How to Attach Kitchen Island to Floor Securely

The kitchen island – often the heart of the home, a multi-functional hub for cooking, dining, entertaining, and even homework. It’s a focal point that adds significant value, aesthetics, and utility to your kitchen. But for all its glory, an island is only as good as its foundation. A wobbly or unsecured kitchen island isn’t just an annoyance; it’s a serious safety hazard, a potential source of damage, and a constant worry.

Imagine leaning against your beautiful, heavily laden island, only for it to shift unexpectedly. Or worse, a child pulling on it, causing it to tip. Such scenarios highlight the critical importance of proper installation. This comprehensive guide will walk you through everything you need to know about how to attach kitchen island to floor securely, ensuring it stands firm for years to come. Whether you’re a seasoned DIY enthusiast or a first-time home improver, we’ll provide actionable steps, expert insights, and practical tips to achieve a professional-grade installation.

From understanding different attachment methods to navigating various flooring types, we’ll cover the essential preparations, tools, and techniques. By the end of this post, you’ll have the confidence and knowledge to tackle this crucial step in your kitchen renovation, transforming your island from a freestanding piece to an integral, unyielding part of your home. Let’s dive in and learn how to securely attach your kitchen island to the floor.

Quick Answers to Common Questions

Is it really necessary to attach a kitchen island to the floor?

Yes, absolutely! For safety and stability, learning how to attach kitchen island to floor is crucial, especially if it has seating or heavy countertop materials, to prevent tipping.

What’s the most common way to attach a kitchen island to the floor?

The most common method for how to attach kitchen island to floor involves screwing through the island’s base cabinets directly into the subfloor or using appropriate anchors for concrete.

What kind of fasteners should I use for how to attach kitchen island to floor?

For wooden subfloors, use long construction screws (e.g., 2.5-3 inches). If you have a concrete slab, you’ll need specialized concrete anchors or wedge anchors to properly attach the kitchen island to the floor.

How do I make sure the island is perfectly level before attaching it?

Before you learn how to attach kitchen island to floor, use shims under the island’s base to achieve perfect levelness in all directions. Once level, you can secure the shims in place or trim them before the final attachment.

Will attaching the island damage my flooring permanently?

While attaching requires drilling holes, these are usually hidden under the island’s base. If you ever remove the island, the small holes can typically be patched, but it is considered a semi-permanent installation.

Why Securing Your Kitchen Island is Non-Negotiable

Before we delve into the “how-to,” it’s vital to understand the “why.” A securely anchored kitchen island isn’t just about aesthetics; it’s about safety, functionality, and long-term durability. Skipping this crucial step can lead to a host of problems that far outweigh the effort of proper installation.

Safety First: Preventing Accidents and Injuries

This is, without a doubt, the most critical reason to attach kitchen island to floor. An unsecured island poses a significant tipping hazard, especially in homes with children or pets. The weight of a countertop, appliances, or even just someone leaning on it can cause it to become unstable. According to consumer safety reports, tip-over incidents, particularly involving furniture, can lead to serious injuries, including concussions, fractures, and even fatalities. A properly anchored island eliminates this risk, providing a stable surface that won’t budge under pressure.

Stability for Everyday Use and Heavy Tasks

Think about the everyday activities that happen at a kitchen island: kneading dough, chopping vegetables with force, using a stand mixer, or even just setting down heavy grocery bags. If your island isn’t firmly anchored, you’ll experience frustrating wobbles, shifts, and instability. This not only makes tasks more difficult but can also be dangerous, leading to dropped items or cuts. A securely installed island provides a solid, unwavering workstation, allowing you to perform all your culinary tasks with confidence and ease. It’s about enhancing the overall functionality and enjoyment of your kitchen space.

Protecting Your Home and Investment

An island that moves or shifts can cause damage to your flooring, walls, and even the island itself. Scratches, dents, or gouges in your expensive hardwood or tile are a common consequence of an unsecured unit. Over time, constant movement can also weaken the island’s structure, leading to costly repairs. By taking the time to secure your kitchen island properly, you’re protecting your investment in both the island and your home’s finishes. Moreover, a well-installed island adds significant value to your property, making it more attractive to potential buyers should you ever decide to sell.

