Bunkie Foundation Options: Which is Best for Your Property?

One of the most important decisions you’ll make for your bunkie is the foundation. Get it right and your bunkie will last decades. Get it wrong and you’ll be dealing with settling, rot, and structural headaches.

The good news: bunkie foundations are simpler than house foundations. Here’s everything you need to know.

Why the Foundation Matters

A bunkie foundation does three things:

1. Lifts the structure off the ground to prevent moisture and rot
2. Distributes the weight of the bunkie evenly
3. Keeps the bunkie level over time as the ground shifts

Most bunkie kits recommend 6–12 inches of ground clearance. This allows airflow under the floor and keeps the base logs away from soil moisture.

Foundation Option 1: Concrete Deck Blocks

Cost: $200 – $600 in materials | Difficulty: Easy | Permanence: Medium

Concrete deck blocks (sometimes called “foundation blocks” or “solid concrete blocks”) are the most popular foundation for bunkies. You place them at regular intervals on compacted gravel, then set the floor frame on top.

Pros:

• Very affordable
• No digging required in most cases
• Can be re-leveled over time if settling occurs
• Usually doesn’t require a permit

Cons:

• Not ideal for sloped terrain
• Can shift over many freeze-thaw cycles
• Not suitable for permanent structures in some municipalities

Best for: Flat to gently sloped sites with stable soil. This is the most common bunkie foundation by far.

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Foundation Option 2: Gravel Pad

Cost: $300 – $1,000 | Difficulty: Easy-Moderate | Permanence: Low-Medium

A gravel pad involves excavating a few inches of topsoil, laying landscape fabric, and filling with compacted gravel (typically 3/4” crushed stone). The bunkie then sits directly on pressure-treated skids placed on the gravel.

Pros:

• Excellent drainage
• Works well on relatively flat ground
• Good freeze-thaw performance compared to blocks
• Inexpensive

Cons:

• Requires excavation equipment for large areas
• Skid-mounted bunkie sits lower to the ground — less airflow
• May not be allowed as a “permanent” foundation in some areas

Best for: Flat sites with drainage concerns. Very popular for cottage properties.

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Foundation Option 3: Helical Piers (Screw Piles)

Cost: $2,000 – $5,000 installed | Difficulty: Requires professional installation | Permanence: High

Helical piers (also called screw piles) are steel shafts with helical plates that are screwed into the ground by a machine. They go below the frost line, which means they don’t shift with freeze-thaw cycles.

Pros:

• Most stable long-term foundation
• Goes below frost line — virtually no seasonal movement
• Works on slopes and challenging terrain
• Can be installed in tight spots
• Minimal soil disturbance

Cons:

• Most expensive foundation option
• Requires professional installation
• May trigger permit requirements
• Overkill for a simple seasonal bunkie

Best for: Sloped sites, soft soil, or permanent four-season bunkies where stability is critical.

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Foundation Option 4: Poured Concrete Slab

Cost: $3,000 – $8,000 installed | Difficulty: Requires professional | Permanence: Very High

A poured concrete slab is essentially a mini house foundation. It’s the most permanent option and is sometimes required if you’re adding plumbing.

Pros:

• Extremely solid and permanent
• Required if you’re adding plumbing (for drain slope)
• Great for all-season use

Cons:

• Most expensive option
• Almost always requires a building permit
• Cannot be easily moved or removed
• Overkill for most bunkies

Best for: Permanent structures with plumbing, or municipalities that require it.

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Which Foundation Should You Choose?

Here’s a quick decision guide:

Your Situation	Recommended Foundation
Flat ground, simple seasonal bunkie	Concrete deck blocks
Flat ground with drainage concerns	Gravel pad on skids
Sloped terrain	Helical piers
Adding plumbing, permanent use	Poured concrete slab
Tight budget	Concrete deck blocks

Do You Need a Permit for a Bunkie Foundation?

It depends on your municipality. In most Ontario townships and cottage country municipalities:

• Deck blocks and gravel pads generally do not require a permit for structures under a certain size (often 108 sq ft or 10 sq m)
• Helical piers and concrete slabs often do require permits
• Size of the structure is usually the main trigger — most municipalities require permits for anything over 108–160 sq ft

Always check with your local municipality before building. Rules vary significantly between townships, and ignorance isn’t a defense.

Tips for Any Foundation

1. Always use compacted gravel under your blocks — never place blocks directly on topsoil
2. Make sure it’s level — use a long level and take your time; this is the most critical step
3. Space your blocks properly — typically every 4–6 feet depending on your floor frame design
4. Use pressure-treated lumber for any wood that contacts or is close to the ground

A solid foundation is worth taking the time to get right. It’s the difference between a bunkie that lasts 30 years and one that needs repairs in five.