Before we get started, here are some important items to keep in mind:
- We typically share boardwalk construction cost estimates per square foot (SF), rather than linear foot pricing that many designers are accustomed to, due the the varying width sizes.
- The foundation system cost ranges listed below are typical for larger projects; the cost per square foot for smaller projects may fall outside these ranges.
- The price range for foundation options is very wide due to the variance in labor rates and material costs by region. Southern states such as Florida generally have lower labor rates than states in the Northeast, for example.
- Depending on where your project site is, shipping rates will impact the project's overall cost.
Boardwalk Foundation Materials: Comparing Timber, Concrete and Steel
As we say, “No two sites are the same.” One of the first steps in a boardwalk project’s design document phase is determining which foundation type will provide the most value within the owner’s allotted budget and specific application. For this reason, in this article we will share cost estimates for a PermaTrak boardwalk installed on seven different foundation options.
Foundation costs are significant drivers of overall project costs as specified materials (timber, concrete, composite, or steel), construction methods and design requirements vary widely.
If you are looking to gather a project-specific boardwalk budget estimate, we encourage you to finish reading the information presented here, then request a boardwalk budget estimate. We will do our best to provide a detailed boardwalk construction cost estimate, specific to your location and project needs.
Boardwalk Design Assumptions
These installed boardwalk price ranges assume a pedestrian loading of 90 psf. Railings are excluded; you can learn more about boardwalk railings here. A boardwalk system like PermaTrak may also be a great fit for heavier live load requirements, including a 5,000 lb. maintenance vehicle (Gator), H5 truck (10,000 lb. vehicle), H10 truck (20,000 lb. vehicle) or higher. You can read more about these requirements and other boardwalk design considerations here. Lastly, we are assuming a geotechnical report has been completed; this report will drive the foundation design process.
Boardwalk Foundation Cost Estimates: Concrete vs. Timber vs. Steel Materials
Now to the good stuff! The eight most common foundation types used to support the PermaTrak boardwalk system:
Precast Concrete Piers (Supplied By PermaTrak)
Cast-In-Place Concrete Shallow Footings (Sonotube)
Timber Piles (Pressure Treated Southern Yellow Pine)
- Steel Helical Piles (Screw Piles)
Driven Steel Piles (H-pile or Pipe)
1. Precast Concrete Piers
These stackable pier components serve as a shallow foundation (spread footing) type of foundation.
If feasible, we recommend using this precast concrete pier system; it is the most cost-effective foundation option for a commercial boardwalk.
The piers are supplied as part of the PermaTrak system. PermaTrak boardwalks installed on this precast concrete pier system typically range from $50-65/SF. This installed number includes boardwalk engineering and design support, material (foundation system, beams and treads) delivered to the site, and labor to install the product.
2. Cast-In-Place Concrete Shallow Footings
Shallow footings (#1-2) are preferred over deep footing options (#3-6) as they contribute to a lower boardwalk construction cost.
These cast-in-place footings could be circular or square. A boardwalk construction cost estimate for PermaTrak installed on a cast-in-place concrete shallow footing is $60-85/SF.
3. Timber Piles
Primarily due to their cost-effectiveness, pressure treated timber piles (aka timber poles) are the most common deep foundation option for commercial boardwalks. 12’’ diameter widths are often specified, while total pile length can be anywhere from 10–40’.
Several variables will impact the price of timber pile installation: site access, diameter of pile required, required driven depth, geographic region, total number of piles, soil conditions, etc.
Although these piles are supplied and installed by the contractor, we use historical data to estimate the total installation costs. Generally a PermaTrak boardwalk installed on a timber pile foundation will cost anywhere from $60-85/SF.
4. Drilled Shaft or Concrete Caissons
In northeastern states like Connecticut or Massachusetts, PermaTrak has been installed on a reinforced, concrete caisson. In Texas, drilled shaft foundations are common because of the expansive clay soils. This drilled shaft or concrete caisson method serves as a deep foundation option. Most PermaTrak boardwalks installed on a cast-in-place caisson system (deep foundation) cost $65-95/SF.
