Building Free-Standing Stairs

In February 2019, our 80’ long suspension bridge took a big hit due to an ice-snow storm. An old maple tree above it snapped and came straight for one of the support posts, taking a few trees along with it. The post snapped about in half and the bridge went sideways. The sad event is chronicled here.

The good news was that all the cables and the cable-locking system components were not affected at all. The eye bolt on the broken post that holds the main cable was bent and that was about it for damage other than the post! After a whole lot of cleaning up of debris, my neighbor and I, with some help from the photographer, installed a new (used) power pole and lifted the bridge back up.

The free-standing stairs on either side of the bridge were constructed of recycled materials way back in 2005 and the decking was not meant to be permanent either, so this disaster gave us an important reminder that we needed to do some updating on our bridge.

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The decking is ready to install later in the summer and meanwhile I screwed down planks to keep the bridge safe to walk on for now. The free-standing stairs became more of a priority because they were already falling apart before the storm.

Here are some instructions that assume you have some carpentry experience. Feel free to email me if you don’t understand something.

Pieces Needed (lengths depending on the rise and run of your stairs):
2 – 4×12 pressure-treated beams (stringers)
4 – 2×4 pressure-treated lumber
5 – 2×12 pressure-treated lumber for the steps

RiseTread

Two rules of thumb for free-standing stairs:
1. One riser plus one tread = approx. 18 inches
2. Two treads plus one riser = approx. 28-29 inches
There are other rules of thumb, such as when dealing with landscaping and low slope terrain, but these two rules will handle almost any building situation.

 

Stairs

When you design your free-standing stairs, you begin with “What is my total rise?” Take that total rise and see how a 7” rise and an 11” run will work (which is the recommended ratio). Divide 7 into your total rise. That will indicate the number of steps (including the landing). My stairs have a 7” riser and 11” tread measured nose-to-nose with a 35″ total rise with a 32-1/2° incline. What if you have a total rise not divisible evenly by 7? Perhaps it’s 34”. 34 ÷ 7 = 4.85. Round 4.85 up to 5. 34 ÷ 5 = 6.8 or 6-25/32 or 6-13/16. With that number, you would just leave the tread at 11”.

If it turns out that you have a total rise that is more evenly divisible by the next higher riser, say 8”, go with that. For example, a 32” rise would give you four 8” steps with a 10” tread (remember the rule of thumb).

Not to belabor this, but you could have a rise of 7-1/2” if it divided into your total rise evenly. And then the tread would be… (you figure it out using the rule of thumb*).

The other question is, “How much space in front of my stairs do I have to work with?” If you are in tight quarters and the rise would end up being more than is comfortable for walking, then you’ll make a landing and turn the stairs at an angle to gain more run that gets you to your final landing. You can also build an alternating-tread ladder stair. I built one and will blog about it soon but I think there are instructions for it online.

Process: The layout is carefully marked on the two 4×12 pressure treated beams (stringers), and cut. The steps will fit into slots in the beams and screwed from the sides. My slots are 3/4” deep.

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To carve a slot, I use my skilsaw to cut multiple passes, then chisel out. It’s easy to knock out the remaining wood after cutting. The very back where the round blade doesn’t reach needs extra work.

2

Pre-drill the holes for the screws.

Each beam is attached to a vertical 2×4 pressure-treated piece, based upon your total rise. Also, each beam has a horizontal pressure-treated piece based on your total run. I used a wood preservative in the slots to give them extra protection from rot.

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For the near-stairs, I screwed in the steps and hauled the assembly to the bridge site.

9

For the far-stairs, I assembled the components on-site.

* 10-1/2”

Thanks for stopping by. Be sure to check out our book about building this strong bridge. Here is the link:

Building a Small Cable Suspension Bridge with the Cable Locking System

Images, diagrams, and text copyright 2013-2020 by Marvin Denmark unless otherwise noted. Please do not copy and post my content anywhere without my permission. Thank you.

Lichen and Moss, Green but not always Mean

What’s that green stuff? People, including house inspectors, don’t like to see anything green on house siding, decking or roofing. As we learned last year, even the FHA has a hissy fit over the color green, and will demand eradication, cleaning and painting, even if the green stuff is not damaging anything.
lichen-HouseIn our case, our 35-year-old house’s cedar siding had a few areas with tiny little hairy lichens happily blowing in the breeze along with a few patches of algae. There were no signs of damage after three and a half decades.

But even though the FHA regulations clearly stated that cedar siding was exempt from the rules regarding wood siding, we still had to provide the funds to pressure-wash and stain the house before we could sell it.

