How To Install A Flagstone Path In A Lawn

Hardscape, How-To's · Written by Roger

131 Comments

flagstone.instl_in-lawn1aThe look of natural flagstone set in grass can be beautiful if done correctly and used in the right situation.

The turf in-between the stones softens the overall look of the path which can help distinguish it from other primary walkways.  At the same time this technique can subtly  connect different “points” in the landscape and direct the eye and traffic.

From a practical standpoint the stone path gives everybody a clean, solid surface to walk on in the event the grass is wet and/or soft.

The process of installing a path like this will vary slightly depending on circumstances such as the condition of the existing lawn.   Or, perhaps there is no lawn to begin with and you want to achieve this look.

The following installation will show the fundamentals.  If you have questions on a particular circumstance you may be dealing with, leave a “comment” and I’ll help you out.

Flagstone selection

Flagstone path stone selection

Flagstone Quality And Layout Are Important

Choose a type of flagstone that is dense and solid.  Stay away from slates and other types that flake, fragment and deteriorate over time.

You want the majority of pieces to be larger in size and no less than 1.5″ thick.  The idea here is that greater size and weight give stability – this is key.

Purchase and layout a good selection of flagstone so you have pieces to choose from.  Notice how plywood is used to protect the paver driveway.

Flagstone path layout

Flagstone path layout

Before you begin the actual site work and preparation, arrange the stones on top of the existing lawn how you would ultimately like them to look.

In this picture to the right the stones are set and ready to be installed.  The homeowner requested that the space between the stones be kept close.  Compare this to the first photo at the top.  This is a different project where spacing was made wider.  Keep in mind the spacing must be wide enough to support the living grass.  Arrange the flagstones no closer than 1.5 – 2.0″ apart.

Remove existing lawn

Remove existing lawn

Preparation And Installation Of Flagstone

The next step after arranging the flagstones is to prepare the base for installation.

Step one, removing the existing lawn, was fairly easy on this job.  The grass happened to be recently planted sod and was not yet deeply rooted.

Working in sections, move 3 – 4 stones at a time off to the side.  The sod can then be peeled back and the stones replaced to their set positions.

Realize, of course, that if you had a well established lawn, removing it would most likely involve some other strategy.  Again, which tactic you use to remove the grass depends on the circumstances.

Base preparation and flagstone setting

Base preparation and flagstone setting

With the flagstones now sitting on bare ground, you are ready to prepare the base on which you’ll set the stones.

Trace the outline of the stone on the ground with a pointed tool of some sort – a trowel works fine.  Using a spade dig down 5 – 6″ within the outlined area.

In this excavated space install 3 – 4″ of crushed gravel.  We like to use gravel no larger than 1/4″ diameter.  It’s small enough to “move & level” with a trowel, compacts well and drains nicely too.

Now sometimes it gets difficult during this base preparation to preserve the narrower strips of earth between stones.  The key is to preserve or replace soil in these narrow strips so they can support grass. If it becomes too difficult to preserve these narrow strips of soil and they combine with the gravel base, take care to ultimately fill these voids with as much soil as possible.  For grass to survive in that narrow space, it must have a deep root system in soil.

Flagstone can be cut if necessary

Flagstone can be cut if necessary

A flagstone path in a lawn is meant to be informal.  Although you can see line design and pattern, there is still irregular shapes in the stone.  The pattern, which unifies the path, is achieved by relating the shape of each stone to one another.

Sometimes, no matter how much stone you have to pick from, you simply can’t find a good match.  This is the time to create the shape yourself by cutting the stone.

In the picture above we’ve arranged the path to widen at the top of a stairway.  Unable to find a stone to fit the situation, we overlapped one stone over another.

Flagstone cut and installed

Flagstone cut and installed

Before making the cut we first mark a line on the bottom stone.  This line mirrors the shape of the stone above with a 2″ space.

The cut is actually made with a diamond blade.  Although diamond blades can be fitted on different types of power saws, here a 2 stroke cut-off saw was used.

After the cut is made the fresh-cut edge is “distressed” with a mason’s hammer to make it look more natural.

