How Much Strength Does Sistering Joists Add?
The answer to this question depends upon your purpose. If you are going to use the joists for something else then it will not make any difference what kind of strength they add.
However if you want to build a wall or ceiling, then it makes sense that the stronger the wood is, the better. So let’s see how much strength does sistering joists add.
Sistering Joists With Plywood
In the case of using plywood for the sistering, it would be best to do so with 1×6 boards. These are called “staple” size because they are used in many construction projects.
You could even say that these are the same size as 2×4 boards but smaller than 3/4″ thick. They are easy to work with and do not require glue.
If you decide to use 2×4 for the sistering, then you need to consider the thickness of the two pieces of plywood. A good rule of thumb is that the thicker one should be at least half as thick as the thinner one.
They are usually available at hardware stores.
So, let’s look at the math involved in sistering plywood with 1×6 boards. So if the sister board is 3/4″ then the sistering board should be at least 3/8″.
We can use the same rule when deciding on the size of plywood to use. The sister board should be around 1/2 the size of the plywood sheet you are using.
Two 1/2 sheets would equal a full sheet.
By using these rules, you can come up with your own table for easy reference in the future.
1×6 boards are 3 1/2 inches wide and 1/2 inch thick. This gives a total of 3 3/4 inches.
If we divide this by 2 (one thickness of the plywood), then we get 1.875 which closely rounds up to 2. So if you were to sister two pieces of plywood with two 1×6 boards, then the plywood would be equally strong as a single 2×4 board.
Sister Board Plywood Thickness Sister Board Size 3/8″ 1×6 1/2″ 2×4 5/8 1×4 7/8 2×3
Simple Joist Sistering
If you decide to use plywood for sistering. The next step is to determine the size of plywood you need.
Just remember that you need to use at least two sheets of plywood. The size of these two sheets will be your minimum standard.
Let’s look at the math for a full sheet of plywood. A full sheet of plywood is 4 feet by 8 feet or 3 2/3 feet by 7 feet.
To use all of it, you would need to use two 2 foot by 8 foot boards. This means that you can sister 4 sheets with 3 2/3 board.
After you have this measurement, then it is time to start cutting. Start off by buying more plywood than you actually need.
This way if you make any mistakes while cutting the plywood, then you will have some left over.
When cutting the plywood, always use a straight edge and a sharp utility knife or a good pair of scissors. It is best to use a circular saw but this may not always be an option for you.
Alternatively, you can sister 5 sheets with a single 5 foot board. This means that you can sister 6 sheets with 2 2/3 boards.
So if you use 4 feet by 8 feet plywood sheets for your sistered joists then you can sister anywhere from 4 to 6 sheets.
Now remember that the minimum size for sistering plywood is a 1/2 inch thick by 3 1/2 inch wide piece of wood. Any smaller than this and the plywood will start to bend under pressure.
Now if you only sister 4 sheets of plywood with 2 2/3 boards, then this will equal:
(4 feet by 8 feet) (1/2 inches) (2 2/3) = 12 square feet
Since plywood is sold in squares, the number of sheets you can sister is a function of plywood square. 12 divided by 4 equals 3.
Remember that the maximum size is a full sheet of plywood. You have 4 feet by 8 feet plywood which equals to 32 square feet. This means that you can sister between 4 and 6 1/2 sheets of plywood.
You can sister anywhere from 4 to 6 sheets of plywood with 1/2 inch thick by 3 1/2 inch wide pieces of wood. So you can sister at most 3 sheets of plywood.
If you were to sister 4 sheets of plywood then you could sister a total of 5.
So if you want to sister six sheets of plywood, then the full minimum would be 2 feet by 8 feet. Let’s assume that the plywood is 5/8 inches thick and that you want to sister all six sheets.
The first thing we need to do is determine how many 2-foot sections we need. In this case we need 4.
Now we need to cut these sections in half. This is easy enough, just eyeball a line down the middle and split it. Now we have a bunch of 1-foot sections and 2-foot sections. Take all the 1-foot sections and stack them together; this will be our middle layer. Now take all the 2-foot sections and stack them; this will be our bottom layer. Now, take the middle layer and put it on top of the bottom layer. Congratulations! You’ve just finished your workbench.
Now you need to make your table saw sled. If you are planning to cut more than 2 or 3 sheets at a time then I highly recommend making one.
You can find plans online with a simple search.
Now stack the plywood into manageable pallets; I stacked mine 4 feet high and about 1.5 feet wide.
Now tie the stack together every foot or so with a piece of rope.
Now, take the pallet to your truck. If you have more than one layer then put 2x4s under the bottom layer to give your floor of your truck some support.
Then stack it as many layers as you can before taking it to the job site.
Then, unload it by yourself and carry it where you need it to go. In my case I had to carry it about 500 feet to a clearing where I could set it up.
If you have an old door that you no longer need then nail it over the opening of the shed to keep out dust and dirt when moving the wood in.
Now comes the fun part. Take your circular saw and cut the pallets apart.
You’ll need to use a carpenter’s square sometimes to ensure you cut them at a 90 degree angle.
Now take the pallets apart and lay them out where it is most convenient for you to nail them. In my case, I put the solid wood side up because I thought it would be easier to nail into compared to the plywood side.
My shed had an eave that extended about a foot past the roofline on all sides so I just stacked the pallets under that and nailed them into the side wall of the shed. A couple of the stacks were too tall to fit under the eave so I just made those short two-stacks.
I put up sheet goods on the wall where the pallets would be touching just to keep them from damaging the wall.