When designing a boardwalk on cast-in-place caissons, designers will consider site conditions, industry standard casing sizes, and finished boardwalk elevation (height above grade). All of these factors influence the structural engineer’s design for diameter and depth of the caissons. The photo here a multi-use path project shows a walking surface at roughly 5-6’ above grade.
5. Steel Helical Piles (Screw Piles)
Steel helical piles, sometimes referred to as screw piles, are less common than options #3 and #4 as a deep foundation option, but they may provide several distinct advantages over timber or concrete foundations for your project site. Increasing in popularity and recognition, more designers are looking to helical piles as an environmentally friendly foundation option, especially if the boardwalk or pedestrian bridge needs to be installed in a sensitive wetland, or via top down construction.
Depending on the required diameter of the central steel shaft, and number and size of attached helices, a PermaTrak boardwalk system installed on a steel helical pile foundation will typically cost $75-95/SF. See an example of a PermaTrak project installed on helical piles here.
6. Fiberglass Composite Piles
Fiberglass composite piles have emerged as another cost-effective option to traditional deep foundation options described in #3 and #4 above. Fiberglass composite piles combine light weight with high capacity. This combination makes them ideal for locations with difficult access or requiring top-down construction methods.
Additionally, fiberglass has a significantly longer design service life than either timber or steel in most environments. For most applications, a 10” or 12” diameter pile provides more than enough axial and lateral capacity. Typical costs range from $75-95/SF.
7. Driven Steel Piles (H-pile or Pipe)
Other types of steel piles are less common for boardwalks and pedestrian bridges. They may, however, serve as a durable deep foundation option if the project’s budget allows.
Depending on pile size and required driven depth, a PermaTrak boardwalk system installed on a driven steel pile foundation will typically cost $80-110/SF.
8. Driven Concrete Piles
Less common than options #1-5, precast concrete piles offer durability and longevity as a deep foundation system. An installed boardwalk cost range for the PermaTrak system on a driven, precast concrete pile foundation is $80-120/SF.
What the PermaTrak System Includes
The boardwalk cost estimates listed above include production and shipment to the job site of the following PermaTrak components:
Precast concrete pier system (if applicable) – consists of a base, riser(s) and cap
Reinforced, precast concrete beams – replacement for stringers, runners, headers, and/or joists from a traditional timber boardwalk system
Reinforced, precast concrete treads – replacements for planks or boards on a timber boardwalk system
Internal polyurethane connector pins as required
Rubber bearing pad – to be laid on top of beams prior to tread installation
Integral color for all precast concrete elements
Integral form liner finish for all tread walking surfaces
*Note: See our PermaTrak Components page for a schematic drawing of our boardwalk system with these components. Or you can learn more about a PermaTrak boardwalk installation process to see how these components are installed.*
Also included in these SF price ranges are the following:
Engineering and site-specific design support
Detailed construction documents and shop drawings submitted by a registered P.E.
You can read an article with more information on what this engineering support includes.
Other recent projects have shown this same result: a concrete boardwalk costs less than a timber boardwalk. How can this be possible? The answer is that PermaTrak's precast concrete beams can span at least twice the length of a timber stringer or "runner". Installed costs can vary widely by project and longer spans don't always make for the best design option.
Longer Spans with Concrete Beams = Less Footings = Cost Savings
Design Assumptions and the Evaluation Process
Hopefully this boardwalk square foot pricing information is helpful for your preliminary budget estimating purposes. But keep in mind, these installed price ranges are meant to be “ballpark” numbers. I’ve made multiple assumptions relative to soil conditions, site access, live load requirements, etc. that need to be designed and verified by a professional engineer. Feel free to request a more specific budget estimate by clicking here, or give us a call and we will do our best to help with more technical information on the foundations described above.
We understand how much work goes into the evaluation process for commercial boardwalk materials: initial costs, the owner’s experience with other materials, constructability, associated maintenance costs, etc. Hopefully this information is helpful as your project develops into design and construction documents.