depends whta size panels you are using as to what size posts you should use, but you should allow 2 feet over the height of the panel and the gravel board. Gravel boards are normally 6 inches high, although you can use more than one if needs be. remeber you are limited to 6 feet 6 inches for a garden fence under planning etc.
Get the stuff from a decent fencing supplier.
clear the old fence away and any obstructions.
buy a post level (£3) and a fencing spade/trenching spade (£15-£20)
the first post against the house will normally be fixed to the wall rather than in a hole due to the foundations. run a string line from this post to the post at the opposite end. you now have a straight line for the fence to follow. As long as the posts are plumb and just touching the string line you will have a straight fence.!
now place the first gravel board in position and level the soil underneath it s it sits level. you now know where the next post will be so dig the hole there at the end of the board. It will get easier as you go, but dig the hole 2 feet. mark the post with a pencil mark, working down from the top. the mark needs to be the distance down the post of the height of the panel and the height of the gravel board. eg 6feet 6 inches. drop the post in the hole. if the pencil mark is at the top of the hole then you are spot on. in the hole too deep, above the hole then too shallow. the hole should be straight down and bell out at the bottom, and the smaller the better.place the post in th hole with the post level on and get it plumb. make sure its just touching the string line and not pushing it out of line. If it does this and its plumb then you are spot on. you may need to alter the hole to suit slightly.
Put the gravel board in position and then the fence panel, so they both sit in the slot of the wall plate you started with.Now pour in some post mix (hanson stuff is best, easy and less messy) but not too much. you want to get the post standing up, but so you can still move it. Bring the post up level so the gravel board and panel are in the slot, th posts plumb and its spot on with the string line (easier with two people, but you can do it on your own with practice!) pour in the rest of the postmix. Now ram it firm with a metal rod or some timber. Now add the water.
Now just repeat all the way down. you may have to cut the last panel and gravel board to fit. The gravel board will cut easily with an angle grinder.
if the garden slopes start at the high end first.
hope it all makes sense! if not look here, theyve got pictures as well!
http://www.avsfencing.co.uk/product...asp?RETTRA=RET&ID=1&SUBID=4&PRODID=42&USERID=