Compliance and Professional Standards

In many regions, building codes may have specific requirements for anchoring large, heavy kitchen islands, especially if they include plumbing or electrical connections. While specific residential codes vary, the general principle is that permanent fixtures should be stable and safe. Professional installers will always fasten a kitchen island to the floor as a standard practice. Adhering to these standards ensures your home is safe and compliant, preventing potential issues during inspections or insurance claims.

Essential Preparations Before You Attach Your Kitchen Island to Floor

Successful installation begins long before you pick up a drill. Thorough preparation is key to ensuring a smooth process and a perfectly stable island. Don’t underestimate the importance of these preliminary steps.

1. Finalize Island Placement and Layout

Before you even think about attaching anything, confirm the exact location of your island. Use painter’s tape to outline its footprint on the floor. Walk around it, open cabinet doors, and ensure there’s adequate clearance. A general rule of thumb is to have at least 36-42 inches of clear pathway around the island for comfortable movement. This is your last chance to make adjustments to the layout before committing to the installation.

2. Check for Utilities: Crucial for Safety

This is arguably the most critical preparatory step. If your island will have plumbing (sink, dishwasher) or electrical outlets, you absolutely must verify the location of these lines in the floor before drilling. Use a stud finder that can detect electrical wires, pipes, and other obstructions. For an even more accurate assessment, especially if you’re uncertain, consider using an infrared camera or consulting with a professional. Drilling into a water pipe or electrical line can be extremely dangerous and costly. Mark all detected utility lines clearly on the floor to avoid them during installation. This step is non-negotiable for anyone learning how to attach kitchen island to floor.

3. Assess Your Flooring Type and Subfloor

The method you use to attach your kitchen island to the floor will heavily depend on your existing flooring and the subfloor beneath it.

• Hardwood/Laminate/Vinyl: These often sit atop a wood subfloor. You’ll likely need to drill through the finished floor into the subfloor or joists.
• Tile: Drilling through tile requires specific techniques and drill bits to prevent cracking. The goal is to anchor into the subfloor beneath.
• Concrete Slab: This requires different anchoring hardware, such as concrete anchors or lag shields.
• Radiant Heating: If you have radiant heating coils embedded in your floor, drilling is a definite no-go. You’ll need alternative attachment methods or professional consultation.

Understanding your floor composition will guide your choice of fasteners and tools.

4. Gather All Necessary Tools and Materials

Having everything on hand before you start will save you time and frustration. Here’s a typical list, which may vary slightly based on your chosen method and floor type:

• Power Drill/Impact Driver: Essential for drilling pilot holes and driving screws.
• Drill Bits: Wood bits, masonry bits (for tile/concrete), and spade bits (if using blocking).
• Stud Finder: To locate joists and avoid utilities.
• Measuring Tape, Level, Pencil/Marker: For accurate placement and marking.
• Safety Glasses and Gloves: Always prioritize safety.
• Shims: To level the island if your floor isn’t perfectly even.
• Fasteners: Appropriate length and type for your method (lag screws, cabinet screws, concrete anchors).
• Wood Blocking/Cleats: If using the blocking method (2x4s or similar).
• Construction Adhesive: Optional, but can add extra stability for blocking.
• Caulk Gun and Construction Adhesive/Liquid Nails: If you plan to use adhesive for blocking.
• Grout or Caulk: To seal around screws if drilling through tile or for a finished look.

Popular Methods to Attach Kitchen Island to Floor

There isn’t a one-size-fits-all solution for anchoring a kitchen island. The best method depends on your island’s construction, your flooring type, and your personal preference for a secure hold. Here are the most common and effective techniques.

1. The Blocking and Cleats Method (Most Common and Versatile)

This is often the preferred method for finished floors and is highly recommended for its strength and minimal floor damage. It involves creating a wooden frame (blocking) on the floor, inside the island’s footprint, and then screwing the island’s base into this frame.

• How it works: You cut 2x4s or 2x6s to create a rectangular frame that fits snugly inside the island’s toe kick area or base. This frame is then securely fastened to the subfloor. Once the blocking is down, you set the island over it and drive screws from inside the island’s base into the blocking.
• Pros: Extremely strong, hides fasteners, works well with various flooring types (especially hardwood and tile), allows for easier future removal if needed without extensive damage to the island. It effectively spreads the load.
• Cons: Requires precise measurements and carpentry skills for the blocking, adds a small amount of height to the island if not recessed.
• Best for: Almost all kitchen islands, especially those with a toe kick area, and most finished floors where you want to conceal the attachment points.

