US3775925A

US3775925A - Roofing panel with drainage means

Info

Publication number: US3775925A
Application number: US00203984A
Authority: US
Inventors: K Fujita
Original assignee: Fujita Kenzo Kogyo Co Ltd
Current assignee: Fujita Kenzo Kogyo Co Ltd
Priority date: 1970-12-02
Filing date: 1971-12-02
Publication date: 1973-12-04
Anticipated expiration: 1990-12-04

Abstract

A roofing panel which is provided with long corrugations formed respectively along both the right and left sides and both the front and rear sides of the roofing panel, whereby the front side corrugation of the roofing panel is overlapped on the rear corrugations of two other roofing panels which are arranged in parallel at the front side of the roofing panel when the roofing panel is coupled to other roofing panels so that the front and rear sides of a roofing panel are joined with those of other roofing panels and the either of the right-and left-side corrugations of the other roofing panel when the roofing panel is coupled to other roofing panels and which is provided with the water drains to prevent water or rain from intruding into joined portions and remaining on the roofing panels.

Description

[111 3,775,925 [451 Dec. 4,1973

[ ROOFING PANEL WITH DRAINAGE MEANS [75] Inventor: Keiich Fujita, Kanagawa, Japan [73] Assignee: Fujita Kenzo Kogyo Co., Ltd.,

Kawasaki City, Kanagawa, Japan 22 Filed: Dec. 2., 1971 [21] App]. No.: 203,984

[30] Foreign Application Priority Data Dec. 2, 1970 Japan 45/120019 Feb. 2, 1971 Japan 46/4646 Feb. 22, 1971 Japan 46/10384 [52] U.S. Cl 52/534, 52/536, 52/547 [51] Int. Cl [58] Field of Search 52/536, 556, 549, 52/547, 545, 535, 533, 534

[56] References Cited UNITED STATES PATENTS 955,855 4/1910 Day 52/534 256,083 4/1882 Walter 52/534 3,114,218 12/1963' Macquere... 52/536 1,634,126 6/1927 Tyra 52/547 150,642 5/1974 Weybrecht.. 52/533 525,098 8/1894 Friedel..... 52/534 309,134 12/1884 Cooper 52/536 1,434,166 10/1922 Thompson 52/534 1,597,993 8/1926 Meurer 52/534 2,269,872 1/1942 Gaston.... 52/534 2,211,508 8/1940 Little 52/533 FOREIGN PATENTS OR APPLICATIONS 210,793 2/1924 Great Britain 52/533 750,910 8/1933 France 52/534 Primary Examinerl-1enry C. Sutherland Assistant Examiner-Leslie A. Braun AttorneyJames E. Armstrong et al.

[5 7 ABSTRACT A roofing panel which is provided with long currugations formed respectively along both the right and left sides and both the front and rear sides of the roofing panel, whereby the front side corrugation of the roofing panel is overlapped on the rear corrugations of two other roofing panels which are arranged in parallel at the front side of the roofing panel when the roofing panel is coupled to other roofing panels so that the front and rear sides of a roofing panel are joined with those of other roofing panels and the either of the right-and-left-side corrugations of the other roofing panel when the roofing panel is coupled to other roofing panels and which is provided with the water drains to prevent water or rain from intruding into joined portions and remaining on the roofing panels.

13 Claims, 19 Drawing [Figures PATENTEU DEC SHEET 3 BF 6 PATENTEU WI 3 SHEET 8 OF 6 ROOFING PANEL WI'III DRAINAGE MEANS BACKGROUND OF THE INVENTION The present invention relates to a roofing panel.

Conventional. roof tiles made by burning clay have great disadvantages in that the weight per roof tile is heavy and the roof tile itself is prone to breakage. Thus, it is disadvantageous in use because a lot of physical effort of skilled workers is required to convey a number of roof tiles for roofing to a high position and therefore the roofing cost is high.

On the other hand, when conventional metal plate roofing material is used for roofing the house, it has been necessary to extend the metal plate roofing material by the hands of skilled workers. Therefore, it is disadvantageous because plate working of the metal plate is required at the site of roofing work, highly skilled roofing techniques are required and partial repair after completion is difficult.

The present invention provides a roofing panel made of a metallic plate or synthetic resin plate which. can eliminate and avoid the disadvantages described above.