This last picture also shows a string-line set up.  The string is set at an equal height from the “finish grade” at each end of the walk.  You can check the uniformity of height and pitch of your walk by referencing this line at any point.  Realize, however, that there are times when your walk’s finished height may have to follow a particular grade contour that is critical for drainage.  Again, this is a particular circumstance you’ll have to identify on your site and adjust to accordingly.

The basic tools for actually setting the flagstones are a mason’s trowel and rubber mallet. The trowel lets you move and adjust the gravel base while the rubber mallet lets you tap the surface of the stones to set them firmly.  As mentioned, the string line is helpful to check your walk’s height and pitch.  A tape measure is used constantly.  And last but not least, a bubble-level is important to check each stone.  Also, by bridging the level from one stone to the next you can check the “height / pitch” relationship of one stone to the other.

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    131 Responses to “How To Install A Flagstone Path In A Lawn”

    1. Steven Says:

      Roger:

      Thank you for the article. I went through most of the comments and have a question. I am extending my current patio and I want to use flagstone with 4-6″ of grass (already well established) between each stone. The seller of the flagstone said that I would need a layer of concrete as the base if I purchased 1″-1.5″ flagstone. If I purchased 2″-2.5″ flagstone, I dont need to put concrete below the stone. Based on what you said…

      “I wouldn’t use sand if you’re using 1/4″ gravel or smaller for your setting base. The gravel will work fine for setting the flagstone.”

      …I am leaning in the direction of the 1″-1.5″ flagstone on a 3-4″ base of 1/4″ gravel. Is this correct?

      Thank you in advance for you time and answer.

    2. Roger Says:

      Steven,
      The thicker the better for dry-set flagstone work. The reason is stability – the bigger and heavier the piece of stone, the more stable it will be.

      Having said that, it would be OK to use the 1 – 1.5″ flagstone (set on 1/4″ gravel), but do your best to use large pieces. I would say nothing smaller than 18 X 24″. If you set them nice and solid on that 4″ base and then have 4-6″ of soil and grass between them, you should be fine. The lateral support that the earth and grass give will help secure them. Try to make sure when you’re setting each stone that there’s no wobble to the stone…no matter where you step on it.

    3. Beverly Hull Says:

      I have a Bermuda lawn that probably has very deep roots. Would you recommend some type of material, cloth, plastic or……to keep the
      Bermuda at bay? Thank you for your assistance. Bev

    4. ceasar Says:

      Thank you for this great advise. I have one question my customer ask me to expand her drive way with flag stone for a extra car( her son is starting to drive). I really need to know if this is OK to do. Am worried about weight, possible cracking?? And she wanted grass joints. Is this OK to do?? Extra precaution to make sure job lasts. Please help. These is my first flagstone job am comfortable your advise was great just wanted to make sure if needed I do the extra steps. Thank you

    5. Roger Says:

      Hi Ceasar,
      Thanks for your question. I’m so glad you’re researching how to do this work for your customer correctly. They’re lucky to have you doing the work.

      I contacted my friend and colleague Dave Kennedy, who is one of the contributors here on LandscapeAdvisor.

      Dave sent over a picture of a flagstone driveway landing he did back in 2000. He said the flagstone he used was bluestone and it averaged between 3 and 4″ thick. It was dry laid on a 1 ½” stone base with 3/8” bedding stone. The flagstone is driven on everyday and no stone has cracked in 13 years.

      Hope this helps.

    6. Cherylynn OMelia Says:

      I bought a fifties cottage and would like to do a flagstone path and patio in the grass/backyard. I have not done this type of work before. I am somewhat strong; however, I am female. Will this be an overwhelming job for me?

    7. Roger Says:

      Cherylynn,
      There are a couple of stages of flagstone setting that can be physically demanding.

      Excavating the area to the proper depth can be difficult depending on the size of the area and the hardness of the ground. You certainly can and should consider renting a mini-excavator for the task if it’s too big a job.

      After excavation you’ll need to bring in the “base stone/gravel”. You can have that delivered and then move it to the patio/walkway area with a wheelbarrow.

      The flagstone can also be delivered and you can move the pieces with the wheelbarrow too. For dry-laid flagstone work I always recommend bigger and thicker pieces for stability. This is where it may become difficult for you. Perhaps at some of the more physically demanding phases you could get some help. For example, having two people to maneuver the flagstone pieces and help set them would be great.

