ZIPPER STAIRS - a New Type of Stairway Using Nylon-Cement

About: I'm a refugee from Los Angeles, living in backwoods Puerto Rico for about 35 years now and loving it. I built my own home from discarded nylon fishnet and cement.

Stairways have been a part of architecture for thousands of years. Zipper Stairs are a new type of stairway.

My inspiration for zipper stairs came from a visit to Mesa Verde National Park, where the Anasazi Indians had carved hand and foot holes in the rocks to climb up to their cliff dwellings. Their holes were small, and were probably chipped out with much difficulty using crude tools. If one were to expand the holes until they touched each other, something they did not do, the end result would be similar to zipper stairs.

Stairs are used to climb an inclined plane. They have a vertical face and a horizontal face. As the inclined plane gets steeper, the vertical face gets higher and the horizontal face gets narrower. The higher the step, the harder it is on ones knees. As the horizontal face gets narrower, ones foot eventually doesnt fit on the step, unless the foot is placed sideways, which is awkward. Going up and down traditional steps becomes more dangerous the steeper they get.

Using zipper stairs on the same slope, there are more steps, so the vertical rise for each one is shorter and more comfortable for ones knees. Also, by turning the steps at an angle to each other, one gets the diagonal distance of the rectangle for ones foot, which is longer than the short distance provided by normal stairs. Zipper stairs are more comfortable and safer for steep slopes than are traditional stairs.

This instructable will show some of the zipper stairs I have made over the years and follow one stairway project from beginning to end.

Step 1: The Project Begins

This is the work site at the beginning of the project. There are two basic problems; the stairway, and water drainage, which has gouged out a ravine next to where the stairs will go. This instructable covers only the stairway.

The slope is steep, a perfect place to use zipper stairs.

After the stairs are carved into the dirt, and the ravine is filled, everything will be covered by a layer of nylon-cement. Nylon-cement is a combination of nylon fishnet and cement, a material I developed many years ago, and have built my whole house out of. You can see one project I have done with it on my road repair instructable,

Think of nylon-cement as you would a layer of fiberglass. The fishnet replaces the glass cloth, and the cement replaces the resin.

Step 2: The Inclined Plane

Stairs are basically flat areas on an inclined plane where you can put your feet. On a steep plane, such as this one, zipper stairs are safer and much more comfortable to use than are traditional stairs.

With traditional stairs, as the slope increases, each step becomes more difficult. Higher steps are harder to make for people with weak knees and hips. Traditional stairs also have narrow steps on steep slopes, with no way but sideways to place your foot.

With zipper stairs there tend to be more steps that work into the pattern, and each step has a lower and more comfortable height. Since sipper stairs are set at an angle there is more distance on each step for one to place the foot.

I think that zipper stairs are probably safer for small children to climb up and down than are traditional stairs. With traditional stairs, a body starts rolling and keeps rolling to the bottom. With zipper stairs, a child would tend to bounce from side to side, and soon come to a stop.

On lower slopes, there is nothing wrong with traditional stairs. As the slope increases, however, the traditional stairs should morf into zipper stairs. Zipper stairs are not always at 90 degree angles to one another. There is an angle to fit just about any situation.

Step 3: Carving the Steps

This is a sculpture moment. Always keep water runoff in mind.

The basic tools I used to carve the hillside were a hoe and a machete. I am fortunate to not have granite here, as far as carving goes. We have a lot of clay, and a semi-hard rock called "tosca", which is like hard clay.

I started at the top. From above, you can look down and imagine at what depth the next step will be. A long-handled hoe will let you stand where you are and carve out the step below it. Then you can stand on the new step and carve out the following one. It is fairly safe to carve on a slope this way, and most of the excavation dirt slides down the inclined plane to the bottom.

After roughing out the design, you can tweak it with the machete, sharpening up the edges of the steps for example.

Step 4: Splatter Coat

The splatter coat is a quick step that locks down loose particles of dirt and make plastering easier.