2. Lag Screws/Bolts Directly into Subfloor or Joists (Maximum Strength)

For the ultimate in strength, particularly for very heavy islands or those without a toe kick, direct fastening with long lag screws or bolts is an option. This method bypasses the need for internal blocking by driving fasteners directly through the island’s base into the structural elements below.

• How it works: After precisely marking the island’s position, you drill pilot holes through the bottom of the island’s base (usually inside the cabinet boxes) and directly into the subfloor or floor joists. Long lag screws or heavy-duty cabinet screws are then driven through the island and into the subfloor/joist, creating a direct, robust connection. Washers are often used under the screw heads for better grip and to prevent pull-through.
• Pros: Provides an incredibly strong attachment, ideal for very heavy islands or granite/stone countertops, can be less visible if screws are strategically placed within cabinet interiors.
• Cons: Requires precise alignment with joists, can be more challenging to remove without damaging the island base, visible fasteners if not cleverly hidden, might not be suitable for all flooring types (e.g., concrete without special anchors).
• Best for: Heavily used islands, islands with integrated appliances, or when you need the absolute strongest connection. Ideal when you have clear access to joists.

3. Cabinet Clips or Brackets (For Modular or Existing Cabinetry Integration)

If your island is made up of individual base cabinets or if you’re attaching it to an existing run of cabinetry, cabinet clips or specialized brackets offer a clean and effective solution.

• How it works: These metal or plastic clips are designed to join cabinet boxes together, or to secure a cabinet base to the floor. They are typically screwed into the cabinet’s frame or base and then into the floor, or into adjacent cabinets.
• Pros: Relatively easy to install, less invasive on the flooring than direct lag screws, can be used to join multiple cabinet units to form an island, provides a secure and stable connection.
• Cons: May not be as strong as direct lag screws for very heavy, standalone islands, some clips might be visible if not concealed properly.
• Best for: Modular kitchen islands constructed from standard base cabinets, or when integrating a new island with existing cabinetry.

4. Construction Adhesive (Supplemental or for Specific Scenarios)

While not typically recommended as the sole method for attaching a kitchen island to the floor due to its limited long-term reliability against tipping forces, construction adhesive can be a valuable supplemental fastener or a primary choice in specific, lighter-duty applications where drilling is absolutely not an option (e.g., radiant heating).

• How it works: A strong construction adhesive (like Liquid Nails or a polyurethane-based adhesive) is applied to the bottom edges of the island’s base or to the blocking before it’s set in place. The island is then pressed firmly onto the floor.
• Pros: No drilling into the finished floor (if used with blocking), can provide additional stability when combined with mechanical fasteners, an option for floors with radiant heating.
• Cons: Not strong enough on its own to prevent tipping hazards for a heavy island, difficult to remove without damaging the floor, takes time to cure, long-term bond strength can be affected by moisture or temperature fluctuations.
• Best for: As a secondary reinforcement with mechanical fasteners, or for very light, non-load-bearing islands where drilling is impossible, with careful consideration and understanding of its limitations.

For most DIYers and professional installations, the blocking and cleats method offers the best balance of strength, ease of installation, and floor protection. For the remainder of this guide, we will focus on this method as it’s highly versatile and robust for how to attach kitchen island to floor.

Step-by-Step Guide: Attaching Your Kitchen Island Using Blocking

This section provides a detailed walkthrough for using the blocking method, ensuring your island is as solid as the ground it stands on. This is the most common and highly recommended approach for attaching a kitchen island to the floor.

1. Tools and Materials You’ll Need (Recap and Specifics)

Before you begin, ensure you have all the necessary tools and materials at arm’s reach.

• Island Cabinets: Assembled and ready.
• Wood Blocking: 2x4s or 2x6s (pressure-treated if in a damp environment, though less common for interior kitchen use).
• Power Drill/Impact Driver: With clutch settings.
• Drill Bits: Pilot bits appropriate for your screws (wood, tile, concrete). Larger spade or Forstner bit if recessing screw heads.
• Stud Finder: Essential for locating floor joists and avoiding utilities.
• Measuring Tape, Long Level, Straight Edge, Pencil/Marker.
• Shims: Wooden or plastic, for leveling.
• Construction Adhesive: (Optional, but recommended for extra bond for blocking).
• Wood Screws: 2.5-3 inch construction screws for attaching blocking to subfloor.
• Cabinet Screws: 1.5-2 inch screws for attaching island base to blocking.
• Safety Glasses, Hearing Protection, Work Gloves.