      If you approach it casually and take care to not push yourself beyond your physical capability, you could make it a nice DIY project. Please be careful. I have back issues from years of landscape construction work and I would not want you to have anything similar.

    8. Roger Says:

      Hi Bev,
      I don’t have any experience with Bermuda grass as it’s grown in the southern part of the US.

      I would think a barrier of some kind that’s strong & solid and goes down into the earth several inches would control its spreading. Masonry, stone, heavy plastic, etc. These are the same methods we use (to one degree or another) to control any number of spreading/invasive plants.

    9. Joey Zamora Says:

      My parents just moved into a new home in Houston where the sod was just laid a few days ago and there is a good layer sand laid underneath the sod. I’m wanting to lay a flagstone walkway on the side on the house leading to the poolhouse. My question is can I get away with using the sand that is under the sod instead of using gravel to stabilize the flagstone. I will be using large pieces of flagstone with 6″-8″ spacing between the stone

      Thanks,

    10. Roger Says:

      Joey,
      You should be OK. I’m curious why there’s a layer of sand underneath the sod. Is the soil naturally sandy or did the installers add the sand?

      Since the sandy ground should drain well and Houston is in a warmer climate zone, the flagstone should set just fine. Plus you’ll be using large pieces…great!

    11. Liz Says:

      We are considering stone pavers of some type through a lawn area. Will extra work need to be done between the pavers or can we just mow over the walk as a whole? Thank you for your input.

    12. Roger Says:

      Hi Liz,
      I’m not sure I understand what you’re planning to do.
      Most manufactured pavers are set so that they touch and form a continuous surface. With that you’ll not have any grass growing between the paver units.
      Now there are some manufactured “pavers” that mimic flagstone, both irregular shape and dimensional pattern, e.g. 12 X 18″, etc. Something like these you could set as we did on this project and have grass growing between them. And just like on this project, you’d run the lawn mower right over them.
      I’ve found that over time the grass does begin to grow over the edge of the stone. Perhaps once a year you should take a knife or some other edging tool and cut back the encroaching grass to the original edge.

      Here’s an example of such “pavers” from Techo-Bloc. http://www.techo-bloc.com/homeowners/index.php?p=Products&e=view&categoryId=3

    13. Allie Says:

      Hi Roger,

      This is a really great article showcasing some really beautifully done work.

      I’m about to install a flagstone path across what will be a large lawn area. The soil on the property is very sandy & compacts very tightly. I’m wondering if we could forgo the crushed gravel if the soil base is thoroughly prepared & compacted, and the flags are wiggled into place to insure good contact. The flagstone will be a very durable 2-3″ thick with 12-18″ spacing of lawn in between pieces.

      I’d really appreciate your thoughts!

      Best,
      -Allie

    14. Allie Says:

      I forgot to specify—this site is in coastal CA where we never get hard freezes, and the soil is extremely well-draining.

      Thanks again :)

      -Allie

    15. Roger Says:

      Hi Allie,
      Considering the flagstone you’ll use is 2-3″ thick, existing soil is sandy and well-drained, and your temperatures are moderate, I think you’ll be fine working with your ground as the base.

      Plus, the fact that the existing soil is sandy will make it relatively easy to adjust when leveling and stabilizing each flagstone.

      You might consider keeping a small amount of the excess sandy soil just in case there’s some settling.

    16. DJ Says:

      We live in San Antonio Tx on 2 acres. We are building a pool with a flagstone patio. We don’t want to mow or water grass. We were going to just lay down extra flagstone to take up some of the land but now our pool builder is talking to us about synthetic grass. Can flagstone be laid on top of synthetic grass? Nothing but dirt right now. So anything would be an improvement. Thanks for the help.

    17. Roger Says:

      DJ, I’m not completely clear on your situation, but here are some of my thoughts.

      A common look for an inground swimming pool is to have a patio/walkway around it. And this can be made from a number of materials, such as the flagstone you were planning. Typically flagstone is either “dry-set” on a prepared base or “wet-laid” on a concrete base. You could create a look that combines grass with the flagstone like is shown in this post. I’ve done this before, but used “patterned” flagstone, i.e. squares & rectangles. It’s not the most practical thing because cutting & maintaining the grass in-between the stones is a challenge and invariably causes grass clippings in the pool.

