How to Put Artificial Grass on Stairs and Steps

This page is for homeowners who want turf on porch steps, garden steps or the stairs down to a turfed yard. Most guides treat stairs like a small patio, but a stair has height rules and turf changes the heights. We lay out the code numbers, show what turf does to them, and give a fitting method that keeps them.

Key takeaways

• The IRC caps a home riser at 7 3/4 inches, and the tallest riser in a flight may beat the shortest by no more than 3/8 inch.
• Turf on the treads only adds its thickness to the bottom riser and takes it off the top riser, so the gap between them is twice the turf thickness.
• So turf on treads only must be 3/16 inch thick or less. Turf the top landing too and the limit is 3/8 inch, and if you turf both ends the risers do not change.
• Count the whole turf thickness, pile and backing, and subtract any unevenness the stair already has.
• Glue every piece, start at the bottom, roll it, and keep off for about 12 hours.

What are risers, treads and nosings?

A tread is the flat part of a step you stand on. A riser is the height from one tread to the next, and the code measures it from the front edge of one tread up to the front edge of the next. The nosing is the front edge of the tread, and on a stair with solid risers it sticks out past the riser face below it. A flight is a run of steps with no landing between them, and a landing is the flat floor at the top or bottom.

For turf, one more word matters: total thickness is the full height of the turf as laid: pile height plus the backing, plus any pad. On a spec sheet the pile height is often the only number shown. Measure a sample from the bottom of the backing to the tips of the blades, because that is the number that changes your steps.

What does the code say about stair risers?

The rules for home stairs are in the International Residential Code (IRC), Section R311.7. It is a model code that your city or state adopts, sometimes with changes. We read the 2018 text as quoted in the Town of Timnath, Colorado stair guide.

The number that decides turf is the 3/8 inch, because turf can stay inside every other line of this table and still break that one.

What does turf do to the riser heights?

Turf on a tread raises that tread by its total thickness. If every tread gets the same turf, the middle risers do not change. Each tread goes up by the same amount, so the gap between any two treads stays the same.

The ends are different. At the bottom you step up from a walk or the ground, which has no turf, onto a first tread that does. So the bottom riser grows by the turf thickness. At the top, the last tread has turf and the landing does not, so the top riser shrinks by the turf thickness.

Now the 3/8 inch rule compares the tallest riser with the shortest. One end got taller by the thickness and the other got shorter by it, so the gap between them is twice the turf thickness. That is the point most guides miss. Even a turf sold as 3/8 inch thick, used on the treads alone, opens a 3/4 inch gap.

So the turf limit depends on which ends you turf:

Two more checks apply. The bottom riser must still be 7 3/4 inches or less after you add turf, and the 3/8 inch budget is shared with the stair as it is now. Measure every riser first. If the old stair already varies by 1/8 inch, you have only 1/4 inch left for turf.

Why not use tall lawn turf on steps?

Turfing both ends fixes the risers on paper, but it does not make a tall pile a good stair surface. We see three reasons to keep stair turf short, and the last two are our view.

The landing moves too. Turf on the top landing raises the floor at the door, and a 1 3/8 inch turf there leaves little or no drop to the threshold. Our turf on concrete guide asks for at least 1/4 inch, ideally 1/2 inch, of fall from the door to the turf.

The nose stops being a clear edge. The code caps the nose radius at 9/16 inch, yet a long pile folded over the front of a step makes a soft, rounded edge, and you cannot see where the step ends.

Tall pile squashes under a heel. A short, dense pile gives a firmer step. The putting turf types page covers short, dense products, and pile height explains why shorter blades resist matting.

Our rule: on stairs, use the thinnest turf you can find, and turf the landing and bottom pad whenever the turf is thicker than 3/16 inch. One turfed end is enough for the code up to 3/8 inch, but it spends the whole 3/8 inch budget, with nothing left for an old stair that is already a little uneven.

Do you need turf on the risers too?

Not for riser height, since turf on the riser face does not change the gap between treads.

It matters for the nosing. If you wrap the tread turf over the front edge, the nose sticks out farther by the turf thickness. Take a 1 inch nose and wrap 3/8 inch turf over it with a bare riser below, and the nose now projects 1 3/8 inches, past the 1 1/4 inch limit. Turf the riser face below with the same turf and the projection goes back to 1 inch. So our rule is simple: if you wrap the nose, turf the riser.

How do you install artificial grass on stairs?

We could find no turf maker instructions for stairs, so the steps below are our method. It borrows the order and the prep from two makers of rubber and vinyl stair treads, VPI and Shaw.