2. Marking the Island’s Footprint and Locating Joists

1. Position the Island: Carefully place your assembled kitchen island exactly where you want it. Use a level to ensure it’s sitting plumb and level on all sides. Use shims if necessary to achieve a level surface – the floor may not be perfectly even.
2. Trace the Base: Once perfectly positioned and leveled, use a pencil or marker to trace the exact outline of the island’s base (specifically the toe-kick area) onto the floor. This is where your blocking will go.
3. Locate Joists/Subfloor: Carefully slide the island aside. Now, using your stud finder, scan the marked area for floor joists. Mark the center of any joists you find within your island’s footprint. If you have a concrete slab, you’ll be drilling directly into the concrete, so mark your desired anchor points. Remember to be extra cautious and double-check for any utility lines you marked during preparation.

3. Installing the Blocking to the Floor

1. Cut Blocking: Measure the inside dimensions of your island’s toe kick area. Cut your 2x4s or 2x6s to create a rectangular frame that will fit snugly inside this area. You want the blocking to be close to the perimeter but not interfere with any internal cabinet structures or adjustable feet.
2. Test Fit: Place the cut blocking frame on the floor within your traced outline. Ensure it fits correctly and doesn’t interfere with the island’s seating.
3. Apply Adhesive (Optional but Recommended): If using, apply a bead of construction adhesive along the bottom edge of the blocking pieces before securing them. This provides an extra layer of stability.
4. Secure Blocking to Floor:
   • For Wood Subfloor: Place the blocking. Drill pilot holes through the blocking and into the subfloor, aiming for joists where possible for maximum hold. Use 2.5-3 inch construction screws, driving them every 12-16 inches. Ensure the screw heads are flush or slightly recessed. If you’re drilling through finished flooring (hardwood, laminate, etc.), choose a drill bit appropriate for that material first, then switch to a wood bit for the subfloor.
   • For Concrete Slab: Use a hammer drill and appropriate masonry bit to drill pilot holes through the blocking and into the concrete. Insert concrete anchors (e.g., Tapcons, sleeve anchors, or wedge anchors) and secure the blocking according to the anchor manufacturer’s instructions.
   • For Tile Floors: Use a specialized tile drill bit (diamond-tipped or carbide-tipped) to drill through the tile first, taking care not to crack it. Once through the tile, switch to a wood or masonry bit to drill into the subfloor or concrete. Then proceed with the appropriate screws/anchors.
5. Check Level: Use your level to ensure the top surface of the installed blocking is level. Shims can be used underneath the blocking if your subfloor isn’t perfectly flat.

4. Positioning and Securing the Island to the Blocking

1. Move Island into Place: Carefully slide the island back over the installed blocking frame. Ensure it aligns perfectly with your initial traced outline and is centered over the blocking.
2. Level Again: Double-check the island’s level using your long level. Adjust with shims underneath the island’s base (between the island and the blocking) if needed, ensuring the shims are hidden once installation is complete.
3. Drill Pilot Holes: From inside the island’s cabinet boxes or toe-kick area, drill pilot holes down through the bottom of the island’s base and into the blocking. Aim for at least 4-6 attachment points, ideally one near each corner and a couple along the longer sides.
4. Fasten Island to Blocking: Drive 1.5-2 inch cabinet screws (or appropriate length for your island’s base thickness) through the pilot holes in the island’s base and into the blocking. Ensure the screws are driven straight and are tight, but do not overtighten, which can strip the wood or damage the island. The goal is a secure, unyielding connection.

5. Finishing Touches

Once the island is securely fastened, double-check all connections. If you used shims, ensure they are neatly trimmed and hidden. Consider applying a bead of caulk around the base of the island where it meets the floor for a finished look and to prevent dirt accumulation. If your island has adjustable feet, ensure they are retracted or removed if the island is now solely supported by the blocking. Your island should now be rock-solid and ready for years of use!

Addressing Different Flooring Types and Potential Challenges

While the blocking method is versatile, each flooring type presents unique considerations when learning how to install kitchen island to floor.

Hardwood Floors

• Challenge: Drilling through finished hardwood requires care to prevent splitting or splintering the wood.
• Solution: Use a sharp wood-specific drill bit. Start with a smaller pilot hole and gradually increase the size if necessary. Ensure the screw heads sit flush or are slightly countersunk to avoid snags or damage. If you ever remove the island, the screw holes in hardwood can be filled and refinished, but it’s more noticeable than in a subfloor.

