How to set fence along slope? Tips/tricks?

[hazmat]

After many delays - weather, sick dog, other activities, I've actually set 3 posts on my fence project. I have found my new england rocks - they were hiding under the fence line.

Anyway - the ground slopes a bit. I'm getting ready to nail the boards to the posts. I've set the posts plumb. How do I set the height of the boards to follow the slope? I can think up several approaches:

1 - measure 4' at each post or every other (16' boards) - fence could be wavy

2 - use laser level & grade rod + lots of math to determine height at each post - potentially time consuming - should result in straighter fence. How do I account for one side where the high point is in the middle of the fence?

3 - run string at 4' height - will it droop too much?

4 - cobble together a long straight edge - 24'? Use that minimize wavyness.

5- Use laser pointer clamped at desired angle at 4' height.

How do y'all do it? Looking for ways to save time...

 

[KaiB]

Here's how its done in horse country.

Once all your posts are planted, you'll decide how high you want the top of the top board (remember this is going to be an average height). Find a fence you like and measure its height along several points; also measure the space BETWEEN the boards while you're at it.

Pull a string (at that height) from a corner post to a corner post or intermediate post...this can be a long run. Stand back and eyeball the string and have someone tack a small nail on however many posts it takes to get a smooth "flow" to the string (relative to the ground surface, background and topography)...this is an art. The string will rest on these tacks.

Remember that you are working for an average height, but the most important line you are looking for is the flow of the top of the top board. Since you are copying a fence you like, you know that the height and the spacing will give you good results. (i.e. not too much space btw. boards, and not so tall that the bottom board is too far off the ground).

Once you are happy with that, run your top board just (like 1/16") beneath the string, you will be bending and bowing the board as you nail it to conform to the flow of the string.

Once you've got two top boards on, you can go back to the corner and start with the middle board (1/2 of the length of the first top one, the third board down will be the same length as the top one, i.e. stagger your joints)...you already know the space between boards and you will have cut a piece of scrap or a stick at that length...just use that scrap to measure between boards as you nail the middles and bottom.

Oh yeah, the top nail in the top board will be driven at an angle DOWN. Once you have completed your fence, you will be cutting the top of the posts flush with the top board. This cut is made at an angle and you don't want to bugger up your saw on the first nail.

Best of luck...I hope this is understandable, it comes from way too many miles of three/four rail fence.

 

[hazmat]

Thanks - makes alot of sense.

Followup question - do you set the posts at slightly less than 8' on center to account for the geometry of the slope? Ie if two posts are plumb at 8' OC - if the angle of the board is large, the distance the board has to span will be longer than 8' - catch my drift????

 

[KaiB]

That depends entirely on the boards themselves...check with your mill (or whatever source you are using) regarding the length.

Easiest way to go about this is a trailer with a small generator and drop cord to run a skill saw...you will be cutting boards to fit as you go.

Edit to add: See, the only time you will use a tape measure is to measure somebody else's fence...the rest of your work is done by eye. A good fence guy can make a fence roll and flow with the land as tho it grew there.

If you have a short section with a very steep drop, you will not be able to bend the boards enough; here you will use 8' pieces to create a sharp angle (i.e. "I wanted to do that" look) to get off of the drop, and then continue with the flow of the string.

 

[hazmat]

...See, the only time you will use a tape measure is to measure somebody else's fence...the rest of your work is done by eye. A good fence guy can make a fence roll and flow with the land as tho it grew there.
....

You're asking alot for this engineer to put down his tape measure - but I'll try... Hi my name is hazmat & I'm a measuraholic

Actually my first thought was to use the board to set the distance to the next post - no measuring required, But I'd have to know how what angles I wanted to follow the slope. It's the classic chicken & egg problem. I guess I'll set the posts a little short of the board lengths & trim to fit. I'm near the house so I can run the skill saw no problem (though I may have to round up my extension cords from their various hiding spots).

 

[Lloyd_E]

Dido KaiB.

I used a story board pole. Vertical piece of board with measurements for 3 rails. It rested on the ground and marked the heights.

I towed behind garden tractor a trailer with generator, compressor and air nailer (3.5" nails) along with other tools...

I would stand back and check everything as I went along. Top rail gets capped with 1x6 board with 1/2" overhang over posts.

Good luck.

Lloyd

PS: I tarred tops of posts plus added a piece of roofing felt/tar paper before adding cap rail.