1. Measure every riser and tread. Write them down and work out your turf limit from the table above.
2. Prepare the steps. VPI asks for concrete steps that are dry, clean and fully cured, at least 6 weeks for new concrete. Fill cracks with a Portland cement based patch, not a gypsum one, and make sure wood steps are nailed tight and free of polish.
3. Cut and dry fit every piece. VPI says every tread and riser piece must be trimmed and dry laid before any glue goes down. Run the grain the same way on every piece, as in seaming.
4. Start at the bottom. Shaw's directions say to start at the bottom and go up.
5. Glue each piece fully. Use an outdoor turf adhesive across the whole tread and riser, since nails do not hold well in concrete steps. Press the nose hard: VPI asks for full contact at the step edge.
6. Fit each riser piece tight up under the nose above. VPI fits its riser material tight to the upper step nosing. Our method then folds the tread turf over the nose so it covers the top edge of that riser piece, and water runs off the nose instead of into a cut edge.
7. Roll it. Both VPI and Shaw roll every tread and riser with a hand roller so the backing beds into the glue.
8. Keep off. Shaw says to let steps set 12 hours before foot traffic. MAPEI's one-part turf urethane gives about 12 hours to light traffic and about 7 days to full service. Our walk-on guide has the full table.

We skip infill on stairs, because loose sand at a step edge rolls under a shoe and washes down the flight. Choose a turf that is made to go without it; do you need infill covers which products those are.

Leave the tread slope alone: the code allows treads to fall up to 1 in 48 so rain runs off. Turf with a perforated backing lets that water through to the step and out over the nose.

Worked example: a 4-step porch stair

For the material, our arithmetic: each riser face is 7 1/4 inches and each tread is 11 inches, so four risers and three treads add up to 4 x 7.25 + 3 x 11 = 62 inches, about 5 1/4 ft, before the porch and walk. Cut each piece separately and add a few inches each for trimming.

What this page does not cover

This page covers home stairs under the IRC, not stairs in shops, offices, apartment buildings or other buildings under the commercial code. Your city may have adopted a different edition or changed the numbers, so ask your building department before you start. We did not find slip test data for turf on wet steps, and we have not tested any turf or glue on a stair. Turf on wood deck stairs is outside this page, so ask the deck maker before gluing anything to them. A flight with four or more risers needs a handrail whatever the surface, and turf does not change that.

Sources

• Town of Timnath, 2018 Residential Stair Guide: IRC R311.7 riser, tread, nosing, slope and handrail rules.
• VPI, Rubber Stair Treads, Riser and Nosing installation instructions: concrete and wood step prep, dry fitting, riser tight to the upper nosing, full contact at the nose, rolling.
• Shaw, Resilient Step and Riser Directions (rev. 06-26-2019): start at the bottom, roll each piece, 12 hours before foot traffic.
• MAPEI Ultrabond Turf PU 1K data sheet: light traffic after about 12 hours, into service after about 7 days.

Frequently asked questions

Can you put artificial grass on outdoor concrete steps?

Yes, if the steps are sound and the turf is thin enough to keep the riser rule. Clean the concrete, fill cracks with a cement-based patch and let new concrete cure at least 6 weeks, as VPI asks for its treads. Glue every tread and riser piece fully. Turf the landing and bottom pad too unless the turf is 3/16 inch thick or less.

How thick can turf on stairs be?

On the treads alone, 3/16 inch or less, because the bottom riser grows and the top riser shrinks by the same amount. With the top landing or the bottom pad turfed as well, up to 3/8 inch. With both ends turfed, the risers do not limit it, but the door threshold and the nose edge still favor short turf. Always count the whole thickness, backing included.

Should the turf wrap over the edge of each step?

It can, and it hides the cut edge of the riser piece. But wrapping makes the nose stick out farther by the turf thickness. The code allows a nose of 3/4 to 1 1/4 inches. If you wrap the nose, turf the riser face below it with the same turf so the projection stays where it was.

How long before you can walk on turfed stairs?

About 12 hours for careful walking. Shaw's step and riser directions give 12 hours before foot traffic, and MAPEI's one-part turf urethane gives about 12 hours to light traffic. Full bond strength takes about 7 days on the urethane sheets that state it.

Do turfed steps need a handrail?

The IRC asks for a handrail on at least one side of any flight with four or more risers. That rule does not depend on the surface. A three-riser garden step needs none under that rule. Adding turf to a four-riser porch stair does not create or remove the need, so check your stair against it before you start.