Tile Floors

• Challenge: Tile is brittle and can crack if not drilled properly. Drilling into grout lines is generally not recommended as it provides less grip and can compromise the grout.
• Solution: Use a specialized tile or masonry drill bit (diamond-tipped for ceramic/porcelain, carbide-tipped for softer tiles). Start drilling at a slow speed with light pressure, or use a piece of painter’s tape to prevent the bit from wandering. Keep the drill bit cool by occasionally spraying with water. Once through the tile, switch to a wood or masonry bit to penetrate the subfloor or concrete below. Carefully caulk around the screw heads if desired for a watertight seal and aesthetic finish.

Concrete Slabs

• Challenge: Requires specialized tools and fasteners.
• Solution: You’ll need a hammer drill and masonry bits. Use appropriate concrete anchors such as Tapcons (self-tapping concrete screws), sleeve anchors, or wedge anchors. Ensure the pilot holes are drilled to the correct depth and diameter for your chosen anchors, as per the manufacturer’s instructions. This method creates a very strong bond, crucial for anchoring a kitchen island on a concrete foundation.

Laminate/Vinyl Floors

• Challenge: These floors are typically thinner and designed to “float” over the subfloor. Drilling directly through them can compromise their integrity or warranty.
• Solution: Similar to hardwood, use a sharp wood bit. Be aware that drilling through a floating floor can pin it down, potentially leading to buckling or gaps in the future if the floor needs to expand/contract. The blocking method is excellent here because you’re distributing the load and securing into the subfloor beneath.

Radiant Heating Considerations

• Challenge: Drilling into a floor with embedded radiant heating coils or electric mats is a catastrophic mistake.
• Solution: If you have radiant heating, drilling directly through the floor is not an option. You must explore alternative attachment methods:
  • Strong Construction Adhesive: As mentioned, this can be used as a primary attachment if the island is relatively light and not subject to heavy lateral forces. However, it’s generally not recommended as the sole method for stability.
  • Island Design: Consider an island design that doesn’t require floor attachment, such as one with very heavy legs and a low center of gravity, or one that is secured to an adjacent wall.
  • Professional Consultation: If in doubt, consult with a radiant heating specialist or a structural engineer to explore safe attachment options or design modifications.

Long-Term Stability and Maintenance for Your Kitchen Island

Once your kitchen island is securely attached, the job isn’t entirely over. A little ongoing attention ensures its long-term stability and prevents future issues. Understanding how to keep kitchen island from moving is an ongoing commitment.

Regular Checks for Looseness

Over time, due to daily use, minor shifts in your home’s foundation, or even just the expansion and contraction of materials, fasteners can sometimes loosen. Make it a habit to periodically check your island for any signs of wobbling or movement. A simple test involves firmly pushing against the island from different sides. If you detect any give, it’s time for a quick inspection.

Tightening Fasteners

If you discover any looseness, the first step is to locate the original attachment screws (from inside the cabinet base, or where the blocking is secured to the floor). Use a screwdriver or drill to carefully tighten them. Be mindful not to overtighten, as this can strip the screw hole. If a screw hole is stripped, you may need to use a slightly longer or wider screw, or insert a wood dowel and glue it into the hole before redrilling for the original screw.

Addressing Floor-Leveling Issues

If your home settles over many years, or if your floor wasn’t perfectly level to begin with, the island might develop a slight tilt. If this happens, you may need to re-level the island by adding or adjusting shims between the island base and the blocking. This might require temporarily unscrewing the island, adjusting the shims, and then re-securing it. Maintaining a level surface is crucial for both stability and the longevity of your countertops.

Protecting Your Floor

While the blocking method minimizes direct contact with the finished floor, it’s still good practice to ensure the toe kick or base of the island is not causing any abrasion. If you’ve used any shims that extend past the island’s base, trim them neatly. For added protection, you can apply a thin bead of clear silicone caulk around the base where it meets the floor, not only for aesthetics but also to prevent moisture or debris from getting underneath. This is particularly important for wooden floors to prevent moisture damage.

