How deep does a deck footing need to be?
For most deck applications, in most jurisdictions, the width of a footing should be 20 inches round and a minimum of 24 inches deep. It is important that the base of the footings be solid, and in many cases you will need to keep digging until you reach undisturbed soil.
How do you calculate deck footings?
To calculate the load, you should use 40lbs per square foot for live loads (these are variable loads that are dynamic such as the weight of people and furniture) and 15 lbs per square foot for dead loads (this is the weight of the materials used for the construction of the deck) for a total load weight of 55 lbs per ...
How many footings do I need for a 20x20 deck?
Quick Attached Deck Footing ChartSize of DeckBeam SizeNumber of Footings16' x 16'(3) 2×8320' x 12'(2) 2×8320' x 14'(2) 2×8320' x20'2 beams (2) 2×86 (2 rows of 3)4 more rows
How many footings do I need for a 12x12 deck?
For an attached 12 x 12' deck, you'll need at least 3 footings, plus at least 2 more if you're planning on building stairs with it.
How many footings do I need for a 12x16 deck?
A standard deck will need four footings parallel to the house, but they will need to be temporarily braced by 6 inch-by-6 inch posts.
How deep and wide do footings need to be?
The minimum depth of footings below the surface of undisturbed soil, compacted fill material or controlled low strength material (CLSM) shall be 12 inches (305 mm). Where applicable, the requirements of CBC Section 1809.5 shall also be satisfied. The minimum width of footings shall be 12 inches (305 mm).
Does a freestanding deck need footings?
According to the main code provision for footings, the only requirement for building a deck that is freestanding is that it must have a minimum footing depth of 12 inches below the undisturbed ground surface. There is no need to extend a footing below the frost line, as is required for standard decks.
How far apart should 4x4 deck posts be?
6 feetFor Building a Deck Railing, Deck Frame, or Fence The maximum spacing of 4x4 deck posts should be 6 feet on center, while the maximum spacing of 6x6 deck posts should be 8 feet on center.
Can you use 4x4 posts for a deck?
In the past, many decks were built with 4x4 support posts (also called structural posts). But these can bow seriously, even if a deck is only 3 feet off the ground. For that reason, we strongly recommend that you use 6x6s instead, even if your building department does not demand them.
Can I use deck pier blocks instead of footings?
Pier blocks can be used instead of footings for a ground-level deck not requiring permits. Piers blocks can also be used if the frost level depth is less then the height of the pier block. Allowing you to set the pier block below the frost level on stable ground.
How far apart should posts be for a deck?
Starting with your perimeter, mark the location of each deck post to locate the fitting position. In general, posts should be spaced no more than 8 feet apart. Some builders position them every 4 feet for a completely rigid frame. The maximum distance between footings is determined by the size of your joist material.
How many posts do I need for a 10x10 deck?
A freestanding 10' x10' deck needs 4 posts, supporting two pairs of 2-ply non-incised 2×8 beam, upgrading the beam to 3-ply using incised wood.
How do you calculate footing size?
To determine the size of the footing, a simple formula is used: Structural Load (lbs) / Soil Capacity (psf) = Footing Surface Area Required (sq. ft.)
How many posts are needed for a 10x10 deck?
A freestanding 10' x10' deck needs 4 posts, supporting two pairs of 2-ply non-incised 2×8 beam, upgrading the beam to 3-ply using incised wood.
How are deck post locations determined?
Deck footings have to be placed just right so that the posts they support land in the center of each footing. Pay attention to the framing plans. They might not call out the location of the footings, but they will at least show the centerline of the beam and the spacing of the posts.
What determines the spacing of a deck footing?
Firmer soil requiring both smaller and fewer footings. This is important in a deck designed, but ultimately the spacing of the footing is determined by beam strength, not soil bearing. If the beam is strong enough but the soil is not as a general rule, the decking footing size will be increased.
How much does it cost to increase the footings on a deck?
Saving both time and money in building the deck. Increasing the footings spacing by 2’ for less than $20. A concrete footing will cost that and more.
How to increase footing spacing?
Increasing the depth or number of plies of a beam will allow you to increase the footing spacing. For example, the difference between 6’ spacing and 8’ for an 11’ deep joist is a 2×8 two-ply instead of 2×6 beam. Often this is the deciding factor for footing spacing. More beam means less footings.
How many footings are there in Canada?
There are three default footing spacing in Canada, 4’ (1.2m),6’ (1.8m) and 8’ (2.4m) provided by the Canadian Wood Council. A good start in figuring out a deck’s footings. The biggest controlling factor is the size of the beam. The larger and stronger the beam is the larger the footing space can be. Personally, I prefer a bigger beam requiring fewer footings. Of course, the beam is supporting joist, the length of the joist and the load they support contributes to the beam and footing requirements.
