Pouring concrete steps on top of existing slab năm 2024

If your concrete starts looking tired and worn out, it might be time for a refresher. Homeowners may wonder: Can you pour concrete over concrete? This guide will tell you everything you should know about pouring concrete over an existing concrete slab, including the pros and cons and how to know if you should start from scratch.

Can You Pour Concrete Over Concrete?

Yes, you can pour fresh concrete over existing concrete. As long as your concrete is in mint condition, this task is doable. If you decide to pour a new mixture over an old slab, be sure it is at least 2 inches thick.

Can You Pour Over Concrete With Cracks in It?

If the old concrete is severely damaged—with cracks or signs of crumbling—it’s not a good idea to pour fresh concrete over it. Think of the existing concrete slab as a foundation for the new layer. Cracks, settling, and other signs of structural issues will only continue to develop if you pour concrete over the problem areas. It is crucial to repair concrete cracks with appropriate masonry filler that will adhere to the current concrete. Pouring concrete over concrete should only occur once you have a fully repaired clean slate.

Pros of Pouring Concrete Over Concrete

Though you can pour concrete over concrete, it’s not always advisable. Sometimes, there are benefits. But in several cases, you’re better off removing the old concrete before pouring a new layer. Here are some pros and cons to consider.

Time-Saving

Very few home improvement projects require such time-intensive work as breaking up concrete. The time commitment and hard work involved are reasons why many homeowners are interested in just adding a fresh layer on top versus breaking concrete, removing it, clearing off the area, and placing a new load in its place.

Cost-Efficient

Besides time, adding a new layer of concrete at your desired thickness can save money. The average cost of concrete is $120 per cubic yard, making the entire project costly, from removing to adding a new concrete layer. But if you were only pouring concrete over the concrete layer you already have, you can save money by cutting out the labor and disposal costs of removing old concrete.

Boost Appearance

Your concrete might be a little unsightly to look at if it has deep cracks or is crumbling. But by adding another concrete layer on top of it, you can make your old, cracked concrete look like the new kid on the block.

Cons of Pouring Concrete Over Concrete

Photo: Jung Getty / Moment / Getty Images

You shouldn't sweep all concrete problems under the metaphorical rug with a new layer. Pouring concrete over concrete can lead to issues either immediately or several years down the line.

Decrease Life Span

Concrete can last for up to 100 years under the right conditions. But if you pour a new layer of concrete over a much older one, you won’t get nearly as many years out of it since the older layer of concrete underneath will show signs of aging, like sinking, more quickly than your top one. This inconsistent aging will cause you to replace your entire slab sooner than you thought (or wanted to).

Increases Height

It goes without saying, but adding a concrete layer to the one you already have will add some height to your slab’s overall level. Height might not be an issue for some homeowners. For one, the added layer could create a tripping hazard or keep exterior doors from opening correctly. The weight of the concrete could also weigh down the original one below, throwing its level off-kilter if it sinks.

More Cracking

Large cracks throughout your concrete slab can be caused by problems underneath it, like improper leveling and tree roots. So, while you can place a new concrete layer on top of the original one, you'll only cover the cracks briefly before the top layer starts cracking, especially if your two layers bond to each other.

Can You Add Stamped Concrete Over Existing Concrete?

Adding a stamped concrete overlay to existing concrete is a doable—and very stylish—solution. The process of stamping concrete is a type of concrete forming that adds a design to the texture of the overlay before it dries. Depending on your preference and budget, designers can add simple or complex designs that imitate brick and stone.

A stamped concrete overlay is very similar to pouring concrete over concrete, but the installation process includes appropriate bonding agents to ensure stability. The cost of stamped concrete is also higher than a traditional overlay—between $8 and $28 per square foot—but many prefer the look and cost compared to traditional pavers.

And while stamped concrete is a common alternative to ripping up the concrete, you still need a solid base for the process to work. The original concrete slab should be void of cracks, heaving, sinking, or damage from tree roots to receive the stamped topping.

Pouring Concrete Over Concrete vs. Replacing

While pouring concrete on an existing layer isn’t impossible, it’s also not foolproof. Your first step to ensure that your new concrete slab lasts is to fix any problems impacting the foundational concrete. If you don’t, you’ll face the same ones with your new slab.

