face at an angle of less than 90 degrees.

20. The block of claim 13, wherein the posts are round.

21. The block of claim 20, wherein the posts have rounded edges.

22. The block of claim 13, wherein the intermediary surfaces are grooved.

23. A retaining wall comprising stacked courses of the block of claim 14 wherein the front faces of the blocks combine to form a decorative face of the retaining wall, and wherein the lower face of each block in a succeeding course is placed over the upper faces of the blocks in the next lower course, in a manner that the groove of each block in a succeeding course is positioned over the posts of adjacent blocks in the next lower course.

24. The retaining wall of claim 23, wherein the first and second courses are laterally offset.

25. The retaining wall of claim 23, wherein said retaining wall has a set back from said first course to said second course.

26. The retaining wall of claim 23, wherein said retaining wall set back is defined by the relationship of the overlap between the groove and posts of successive courses.

27. A retaining wall comprising:

a) a lower tier of blocks arranged side by side, each block in the lower tier having a body with two posts extending from a top surface;

b) an upper tier of blocks arranged side by side and laterally offset from the lower tier, each block in the upper tier having a body with a groove configured to receive the posts in the bottom surface said upper tier being positioned on top of the lower tier with the groove in the upper tier being placed over the posts in two adjacent blocks in the lower tier.