I usually do this step in the late afternoon, so the cement has the cool and moist night time for hardening up well. If cement dries out before it cures, it hardens up less. Thin layers dry out faster, so I prefer to work after the heat of the day.

When doing the splatter coat, wear old clothes, eye protection glasses, and a hat if you get really messy. Doing the stairs, it was mostly my feet and lower legs that got splattered.

Mix a bucket of water and cement, without sand, and stir it up. You get a slurry that we call "lechada." The mix consistency is like watery paint. Use a big brush, the kind cement workers use, to fling the lechada.

To test the consistency, fling some on the ground. If you can see the color of the ground showing through, the mix is too thin. Add more cement. If the mix becomes too thick, it becomes harder to fling. Anything more than the minimum needed to cover the earth is probably wasting cement.

The splatter coat usually hardens up enough overnight that by the next afternoon one can walk on it and continue with the next step.

Step 5: The First Coat

Ideally you want the fishnet to be in the middle of the layer of cement, not at the bottom. Plaster the steps once, put down the netting and then plaster it again. Use the normal 3 to 1 mix of sand and cement.

If it was more convenient to work on the sides of the project, I would normally put down the fishnet and the finish coat right away, while the bottom layer is still fresh. This difficult terrain calls for a two-step process, putting down the first layer and letting it harden so that one can then walk on it to do the net and finish layer. If the first layer of cement stays clean, the second layer should adhere to it well.

Sweep the steps after the cement hardens up a little bit, to knock off any rough spots that might make the following steps more difficult.

Step 6: Laying Down the Fishnet

By the following afternoon, you should be able to walk on the splatter coat layer without damaging it too much. Lay down the fishnet. Because of all the angle changes, the net will probably have to be cut some to make it conform to the shape. Fishnet is very flexible, however, and can stretch to fit without cutting a lot of times. To cut it, I use a sharp machete.

I made the biggest recycling score of my life when I got my fishnet free as waste from the tuna fishing industry. This is the last of my supply, however, and no more is available locally. New fishnet is not cheap. Some chemist should figure out a way to recycle our waste plastic into a mesh material for plastering.

Step 7: Top Coat

The top coat of cement can receive a wide variety of textures. Steps can be slippery when wet, or covered with algae. To help improve traction, create an appropriate texture. One of my favorite techniques is to stipple the surface with the strings of a floor mop. One can also brush the surface with a broom head to create parallel lines, or stipple to make rough peaks. Any tool leaves a mark.

If your cement mix is too thick to penetrate the fishnet and adhere to the bottom coat, water down some of it and rub it in with your gloved hand. Put the thicker mix on top of that and create your final texture. For these stairs, I swept the surface with a broom to create the final texture.

When it hardens up enough to spray with water, try to keep it damp during the heat of the day. You should be able to walk on the project in a day or so.

Step 8: Other Examples of Zipper Stairs - 1

This is the first and only example of a zipper stair in the air that I have ever done. Because of a shortage of fishnet, I did most of this project the traditional way, with ferro-cement. Instead of fishnet, I used three layers of chicken wire to hold the cement. It works, but nylon-cement is so much more user-friendly I hated to go back to the old technology.

Step 9: Other Examples - 2

These photos show some of the zipper stairs I made back in the 1980's. Trying for the minimum thickness, I only did the splash coat and top coat. The stairs and walkways held up pretty well considering how thin the material was, about 1/4 inch thick. Made thicker by having a first coat underneath the nylon, I'm sure they would have held up better. Erosion was controlled, at least. We get a lot of rain here and dirt steps don't last long.

As you can see, cracks do form, and weeds do grow in the cracks. A string trimmer takes care of most of the weeding.

People tend to step on the edge of steps, instead of in the middle of the step. The steps tend to get damaged on the front face of them because of that. I make the front faces thicker now when I make steps. Also, tree roots can grow under the thin layer of cement and break the step as the root grows. If roots rot away under the cement, they cause hollow areas, which can cause the nylon-cement to break and sink in under the weight of a person.



