![]() ![]() Įven after the ground has thawed your deck may not return to the original level because rocks or dirt will fall into the hole under the footings. How soil type affects your footingsįor instance heavy clay soils hold a lot more water than sandy soils and will have a lot more problems from freezing,when water freezes the expansion rate is about 10 percent and puts a large amount of pressure about 50,000 lbs.per square inch so a great amount of pressure more than enough to lift your deck up and cause a lot of problems. It is important to check local building codes for the construction requirements in your area these requirements will include minimum diameter and a minimum depth of the footings.įootings typically must extend below the frost line to prevent shifting during freeze-thaw cycles. ![]() Putting the permanent posts into the hole and concreting them in something I wouldn’t recommend because water will get between the concrete footing and the timber post and will stay there and eventually rot the post.Īn advantage of building this way is that the footings will be at the right height and you can get all the concrete part of the footings to be below the ground level which looks a lot better.īy using a metal and preferably a galvanized steel bracket set into the concrete footing and bolted to the post so that the post is above the finished ground level will greatly extend the life of your deck I would also recommend using all galvenized fittings and bolts to construct your deck.īefore building your footings ask your local building department the what the footing requirements are for your area they should be able to tell you about frost depth requirements and the shape and size footings you need for your deck this will be different for every area and climate and soil type. Or you could build the deck before you make and pour your concrete footingsīy building the deck using temporary posts to hold up the frame while you build it.Īfter you have finished building the deck the permanent posts can be installed if there is any posts under the deck all of those post holes should be marked out and dug before the deck is built. ![]() Theoretically, if kept in a moist environment, concrete will gain strength forever, however, in practical terms, about 90% of its strength is gained in the first 28 days. The industry has adopted the 28-day strength as a reference point, and specifications often refer to compression tests of cylinders of concrete which are crushed 28 days after they are made.ĭuring the first week to 10 days of curing it is important that the concrete not be permitted to freeze or dry out because either of these, occurrences would be very detrimental to the strength development of the concrete. A typical strength-gain curve is shown in Figure 1. Thereafter the concrete continues to gain strength as it cures. A chemical reaction called hydration takes place between the water and cement, and concrete normally changes from a plastic to a solid state in about 2 hours. When first mixed the water and cement constitute a paste which surrounds all the individual pieces of aggregate to make a plastic mixture. This is what the Civil Engineering Department wrote about concretes properties and curing time.Ĭoncrete is an artificial conglomerate stone made essentially of Portland cement, water, and aggregates. One thing I would recommend is that don’t make the mixture too wet because that will weaken the concrete. If you are going to mix your own concrete on site then follow the instructions on the cement bag. When building any footings or foundations and to ensure a solid footing for any permanent structure like a deck you should always use a structural strength concrete mix if you are getting ready mixed concrete delivered then tell your supplier what you are using it for and they will send you the right mix for your job. If you use a concrete that has a quick setting additive you need to wait a minimum of one sunny day, if you are using a standard concrete footing mix I would recommend waiting for a minimum of seven days and a maximum of 28 days, of course, that is if the conditions are right for the concrete to cure and set hard. Because the footing of a deck is the most invisible part of the construction they can be the most overlooked part but get this wrong and you could have problems later in the life of your deck so putting a heavy weight on your footings before they are set and hard can weaken your deck.
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