SUMMARY The present invention generally relates to a roofing panel arrangement made of a metallic plate or synethetic resin plate; which is provided with an overlapping corrugation at one of right or left sides of the roofing panel and an overlapped corrugation along the rest of the right and left sides of the roofing panel, wherein the rear side of the overlapping corrugation is formed so as to be adapted to cover and fit onto the overlapped corrugation of the other roofing panel; which is provided with a front corrugation at the front side of the roofing panel and a rear side corrugation at the rear side, wherein the rear side of the front side corrugation I is formed so as to be adapted to cover and fit onto the rear side corrugations of a pair of other roofing panels which are arranged in parallel in the front side of .said roofing panel; and which is provided with water drains formed between the front side corrugation and the overlapped corrugation or between the front side corrugation and the overlapped corrugation and overlapping corrugation so that the water drains are open toward the front side of the roofing panel and the groove portion which divides the rear side corrugation into the right and left parts and is open toward the rear side of the roofing panel.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is illustrated in detail by the accompanying drawings whereon;

FIG. I is a plan view of an embodiment of a roofing panel according to the present invention,

FIG. 2 is a front view of an embodiment,

FIG. 3 is a rear view of said embodiment,

FIG. 4 is a left side view of said embodiment,

FIG. 5 is a right side view of said embodiment,

FIG. 6 is a cross sectional front view along line VI VI in FIG. I,

FIG. I is a cross sectional left side view along iine VII VII in FIG. 1,

FIG. 8 is a cutaway plan view of part of the roof I formed with a plural number of the roofing panels which are arranged consecutively,

FIG. 9 is a magnified cross sectional view illustrating the roofing panels of said embodiment which are joined,

FIG. W is a plan view of the second embodiment of the roofing pane] according to the present invention,

FIG. II is a plan view of the third embodiment of the roofing panel according to the present invention,

FIG. 12 is a front view of said embodiment,

FIG. 13 is a rear view of said embodiment,

FIG. 14 is a left side view of said embodiment,

FIG. I5 is a plan view of the fourth embodiment of the roofing panel according to the present invention,

FIG. 16 is the magnified cross sectional side view illustrating the joined roofing panels of said embodiment, and

FIGS. 17a, 17b and ll'7c are a magnified cross sectional views illustrating the embodiment of the rear side corrugation and i the overlapped corrugation of the roofing panel according to said embodiment.

DETAILED DESCRIPTION Referring to FIG. 11, there is shown a roofing panel I which is made in a rectangular 'form with a plate material such as, for example, a metal plate and wherein such material is capable of being pressed or synthetic resin plate.

The roofing panel is provided, as shown in FIG. 1, with an overlappingcorrugation 2 at the left side of the roofing panel. along the widthwise direction, that is, the slope direction obtained when theroofing panel is fixed to the roof base, and overlapped corrugation 3 isprovided at the right side in parallel with said overlapping corrugation 2. Furthermore, the roofing panel is provided with front side corrugation 4, which intersects at a right angle the direction of the roof slope at the front side of the roofing panel, that is, the lower side of the slope and rear side corrugation 5 in parallel with the front side corrugation to be at the rear side of the, roofing panel. 1

The main surface of the roofing panel according to the present invention is surrounded by said corrugations and accordingly a rectangular plate area is formed at the center of the roofing panel.

Said overlapping corrugation 2 and overlapped corrugation 3 are provided to consecutively connect a plural number of roofing panels in the lengthwise direction as shown in FIG. fi. The rear side of overlapping corrugation 2 forms groove 21 in parallel with overlapped corrugation 3 so that the overlapping corrugation covers and fits onto overlapped corrugation 3 of roofing panel adjacent tothe left side of the original roofing panel, and said overlapped corrugation 3 is formed so that it fits to groove 21.

Front side corrugation 4 and rear side corrugation 5 are provided to consecutively connect a plural number of roofing panels along the direction of the roof slope. The reverse side of said front side corrugation 4 forms groove 4i in parallel with the front. side corrugation andrear side corrugation 5 is provided with the groove portion 6 which isopen from plate area 11 to therear side. The rear corrugation is divided into the right and left portions and is formed with a pair of corrugations 51 and 511' which are opposed in series. To connect a plural number of the roofing panels in the direction of the roof slope, groove 41 is formed so as to be adapted to cover and fit ontothe upper surface of corrugations 51 and 51' which are located between groove portions 6 of a pair of roofing panels arranged in parallel in the direction of the roof slope and the front end of overlapping corrugation 2 of roofing panel adjacent to the rear side of the original roofing panel is positioned at the upper surface of groove portion (6. Thus, the front side of roofing panel l is formed so that it fits with the rear side of a pair of roofing panels adjacent in sequence along the direction of the roof slope; for example, the front-side and rear-side corrugations can be formed originally by pressing.