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    71 Discussions


    11 months ago on Introduction

    I just deconstructed a mattress and found the wired springs covered by a plastic mesh. I thought at first it was also wire, it looks like hardware cloth.


    4 years ago on Step 9

    I really want to try making some of these. I have 3 acres down the hill.

    1 reply

    Reply 4 years ago on Step 9

    Good luck. The key is getting the fishnet. Let me know if you actually do the project. I never get to see any physical evidence that my teaching is being used, which is the main goal of doing it in the first place.


    5 years ago on Introduction

    Fantastic project! Favorite and collected! I know from my experience with ropes that nylon stretches, especially when wetted. Can you get netting made of some other material that is more static to embed in the concrete? I think that might help extend the life of the concrete by reducing the amount of fracturing once a crack starts to form.

    1 reply

    Reply 5 years ago on Introduction

    Nylon has better longevity than many plastics. I don't know what else might work as well. What I would like to see is our plastic trash turned into some sort of plasterable plastic mesh.


    5 years ago on Step 9

    Here is where you can get more fishnets.


    6 years ago on Introduction

    Insane Genius { my compliments to you sir !} zipper stairs rock my son is building a bag house he's gonna love these stairs

    Thanks for a great idea and an outstanding Ible !

    1 reply

    Reply 6 years ago on Introduction

    Thanks. Send a photo if your son uses the idea, It's nice to see people actually using the info.


    6 years ago on Step 8

    Great solution to a steep incline.

    On such a steep stairs, I'd like to have a rail or rope to grab. It's often best to descend while facing the slope. Toes are better on a narrow step than heels.

    You're a refugee from LA. Did you work on the original "planet of the apes"?

    1 reply

    Reply 6 years ago on Step 8

    I have never done really steep zipper stairs. When the slope is low, there is no need to angle the steps. The steeper the slope, the more angle. I think you could probably work them into a really steep slope making it more like a narrow slot with steps on either side, narrow in themselves but since you would be stepping more side-to-side, the foot should still fit comfortably. It probably would be fairly comfortable both ascending and descending.

    Nope, I never worked on the original Planet of the Apes.


    6 years ago on Step 8

    On such a steep stairs, I'd like to have a rail or rope to grab. It's often best to descend while facing the slope. Toes are better on a narrow step than heels.


    Reply 8 years ago on Introduction

    The problem with these, and with Jefferson stairs (which are similar, but not the same as these) is: they are for young, able people. Older folks tend to take stairs one-at-a-time, or a couple and then rest. With these, and Jefferson stairs, there is no place to put two feet on the same step (so one remains "level"). As with Jefferson stairs, once you begin, you go till you hit the top. You can stop, but then you're straddling steps with one foot at one level, and one at another. As with Jefferson stairs, these won't pass code in most places. I think they are very cool and took some obvious intelligence to design, but I dislike designs that exclude certain folks. Little ones tend to take stairs like older folks, one-at-a-time, so they are excluded, as are older folks. Also excluded are moms leading up little ones. Perhaps if each tread were lengthened a person could rest on one step easily, which would make it more accessible for little guys and older folks, and parents with kids in tow.

    Concerning your comments on "traditional stairs", it's all in the design. If someone tries to build a stair with a very short overall run, the only way to accomplish that is to increase the individual rise of each tread or decrease the tread length. However, there are codes governing this and they stipulate that the rise and run of each tread falls within an (easily scalable) specific height or length, which (by default) limits the slope of any stair. No stair built today would ever pass code where (as you say) "ones foot eventually doesnt fit on the step, unless the foot is placed sideways, which is awkward." Treads must be a certain length (length here is measured from one rise to another). The IRC stipulates the following codes: "10” minimum tread length, measured from nose to nose of adjacent treads, is required. IRC RR 314.2 16. Risers shall not measure more than 7,3/4”. IRC RR314.2 17. A maximum 3/8” differential is permitted from the largest to the smallest tread, or the largest to the smallest riser. IRC RR314.2" These are easily climbed by the young and old alike.

