# how to lay out radius

Discussion in 'Hardscaping' started by treemover, Jan 19, 2014.

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1. ### alldayrjLawnSite Gold Memberfrom Long island, NYMessages: 3,793

Why not just free form curve it? Or get a little pedal boat.

Or lay it out flipped 180 degrees on land then measure and flip it back to the pond
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2. ### treemoverLawnSite Senior Memberfrom lost in the trees, ksMessages: 422

Architect wants radius, I don't think it could be done free hand. If I set it up on land, I still need center point for reference? Correct? The wall will be about a 100' radius
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3. ### 1idejimLawnSite FanaticMale, from State of JeffersonMessages: 11,316

You do it on paper I will post the method after I finish wh I'm doing
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4. ### PaperCutterLawnSite Bronze Memberfrom Northern VAMessages: 1,996

Depends how detailed and accurate the drawings are. If we can't get a center point (it's inside a house or down a cliff) we do this:
- on the drawing (in CAD) break the arc into segments
- select fixed points (house corner, tree, etc) and label them A,B,C, etc
- figure out the dimension from TWO of the fixed points to the point on the arc, so A= 57'-6", B= 43'-2" for example and note it on the drawing
- print the drawing with the annotations and lay it out in the field.

You won't get the radius perfect, but you'll be able to get pretty close. Tell the architect that if he sticks the radius point in an impossible location, he gets what he gets. The first time I ever put the radius point for a wall in the house, my boss told me I had to figure out how to lay it out. Those things stick with you

5. ### PaperCutterLawnSite Bronze Memberfrom Northern VAMessages: 1,996

oh and obviously you can do it on the plan with a scale as well, just won't be as accurate as popping the points in CAD

6. ### 1idejimLawnSite FanaticMale, from State of JeffersonMessages: 11,316

It's not that hard to do and accurate as the person doing the layout. I'll post the steps in a bit.
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7. ### 1idejimLawnSite FanaticMale, from State of JeffersonMessages: 11,316

Ok. Two pretty simple ways to do this accurately.

One is for small radii. Does not apply you.

The other is for large radii. This applies.
Draw a longitudinal line through the center of the architectural drawing.

Establish a removed parallel line. Say 100 feet.

Establish a transverse line to intersect the centerline. Create a removed parallel line.

A radius point is a negative reference point. What you are doing is creating a positive reference point.

Scale your drawing from the negative and positive RPs.

Measure back from the positive and deduct the appropriate setback for your hubs.

It's a lot simpler than it sounds. I learned this method 40 years ago, a tad before cad.
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8. ### TX EasymoneyLawnSite Platinum Memberfrom Texas-The Hilly partMessages: 4,082

Geometry! Good stuff!

9. ### Armsden&SonLawnSite Silver Memberfrom adirondacks, NYMessages: 2,358

All of that geometry sounds super confusing..... Yes, I could say "roll up your pant legs" but I won't. I think RJ was onto something with the "flipped" or a reverse. Set up a couple pieces of scrap plywood and mark a radii on them within sight of the pond so you know that you are close enough for scale. Then simply jig out that radii from the plywood and flip it over... voila!

10. ### alldayrjLawnSite Gold Memberfrom Long island, NYMessages: 3,793

1idejim explained what i couldnt but yes, you lay out the inverse. I think this is way more work than getting a pedal boat though. And would make for a great company photo op

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