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Sloped Grades: When a site follows the natural organic rising or falling topographic contours of the land. Terraced, Grade: When a sloping grade has been re-purposed into a series of graduated plateaus. For more information on Stepped, or Terraced Grades |
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Showing Options A & C | Showing Option B |
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Sloping grades for gates, fencelines, and driveway gates are dealt with in a hierarchy of solutions, listed below as Options A -C TYPES OF SLOPES * UP/BACK: If you approach the property and the driveway is sloping uphill, we of course need to know the exact rise and fall for the overall span. This is important simply because if the gates are to open in toward the property, they need to clear the rising grade at 90-degrees. If you as a homeowner are doing this, then take a straight-edge such as a 2x4 that is half the width between columns or posts and with one end at the column where the gate hinges. Mimic the 90-degree opening arc with a level set on the 2x4 and either raise or lower the straight-edge until the level reads level. Either make a mark, and then measure from the low point on the grade to your mark, or measure while holding the straight-edge. This will give you the drop for that particular gate leaf. * LEFT / RIGHT: If the slope of your driveway is left to right as you approach from the street, then we also need to know that exact rise or fall. This is important because you may be left with an undue clearance at the bottom of one gate and not so with the other. To gather this measurement,and in lieu of a transit, you can opt for a string-line and a $4 line level. Hold one end of the string on the high end of the driveway surface at the base of the column. Walk the other end of the string-line to the other column and clip on the line level and raise the line until the bubble is between the lines. Measure that distance from the line to the ground. Left to Right slopes are dealt with on a sliding scale. PRICING:
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Marin County, CA
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Marin County, CA
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Oakland, CA A grade that slopes 10" over just 12-ft. Were we to run the bottom rail parallel (Option B), the gate would appear off balance, or asymmetrical, with one side of the gate a full 10" taller than the other side. So we added a rubber sweep to the bottom of the gates, dadoed into a groove so when the left gate opens, the rubber sweep simply folds under as the grade gets higher. The eye remains untainted in considering the gate itself as true and square, and seems to more or less ignore the sweep as if it were a threshold. |
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OPTION 'A' The top edge of the bottom rail is level, with the bottom edge following the slope.
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OPTION 'A'
Gate style #5 on the left. |
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OPTION 'B' The driveway sloped 19" down from right to left over a span of 18-ft. Therefore, both gates are mounted to a single-span steel frame --exposed on the property-side--that is hinged on the left and and the entire assembly swings in toward the property. |
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Marin County, CA OPTION 'B' Our Driveway Gate #9 in Marin County has a slope of 5-1/2" over 14-1/2 ft. Just enough to draw the eye were it left exposed. So our solution was again to run the bottom rail parallel and have the vertical pickets within the gate grow increasingly longer. Almost unnoticeable in the photo, but the left side is 5-1/2" taller than the right side. |
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Salinas, CA OPTION 'B' An example of a partially Biased fence (Option B) . Had we opted for Option C, a fully Biased panel with the entire panel a parallel to the grade, we would have lost our continuous level line along the top from one side-wall to the other. Although the far right side of the panel ends up with a foreshortened height a toddler could climb, it seemed to the patron the be right option. |
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Ventura, CA OPTION 'C' We must be careful, when designing to to a dramatic slope, lest we're left with something akin to Dr. Seuss. Scribing the Gate's top arch of an off-set elliptical gate requires hauling out the college trigonometry textbook (Unlike a standard double gate, the apex of the arch is NOT in the center of the two gates) |
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OPTION 'C' Driveway Gates style #13-2 18" drop over 14' |
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OPTION 'C' Drive gates style #6-3 In the Sea Cliff neighborhood of San Francisco, where sloped grades are commonplace, we have an 6" drop from left to right. This also translates into two stone columns flanking the gate that are the same net height, but 8" different on the level plane of the surveyor's eye. We are left with only Option C, suc that both sides of the gates align with the top of their respective columns. To complicate matters, we have an arching top rail. The apex of this arch is now shifted in relation to the overall off-set circumference of that arch.To arrive at the angles required in the shop, we turn to our Trigonometric co-sign functions. It can get complicated. The drawings from that project are shown below.
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San Francisco, CA OPTION 'C' To Driveway Gate Style #6-3 |
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OPTION 'C' Fence-lines vary slightly when dealing with sloping grades. There are multiple panels over an extended run, and often with the advantage of being able to modify, or feather the grade. More information and examples of sloped grade and Stepped Panels can be viewed at Regarding Stepped Panels The same options: --Option A): Stepped Panels. To maintain the panel construction as square assembly and step each panel an equal climb up the hill. So if the panels are 5' wide each and the slope is consistent, at every post there is an equal step up. To calculate this equal step, simply string a line from the first post to the last at the desired fence height. Mark where it intersects each post and with a square, pencil a level line across the post. When setting the panels, raise each panel to the line on it's far post and you have equal steps. Option A is approximately 4% above the panel cost Hint:
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Sonoma County, CA![]() |
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One of our earliest fencelines, circa 1995. And one of the more complicated. Ecompassing the entire property, with stepped elevations, sloping grades, sidewalk frontage heights of some 85 panels total. The sort section shown, we have a grade that slopes unevenly to where the angle changes with each panel. If possible, it's always best to feather these grade into a single slope. But when that's not possible, we have this result, which can, from a distance, be like the rolling wells of an Atlantic storm in deep January. |
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Marin County, CA A young Ben at 11 yrs old, posing for a portrait upon completion of this project. |
In-Progress
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On a scientific calculator, the procedure is fairly simple. Our angle of cut on the below example with an 8" drop over 198" is 2.3137º |
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The angle itself is transferred to the cut-off saw. If that cut is .5º off, the extrapolated rise will be off exponentially to the overall rough opening and the result will be a set of gates that are not parallel to the sloping grade. |
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The Designs of Prowell Woodworks are protected by Patents and Patents Pending. |
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