Tips for a Successful & Budget Friendly DIY Flagstone Patio AND Homemade Stream

Have you ever read, or watched, so many how-to articles or videos, and then tackled a project making your own rules thinking it would turn out ok in the end, only to realize that you should have taken the warnings and tips from others more seriously? I learned the hard way when I tackled our most recent project: our new flagstone patio. If I had taken the tips I learned from those videos and articles seriously, I would have saved myself 3x the effort I ended up having to expend, as well as some tears. Thankfully I followed the tips I learned on how to do a DIY stream, so that project went smoothly. 

Today I will share with you the articles and videos that I found to be incredibly helpful, as well as some tips I learned that can't be skipped, as well as how much we spent on the overall project. 

First off, one of my biggest reasons for posting how to articles is to help you realize that almost everything can be improved on a budget, and be done by you. Yes, if you had unlimited financial resources, you can improve things rather easily by hiring an expert. Sometimes, even without an unlimited budget you should hire an expert for some projects, but for a patio and stream you can do it yourself! 

When we first moved into our house we discovered there was a gas leak, and it ended up being found underground in our backyard. Unfortunately the gas line had to be dug up and so within the first month of moving in, we paid $2,000 to get the line excavated, and thus paid to have our backyard destroyed:

It was pretty disheartening. We learned that when filling in a hole you need to not skimp on dirt, but overfill the trench because with rain, sprinklers, and general settling, the hole ends up much lower than you'd expect, and because of that, we have a 2" drop in our lawn where it was once excavated. Someday we will work to have this remedied, but it taught us that skimping in areas on projects due to time, cost, supplies, etc. can come back to bite you. I wish I had remembered not to skimp on things when we started our flagstone patio project.

What started off the chain of projects was that the upper parts of our waterfall, that were put in prior to us moving in, started leaking. This is what they looked like before:

Before: Closeup of the uppermost part of our 3 part waterfall

Before: Overall look of our three part waterfall

For those of you who are wondering what that brown covering is that is showing, 3 years ago we bought Rock on a Roll to cover up the black pond liner as shown below:

We thought it looked so much better once we put it in (which it really did improve it), but still the waterfall looked so rudimentary:

Once the waterfall area started leaking, we were ready to get rid of the pond entirely. We had gotten an expert to come out and quote how much it would cost to make the waterfall and pond look nice, and it was over $10,000! We figured that once it stopped working, we would have to get rid of it because we weren't going to spend that much money on a non-necessity. However, when we thought of all the fill dirt we would need to fill in the hole of the pond, and then thought about how we had a working pump and hose still, we decided to reconfigure the upper area to look more like a stream. We enlisted the help of our four boys and filled in the holes that were there, and dug a stream instead. 

Stream Tip #1: You don't need to dig very deep/wide

They dug about 8 inches deep and about 2-3 feet wide. Unfortunately I didn't take any during pictures, but some words of advice that I learned was that you don't need it very deep, just deep enough for the rocks you are going to put on the sides to slightly rise above the bank. 

Stream Tip #2: Make it curve naturally

You also want to make it look natural by creating a lazy arch to it, rather than sharp angles or just a straight line. 

Stream Tip #3: Put barrier down before pond liner

Once you have dug your stream, put down cardboard, newspaper, or something that will allow the pond liner to be on something other than dirt or rocks (to help prevent puncturing). 

Stream Tip #4: Lay pond liner starting from bottom of stream to top

We bought this PVC liner from Lowes, and needed two packs for the 25' x 3' wide stream we had just made. Since the liner wasn't in the dimensions we needed, we laid it down, allowed for it to extend over the bank about 10" or so (enough to stake it down and cover with rocks and mulch), and then cut the excess. Your stream does not need to be steep, and only needs to be 2 inch drop per 10 feet of stream per the Family Handyman, but you do need to make sure that the pond liner at the bottom of the stream, is below the upper pond liner of the upper part of the stream. As the water moves down the stream, you don't want it hitting overlapping pond liner and going under that liner. If you lay them over each other as the water flows down the stream, as long as you overlap the two layers by several inches, you don't need to worry about a leak. Since I had excess pond liner, I was able to have two layers of the PVC liner in areas I was worried about foot traffic, thus preventing holes. This liner seems like it would be easy to puncture, but it is surprisingly very strong and the two layers were probably not necessary.

Note: The above link for the Family Handyman was a very valuable resource that provides every step you need to take to create a stream and waterfall from the very beginning. Plus, his stream and waterfall look WAY more professional than mine turned out.

Stream Tip #5 Optional: Rock on a Roll adds protection and aesthetics

Like I mentioned above, 3 years ago I purchased Rock on a Roll to hide the black pond liner that showed. After 3 years it is in like new condition (except for some coloring of where the water line hit). This stuff is built to last, and it has withstood me changing up where I put it many times, so it malleable and durable. I laid it down over our pond liner before placing the rocks, and thus as rocks move or shift, it will look like it is either a rock wall or a sandy stream bottom.

Stream Tip #6: Place large rocks then small rocks

There are fancy streams out there with boulders, and waterfalls, etc. but ours is a simple stream that incorporates 4-8" Cobblestone and 1 1/2" River Rock. I first placed the longer and larger cobblestones along the inside walls of the stream bed, with as many of them slightly rising above the bank's edge as possible. I then placed a few in the middle of the stream bed, keeping in mind to not create a dam. I then used a few, ideally the more flat ones, around the outer edges of the stream. Lastly, we used about 1/2 ton of the river rock to go along the banks of the stream 5-7" out, as well as the bottom of the stream. 

