Divide the width by 12 to convert it to feet. Divide the length by 12 to convert it to feet. Determine the depth or thickness that is required for the footing in inches. Multiply the width by the length and then by the depth. The diameter of the footings commonly range between 8 and 24 inches. Most builders use inch diameter footings. Before calculating the size and number of deck footings , you'll need to know the type of soil you're building on. How deep and wide do footings need to be?
Depth: Footings should extend to a minimum depth of 12 inches below previously undisturbed soil. Footings also must extend at least 12 inches below the frost line the depth to which the ground freezes in winter or must be frost-protected. Width: Footings should have a minimum width of 12 inches. How many footings do I need for a 20x20 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. At UglyDeck. As you begin your deck plans, you can get a hands-on feel for these amazing maintenance-free decking materials by heading to one of decking showrooms , like our new Mandan, ND location!
We also have several photos of completed projects on our website that are sure to inspire ideas for your own deck designs! No matter where you live in the U. 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. If there are extreme point loads on a deck, like a pergola post, it is often better to reduce and adjust the footings spacing to place the footing directly below the additional load. A footing can support a much greater weight directly applied then pushing down at a distance. You can hold a heavier weight much longer centred on your body then outstretched arms.
Footings are the same, placing the point load directly above, increasing the load the footing can support. Long runs of stairs also require footings on the ground. Two additional footings to support the stairs are a good idea. You have heard that you should always use treated lumber for a outdoor project. But what is pressure-treated wood? Pressure-treated lumber, is wood that is professionally treated and infused with The nature of a construction or renovation project and your budget will Soils are classified as mostly gravel, sand or clay.
Gravel-type soils can support the most weight, typically up to 3, pounds per square foot. The weaker the soil the larger you should make the bearing surface of the deck footers.
It will act as a ledger along the entire side to help connect the wooden deck beams and joists to the existing structure. If you live in a damp climate, you should also attach metal flashing along the side of the existing structure to drain any water away from the wood-to-wood surfaces between the ledger and the deck beams and joists. The flooring above will support more weight and be less likely to sag over time. Stairs and traffic pathways receive extra weight and vibration and should be supported by footers and beams.
Place footings at each corner of the stairs and at two-foot intervals if stairs are longer than a few feet. When building a deck or any other construction project bigger than a few square feet, you should always check with your city or village to make sure it complies with local rules. Take your drawing to the engineering department of whichever government agency issues building permits.
Hot tubs and other heavy objects will require additional footings and larger deck beams. The load can be calculated based on the size of your deck, the soil properties, and what the deck will carry.
For furniture and people, use 40 psf pounds per square foot , and structural materials or dead load, add 15 psf.
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