When building a ladder-back rustic chair you must first look at it as a functional piece of funiture. After this, you can think about its artistic appeal, which develops from your arrangement of natural materials which have varying degrees of texture, colour, and natural beauty.
First and foremost, you must think about the chairs ability to handle the load it will carry, and the strength of material you will have to use.

The ladder-back design gets its strength from using one continuous piece of wood which forms the back legs and the back rest of the chair. This material must be prepared properly to ensure it maintains its strength.

I have suggested certain materials for you to use for the following process in my article on 'How to Prepare Wood'. Keep in mind that when you are using softwood, the diameter of your material must be larger than if you are using hard wood, to insure its strength.
The ladder-back is my preferred design in chairs because of it's strength and the flexiblity in choices of seats and back rests that can be used. Its strength comes from two parallel pieces which are connected by cross-pieces.

The parallel pieces form the back legs and support the back rest, while the connecting cross-pieces hold the back of the seat and support and help form the back rest itself. When constructed this chair resembles a ladder. Hence the name, ladder-back chair.
The first piece to be assembled is the ladder. You must first decide on the overall height of your chair. I find that 38 inches is a good overall height.

You must then decide on the type of seat and back that will be used on your chair. If you are going to use a solid piece of wood for the seat, then you must decide on what type.

If you are using softwood, I would suggest using at least a 1 1/4 inch thick piece of wood. If you are using hard wood, I would suggest its thickness to be 3/4 inch. If you are using wood to form the back rest, I would suggest its thickness to be 3/4 inch in softwood or 1/2 inch in hardwood.
The backrest can also be made using rungs, the vertical crosspieces, made of rustic materials. It can also be meshed, much like a snowshoe, using string or mesh. There are many different types of materials, or combinations of materials, which can be used to form the seat and backrest of the chair.
Once you have selected the material for the chair, cut two pieces to form the uprights of the ladder, at the proper length. Draw a straight line on each upright using a straight edge from one end to the other, at the center.

Place the pieces parallel to each other, on a flat surface, with one end up against a stop. This can be achieved by placing the pieces on the floor with one end against the wall.

Using a two foot square area, place the first piece at a 90 degree angle to the stop and go by the lines drawn on the piece earlier.

The second piece must be placed parallel to the first at whatever width you wish the back of your chair to be. I would suggest 14 inches and always use the straight lines drawn earlier to make your measurements.
You must now decide where to place the diagonal pieces in your ladder to complete this section of your chair. A piece must be placed at the bottom about four inches from the stop. Place a mark on the straight line, on both uprights, at this distance from the stop.

Then place a mark on the inside of each upright, in line with the first mark, and in the center of the inside of the upright. Next, measure the distance from each mark on the straight line of the upright. Cut a piece of material at this length to use as the bottom cross piece and be sure to mark it so that its place may be identified during assembly.

The next diagonal will support the seat. I would suggest placing the seat at 19 inches, although it is best to determine whatever height is comfortable for you to use. To figure out where to place this piece you must descide what type of seat you will be using.

When using a wooden seat you must take into consideration the thickness of the seat, as well as the diameter of the hole drilled into the upright to hold the diagonal supporting the seat.

For example, if the seat will be 1 1/4inches thick, then this must be taken off the height you established for the seat earlier. If the hole in the upright will be 1 inch, then half that (1/2inch) must also be taken from the overall height.

If you are using 19 inches for your overall seat height, then using this example, the height of the second diagonal will be 17 1/4 inches. If you are going to lash the seat, like a snowshoe is built, or using a cloth like material, then you must consider the size of the hole to be drilled into the upright for the diagonal.

In the example given earlier, only the one inch hole in the upright must be considered. Therefore, the height of this mark will be 18 1/2 inches from the stop. Once the height has been established, measure up this distance from the stop and place a mark on the straight line drawn on the uprights.

Another mark must be placed on the inside of the two uprights in line with those placed on the stright lines. The distance between the marks on the striaght line must be measured and a piece cut too this length to act as the diagnal,supporting the seat.
The two diagnals which will support the back rest are the next to be placed in the ladder.The diagnal at the bottom of the back rest must be placed high enough too allow yourself room to wook on the seat and back rest.
I usually place it at 3 1/2 inchs from the seat and add 1/2 inch for a1inch hole in the upright which leave it 4inchs from the seat or 23inchs from the stop.Using the same procedure as just discribed mark the uprights for the bottom of the backrest,measure, and cut the diagnal.
The diagnal at the top of the back rest can be place 3inch from the the top off the upright to the center.Too achomplish this repeat the steps for marking, measuring, and cutting you used for the bottom diagnal at the top.
With the uprights and diagnals cut too length and marked it is time too make the tensions and drill the corsponding morisons.A low RPM drill must be used too make the tension and can also be use too drill the hole, or a drillpress can be used but only to make the hole
When drilling the morisions, drill on the mark made on the inside of the uprights so that the botttom of the hole lines up with striaght line on the upright. For the best results use a drillpress with a u-shaped craddle too support the piece will drilling.
To make the tennions I use a tennions cutter which attachs to a low RPM drill.This device will leave an accourate and clean cut when making the tennions at the end of the diagnals.
The size off the tennions and morsions will depend on the strength off the wood being used in your chair.As a general rule I make them 1 inch if I am using soft woods and 3/4 inch if I am using hardwoods.
If a wooden seat or backrest will be used for your chair, then the diagnals which support them must be flatenned on one side, after the tennions have been cut.Too achieve this, a jointer will give you the best results, althought a drawknife,chiesel, or axe will do the job. You must be carefull not too cut into the tennions which ever method you use.
Wonce all the pieces for the ladder fave been properly prepared fit them together dry(without glue). You may have to recut some of the diagnals.
The ladder can be glued together wonce it has been dry fitted to your satification.Use a good quilty wood glue and clamps or straps too hold the pieces together for the required dring time off the glue.
If you intend to use a wooden seat do not glue the diagnal which supports the seat since it must be ajusted latter. When using a wooden backrest a board must be used too insure the flat sections off the diagnals supporting it are lined up properly, to do this use clamps and be sure not to glue this board.
If you wish to use vertical upright between the horizontals then they must be added at this stage of building. In the case off this design the horizontal diagnals remain round.
After dry fitting the uprights and the horiziontal diagnals place a straight line on the inside off each off the two diagnals which form the backrest. Place marks along this line where you intend to place the vertical rungs off the backrest.
Measure the distance between the corasponding mark too about the middle of each horizontal diagnal. After cutting the vertical rungs to length make the nessary morissions and tennions, then dry fit the ladder with the vertical rungs.
Wonce it has been dry fit too your satification dismantal the ladder carefull, be sure to number each morrision with each related tennion too insure it goes back together the same way. This numbering system would also apply too the wooden backrest and at all times when projects are dismantaled after dry fitting. The same prcedure is used when gluing this chair together and also the horizontal supporting the seat must not be glued if you are using a wooden seat.