Professional Inspection for Complex Issues

If you’re experiencing significant or recurring issues with island stability, or if you suspect structural problems with your floor or subfloor, it’s always best to consult with a professional carpenter, contractor, or structural engineer. They can diagnose underlying problems and recommend appropriate solutions to ensure your kitchen island remains a safe and reliable fixture in your home.

Comparative Analysis of Kitchen Island Attachment Methods

Choosing the right method for attaching your kitchen island to the floor depends on several factors. This table provides a quick comparative overview to help you make an informed decision.

Attachment Method	Strength & Stability	Installation Difficulty	Floor Type Suitability	Visibility of Fasteners	Ease of Removal
Blocking & Cleats	Excellent	Moderate (requires precise cuts)	All (with appropriate drilling)	Hidden (inside island base)	Moderate (remove screws from island & blocking)
Lag Screws/Bolts Directly into Subfloor/Joists	Superior	Moderate (requires accurate joist finding)	Wood Subfloor, Concrete (with anchors)	Hidden (inside island base)	Difficult (long, deep screws)
Cabinet Clips/Brackets	Good to Excellent	Easy to Moderate	All (screws into cabinet, then floor)	Minimal (can be hidden)	Easy (unclip/unscrew)
Construction Adhesive (Sole Method)	Poor (not recommended for primary)	Easy	All (no drilling)	None	Extremely Difficult (can damage floor)

*Note: “Floor Type Suitability” assumes proper drilling techniques and fasteners are used for non-wood subfloors. Construction adhesive as a sole method is strongly discouraged for heavy, load-bearing islands due to safety concerns.

Conclusion: A Secure Island, A Safer Kitchen

Attaching your kitchen island to the floor is more than just a step in a renovation project; it’s an investment in the safety, functionality, and longevity of your most used space. A properly secured island transforms from a potential hazard into a rock-solid centerpiece, ready to handle all the demands of daily life, from frantic meal prep to lively family gatherings. We’ve explored the critical reasons why this step is non-negotiable, delved into essential preparations, and provided detailed guides on the most effective methods, with a focus on the robust blocking technique.

Remember, attention to detail in planning, meticulous execution during installation, and an understanding of your specific flooring challenges will pave the way for a successful outcome. Don’t rush the process, double-check your measurements, and always prioritize safety, especially when dealing with utilities. Whether you opted for the versatile blocking method, the sheer strength of lag screws, or integrating with cabinet clips, you’ve taken a crucial step towards a more secure and enjoyable kitchen environment.

With your newfound knowledge and the actionable steps outlined in this comprehensive guide, you can confidently undertake the task of securing your kitchen island. The satisfaction of a perfectly stable island that stands firm under every culinary adventure and family moment is immeasurable. Enjoy your beautiful, functional, and most importantly, safe kitchen for years to come!

Frequently Asked Questions

Why is it important to securely attach my kitchen island to the floor?

Attaching your kitchen island to the floor is crucial for safety and stability. It prevents the island from tipping over, especially if it’s heavily loaded or has children climbing on it, and ensures a stable surface for meal prep and dining.

What are the most common methods to attach kitchen island to floor?

The most common methods include using L-brackets secured to the inside of the island’s base and the subfloor, toenailing through the island’s base directly into the floor, or using internal wood blocking. Each method aims to create a strong, stable connection that prevents movement.

What tools and materials will I need to attach kitchen island to floor?

You’ll typically need a drill, appropriate screws (e.g., cabinet screws, construction screws), a level, shims for leveling, and potentially L-brackets or wood blocking. Always choose screws long enough to penetrate the subfloor adequately without going through to the floor below.

How do I attach my kitchen island to a floor with tile or hardwood?

When attaching to tile or hardwood, you must drill pilot holes carefully to avoid cracking tiles or splitting wood. For tile, use a masonry bit initially; for hardwood, a standard wood bit. Ensure screws are long enough to pass through the finished flooring and into the subfloor or joist.

How can I ensure the kitchen island is perfectly level before I attach it to the floor?

Use a long spirit level to check the top and sides of the island. If it’s not level, place shims underneath the island’s base at the low points. Once level, you can secure the shims in place with small nails or glue before fastening the island to the floor.

Should I try to attach the kitchen island to floor joists or just the subfloor?

Whenever possible, it’s best to attach your kitchen island directly to floor joists for maximum security and stability. If joists aren’t accessible, securing it firmly to the subfloor with appropriate screws and potentially adding blocking underneath will provide sufficient stability for most islands. Always locate joists with a stud finder if possible.