How To Install A Flagstone Path In A Lawn

Hardscape, How-To's · Written by Roger

173 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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    173 Responses to “How To Install A Flagstone Path In A Lawn”

    1. Matthew Says:

      Hello roger
      I’ve read through all of your comments and they’ve really helped. I’m doing a flagstone walkway for the first time here in San Antonio tx. My question is is there a way that you figure out how much material for the base to purchase? I don’t want to buy too little and would hate to get too much. Other than that I think I’ve got it. Thank you

    2. Roger Says:

      Matthew,
      To calculate the amount of material you will need to cover an area you need to know 2 things: 1) the square footage of the area, and 2) the depth of the planned material.

      To calculate the square footage of a square or rectangle simply multiply the length X width. For other shapes use one of these formulas.

      Once you have the square footage of the area, and know the depth of the material you plan to use, look up the amount you’ll need on this chart. The chart is applicable for any material you plan to use.

      If you’re not excavating the entire walkway area, but rather just under each individual flagstone, you can figure slightly less base material.

    3. richard mitchell Says:

      Should the elevation of the flagstone walkway be flush with the top of the grass or with the top of the underlying soil. It would appear to be the later.

    4. Roger Says:

      Richard,
      You are correct. The top of flagstone should meet with the soil level. Of course this is presuming the grading in the area is fairly consistent (not up and down). Otherwise you could have one edge of the stone meeting grade nicely, but on the other end it’s not. In instances like that I’ll recommend correcting the grade(s) as part of the walk install.

    5. Roger Says:

      James,
      Years ago we used sand and had problems with the flagstones occasionally “heaving” in freeze-thaw cycles. Although “coarse” sand will technically drain well, if the sub-base (earth beneath sand) is not draining well, then the moisture is partially retained in the sand.

    6. kelly Says:

      if you are still reading these posts, need help installing manufactured bluestone on grass where there is currently no grass. I had adjust the slope (wheelbarrow at a time0 with fill and clay soil.) Do I put down the topsoil, 4 inches at least, tamp it down then set in the stones (stone dust and water) by carefully scraping away the least amt of topsoil, set the stones to soil grade then seed the area?

    7. Roger Says:

      Kelly,
      Try not to set the flagstone on any top soil. The best scenario is gravel first, as I describe in the article. If you can find a gravel that’s 1/8 to 1/4″, that would be great. And not round gravel, but “crushed”.

      You can use stonedust if need be. It’s not necessary to wet it. Coarse mason sand would work too. We like to use gravel because it does not hold water/moisture. Here in the northeast that’s important to avoid “heaving” during the winter.

    8. Debra Lloyd Says:

      I left for the city, while landscapers installed the flagstone in bare ground. Then they seeded all through the path. They left me with enough inventory to finish what I wanted done. I thought I could trace the stone out on the earth, lift the stone and dig out…that’s ridiculous. I’m thinking I should just shovel a route 1.5″ deep and drop the stones down, cover around with earth. The landscapers did not use sand or gravel underneath. I have to do at least another 20′. I’m 66, hearty but not crazy. What’s my best route?

    9. Roger Says:

      Debra,
      The method your landscapers used by leaving out any base preparation is already minimal. You can’t simplify it any more than that.

      You could do it in stages (e.g. 5′ at a time) to break up the task.

    10. LeRoy Haynes Says:

      I would like to have moss growing between my stones. Any suggestions of what to use. There seems to be an abundance of moss in parts of our yard. Can that be transplanted? Can the stones be placed right on the earth without gravel? What is the risk there? My walk will slant down to the road so using a string to check the level probavly won’t work. Any suggestions?

    11. Roger Says:

      LeRoy,
      Here’s a great article all about using mosses in the landscape.

      It’s a good idea to use a small gravel or even a coarse mason’s sand to set the flagstone. Just make sure you dig down to provide enough space for the gravel or sand, and to set the flagstones flush with the surrounding earth. Use the adjacent ground levels to determine the height of each stone — in this case a string line is not needed.

    12. Shirl E. Gilbert II Says:

      I have hard clay soil(Baton Rouge, LA, what tools do I use to dig out the soil to the shape of the flagstone ??, and can you use sand for the base to lay the flagstone down on?? I see several bases, crushed rock, gravel, sand, etc, which is best ?? I’m laying a flagstone walkway from my front sidewalk to my back yard, some 80′, is that too long a run for this kind of walkway???
      Thanks,
      SEGII

    13. Roger Says:

      Shirl,
      To loosen the clay soil to remove for the base material I’d use a mattock and/or a grape hoe. With the soil loosened you can then use a flat shovel (or similar) to excavate the soil to the proper depth.

