Whether you're about to become new hot tub owners, planning a larger spa installation, or want to transform an unloved corner of your garden with a gravel pad, concrete slab, or solid foundation, this hot tub base step-by-step tutorial is for you!
Since moving into our new house, we inherited a very overgrown and sad rose bed set within a large concrete slab.
Sadly, the roses were established, but its location outside our back garden felt like the perfect place for a new hot tub - especially so we could soak our achy bodies after a hard day of renovating.
We needed to do the hard work of relocating the roses, digging out the topsoil, and filling it with hardcore to create a solid base that could withstand the total weight of a full hot tub. Let me show you how!
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✔️ Why You'll Love This Project
Here are a handful of reasons why we think you'll love installing the perfect hot tub base:
- No need for a concrete foundation or slab
- It's good DIY exercise - no gym fees included!
- Uses gravel grids or EZ Pads, which help stabilise the gravel
- Creates a heavenly place to relax and unwind daily
- You don't need to hire a pro - just bring muscles!
- Perfect for larger spas, not just an inflatable hot tub
- Transforms an unloved space and gives it a purpose
- Satisfying to complete and create something bespoke
- A gravel pad or crushed stone base is budget-friendly and holds the weight of a hot tub
- Gravel bases are easy to maintain, create good drainage, and provide a sturdy hot tub foundation
❓Why the Right Hot Tub Foundation for Your Needs?
When looking into hot tub options, I recommend asking your hot tub dealer. We were informed that a minimum 4" concrete pad is sufficient for the weight of a 5-person spa.
It's not only important for a foundation to be strong enough to handle the total weight of a hot tub, but also for the base to be a level surface or solid foundation. This ensures even weight distribution and prevents cracking under stress.
A flat surface is also key to preventing rain water puddles. That's where pea gravel and gravel grids come in handy. They're DIY-friendly and allow water to drain away quickly.
⚒️Tools and Material Notes
You can refer to my shorter printable guide in the how-to card at the bottom of this post. However, I recommend reading the entire post as I have more detailed tips, tricks, and step-by-step images.
Please note that as an Amazon Associate, I earn from qualifying purchases made through affiliate links.
Tools
- Shovel
- Post hole digger
- Tamper or rammer
- Strimmer
- Rake
- Garden fork
- Wheelbarrow or garden trailer
Materials
- Gravel grids for a grabel base or EZ Pads
- Medium-grade gravel or pea gravel recommended
- MOT Type 1 aggregate
📋 Step by Step Instructions
1. Remove vegetation:
My rose bed was so neglected it had turf in it. I used a fork to pry out all the grass, weeds, and brambles before carefully relocating the rose bushes.
2. Dig down to the required level
You need 4-6" of hardcore and 2" for the gravel grids filled with gravel.
I decided to dig 6" below my desired final level. There's a lot of topsoil to remove, so either find a place in your garden for it or organise a skip.
3. Lay a weed control membrane:
Even if the soil looks clean, weeds can hide anywhere.
Cover the entire area with a good quality membrane to prevent regrowth.
4. Lay and compact hardcore
Use MOT Type 1 aggregate (2" to dust). Compact with a rammer or mechanical whacker - the material locks together, creating a solid base.
Drag a straight edge across to ensure a level foundation, moving material from high points to low points if needed.
5. Install gravel grids
Cut and lay all the full grids first. These lock together and reduce movement under the hot tub's weight.
EZ Pads or other synthetic hot tub pads are great options for additional stability.
6. Fill grids with gravel
Tip gravel into all the grids equally, raking until it's level.
This reinforces the solid base and completes the gravel pad.
Tip: Use the best quality weed control you can buy, or consider using a double or triple layer, as some weeds, such as horsetail, can be incredibly difficult to suppress.
⚖️ Project Variations
Here are different ways to enhance or personalise your hot tub gravel base base:
- Concrete Base/Concrete Pad: Super sturdy and long-lasting. Can be customised with finishes or stamped patterns. Requires more skill, longer curing time, and is harder to relocate.
- Paver Patio Base/Concrete Pavers: Creates a beautiful patio area with good drainage. Individual pavers are replaceable, but can be more expensive.
- Deck Base/Wooden Decks: Perfect for sloped gardens or creating a multi-level outdoor space. Built-in wooden frame provides extra support and a stylish surround.