      The idea of using artificial turf would solve the problem of cutting & lawn maintenance. And the base preparation you would do for the flagstone should be similar to how you’d prepare for artificial turf. If you used artificial turf in-between the flagstone, I’m not sure how that would work. Specifically, how do you securely install smaller strips of artificial turf so they don’t move?..although I’m sure there’s a method. Is that the look you’re going for?

      Otherwise, you could do a flagstone patio/walkway without turf in-between, and then cover other open areas with the artificial turf.

      You could also use all artificial turf – right up to the pool coping.

      Again, it’s hard to give advice on matters like this when I’m not actually there to see and discuss with you. Don’t hesitate to comment again if you have further thoughts or questions.

    18. May McIntosh Says:

      Hi there!
      I live in Coquitlam BC. Our soil is very thin 1″ and we have clay,silt and rocks underneath. We never had drainage problems as we are on a hill, on the high side. We had a large plastic sandbox for 5 years and removed it last week. The ground under it is now compact soil (mind you loaded with earthworms!). I didn’t lay 4″ of sand under each flagstone, only 1″. Now I have standing water against the last row of stone against a retaining wall. I think because I lifted the sandbox, I’ve exposed a compact ground that isn’t used to draining yet. I used a pitchfork to aerate around the stones. Should I dig a drainage trench and dry well or wait for the ground to revive after a couple weeks? My final plan is to grow mossy ground cover between the stones.

    19. Roman Says:

      Hi Roger. Thank you for providing us with your article. I am in the process of installing flagstone slabs. I want to have these set in with the grass growing in between the gabs. These slabs are 2″to 3″ thick. The first challenge was moving them from my driveway back into my backyard, they weigh in range of 200 to 300 pounds. I lay them down in the best possible pattern. They sat for a week. I just scraped the grass from under each one of them and added decomposed granite, in some spots where needed to keep them from wobbling. A couple of them broke because they were thinner on some corners as a stepped on them to verify that they were stable. I thought the weight on these slabs would be enough to keep them in place. The turf they sit on is fairly leveled with a small slope to where water will run off. I am not at ease, thinking that some day they will break. I know about the gravel and sand base technique. However, I wanted to know if they stones would be ok with just a sand base. I know the hard work involved in digging and filling for each stone. I need some advice on the least expensive and more reliable method of material to use under those stones. Or should I leave them as they are with soil and some decomposed granite I use? My next step was to let them sit for a while and settle. Then I was going to force sand through the sides with water pressure, to keep them from breaking in the future.
      Thank you, Roman

    20. Roger Says:

      May,
      Without seeing the situation it’s hard to give precise advice, but it’s important the area you’re working on has pitch (amount of slope). In other words, there should be approximately 1/4″ of pitch per 1′ of run. So if the area is 6′, you should have 1.5″ of pitch, which will ensure that water moves out of the area and continues on its way.

      It’s likely the compacted ground is not helping, but proper pitch is the most important factor.

    21. Roger Says:

      Roman,
      There’s no question the stones will be better off when set in a well-drained, stable base. A coarse, masonry sand would be a good choice, but we really like to use crushed stone in a very small size.

      Could you get someone to help lift the stone vertical so its on edge? Then, as the one person holds the stone vertical, you could dig out the existing soil, turf, etc. and fill will coarse sand or smaller gravel. Lay the stone down together and check that it’s set right. You can either lift again to adjust, or tweak as it sits by packing from the sides.

      It’s great that you have pitch (slope) so that the water drains properly. I’m sure you’ll continue to maintain that if continue to work on the stones.

    22. Brendan Says:

      Hello Roger. I am in the process of expanding my patio into my garden. Basically what I did was reclaimed a section of my stone driveway and and a section of my garden. I want to use the irregular flagstone spaced 5-7 inches apart and grow a Blue Star Creeper ground cover as well as strategically placed plants to make patio/garden area so the garden feels less separated from the sitting and entertaining area. I decided to use fill dirt and top soil to level the area that was once the driveway rather than just pour and tamp a paver base so the plants will have sufficient soil to root and thrive. I found your article to be the most compatible with my design idea because it only calls for the paver base to be put beneath each individual stone. I called the stone yard to order my paver base and he sent over what he called “quarry dust.” It doesn’t seem as though this quarry dust packs down as tightly as the paver base I’ve used before but it does seem to allow me to forgo using the paver base and then using sand in order to level the stones. My question is will this “quarry dust” be enough to keep the stones from settling and sinking into the ground. I am concerned since the fill dirt is about a 1 foot deep and was just recently put in. I did use a lawn roller to compact the fill dirt so I don’t expect too much settling but would like to protect myself from having to pull these stones up again in a couple of years.