      Although you could use a coarse mason sand for the base, I’d recommend a small, crushed gravel — especially with a clay sub-base which does not drain well.

      80′ is a relatively long walkway, but this type of walk should work well.

    14. Shirl E. Gilbert II Says:

      Thanks Roger, your response is very helpful. I will start the project next weekend.

    15. Patrick Says:

      I intend to let the stones to sit on the grass for a period of time (2 weeks say) so that the grass below the stones are dead and therefore easier to remove as well the shape of the holes easily identified for digging…. would this be a good / workable idea…. I know contractor normally don’t have the luxury to wait… but as homeowner I do… do you think I should go for this “technique”….

    16. Patrick Says:

      One more question… I intend to use a Angle Grinder to cut existing sod out of the hole hopping to have a nice clean edge for laying the stones…. would this make sense as I never see such method from the internet and I think it might work and I haven’t bought the Angle Grinder yet… but intend to buy one just for this…. please let me know what do you think about that too. Thanks.

    17. Roger Says:

      Patrick,
      Well that’s an interesting technique you describe to mark where the stones will go and where to cut to remove the grass. And certainly that would work, especially given the time you have.

      On the job I’ll use any number of methods depending on the situation. For example: I always have a bucket of granular lime (same as used in the garden) to mark-out lines on the ground. It’s not permanent and doesn’t harm anything. I’ll scoop up some lime with a coffee can and sprinkler an outline of each flagstone. After lifting the flagstone I can cut out the shape.

      Your other question is about using a grinder to cut the sod. If you’re looking for a clean, accurate cut it’s really not necessary in this situation. Frankly, you want the cut outline to be slightly larger than the stone itself. You’ll need that little extra space to adjusting the stone. Also, within a week or two the grass will easily grow back up to the flagstone.

      The tool I use most often to cut the outline and help with removing the sod and soil beneath is a “heavy duty” spade.

    18. Barbara Says:

      Roger, I laid a stone pathway thru my backyard a month or so ago thinking if I just lifted the existing layer of sod (it was only put in last summer) I could just lay it on the existing ground… Of course that didn’t work. I am wanting the grass to be between the stones but, while the stones are slightly above the ground, the grass stays way too tall after mowing over. I’ve attempted to raise the stones by adding gravel under them but I’m not sure the depth to set them at to keep the mower from hitting and the grass from taking over? Seems if they’re laid too high they would be a tripping hazard? As Patrick said above, I’m wishing I’d have just laid them on the existing grass and let them settle! Doesn’t help that the yard is a slight downhill incline.

    19. Roger Says:

      Barbara,
      The top of your flagstone should be even (same level) as the “soil level” of the adjacent grass. This provides a smooth, consistent level for the mower to travel over — and eliminates any trip hazard.

      Invariably the grass will begin to creep over the flagstone. You can “keep after it” by trimming with a line trimmer (with some regularity), e.g. every time you mow or every 2-3 weeks. Or, wait till the grass has grown over the flagstone an inch or two and then trim each stone using a knife (or similar). You might only have to do this once or twice a year.

      As far as setting the stones on an slight incline grade: the flagstone should mirror the grade/incline and match the surrounding soil level.

      Hope this helps.

    20. Sam Says:

      Hello Roger,

      I am exploring to have a small patio (About 125 to 150 sq feet) by my basement door. Want to go economical route. Do not know what my options are. Recently, I installed drain pipes to prevent water puddle in the area. Thank you.

    21. Roger Says:

      Sam,
      So smart you’ve taken drainage into consideration!

      In terms of your choices, of course there are many. I would choose a material 1) you aesthetically like, and 2) can be dry-set (i.e.) set without cement.

      I suggest visiting stone yards and masonry supply places for ideas and suggestions. We have several in our area, and they have displays showing exactly how each material looks. I often meet with homeowners at these places to choose their materials. Also, bring photos with you to show the setting where the proposed patio is going.

    22. Tim Says:

      Installing flagstone walkway on established yard. Should I remove area with sod cutter, then cut out and apply base

    23. Roger Says:

      Tim,
      You could either remove the sod throughout the entire flagstone path or use the flagstone pieces as templates and just cut the sod out within that shape.

      That’s a call you’ll need to make based on personal preference. But here’s a few things to consider.

      If the existing sod/lawn is thick and healthy, you may want to preserve that and cut out for each stone.

      On the other hand, if the existing sod/lawn is thin and weak it probably makes sense to treat the path as one and remove all the grass.

      Another way to look at it (again, it’s personal preference) is leaving the existing lawn and just cutting out the grass underneath each stone is tedious work. The thinking here is you’d rather take the time and effort at the end patching in with new sod or top soil and seed.

      You can see that the method you choose depends on the site conditions, how long the walk is, and how you would prefer to work.

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