Do you need footings for a hot tub?
Some situations require closer footing spacing. One extreme is hot tubs. Hot tubs put a lot of weight on a deck and require additional footings. Both to support the extra weight and distribute the weight evenly. Often its better to build the footing and beams to support the hot tub separate from the main deck. Considerably increasing the number of footings but safely supporting the hot tub.
Can a deck beam overhang?
It may be called the International Residential Code, but local code will overrule this at times. In Edmonton, Alberta, a deck beam can only overhang one and a half times the nominal depth of the beam.
Is it better to build a deck to local code?
Always better to build to or exceed local code. Let’s look over some of these factors to ensure that your deck is built to last. Quick references, easier to upgrade beam then adding footing, layout footing evenly for best results, but keep in mind the end use of the deck and adjust footings as required.
What woods are used for framing?
Red Pine. And combination woods, such as Douglas Fir & Western Larch (Douglas Fir-Larch), Hemlock & Fir (Hem-Fir), and Spruce-Pine-Fir. All are high-quality woods to use for framing purposes, however, your geographic region plays a role in which woods will be available to you.
Do you want to have a few beams?
However, from an aesthetic perspective, you’ll want to have as few beams as possible since they will be visible from your ground floor and can ob struct views. According to our beam span chart resource, the span of a beam is dependent on a few variables: the species of lumber, size of lumber, and the load it carries.
Can you use steel beams instead of wood?
Steel Alternatives to Wood Beams. If you’re building a deck, wood isn’t your only option for beams. Unlike wood, steel beams are not susceptible to the elements and won’t warp over time. They make for a stronger, straighter, safer, and smarter alternative to wood substructures and may be more economical in the long-run.
Do deck joists need to be supported?
While joists provide a horizontal support system for deck boards, beams provide support for the joists. Your beams will need to bear the load of not only your decking materials, but additional components of the frame itself. For this reason, it’s important to calculate how many beams (and concrete footings to secure each beam) your deck will need.
Choose a beam
Several factors determine which beam setup to use.
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Why do you need a deck footing?
In general, a deck footing is usually used if it is going to be higher than your waist or larger than 100 square feet. The footings ensure that the deck will not fall, tip or rot away after a few years. Footings are especially important in areas that have troublesome soils because it helps keep the foundation set and prevents it from settling.
What are footings?
For those who don’t know what footings are, they are an important component during deck construction because they provide the foundation that will support your deck. Large decks that are attached to the house should always have footings because they act to spread the heavy load of the deck from the surface of a support post over a large surface of the soil so the ground can adequately support it.
How big is a deck block?
The biggest you’ll ever see a deck block is about seven inches, which is why they’re a great option for decks so close to the ground.
Why are footings important?
Footings are especially important in areas that have troublesome soils because it helps keep the foundation set and prevents it from settling. Footings also have to be set lower than the frost line so that it can prevent the deck from moving when the soil freezes during the winter.
Do you need footings for a large deck?
As mentioned before, it’s always a great idea to have your large decks supported by footings so that it doesn’t get destroyed after you spent a lot of money building it. But this rule only really applies to large decks because smaller decks that are a few inches off of the ground can sit securely on concrete blocks, which should be reinforced with some rebar.
Can you put a wooden deck over a concrete slab?
Putting a wooden deck surface over a concrete slab will allow the deck to stay stable without the usage of footings.
Do deck blocks save change?
They will save you a good chunk of change, but you should be sure to buy more than enough so you have plenty of support for your deck. The last thing you want is an uneven deck that begins to sink into the ground. Deck blocks come in two different types.
How wide should a house footing be?
As you can see, heavy houses on weak soil need footings 2 feet wide or more. But the lightest buildings on the strongest soil require footings as narrow as 7 or 8 inches.
How much does a 12 inch footing weigh?
A 12-inch footing is 1 square foot of area per lineal foot, so the code is saying that the portion of a two-story wood house that bears on the outside walls weighs about 2,500 pounds maybe a little conservative, but reasonable.
How does soil bearing capacity relate to the size of footings?
So, how does soil bearing capacity relate to the size of footings? The footing transmits the load into the soil. The lower the bearing capacity of the soil, the wider the footing needs to be. If the soil is very strong, the footing isn't even strictly necessary just the soil under the wall would be enough to hold the building up.
Do you have to do engineering on a house?
In practice, you don't have to do this engineering on most houses. The amount you'd differ from a standard code-compliant footing isn't worth worrying about. Unless you have retaining walls or some other special situation, an engineers fee probably isn't justified.
Do masons need footings?
Regardless of bearing requirements, masons and poured-wall contractors want footings for their block or their forms to sit on. But the lesson to take is that when soils are very strong, (4,000-psf capacity or better), the footings may not be strictly necessary from the standpoint of bearing.