    23. Scott Says:

      Great walk thru! Thank you!

      I am starting from scratch – no lawn in place, no flagstones. Tillered and prepped the area
      (pretty small – 14×14) for planting sod. I see one of two approaches:

      1) Lay down the sod, give it a couple three months to take root, and then remove the sod where I want the stones to go (essentially as you have described). Downside here of course is the extra time and wasted expense on sod that gets cut out.

      2) Lay the flagstone wide enough – 3 to 5 inches or more – and then work the sod into the cracks. My concern here is that the more narrow and irregular pattern to the new sod won’t take root. Is this concern valid?

      I prefer the second approach for sake of time and money, but don’t want that sod to go dead or shallow.

      Thanks much!

    24. Rita Says:

      Could I simply place the stones on the existing grass which would kill the grass after a bit of time? Wouldn’t the stones “settle” into the lawn allowing me to mow over them?

    25. Jon Says:

      does a walkway made out of irregular flagstone has to be complete flat? i have seen some work where it the walkway made out of irregular flagstone is not completely flat that they are some stones higher than other.. is the right?

    26. Roger Says:

      Brendan,
      Your design idea sounds great. The wider spaced flagstone with low plants between them is a great look and will make for a nice transition to the nearby patio.

      I’m not too concerned Where you’re setting flagstone in the previous stone driveway area. That ground is presumably well compacted.

      It’s the section of existing garden where settling could be an issue with the flagstone.

      Quarry dust should eventually bind and get quite hard. The roller will help with compaction. Whenever you’re compacting materials you should do it in “lifts”. That means to first compact the base of your excavated area, then add 4″ or so of new material (e.g. quarry process) and compact that. Then add another 4″ or so and compact that – and so on until you reach the desired height of compacted base material. The one inch setting layer of sand (or quarry dust) you use last for leveling the flagstone becomes compacted as you set and tamp each stone.

    27. Roger Says:

      Jon,
      Unless you’re trying to achieve some type of irregular look, I would make all your flagstone edges as even as possible to one another. Pitch is another topic entirely, and I have an article here on that.

      When walking surfaces have uneven edges it becomes a real safety hazard, not to mention a nightmare to shovel snow.

    28. Roger Says:

      Scott,
      I like the way you’ve thought this through and your 2 “approaches”. And, as you’ve mentioned, there are pros & cons to each.

      I’d also go with the second approach. Try to keep the space for the grass joints wider – leaning more towards 5″. And after the flagstones are set (with gravel/aggregate), go through each joint and just clean them up of any excess gravel and replace (where necessary) with top soil. You could even add a soil additive like Soil Moist to this joint soil to help keep it from drying out prematurely and until its roots take hold.

    29. Roger Says:

      Rita,
      I’m afraid that just setting the stones on your existing lawn would not work too well. At the very least I would set the stone, trace around it, and remove the grass and enough soil to recess the stone flush with the surrounding grade.

    30. Beth Ann Says:

      This is all helpful information. One question – I have St Augustine grass and I am wondering how well it will work in between the stones. Do you think that it will be a lot of extra work to as the “runner” of grass with start growing onto the rocks?

    31. Roger Says:

      Beth Ann,
      I don’t have any experience with St. Augustine grass, but most grasses (even in our northeast location) just by their nature spread – some more aggressively than others.

      In our area I find that if the grass is cut back to the flagstone’s edge once/year, the look and function is maintained. I use a heavy duty knife with a 4″ blade. It’s the same one I use when laying sod and cutting/fitting the sod around objects.

      Just find the edge of the stone under the over-growing grass and stick the knife in right against the stone. Simply trace the outline of the flagstone while cutting with the knife. I keep my sharpening stone nearby to freshen-up the knife’s edge every now and then.

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