The deed was done and the sale went through. We just hope they were careful, as pressure-washing can be much harder on cedar siding than any amount of lichen.

Lichens are a “plantlike” hybrid of fungus and algae that grow all over the world. The self-sufficient stuff can flourish anywhere as long as it gets a little bit of moisture on occasion. It doesn’t retain much of that moisture and it doesn’t take root, making it easy to remove and control. Lichens don’t bother trees and shrubs unless their growth blocks light to the leaves. But people freak out about lichens anyway.

Moss, on the other hand, is a real plant, and even though anything green growing on a roof is often called moss, this is the real bad guy. Mosses are generally found in shady, wet places. That’s why we see mosses in the woods, especially in wetter climates such as western Oregon. We also see them on roofs, decks, and other structures where debris and water can collect and provide a foothold for it to grow and spread. Mosses break down whatever they attach to, providing a surface cover and moist soil environment for other plants. It’s great stuff, but not if it’s chomping on your house or your bridge!
MossyBridge

This is one of our small trail bridges, in sad need of a good cleaning. It is obviously located deep in the woods, and is victim to leaves, fir needles, vines, sticks, and of course, moss.

My spousal unit came up with an easy way to clean the leaves and other debris that collect on all our bridges. A long-handled squeegee for washing windows makes quick work of the task. But alas, this bridge decking has been adopted by moss mostly because of our neglect. For now, we plan to carefully chip the rest of the green stuff away with a knife, as the decking appears to be secure enough for another year or two anyway.

The under-structure is pressure-treated and so far oblivious to the spongy, green, wood sucking plant. Lichen would have been welcome!

MossyBridge2MossyBridge3

 

 

 

 

 

 

 

 

Thanks for stopping by! Be sure to check out our bridge book. It includes some cool ideas that apply to other projects, like how to put a really tall post into a deep hole when you aren’t that tall. Amazon has the book on sale for about $13.00 right now. Here is the link: Building a Small Cable Suspension Bridge with the Cable Locking System
Images, diagrams, and text copyright 2015 by Marvin Denmark unless otherwise noted. Please do not copy and post my content anywhere without my permission. Thank you.

A Conflict between treated wood and metal parts

Pressure treated wood is a popular product for outdoor construction, i.e. bridges and decks. The chemicals (including chromated copper arsenate – CCA) that were used to treat wood in the U.S. and perhaps other countries were revised in recent years to remove at least some of the potentially harmful properties. The new formulations did help with the environmental risks, but they caused new problems for construction. When wood treated with the new chemicals was exposed to metal parts, the metal tended to corrode, even moreso in water contact environments, in only a few years. The pressure treatments I’m talking about are alkaline copper quaternary (ACQ) and copper azole (CA), which are both active corrosion materials.

So, the experts started recommending using galvanized steel or stainless steel for any metal parts, i.e. connector plates, joist hangars, and fasteners, that came into contact with pressure treated wood. Galvanized steel or stainless steel would withstand the chemicals for a while. So at least, the corrosion rate would be slowed down.

In my experience in remodeling, and specifically rebuilding decks, I found that some structures that had used ACQ or CA showed exactly how corrosive the treatments were. Galvanized steel joist hangers were nearly destroyed in only a few years.

I had this concern in mind when I built my suspension bridge. The cable locking system parts are hot-dip galvanized steel. But I also added a padding-wrap made of a bituminous material to add more protection between them and the painted (another layer of protection) pressure-treated beams that supported the bridge. Maybe I over-did it a little, but I like the things that I build to outlive me.

In building our new house, I ran into the problem again. In Oregon (and I’m guessing other states in the U.S.) it is required to install foundation anchor bolts in the stem wall foundation. These are to tie the house to the foundation. The bolts go through the pressure treated wooden plates and are secured with nuts. I had the issue again of metal making contact with pressure treated wood. I used ungalvanized (standard, but oversized to 5/8″ vs 1/2″ bolts) because I’m not convinced simple galvanization is the answer anyway. I opted to protect the bolts with a sleeve that I made from polyethylene tubing (5/8″ interior) material.

Bolt1

The bolt came through the hole in the pressure treated plate…

Bolt2

and then I used a water impervious roofing material tab…

Bolt3

before adding the galvanized steel plate.

Bolt4

At the completion all metal was completely isolated from the treated wood.

Thanks for stopping by! Be sure to check out our bridge book. Amazon has the book on sale for about $12.00 right now. Here is the link:

Building a Small Cable Suspension Bridge with the Cable Locking System

Images, diagrams, and text copyright 2013-2014 by Marvin Denmark unless otherwise noted. Please do not copy and post my content anywhere without my permission. Thank you.