Said corrugations may be formed so that they fit each other as described above and may be shaped in a desired form; for example, they may be formed so that the shape of the section is curved as shown in FIGS. 6 and 7. To prevent intrusion of. water or rain, it is desirable to form the corrugations so that the extreme left portion of corrugation 51 of rear side corrugation intersects at a right angle the extreme rear portion of over lapping corrugation and the former continues to the latter. Similarly, it is desirable to continue the extreme right portion to the extreme rear portion of overlapped corrugation 2 so that the former intersects at a right angle with the latter. Furthermore, it is desirable to separate both end portions 4a and 4lb of front side corrugation 4- from overlapping corrugation 2 and overlapped corrugation 3 and to provide a pair of water drains 7 and 7' between

end portions

4a and 4b and the front ends of overlapping corrugation 2 and overlapped corrugation 3. In this case, the rain on roofing panel 1 can be smoothly drained toward the front side.

If roofing panel 1 is formed as described above, fitting portion 42 which is open toward the front side is provided around the center of groove 411 at the rear side of front corrugation 4 and the fitting portion closely fits with the upper surface of the front side of overlapping corrugation 2 of the other roofing panel arranged adjacent to the front side of the original roofing panel. Moreover, an outwardly open fitting portion 2a is provided by chipping the external side of the rear end of overlapping corrugation 2 and fitting portion 2a is formed so that it closely fits to the upper surface of the extreme right of overlapped corrugation 5 of other roofing panel 11 adjacent to the left side of the original roofing panel.

it is desirable to provide at least one corrugated passage lla with the corrugated section as shown in FIG. '7 at plate area ill of said roofing panel 11 to smoothly drain the water and rain on the roofing panel to water drains 7 and 7. When providing said corrugated passage lla, vertical vibration of plate area ll of the roofing panel due to the flush of rain can be prevented.

Roofing panel l is provided with a plural number of holes 8 for fixing the roofing panel to the roof base. As shown in lFlG. 9, holes 8 are provided at the portions of the corrugations such that fixtures 9 such as nails, screws, etc. can pass through the corrugations of two roofing panels at the same time. if desired, a waterproof adiabatic sound absorber Iltl can be attached to the lower surface of roofing panel ii.

Since this embodiment is designed as described above, overlapping corrugation 2 is overlapped, as shown in PEG. 8, on overlapped corrugation 3 of other roofing panel 1 arranged adjacent to the left side of the original roofing panel when fixing consecutively the roofing panels to roof base 12. Thus, by repeating the above, a plural number of roofing panels 11 can be connected in the lengthwise direction. Front corrugation 4 of roofing panel l is overlapped on

corrugations

51 and 511 located between the groove portions of a pair of other roofing panels ll arranged adjacent to the front side of the roofing panel. By repeating this, 'a plural number of roofing panels ll can be connected in the direction of the roof slope. Overlapped corrugations of the roofing panels can be fixed to the roof base by passing fixtures 9 through the holes provided at the corrugations, to the roof base 12. I

Roofing panel 1 of this embodiment of the present invention is provided with the protruded corrugations as the joined portions of the roofing panels to prevent rain from entering into the joined portions. However, if the rain flows in large amounts, there is a possibility of intrusion of the rain. To solve this, the following embodiment is offered.

