Attaching countertop to side of kitchen cabinet

The oak top is bolted to steel cantilever brackets
Brackets are:
Fixed into brick/block wall, OR
Fixed into a steel rail hidden behind the cabinets
A single metal leg supports the outer corner

You will need to support the counter top on the overhang.
as over time it will warp and drop.

To create a floating breakfast bar with your solid oak countertop, here’s a simpler plan:

1. Use Strong Brackets: Install heavy-duty brackets (like L-brackets or cantilever brackets) under the oak top. Attach these to the cabinet frame and ideally to wall studs if possible.
2. Reinforce the Cabinet: Since chipboard isn’t very strong, reinforce it by adding solid wood or metal plates where the brackets attach. This will help support the oak’s weight.
3. Limit the Overhang: Keep the overhang to around 12–15 inches to avoid sagging.

With these steps, you should achieve the floating effect. If you have a large overhang, consider adding a discreet leg at the end for extra support.

You will need 2 legs on the end of the new counter top piece and where is joint it can be used 2-3 brackets ( metel plates ) instead 2 legs

It sounds like a beautiful project! Attaching a solid oak countertop to a laminated chipboard cabinet can be a bit tricky due to the weight of the wood. Here are some considerations:

1. Weight Support: Since oak is heavy, attaching it directly to laminated chipboard may require reinforcement. Without proper support, the chipboard could potentially sag or break over time, especially if the countertop is used as a breakfast bar.

2. Brackets and Supports: Metal supports or brackets could help achieve the "floating" look, but they need to be heavy-duty and installed directly into wall studs or reinforced with additional supports. Look for countertop support brackets specifically designed to hold heavy materials like solid wood.

3. Alternative Reinforcement: If you want to avoid visible legs at the end, you could consider using a mix of hidden brackets and installing a supporting framework under the oak that extends back to the wall or other secure mounting points. This could provide the strength needed without disrupting the "floating" appearance.

4. Legs for Extra Stability: While not as sleek as a floating style, adding one or two legs at the far end could ensure stability and prevent sagging, especially for a longer extension.

Extending your kitchen counter to create a breakfast bar can be a great project! Here are some considerations for making it work:

Weight Distribution: Solid oak is quite heavy, so attaching it as a floating countertop can be tricky. Without proper support, the weight could cause the chipboard to sag or fail.

Metal Supports: If you want a floating effect, using metal brackets or supports under the countertop is essential. You can attach these to the wall or the cabinet base for additional stability. Ensure the brackets are rated for the weight of the oak.

Legs for Extra Support: While you might aim for a floating look, adding legs at both ends will provide necessary support. You can choose stylish legs that match your decor, which can enhance the overall aesthetic.

Installation: When attaching the oak countertop, use wood glue and screws to secure it to the chipboard and the metal supports. Make sure to pre-drill holes to prevent splitting.

Overhang: If you have an overhang for seating, keep it within a reasonable length (typically no more than 12-15 inches) to minimize stress on the chipboard.

By combining metal supports with legs, you can achieve both the floating look and the necessary stability for your extended countertop.