Hey guys... I'm building a 490' long 4' tall french gothic picket fence to contain our dog. I have set just about all of the posts and will be ready to install the 2x4 "runners" and then the pickets. I have a few questions though.

1.) Ideally, I would like every post to be covered by a picket so when looking at the fence... you really won't see a post.

My pickets are 3.75" wide and I will probably space them 2" apart. Would I just measure between each post to see how many pickets I need for that section, and "cheat" the gaps so I come out right?

2. When I start to do the pickets, should I just install a picket at each major elevation change and "string" a string on the top of two opposite pickets to keep the in between pickets all even? These pickets are all precut at 48". I want to follow the ground contour so I don't want to cut the pickets. I won't have to right?

Basically, I'm just a little stumped when it comes to installing the pickets.

You need to make yourself something called a story stick. In this case it would be, assuming posts 8' apart, a stick 8' long minus 3.75" or 92.25". This stick will fit exactly between each picket mounted on a post. Your picket get marked on the stick 5.75" from the end you strat with (3.75" picket plus 2" space) This should come out to be 16 pickets between the ones covering the posts, story stick is reused for each section so make it nice and clear

Assuming that your post are exactly the same distance apart the story stick as Bob suggested should work for you. Assuming also that you install the rails level between the post, I would make the story stick out of some material about 2" wider than the distance above the top rail that I wanted the top of the picket. After laying out the picket spacing, mark the ends left and right. Rip the story stick to the width you want the pickets to extend above the top rail. Tack or clamp the wider story stick to the top rail and the narrower one to the bottom. Keep the left ends together and right ends together.

The top story stick will not only set your picket spacing it will also set you height. The bottom story stick will keep your pickets plumb.

Hint:
After cutting the story stick to length, measure it using a metric tape measure. Measure the picket and desired spacing in metric. You will probably be trying several spacing adjustments in order to come out even. It's a lot easier to do the math in metric than in fractions.

Harold is right but my approach is accrate to within .04" with the 5.75" spacing.

Thanks for the replies guys. Not every post is exactly 8' apart but they are close. Also, on one side of my fence the post spacing is about 7.5' (I wanted equal spacing so I had to go to 7.5') but they are spaced approx. the same distance.

1. What's the easiest way to determine picket spacing if the distance between posts are unequal?

2. I'm going to try and make my runners level but some will not be due to the slope of my property. When I start installing pickets, would it be best to nail the first one to a post and then go a post where the ground slope changes and nail one there? Then run a string from the top of each picket so I know where to install the in-between pickets? This sounds like it would keep the tops of my pickets in a line but I'm unsure if some will be off the ground too much for my liking to contain our dog. Remember, these pickets are precut. Am I on the right track?

1. nail your two pickets over your post and measure the distance between their inside faces. Divide by 5.75 and see how close you come to a full number of pickets.
2. Unless you want the height to also be level you need to allow the runners to follow the terrain. The ground raises and falls, the tops of the pickets will raise and fall so should the runners

On a french gothic fence, do I want the tops of the pickets to raise and fall with the terrain? Will the designs not matching up at the top look nice? Do most fence builders use pre-cut pickets?

Yes, pickets are generally precut. If you do not allow the fence to rise and fall with the terrain it will get to be a shorter fence when you come to a rise. you'd have to custom cut each picket. I think a perfectly horizontal fence on varying terrain would be weird

Ok, got it. I began to install the 2x4 rails today but stopped after the first one. I decided to "toenail" screw the 2x4 rail to the insides of the 4x4 posts. The 2x4s somewhat bow outward and this concerned me. It makes me think my pickets will look like they are arciing out but I'm sure its not that much of a bow. I know wood is an imperfect material but this just irks me. I didn't realize this step would be so time consuming. I have to measure between the two posts, cut the rail to length, get it level ( where applicable) and toenail screw it into the post. Is this the preferred method?

My original plan was to nail a picket directly to each post and continue along the rail BUT when the rail bows outward it makes it a bit more difficult to make sure the rail is on the same plane as the post.