We used a similar method to reconfigure the rocks around our pond, but unfortunately due to the pond being steep on some sides, as well as so deep, we couldn't use the Rock on a Roll, and we couldn't put rocks all along the sides and bottom. If you are creating a pond from the beginning, make sure to make ledges around the inside of the pond that can hold your rocks so that it looks more natural.

Bonus Tips: 

We bought a 5' bridge on Overstock for around $110 using Rakuten cash back and coupons, that we then stained and put polyurethane on, (link is to one that is already stained, but probably could still use a coat of polyurethane to extend it's outdoor life). Even though our stream is just 3' wide, we needed the 5 foot span for it to feel stable. 

These tips will also work for a dry streambed that can help for flash flood runoff, or just aesthetics. Since we had the pond pump already, we just brought the pond hose up to the top of the stream, put it into a tupperware box we had cut a hole for the overflow to flow out of, covered it with rock liner and rocks, and that made the stream begin it's natural looking flow.

We bought Ice Plants, Butterfly Bushes and Candytuft.
I am hoping that once we get them established, they'll thrive in the sunny/dry area they are planted.

How to Put in a Flagstone Patio (& what not to do)

Boy did we go wrong on this one. What I found most helpful, and wish I had followed to a T, was this video I found on YouTube:

In the video he explains what supplies you need as well as each step of the process. A few things I have learned that are not covered in the video are:

• Thicker flagstone weighs more = more expensive, but is sturdier and doesn't break or move as easily. I wanted flagstone similar to what he used in the video, because it probably was only about 1" thick, which would be cheaper, and easier to work with. Unfortunately it was not available at our local rock/soil yard, and we ended up getting Arizona flagstone that was about 2" thick. For 70 sq ft we spent $365 for a little over 1.5 tons. We ended up having a little extra, but it is nice to have extra because it is really hard to figure out how to configure them as a puzzle together, so more rocks equals more shapes to choose from. The leftovers we used to make little stepping stones.

I found this picture on my phone from 2 years prior. I was hoping to put in a flagstone patio then, but then forgot about it. Funny to see that two years later we ended up getting the same stuff I had taken a picture of and had forgotten about.

• Another thing I learned is that Polymeric Sand is not advisable to use in between the rocks, but to use the type of sand that he references in the video, which is called all kinds of names. At our local rock/soil yard, it was called Concrete Sand. It is a little courser then you would use in a sandbox, and thus doesn't wash away as easily, or is something ants like to have a hay day with. In regards to Polymeric Sand, some people suggest using it because it creates almost concrete in between your flagstones, preventing weeds and erosion of sand. However, the experts on the subject said that it will eventually settle, crack, and then be a major pain to remove/clean up, and will in the end still allow weeds to come through.
• To calculate how much sand or gravel base you need, here is a helpful equation: 

To determine how much sand, topsoil or stone you need to fill an area:

1. Measure number of square feet in the area.
2. # of square feet x depth in feet = # of cubic feet.
3. # of cubic feet /divided by 27 = # of cubic yards.
4. # of cubic yards x (unit weight in pounds / 2000) = # of tons needed.

Before: What the area looked like before the patio (and us changing up the rocks around the pond:

After: What it looks like with the Flagstone patio put in:

Notice the flagstone walkway using the leftover rocks. We ran out of the better sized rocks and had only little ones to finish the pathway with. Still makes it much easier for my kids to walk through the mulch to get to our trampoline.

What we did wrong & took 3x long to fix:

In the video he talks about digging the area for your patio about 6" deep. Because we had to remove about 2" of mulch, and then dig down about 2" into the soil, I figured it would be good enough. I then leveled the area, tamped it down, then laid the aggregate base, tamped it down, then laid the concrete sand, tamped it down, then we laid out our flagstone pieces to determine the layout.

This is the aggregate base (gray) that goes down first, then the concrete sand (brown)

This is our first configuration attempt

At this point I started to panic. The rocks were so high and I started to question if they were even flagstone rock. The video showed him giving a shimmy shake to each rock and it would work it's way down in the sand, and then you would just need some sand pushed into the cracks courtesy of a push broom. These rocks were way too high, too heavy, and were not allowing us to get them into the sand at all. Plus they weren't going to be the right height with our grass line, or pond area. I was panicking.

So I hefted one rock out of the way, dug and dug and dug, deeper than the layer of the soil, and put a little bit of aggregate in, hefted the piece into the hole, measured it with a level, stepped on it to make sure it was secure, and did that with every. single. rock around the grass perimeter. I realized that I should have dug at least 6" deep, 2-3" deeper than I did originally, and then everything would have worked out fine. Because I had cut that corner, I spent so much time trying to get each rock to it's own individual depth to match the surrounding rocks that had been lowered. It was exhausting and frustrating and I was making very slow progress. We then decided to remove all of the rocks so that I could just dig the entire area to the proper depth, which ended up being annoying, but less time and effort than the one by one rock method. 

Unfortunately, we didn't get the suggested level of aggregate and then sand under every rock because of my mistake. Fortunately, because the rocks are so massive, the patio has endured many rainstorms, sprinklers that spray into sections of the patio, as well as furniture, and it has been incredibly stable still. 

Hard to see the individual rocks due to how sunny it was, but in person,
even though the sand is similar in color, you can tell there is a flagstone patio 😊

From this angle you can see our lovely trampoline that the flagstone path allows for much easier access to now

Overall cost of the project:

In the end I wish we had changed up our stream earlier because it looks so much better than before, and was way easier to accomplish than I expected. And lastly, I wish I had followed instructions on laying a flagstone patio in the first place. I hope that something I have shared will allow you to accomplish one or both projects more smoothly than we did!