Based on Vastu Shastra principles, the copper strip (or any metal patti used for Vastu correction) should ideally be laid perfectly level and flush with the floor. It should not be laid in a slope, as it is intended to create a straight, consistent, and "invisible" energetic boundary (space surgery) rather than acting as a drainage mechanism. 

Here are the key installation guidelines for copper strips based on Vastu requirements:

Level Placement: The top of the copper strip should be level with the floor, creating a smooth, uninterrupted surface to avoid creating a trip hazard or negative energy trap.

Vertical Embedding: While the strip lies flat on the floor, it is often recommended to insert it vertically into a, shallow, narrow, cut groove in the floor rather than just laying it on top.

Single Piece/Tight Joints: The strip should ideally be a single piece, or if it must have joints, they should be tight, ensuring there is no break in energy flow.

Straight Lines: The strip must be installed in a straight line to properly divide or block energy, rather than in a sloping or crooked manner. 

Why Level Installation is Crucial:

Energy Flow: Vastu relies on geometric, straight-line energy boundaries; a sloped or uneven strip disrupts the energy, which can create a new, unexpected Vastu dosh.

"Space Surgery": The method of inserting a strip into the floor is often called "Space Surgery," which implies a precise, technical intervention rather than a sloping construction.

Appearance and Utility: A perfectly flush and level installation ensures a polished, non-patchy look and is necessary to maintain the integrity of the floor. 

In short, the top of the copper strip must be at one level for maximum effectiveness.