Oct 304 min read

Outdoor Pool Grotto Design Inspired by Northeastern Geology: Part 1

Updated: Nov 20

Banner for an outdoor pool grotto design featuring a stone-accented pool area with a slide against a backdrop of trees and green landscape.

When you think of a pool grotto, the mind often jumps to tropical or resort-like imagery.

But for this project located in the Northeast, we wanted to take a different approach—one that draws inspiration from the region’s geology.

By choosing colors and materials that reflect the natural stone formations found throughout the area, we’re creating a poolside feature that feels like it’s always been there, growing organically out of the earth itself.

1. Drawing Inspiration from Northeastern Geology for Color Choices

One of the first things we did was choose a color palette that would fit right into the natural landscape. The warm grays, subtle blues, and rust tones we’re using are inspired by the stones found throughout the Northeast, and these colors will help the grotto look like it belongs in the environment.

Grays: You can’t walk far in the Northeast without coming across shades of gray that give the region its character. The warm gray tones we’re using will match these natural stones, helping the grotto almost blend into the surrounding landscape.
Subtle Blues: Some types of granite and slate have a slight blue tint, especially when the light hits them just right. We’re planning to use these subtle blues around the spillway to create a calming, cohesive look where the water and stone feel connected.
Rust Tones: To add a little warmth and contrast, we’re incorporating rust tones inspired by the iron-rich rocks found in the area. These reds and browns will help ground the design and give the grotto a weathered, natural look.

We’re still finalizing these colors, but so far, they’re shaping up to be a perfect fit for the natural landscape.

Illustration of a naturalistic rock waterfall feature with layered stone formations, cascading water, and surrounding greenery, designed to resemble northeastern U.S. geology. The waterfall flows through rugged rocks and is surrounded by plants and shrubs for a realistic, scenic appearance.

2. Choosing Limestone and Granite for the Pool Grotto

When it came to picking textures for the grotto, limestone and granite were obvious choices. Both are native to the Northeast and offer durability and texture.

While we’re still in the early stages of fabrication, the blend of these two stones is already setting the tone for a natural, rugged look.

Limestone: We’re using limestone for its smooth texture and classic look. It’s the perfect material for areas like the staircase and interior of the grotto, where we want a more refined finish. Plus, its warm gray color ties in perfectly with the local landscape.
Granite: Granite will bring a rougher, more textured feel to the grotto, adding variety and visual interest. It’s a hard, durable stone that will be perfect for the spillway and rock features. The natural grain and speckles of color in the granite give it an earthy look that complements the limestone beautifully. Be sure to MIX and MATCH your rollers throughout. Check out our custom texture roller video for an easy DIY project!

The combination of limestone and granite will give the grotto a natural, layered feel that mirrors the rocky outcrops common in the Northeast.

Photo of an outdoor pool area under construction, featuring a large pool slide with a metal ladder and a nearby control box. The area includes various building materials and equipment, with marked planning details on the ground.

3. Grotto Structure: Foam Core, Steel, and GFRC

Building a large grotto that looks like natural rock, without the weight of actual stone, requires some creative construction techniques.

Right now, we’re in the process of shaping and reinforcing the structure using foam core, steel, and glass fiber-reinforced concrete (GFRC).

Foam Core: We’re using foam core to sculpt the grotto’s rocky shapes. This material is lightweight, which makes it easy to form the organic curves and natural formations we’re going for. We’ve already started shaping the core, and it’s exciting to see the design take shape.
Steel Framework: Behind the foam core is a steel framework that gives the grotto its strength. This framework ensures the grotto will be sturdy enough to handle outdoor elements, like rain and snow, without any issues.
GFRC: Once the foam core is shaped, we’ll install a hybrid GFRC shell for the hardcoat of real stone. This material lets us create the detailed textures of limestone and granite, giving the grotto an authentic, natural look while keeping the feature looking great for years to come.

4. Blending the Pool Grotto with Northeastern Geology

A big part of this project is making sure the grotto doesn’t feel out of place. We want it to look like a natural part of the landscape, not something that was just dropped into the backyard.

That’s why we’re putting so much thought into how the colors, materials, and features blend with the surrounding environment.

Spillway Rock and Rockery: The spillway is one of the key features of the grotto. We’re planning to use granite with subtle blues to reflect the water, creating a calm, soothing effect that makes the water and stone feel like they’re one.
Rust Tones: The rust tones we’re using in some of the stone will add warmth and make the grotto feel more natural, like it’s been there for years. These colors reflect the earthy tones found in the region and will help the grotto blend into the surrounding landscape.
Staircase: The stone staircase is designed to be both functional and beautiful. By using limestone and granite, the stairs will feel like they’ve been carved from the same rock as the grotto, creating a seamless transition between the pool area and the grotto.

Photo of an outdoor pool area under construction, featuring a curved water slide leading into a partially finished pool with a stone border. The pool is set on a stamped concrete patio, with lounge chairs and a fenced grassy area and trees in the background, showing autumn foliage.

Stay Tuned for Progress on the 24-foot Pool Grotto

We’re currently making steady progress on the design and construction.

Spillway: The spillway has some unique features, it has to cantilever a fair amount which requires a network of rebar support to counterbalance the weight.
Interior Grotto Section: Inside the grotto, we’re planning to create a cozy, cave-like space where people can relax. The textures of limestone and granite will give it an authentic, natural feel, like a hidden retreat you might find in nature.
Staircase: The stone staircase will provide easy access to the grotto and blend seamlessly with the rest of the structure. We’re making sure the materials match the rest of the grotto, so everything feels cohesive and natural.

By drawing inspiration from Northeast geology and carefully choosing materials like limestone and granite, we’re ensuring the grotto will feel like a natural part of the landscape.

We’re excited about the direction the project is headed and can’t wait to see the finished product—a peaceful, natural escape that fits perfectly into its surroundings. Stay tuned!