    Your design seems as it is meant (primarily) to solve the problem of maximizing space. By placing more treads (and hence individual rises) in a smaller space (a shorter overall run) it maximizes space, and it is safer than someone building something out of code with unsafe rises or tread lengths - no doubt about that. I just don't see why either need be an option. Even in your example here, you have more room for a longer run, why not just build a standard stair with a safe rise and run? Yours are certainly safer than a steep rise or shallow run, but why do either? It's cool, but it limits accessibility and trades safety for a high "neato" factor. I suppose if someone were building it for themselves, and had limited depth for a regular run of stairs, this might be fun, but what about when they get older? One could just as easily build a circular design, that handily accommodates a limited depth.


    Reply 6 years ago on Introduction

    I am one of those people who take normal stairs one step at a time and I am quite excited about this design. It looks like it would be much easier on my wrecked knee and ankle.

    As for passing code . . . .


    Reply 6 years ago on Introduction

    Okay. Instructables seemed to have cut off my libertarian rant. Oh well. Long story short - too much government; too little innovation.


    Most visitors, including older ones, comment about how much more comfortable these stairs are than standard ones would be, given the same slope.

    These particular steps have plenty of room for two feet to stand and rest on them.

    You should see kids climbing or going down them. They take a step, turn, take a step, turn, take a step, etc. It all looks very safe and manageable to me. Plus, with the shorter rise for each step, that makes it easier for kids, and old people.

    In matters of safety, with standard steps I imagine a kid going thumpety, thumpety, thumpety all the way down. With zipper stairs, I would imagine a zig-zag trajectory, with probably a thumpety, thumpety, stop. Fortunately, no children have ever fallen on the stairs to test this theory.

    As far as building codes go, I'm sure they are there for a good purpose. Stairs have been traditionally made with other building techniques, however, and those are the techniques the codes have been built around. These are sculpted stairs, and what they do they do well, if I do say so myself.

    Circular design stairs have a high "neato" factor, also. I find triangular stairs dangerous in comparison to these basically rectangular ones. The "neato" factor in itself is not bad.

    You are right, they are 'neato" and perhaps I'd eat my words if I saw them in action. From the photos though, it doesn't look as if it would be easy to stand on a single step, and then move on. as you say, doing so causes a change in "trajectory", which (in my humble opinion) is dangerous.

    I'm glad to hear no child has ever fallen, particularly if a lot of kids have climbed them.

    I can assure you that the stair codes are constantly being revisited, challenged and (very rarely) changed based upon many, many local and national meetings. I, myself have attended and presented at local meetings for changes to the codes. The inspectors and officials that are responsible for setting and enforcing the codes are well aware of the different designs (including Jefferson stairs) and have rejected these as unsafe for various reasons. I was actually at a code meeting at the local level in a city (suburb) that was using codes to hinder construction. They were making codes so restrictive that it took either too much time or too much money to make building feasible. The code in question was "continuous rail". Most cities interpret it to mean that the handrail must run from the first rise to the last rise with no breaks in the rail, unless there is a change in direction (at the turn) whereupon a newel (post) may be placed. Some cities don't allow a newel (post) and the rail must be continuous. However, this city interpreted "breaks" to mean that the handrail couldn't have *any* cuts in it. For example, say there was a small opening rake and then a landing with a 90 degree change in direction, which continues on for another rake run, the rail could not be cut and pieced together to create a continuous rail. They interpreted it to mean the rail had to be uncut, which meant it had to be bent rail, which was impossible in many situations (which is what they wanted). So, homebuilders began to design only stairs that were circular or straight with changes that could be covered with bent rail (a real feat in some cases, I don't mind telling you).