I used 3-inch construction nails for nailing the pallets together and a small nail gun (with a compressor) for speeding up the process. It took me about a week to build the racks and I’d say I used around 1,200 nails along with two 4-foot by 8-foot sheets of plywood.
As you can see in the photo, I had several different rack designs I was going to use. Since I didn’t know what would work the best, I decided to just build them all and then play around with them until I found the layout that would work the best.
Also in the photo you can see the two sheets of plywood leaning up against the wall. Those plywood sheets are what I ended up using for the pallet racks. I ended up only building one of the rack designs and using the rest of the plywood for something else (which I’ll talk about later).
So what did I learn from this? Well first of all, it’s impossible to get a forklift into most sheds so a lot of the shed-yards are just stacked along the edge where the roll-up door opens. Most shed-yards are also only about 8 feet high so they can accommodate the largest delivery trucks.
This means you need to put your rack right up against the wall of the shed. If you don’t then you’re wasting valuable space.
I built my rack 28 feet long (the length of my shed) and 12 feet high. This gave me several vertical rows to stack pallets in.
Most of my vertical rows are two pallets high but I have a few that are 3 pallets high because I had to in order to fit them in the shed.
I also learned a trick from the lumber jacks of old. If you center your rows either direction (both side-to-side and front-to-back) then you can create uniform stacks that are the same height every time.
This way when one row is depleted you can easily create a new stack that is the same height as the others.
You can see from the picture how I have several stacks of the same height. Every stack from bottom to top is the same height which makes them very easy to create and organize.
The plywood is actually from the leftover sheets that I used for building the pallet rack. Since I wasn’t able to build one design that worked better than the others I decided to use the rest of the plywood to build more floor to my shed.
This turned out to be a great idea. The ground under the rack is completely dry even though it has been a rainy spring.
Another thing I did was build an aluminum extension out from the bottom to create a walkway under the rack. This way I can get in there and sweep it out without stepping in all the water that runs off the pallets.
I really hate getting my feet wet so this was a must-do project for me.
The rack is working out very well. My only complaint is that I wish the shed was a little longer.
With it being only 28 feet long, I can’t quite fit two full sized pallets in the shed side-by-side. I can only fit them one on top of the other. This means that every once in awhile I have to take a pallet down and turn it around so that the products face a different direction so they all get sold. It’s not really a big deal; I just wish I had a little more space
I’ve also noticed that the pallets seem to be breeding. I’m finding more and more pallets in “hiding” all over the place.
It seems every time I turn around I’m finding another pallet that I didn’t even know I had. This wouldn’t be a problem except that the local trash pick-up charges by the volume of your trash so I keep track of what I have on a spreadsheet. This is getting expensive!
I’m glad I don’t have to pay for the pallets because if I did I’d go broke pretty fast.
So what’s next on the agenda? Well I need to get busy building my sales area because once the snow melts and people start hiking and biking on the trail again it’ll be time for me to get this show on the road. I need to get the word out about my Market.
I could put up signs on the highway telling people to look for the “Yellow Store” along the side of the trail. The only yellow building around here is the grocery store in town and I don’t think they’d like that.
I guess I could paint an old door yellow and lean it up against the side of the building somewhere but that would be temporary at best. I really should build a proper sign.
I’ve seen signs like the ones at supermarkets made out of wood before but those are very expensive. I need to find a cheaper alternative.
I go through my mental Rolodex and come up with some ideas. The best idea is to use pallets because as I’ve said before, I have a lot of them and no longer need to worry about critters making homes out of them.
Once I get the wood I can build them the same way I built my racks. I just need to come up with a design and then go about finding the cheapest way to paint or decorate them.
I could also weld metal sheets onto the pallets for added durability if necessary. I just need to make sure that whatever I build; it’s going to be able to last at least until next season.
Once again, it’s time to head down to the “city” to see if I can find what I need. The library is always a good place to start because you can learn a lot about things without spending any money at all.
I get to the library and ask one of the librarians where the items about building signs are located. She gives me a puzzled look and says that she doesn’t know anything about that but she can show me where the architecture section is.
I explain that I don’t want to build a whole building just yet, just something that will go outside. She says she understands and sends me down one of the halls where I find what I’m looking for.
Most of the books are out dated but they do have a good section on different types of signs and stuff. I learn that the most common type of sign is made out of wood and comes in two pieces, a vertical post and a horizontal top piece.
I also learn that before they had power tools like electric drills, people would create these by hand using a technique called “tenting”. You take a pole and stick it in the ground then lean a horizontal piece of wood against it and fasten it down with pegs, or in some cases, nails.
I think this is perfect for what I’m trying to accomplish; it’s very rustic looking and should look right at home along the trail next to the old rail-line.
Plus, creating them using the “tenting” method is going to be a lot cheaper than buying a bunch of pre-made ones and setting them up.
I make a note that I’m going to need to buy lots of wood screws, tarps, and pegs. I’ll also need to gather up some tools like a drill, hammer, rope, and boards.
I’m going to have so much fun with this I almost want to do it without charging the market for my services.
I take some notes on what I’ve learned from the library and head down to the local home improvement store.
The store is packed and I really dislike these kinds of places so I try to get in and out as quickly as possible.
Sources & references used in this article:
- Extracellular factor (s) following exposure to α particles can cause sister chromatid exchanges in normal human cells (BE Lehnert, EH Goodwin – Cancer research, 1997 – AACR)
- Essential cell biology (B Alberts, D Bray, K Hopkin, AD Johnson, J Lewis… – 2013 – books.google.com)
- An experiment testing the determinants of non-compliance with insider trading laws (JD Beams, RM Brown, LN Killough – Journal of Business Ethics, 2003 – Springer)