Concrete piers are columns of concrete set into the ground, often below the frost line, giving strong, stable, frost-resistant point support that suits heavier saunas and difficult or sloping ground, but they take more work to dig and pour. A gravel pad is a compacted, well-draining bed that's economical and simpler to build, handling frost by draining and moving evenly, and suiting lighter saunas on reasonable ground. Choose concrete piers for strength, frost resistance below the frost line, and heavier or difficult builds; choose a gravel pad for economy, drainage and simplicity on suitable ground. Both are proven cold-climate foundations — match to your ground, sauna weight and budget, and follow local practice.
Two proven cold-climate foundations sit at opposite ends of the effort spectrum: concrete piers, which go deep for strength and frost resistance, and a gravel pad, which stays shallow but drains. Piers suit heavier, demanding builds; a gravel pad suits lighter saunas economically. Which is right depends on your ground, sauna weight and budget. This guide compares concrete piers and a gravel pad.
Two approaches
- Concrete piers: columns of concrete set into the ground, often below the frost line — strong, stable, frost-resistant point support for heavier saunas and difficult or sloping ground. More work to dig and pour.
- Gravel pad: a compacted, well-draining bed — economical, simpler, handling frost by draining and moving evenly — for lighter saunas on reasonable ground.
How each handles frost
| Concrete piers | Gravel pad | |
|---|---|---|
| Frost strategy | Depth — below the frost line | Drainage & even movement |
| Support | Strong point support | Stable, drained bed |
| Heavier/difficult builds | Well suited | Best for lighter saunas |
Piers resist frost by going deep so the ground under them doesn’t freeze and lift them. A gravel pad uses drainage and even movement to reduce frost problems — built well on suitable, drained ground. Both are valid — see foundation depth.
Load: heavier saunas
Concrete piers provide stronger, more stable point support for heavier or larger saunas — solid columns in firm ground. A gravel pad suits lighter saunas, giving a stable, draining bed rather than deep structural support. Match the foundation to your sauna’s weight.
Effort and cost
- Gravel pad — simpler (excavate, add and compact drained stone) and economical.
- Concrete piers — more work and skill (dig holes, often below the frost line, and pour concrete), and typically cost more.
Compare cost against what your ground and sauna need, not price alone — see outdoor sauna cost.
Sloping or difficult ground
Concrete piers can be well suited to sloping or difficult ground — set to different depths to reach firm support and provide point support that copes with uneven ground. A gravel pad suits more level, workable ground. So for a slope or difficult soil, piers are often stronger — though screw piles also suit difficult ground. See building on a slope.
Which to choose
| Choose concrete piers for… | Choose a gravel pad for… |
|---|---|
| Heavier or larger saunas | Lighter saunas |
| Deep frost resistance | Economy and simplicity |
| Difficult or sloping ground | Reasonable, workable ground |
Compare also gravel pad vs slab and ground screws vs gravel pad.
Common mistakes
- A gravel pad on difficult or sloping ground that needs piers.
- Concrete piers where a simpler gravel pad would do.
- Choosing on price alone, ignoring frost and load.
- A poorly compacted or under-drained gravel pad.
- Piers not set below the frost line where required.
Next steps
Match the foundation to your ground, sauna weight and budget: concrete piers for strength, deep frost resistance and heavier or difficult builds; a gravel pad for economy, drainage and simplicity on suitable ground. Mind frost and drainage, follow local practice, and see choosing a foundation to weigh every option.
Frequently asked questions
Are concrete piers or a gravel pad better for a sauna?
It depends on your ground, sauna weight and budget. Concrete piers are columns of concrete set into the ground, often below the frost line, giving strong, frost-resistant point support suited to heavier saunas and difficult or sloping ground, but they take more work. A gravel pad is an economical, well-draining, simpler bed that handles frost by draining and moving evenly, suiting lighter saunas on reasonable ground. Choose piers for strength, frost resistance and demanding builds; a gravel pad for economy, drainage and simplicity. Both are proven cold-climate foundations. See our best-foundation guide.
How do concrete piers and a gravel pad handle frost?
Concrete piers resist frost by being set deep, often below the frost line, so the ground under them doesn't freeze and lift them, giving stable support through winter. A gravel pad handles frost differently — its draining stone lets water pass through and it moves gently and evenly with the ground, reducing frost problems, though it must be well built on suitable, drained ground. So piers use depth and gravel uses drainage and even movement. Both are valid frost strategies; the right one depends on your ground and sauna. See our guides on frost heave and foundation depth.
Which supports a heavier sauna better, piers or gravel?
Concrete piers generally provide stronger, more stable point support suited to heavier or larger saunas, since they're solid columns set into firm ground, often below the frost line. A gravel pad suits lighter saunas, providing a stable, well-draining bed rather than deep structural support. So for a heavier or larger build, concrete piers are often the better choice, while a gravel pad excels for lighter saunas on reasonable ground. Match the foundation to your sauna's weight. See our concrete piers and gravel pad foundation guides.
Is a gravel pad easier to build than concrete piers?
Generally yes — a gravel pad is simpler to construct, involving excavating, adding and compacting drained stone, while concrete piers require digging holes, often below the frost line, and pouring concrete, which is more work and skill. So a gravel pad can be a more straightforward build for a capable person, while concrete piers trade simplicity for strength and deep frost resistance. If simplicity and economy matter and your ground and sauna suit it, a gravel pad may be easier; if you need piers' strength, the extra work is worth it. See our foundation guides.
Is a gravel pad cheaper than concrete piers?
Often yes — a gravel pad uses compacted stone and simpler labour, making it economical, while concrete piers involve digging and pouring concrete, which typically costs more in materials and effort. This cost and simplicity are why gravel pads are popular for lighter saunas on suitable ground. That said, concrete piers' strength and frost resistance below the frost line can justify the extra cost for heavier or difficult builds. So compare cost against what your ground and sauna actually need, not price alone. See our outdoor sauna cost guide.
Which foundation is better for sloping or difficult ground?
Concrete piers can be well suited to sloping or difficult ground, since they can be set to different depths to reach firm support and provide point support that copes with uneven ground, while a gravel pad suits more level, workable ground. So for a slope or difficult soil, concrete piers are often the stronger choice, though other options like screw piles also suit difficult ground. A gravel pad excels on straightforward ground. Match the foundation to your site's conditions. See our guides on building on a slope and choosing a foundation.