Referring to FIG. 10, there is shown the second embodiment of the roofing panel according to the present invention. Overlapped corrugation 3 described in the first embodiment is provided with at least one drain groove 31 for draining rain in parallel with the lengthwise direction of overlapped corrugation 3; accordingly, overlapped corrugation 3 is divided by the drain groove into a plural number of corrugations 311. Furthermore, a pair of corrugations 51 and 51', whichare arranged in series, comprising rear side corrugation 5 described in the first embrxliment are provided with at least one water drain 52 or 52' arranged in parallel with corrugations 51 and 51'; accordingly, corrugations 51 and 51' consist of a plural number of corrugations 511 and 531 l The front end portion of said drain groove 31 is open toward the front side of the roofing panel and the opposed sides of drain grooves 52 and 52' are open toward said groove portion 6, whereby the rain entering into said drain groove 31 can be drained out to groove portion 6 of other roofing panel ll arranged adjacent to the front side of the original roofing panel and the rain entering into drain grooves 52 and 52' can be drained out to groove portion 6. Of said drain grooves, drain grooves 52 and 52' provided at front side corrugation 5 need not always be provided, and in this case a considerable amount of rain can be prevented from intruding.

Other parts of roofing panel 1 of this embodiment are formed as in the case of the first embodiment. if the roofing panel of this embodiment is used, the rain can be almost completely prevented from entering.

if the roofing panel of this embodiment is used on the roof, the rain is collected into the groove portion of the roofing panel; accordingly, if there is heavy rain, the rain flows along the direction of the roof slope and may overflow front side corrugation 4. In this case, the rain may intrude into the joined portions in the direction of the roof slope. If the angle of the roof slope is small or the rain flows angularly due to a strong wind, the rain may flow in a reverse manner and intrude into the roof through the joined portions of the roofing panels. To prevent such intrusion, the present invention provides the embodiment as described below.

Referring to FIG. ii, there is shown the third embodiment of the present invention. In the second embodiment, auxiliary corrugation 8, which intersects at a right angle the direction of the roof slope, is provided at the front part of groove portion 6, and rear end portion 61 of said groove portion 6 is slightly bent upwardly as shown in FIG. 113. The roofing panel made as described above is advantageous because the rain drained in a concentrated manner from water drains '7 and 7' of a pair of roofing panels which are arranged adjacent to the rear side of the original roofing panel, is interrupted by said auxiliary corrugation lid, is clamped and is divided into right and left branch flows, thus being prevented from overflowing the front corrugation and from reversely flowing in a reverse fashion.

Rear side corrugation 5 of the roofing panel of this embodiment is separated into the right and left parts by groove portion 46 as in the case of said embodiment, and separated corrugations El and 51' are further separated by

parallel grooves

53 and 53 into the front and rear parts. Thus, rear side corrugation 5 consists of pairs of

corrugations

512, 513, 5112', and 5li3'. Corrugation 5112 is positioned behind corrugation 5T3 and corrugation 5112' behind corrugation 513'. Said

grooves

53 and 53 are provided in the same plane as plate area ill and provide the same effect as drain grooves 52 and 525' in the second embodiment.

Furthermore, overlapped corrugation 3, as in the second embodiment, consists of corrugation 32 provided at the extreme right of the rooting panel and corrugation 32' provided in parallel with corrugation 32 at the left side of corrugation 32. Groove 33 in the same plane as plate area ii is provided between corrugations 352 and 32'. Said corrugation 5112 intersects at a right angle the overlapping corrugation and is continued to the overlapping corrugation at the extreme left as in said embodiment and corrugation 5112' intersects at a right angle the corrugation 32 and is continued to the overlapping corrugation. On the other hand, corrugations 5113 and 518i intersect at a right angle the said overlapping corrugation and corrugation 32 and are separated from them.

Front side corrugation d is provided at the front side of roofing panel 1 so that it intersects at a right angle the direction of the roof slope as in the case of said embodiment. Open joining portion $3 is opened toward the front side of the roofing panel so that the open fitting portion enters into the rear part of overlapping corrugation 2 of the roofing panel arranged adjacent to the front side of the roofing panel when the roofing panels are joined in the direction of the roof slope.

Recessed portion 22 which is open toward the left side is provided at the rear part of overlapping corrugation 2 as shown in MG. llll so that the recessed portion fits to drain groove 53 of the other roofing panel ll arranged adjacent to the left side of the original roofing panel. Joining portion 223 which is open toward the left side is provided in parallel at the rear side of the recessed portion, that is, the extreme rear portion of said overlapping corrugation so that said joining portion fits into the right end of corrugation $112 of the other adjacent rooting panel ll.

The roofing panel of this embodiment is formed as described above. it is advantageous that prevention of rain is more efiective than the roofing panel of the second embodiment; however, there is still a possibility of the rain intruding through the joined portion due to capillarity. The embodiment described in the following is an improvement of said rooting panel.

