Footings are a very important component of deck construction because they provide the solid foundation that will support your deck.
Your deck's design will determine how live loads (people, furniture, vehicles, etc.) and dead loads (walls, plaster, ceilings, beams, etc.) are transferred from different sections of the deck to concentrated points of contact with the ground.
There are several viable options for deck footings; including: Poured Concrete Footings, Buried Post Footings, Precast Cement Footings, Deck Blocks, and Screw/Helical Piles. Which one you choose will depend on the size and height of your deck and the building codes in your location.
By code, the bottom of a footing must be at least 12 inches deep and below the local frostline—whichever is deeper—and bear on stable, undisturbed soil that is free of organic matter. And the code requires a minimum compressive strength of 2,500 psi for the concrete.
Below are some common footings used in building decks.
POURED CONCRETE FOOTINGS
Concrete footings are made by digging a cylinder into the ground (usually 48” in depth) and filling that cylinder with concrete. If done properly, the base of the footing is belled, and a cardboard tube is inserted. The concrete is then poured into this tube. The design of the bell helps prevent heaving in the winter.
How long do concrete footings last?
Concrete footings typically have a lifespan of around 30 years.
PROS of concrete footings:
Usually, the least expensive form of footing to install.
If poured properly, the top of the footing will be even with the ground and provide a clean look.
Is widely accepted by all cities
CONS of concrete footings:
Need to dig a hole before pouring
Cannot always be used year round
Takes time before you can build on them
Helical piles are commonly referred to as helical anchors, helical piers, or screw piles. Helical piles are a form of a deep foundation system that has been in use since the early 1900’s in waterfront foundations. They work by bypassing weaker soil layers and transferring the loads of a structure to competent load bearing soils.
Helical piles are shafts with helical plates that look a bit like giant screws. This shape allows them to be screwed into the ground rather than pushed. They're hydraulically rotated into the ground without applying any force to your foundation, and a pressure gauge system determines when the required depth is met.
How long do helical piles last?
Though helical piles can be galvanized to prevent rusting, the varying soil conditions can affect the life expectancy. It is generally estimated that helical piers will last over 150 years in normal soil conditions.
Helicals are a permanent foundation solution, that will last you a lifetime. The installation is clean and no excessive excavating is needed. Helical piles can be used for any size project, and they can be built upon the same day, there is no waiting time for curing.
PROS of helical piles
They are the most reliable footing system available
Can be installed year round
They are based on torque and will exceed frost depths
CONS of helical piles
Typically, most expensive option for footings
Can cause damage to your yard since machinery is needed to install
The post is connected to a bracket that sits a couple inches off the ground. Would need to trim out the bas of the post to hide.
Based on time-tested spread pile technology, a diamond pier foundation uses the strength of a precast concrete head to lock in four weight-bearing, galvanized steel pins that transfer the load to a larger area of undisturbed soil than the traditional concrete footing.
Functioning like tree roots, this spread pile technology is fast, smart, low-impact, and sturdy. The pins can take only minutes to drive in, saving you days of labor, and there is no waiting around for a hole inspection, as the pin length is inspected by simply running a tape measure down the pin after installation.
With diamond pier footings there is no excavation, and no mess. The diamond pier foundation can be integrated and installed into your existing landscaping without damaging plants and with no digging and no heavy machinery, you’re left with a clean job site.
How long do diamond piers last?
Diamond piers typically have a lifespan of around 20 years.
PROS of diamond piers:
Easy and quick to install, ready to use after installation
Mid range pricing for materials, but because of ease of installation, labor price is typically pretty low
CONS of diamond piers:
Portions of the concrete pile stick above the ground
Can be hard to trim around
Can be challenging to screen out the underside of a deck with the uneven base of the footing. Does not create the 90-degree angle from the ground to the post.
Now that you know more about deck footings and which type might be right for your deck, we would love to discuss your project with you. Call us or fill out the form on our website to schedule an appointment today. We are working in compliance with all COVID-19 guidelines for construction.