How straight and flat should the new swimming pool gunite be before plastering?

Flatness:

- The gunite surface should be sufficiently flat without significant high or low spots. This helps create an even and uniform base for the plaster. Minor irregularities can be smoothed out during the plastering process, but excessive variations can lead to problems with plaster bonding and overall aesthetics.

Straightness:

- Vertically, the gunite walls should be straight and plumb, which means they should be perfectly vertical. Deviations from plumb can cause the plaster to sag, pool, or not adhere properly.

- Horizontally, the pool bottom and other horizontal surfaces should be level and without any significant dips or bumps. This ensures that the plaster is applied evenly and creates a smooth surface for swimmers.

Tolerance:

- Industry standards allow for a tolerance of approximately 1/8 to 1/4 inch (3.2 to 6.4 mm) when it comes to variations from flatness and straightness. This means that minor deviations within these limits are considered acceptable.

Testing and Remediation:

- Before applying the plaster, it's essential to inspect the gunite surface thoroughly for any deviations. Professional pool builders typically use string lines, levels, and other tools to assess straightness and flatness.

- Any significant irregularities beyond acceptable tolerances should be corrected by grinding, cutting, or adding gunite as necessary to create the desired smooth and level surface.

By ensuring that the gunite base is straight and flat to the recommended tolerances, you can improve the overall quality of the plaster finish and enhance the longevity and aesthetic appeal of your swimming pool.