    At any rate, at this meeting a landscaper presented his case for steps up a walkway that were similar (in some ways) to your design, although his were much less elegant. He presented, they laughed, we moved on. They've seen other designs and rejected them. I presented at the same meeting with a representative from one of the spiral stair companies (the kind that sell as "kits") because of a problem they were having concerning the way the two types of handrail met at the top. The spiral stairs were built with either iron, or wooden handrail that was not available from any stair part supplier. The inspectors were red-tagging it because there was a difference in the profile of the handrail, which they interpreted as a "break" in the rail. We presented a compromise which they took under advisement, which must have worked because the inspectors quit red tagging us. Point being, they know the different designs that are out there, and they reject them as "unsafe".

    I'll tell you why your stairs would be rejected, because only one person may terminate at a time. This is a big no-no in the construction of stairs, particularly a commercial installation (which your stairs have been built for, unless I'm mistaken). Commercial codes are more restrictive than residential codes, but one of the cardinal rules there is that case must be wide enough, and the treads designed such that they accommodate more than one person. This is important, for example, in case of a fire. You can't have one incapacitated person clogging up the entire egress for everyone else. There must be room to tend to that person, while the others continue to exit. The other reason why they would be rejected is for the reason I already mentioned, a person must be able to take one tread at a time and be able to stop, with both feel on the same tread (facing forward) in any installation (even a spiral one). For folks to do that on your design, they would have to make a (rather marked) change in direction, basically turning 45 degrees each time. That is simply unsafe.

    What you say is true, smaller rises are easier for older folks to climb, but that is just one part of the puzzle to making a safe, scalable stair. Smaller rises are easily accomplished in a traditional stair, with standard treads, as long as there is enough room for the overall run. You see these types in some cities, where there are many long, wide treads and small (less than 5") rises built in concrete. There is one in a city center near me with a fountain in the middle.

    I agree with you, the neato factor is important - not more important that safety and accessability - and sholud be considered any time anything is designed for humans to use. I built stairs for 20 years and constructed some pretty neato designs myself, though none as radical as yours. I put up some of the more traditional ones on my Flickr page here:

    In the future I'll put up ones that were more unconventional, including a stair I did for a man that was WAY into fish, which incorporated saltwater tanks in the walls, custom, metal balusters shaped like dolphins and a huge rail that undulated like waves. The problem is, in many of the more custom homes, the homeowners either make you sign a contract prohibiting you "sharing" the design, or posting pics. Sometimes it helps waiting a few years for them to decide no one is going to heist "their" (my) design.

    The most neato thing you've ever done is add testicles to a water spigot. Hands down. It took real balls to do that!

    I'm honored to be talking to a stair expert.

    Unfortunately, your photo link did not work for me. I would like to see your unusual designs (especially the ones you can't show me.)

    Back to the zipper stairs. You can put two feet on one stair while facing forward. If necessary, you just put one foot slightly in front of the other one. That way, both feet get the full diagonal distance of the stair.

    If one person stands on one stair, that leaves the other lane open for passing. The person in a hurry just has to take a 2-step step. I have done that sometimes, playing with younger upstarts who want to race me. I catch up and pass them by using only the steps in one lane. (I'm in pretty good physical shape to begin with.)

    The zipper stair concept is flexible. At a low slope, there is no need to use them. Standard stairs are fine. As the slope increases, the angle at which the stairs meet changes, getting more and more acute. Although I have never had to go beyond 90 degrees, theoretically you could climb an almost vertical crack in a wall, with long narrow steps on either side of you.

    Hand railings are a problem I have not dealt with much yet. In zipper-like stairs on top of my house I once put an overhead hand rail down the center of the stairway, attached to the overhead trellis. It is for my use only, not for visitors.

    Zipper stairs are easy to carve into the dirt and line with nylon-cement. I imagine they would be a lot more difficult as a woodworking project. I have done an above-ground set of ferro-cement zipper stairs at my guesthouse, however (photo attached). The geometry of the rod work is a bit tricky, but fun.

    My construction is not commercial. It is part of my home and private guesthouse.

    GH 09-12-21 (11) -sm.JPGGH 09-12-21 (12) - sm.JPG