If the damage is extensive and there’s no hope of saving your first slab without causing damage to your new layer, save yourself time and future problems by removing and replacing the existing slab with a new one. Yes, pouring concrete over concrete can save you money in the short term, but it’s not worth it if you’re removing both layers within a few years (or months) for the same reason.

If you do need to replace your concrete slab, contact a concrete repair company for the job.

How to Properly Pour Concrete Over Concrete

Now that you know whether this project is possible for your slab, here’s a rough breakdown of how to properly pour concrete over concrete:

• Step 1: Clean your existing slab of all dirt, debris, dust, and any particles that would cause the new slab not to adhere correctly.
• Step 2: Create a perimeter with string and stakes.
• Step 3: Install rebar or fiber mesh to the base.
• Step 4: Decide if you want your concrete bonded or not. If so, prime your existing layer. And if not, install a piece of material to break the bond, like tar paper or sand.
• Step 5: Mix and pour concrete (or self-leveling concrete) over the existing layer.
• Step 6: Level the concrete if using traditional concrete, smooth it out, and wait for it to cure.

Alternatives to Pouring Concrete Over Old Concrete

Before you add a fresh layer of concrete over existing concrete, take a look at the other options in the industry. Repairs, replacement, and resurfacing are your best bets, though each has pros and cons.

Concrete Repairs

Cracks, holes, and concrete spalling are all fixable when you hire a professional, but whether they're worth the hassle is another story. The cost of repairing a cracked concrete driveway, for example, depends on the extent of necessary repairs but ranges anywhere from $1 to $25 per square foot. If you're on the fence about repairing or starting over, always speak with a local concrete driveway pro to compare prices.

Concrete Resurfacing

Concrete resurfacing is very similar to pouring concrete over concrete, but often refers to a slightly different process. After ensuring the existing concrete slab is in good shape, contractors will add a thin layer of concrete—either over top of or combined with a bonding agent—to level out the surface. The end result is a flat, smooth overlay you can choose to stain, stamp, or polish just as you would a fresh layer of concrete.

Concrete Replacement

Let's say you're ready to tear up the old concrete and start from the soil up. If you go this route, keep a few costs in mind. Demolishing and removing old concrete costs around $2 to $6 per square foot. Laying a new concrete slab costs an additional $4 to $8 per square foot, not including the cost of additional drainage or designs.

Bry'Ana Arvie contributed to this piece.

Frequently Asked Questions

No, wet concrete will not bond to dry concrete without an additional bonding agent. The common alternative is adding a sand or gravel layer under a concrete slab to enhance bonding and create a stable foundation. The right choice depends on the height and thickness of your two slabs, local laws, and the use of the specific concrete slab.

You'll find a slurry of natural and synthetic polymers, rubbers, epoxies, and resins used to bond old concrete to new concrete. The right bonding agent depends on the method of concrete pouring you choose and whether you're adhering concrete over concrete or concrete over sand and gravel. Some concrete resurfacing mixtures contain bonding chemicals as well.

Can you pour concrete steps on top of concrete?

Though you can pour concrete over concrete, it's not always advisable. Sometimes, there are benefits. But in several cases, you're better off removing the old concrete before pouring a new layer. Here are some pros and cons to consider.

Is it OK to pour concrete over existing concrete slab?

Concrete, no matter where you have it in your home, is durable and long lasting. However, when it does come time to replace your concrete - be it your driveway or backyard patio - there are a few steps to keep in mind. First, know that you can absolutely pour new concrete over existing concrete.

How do you build steps on a concrete slab?

Instructions.

Measure Rise and Run. Measure the rise and run of the area where you plan to place the steps. ... .

Lay Out Footings. Lay out footings 3 inches wider than the steps. ... .

Anchor Concrete Steps (Optional) ... .

Outline Steps. ... .

Check Square, Level, and Plumb. ... .

Install Riser Forms. ... .

Attach Braces. ... .

Build Perpendicular Steps (Optional).

Will new concrete stick to old concrete?

Fact: Fresh wet concrete does not normally bond well to existing dry concrete. Do you remember elementary school where one of the subjects on which you were graded was “plays well with others”? Concrete would have gotten an F. There is nothing in basic portland cement that will act as a bonding agent.