- Crushed Stone/Gravel Foundation: Affordable, DIY-friendly, provides good drainage. May need periodic levelling, but it's simple to install and perfect for new hot tubs, inflatable hot tubs, or larger spas.
Tip: The best base depends on your budget, DIY skills, soil conditions, and the weight of the hot tub.
🦺 Safety Tips
- Digging Deep: Check for underground utilities before you start, or carefully do it by hand instead of using heavy machinery
- Heavy Lifting: MOT Type 1 hardcore and gravel are heavy - lift with your legs and glutes.
- Level Best: Ensure your solid foundation or gravel pad is level to prevent spills and uneven water distribution.
- Grid Goals: Make sure your gravel grids or EZ Pads are securely interlocked.
- Drainage Matters: Keep the surrounding area free from debris.
- PPE: Sturdy footwear, gloves, and eye protection are essentials.
🧽 Care and Maintenance
With a little TLC, your gravel grid hot tub base will provide a sturdy and reliable foundation for years of relaxation and enjoyment. Here's what we recommend checking:
- Weeds: Check periodically and remove any greenery.
- Level-Headed: Gravel may settle over time; top up if needed.
- Wash and Go: Rinse gravel grids every few months.
- Grid Check: Replace damaged grids promptly.
- Drainage: Keep the area clear to avoid rain water pooling.
💡Pro Tips
Pro Tips for a Picture-Perfect Base
Want to take your DIY hot tub base to the next level? Here are some pro tips to ensure a flawless finish:
- Geotextile Groundwork: Stabilises the base and prevents weeds.
- Compaction is Key: Plate compactor ensures a level foundation.
- Edge Control: Use concrete patio, stones, or decking to contain gravel.
- Gravel Gradient: Slight slope away from the hot tub ensures drainage.
- Underlay Upgrade: Rubber or foam underlay beneath EZ Pads adds comfort and distributes the hot tub weight.
- Finishing Touches: Landscaping stones, bricks, or wooden frames create a polished finish.
❓ FAQ
Ideally, start with a relatively level surface. Slopes may need additional levelling or a wooden deck.
6 inches is usually sufficient, but check your hot tub dealer's recommendation.
Angular gravel like MOT Type 1 or pea gravel works best. Avoid rounded pebbles.
Usually not for backyard hot tub installations, but check with your local council incase you are worried about its location.
The project duration will depend on the size of your base and your DIY experience. Allow a weekend to complete the project, including digging, laying the hardcore, and installing the gravel grids.
If you have basic DIY skills and the right tools, yes. Otherwise, consult a professional.
➕ More Related Projects
Looking for more DIY garden projects like this? Try these:
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The Best DIY Solid Hot Tub Spa Base Foundation
Whether you're about to become new hot tub owners, planning a larger spa installation, or want to transform an unloved corner of your garden with a gravel pad, concrete slab, or solid foundation, this hot tub base step-by-step tutorial is for you!
Materials
- Gravel grids for a grabel base or EZ Pads
- Medium-grade gravel or pea gravel recommended
- MOT Type 1 aggregate
Tools
- Shovel
- Post hole digger
- Tamper or rammer
- Strimmer
- Rake
- Garden fork
- Wheelbarrow or garden trailer
Instructions
- Remove vegetation: Use a fork to pry out all the grass, weeds, and brambles
- Dig down to the required level: Dig out 6 inches of topsoil to allow 4-6" of hardcore and 2" for the gravel grids filled with gravel.
- Lay a weed control membrane: Even if the soil looks clean, weeds can hide anywhere. Cover the entire area with a good-quality membrane to prevent regrowth.
- Lay and compact hardcore: Use MOTType 1 aggregate (2" to dust). Compact with a rammer or mechanical whacker- the material locks together, creating a solid base. Drag a straight edge across to ensure a level foundation, moving material from high points to low points if needed.
- Install gravel grids: Cut and lay all the full grids first. These lock together and reduce movement under the hot tub’s weight. EZ Pads or other synthetic hot tub pads are great options for additional stability.
- Fill grids with gravel: Tip gravel into all the grids equally, raking until it’s level. This reinforces the solid base and completes the gravel pad.
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