Referring to lFllG. 15, there is shown a roofing panel of the fourth embodiment according to the present invention. Rear side corrugation 5 and overlapped corrugation 3 are provided so that these corrugations are positioned as the roofing panel of the third embodiment are formed so that the section at a right angle to the lengthwise direction has at least two

surfaces

3a and 5a with steps as shown in FlG. i'lA, and the rear sides of overlappingcorrugation 2 and front side corrugation d are made in the form of box which is open at the bot tom side. Corrugation lllilll at a right angle to auxiliary corrugation 113 is provided continuously toward the front side.

This embodiment is formed as described above; accordingly, space G is formed along the lengthwise direction of each corrugation between the contact surfaces of the joining portions as shown in MG. 116. Therefore, the capillarity between the contact surfaces is interrupted by space G and the rain sucked up due to capillarity is drained along the lengthwise direction of said space G. The rooting panel of this embodiment is advantageous because it is possible to avoid intrusion of rain due to capillarity and the stepped construction prevents strain and twist in the lengthwise direction and intensities the strength. Furthermore, it is advantageous because the strength of plate llll is increased by providing corrugation Hill at said auxiliary corrugation. As described above, the corrugations of this embodiment may be made so that said space G is formed between joined corrugations when the roofing panels are connected. Accordingly, all corrugations need not always be constructed to have steps for example, as shown in lFlG. ll7g, only the corrugation near the center of plate area llll can be formed with steps, or as shown in lFllG. i712, the upper step portion can be curved. With this construction, the roofing panel can provide similar advantages.

The roofingpanels according to the present invention are formed as described in said embodiments. Therefore, if the roofing panels are used, the continued roof surface can be easily formed by joining the roofing panels in sequence and succession so that the rain does not intrude into joined portions of the roofing panels.

Thus, the roofing panel according to the present invention is advantageous because the skilled workers are not required for roofing work, a number of rooting panels in stack can be transported and the roofing work can be quickly performed.

Furthermore, the roofing panel according to the present invention is advantageous because it can be mass-produced at low cost and can be easily replaced when it is damaged even after it is used to form a continued roof surface.

What we claim is:

l. A rooting panel arrangement involving a plurality of panels adapted for forming a sloped roof, with each panel having a face and back and composed of a plate material and comprising a. an overlapping corrugation being provided at either of right and left sides of the roofing panel in the direction of a predetermined roof slope such that each overlapping corrugation forms a concave groove with the concavity on the back of the panel,

b. an overlapped corrugation being provided at the opposite side to said overlapping corrugation in parallel with said overlapping corrugation so that an overlapping corrugation provided on another roofing panel arranged adjacent to the original roofing panel is adapted to cover said overlapped corrugation,

c. a pair of co-linear rear side corrugations being provided along a rear side of the roofing panel relative to the slope and at a right angle to the direction of a slope in the roof and being divided by a face groove portion approximately at their center,

d. a front side corrugation being provided along a front side of the roofing panel in parallel with said pair of co-linear rear side corrugations such that the front side corrugation forms a concave groove on the back of the panel, and

e. at least one water drain being provided such that it spaces said frontside corrugation and said overlapped corrugation.

wherein the center of said front side corrugation is overlapped on the joined portions of two roofing panels, formed by the side intersection two lower roofing panels and which are arranged in parallel in the lenghwise direction with both ends of the front side corrugations entering respectively into the groove portions of the two roofing panels and one of a pair of the rear side corrugations of each of the two lower connected roofing panels is fitted into the concave groove of the front side corrugation of the original roofing panel.

2. A roofing panel arrangement according to claim ll, wherein a water drain is provided between the overlapping corrugation and front side corrugation.

3. A roofing panel arrangement according to claim ll, wherein one of the divided rear side corrugations is continued at a right angle to the overlapped corrugation.

4. A roofing panel arrangement according to claim 1, wherein one of the divided rear side corrugations is continued at a right angle to the overlapping corrugation.

5. A roofing panel arrangement according to claim It, wherein at least one groove which is open toward the front side is provided adjacent to the overlapped corrugation in the lengthwise direction.

6. A roofing panel arrangement according to claim 5, wherein the bottom of the groove provided adjacent to the overlapped corrugation is formed so that it is positioned in the same plane as the plate area and the rear end portion of one of the corrugations, which are divided by the groove, near the side of the roofing panel is continued to the rear side corrugation.

7. A roofing panel arrangement according to claim 1, wherein a groove which is open toward said groove portion is provided adjacent to at least one of the divided rear corrugations in the lengthwise direction.

8. A roofing panel arrangement according to claim 7, wherein the groove provided at one of the divided rear corrugations which is positioned adjacent to the overlapping corrugation side is formed so that the bottom of said groove is positioned in the same plane as the plate area, and one of the corrugations, which are divided by the groove, at the rear side of the roofing panel is continued to said overlapping corrugation.

9. A roofing panel arrangement according to claim 7, wherein the groove provided at one of divided rear side corrugations which is positioned adjacent to the overlapped corrugation side is formed so that the bottom of said groove is positioned in the same plane as the plate area and one of the corrugations, which are divided by the groove, at the rear side of the roofing panel, is continued to said overlapped corrugation.

MD. A roofing panel arrangement according to claim ll, wherein an auxiliary corrugation is provided in the lengthwise direction on the surface of the front part of the groove portion.

ill. A roofing panel arrangement according to claim Ml, wherein a corrugation positioned at a right angle to said auxiliary corrugation is provided to continue to the auxiliary corrugation toward the front side of the roofing panel.

12. A roofing panel arrangement according to claim ll, wherein an overlapped corrugation is formed in a stepped construction so that the section at a right angle to the lengthwise direction has at least two surfaces with steps.

13. A roofing panel arrangement according to claim ll, wherein a rear side corrugation is formed in a stepped construction so that the section at a right angle to the lengthwise direction has at least two surfaces with steps.

Claims

1. A roofing panel arrangement involving a plurality of panels adapted for forming a sloped roof, with each panel having a face and back and composed of a plate material and comprising a. an overlapping corrugation being provided at either of right and left sides of the roofing panel in the direction of a predetermined roof slope such that each overlapping corrugation forms a concave groove with the concavity on the back of the panel, b. an overlapped corrugation being provided at the opposite side to said overlapping corrugation in parallel with said overlapping corrugation so that an overlapping corrugation provided on another roofing panel arranged adjacent to the original roofing panel is adapted to cover said overlapped corrugation, c. a pair of co-linear rear side corrugations being provided along a rear side of the roofing panel relative to the slope and at a right angle to the direction of a slope in the roof and being divided by a face groove portion approximately at their center, d. a front side corrugation being provided along a front side of the roofing panel in parallel with said pair of co-linear rear side corrugations such that the front side corrugation forms a concave groove on the back of the panel, and e. at least one water drain being provided such that it spaces said frontside corrugation and said overlapped corrugation. wherein the center of said front side corrugation is overlapped on the joined portions of two roofing panels, formed by the side intersection two lower roofing panels and which are arranged in parallel in the lenghwise direction with both ends of the front side corrugations entering respectively into the groove portions of the two roofing panels and one of a pair of the rear side corrugations of each of the two lower connected roofing panels is fitted into the concave groove of the front side corrugation of the original roofing panel.

2. A roofing panel arrangement according to claim 1, wherein a water drain is provided between the overlapping corrugation and front side corrugation.

3. A roofing panel arrangement according to claim 1, wherein one of the divided rear side corrugations is continued at a right angle to the overlapped corrugation.

5. A roofing panel arrangement according to claim 1, wherein at least one groove which is open toward the front side is provided adjacent to the overlapped corrugation in thE lengthwise direction.

10. A roofing panel arrangement according to claim 1, wherein an auxiliary corrugation is provided in the lengthwise direction on the surface of the front part of the groove portion.

11. A roofing panel arrangement according to claim 10, wherein a corrugation positioned at a right angle to said auxiliary corrugation is provided to continue to the auxiliary corrugation toward the front side of the roofing panel.

12. A roofing panel arrangement according to claim 1, wherein an overlapped corrugation is formed in a stepped construction so that the section at a right angle to the lengthwise direction has at least two surfaces with steps.

13. A roofing panel arrangement according to claim 1, wherein a rear side corrugation is formed in a stepped construction so that the section at a right angle to the lengthwise direction has at least two surfaces with steps.