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Avoid the 10 Most Common Deck Building Mistakes

Wednesday, October 12, 2022

Making mistakes when building an outdoor deck is as common as sand on the beach. If you search the Internet for “deck building mistakes,” you’ll find many articles and videos about funny and not-so-fun deck collapses that can be directly related to mistakes in construction. While many home improvement television shows may make it look easy, building a deck is a big job. There are many things to consider and things to avoid in the process in terms of design and safety. This article talks about some of the most common mistakes people make when building a deck and how to avoid them.

Mistake #1: Putting a sill plate on a house is wrong.

The sill plate attached to the side of the house is usually used to support half the weight of the deck. The ledger board becomes a beam and this single board can hold up thousands of pounds of weight. That weight must be transferred to the structural components of the house, not to the surface siding or exterior skin covering of the house. In addition, the ledger board must be attached to the house so that it does not pull apart and cause problems and collapse of the house.

composite decking boards

Here are some of the most common deck-building mistakes people make when attaching deck ledger boards

  • Placing the ledger board on the house
  • Using square head bolts to secure ledger boards
  • Using fasteners that are not resistant to corrosion

Nails are the worst choice of fasteners because they are not strong enough to hold all the weight. Plus, they usually come off easily. If a group of people starts dancing on a deck that is not strong, the deck may come off the house. This can happen without warning and people can be seriously injured.

People often think that square-headed bolts are a good way to fasten ledger boards. In fact, they are not a good choice. Because you can’t see what’s behind the house siding or bricks, how do you know if they’re biting into the solid wood behind the house’s exterior skin? In addition, if the installer is too rough and over-tightens the square head bolts, they can damage the wood and make the square head bolts much less effective.

Many modern treated woods have copper in them. This copper stops the wood from rotting. Copper and iron are two different types of metals. All fasteners and structural links on outdoor decks are made of iron or steel. When copper and iron are mixed with water, an electrochemical reaction occurs. This causes the steel or iron to rust and decompose.

This means that all fasteners, especially those used for ledger boards, must be made of stainless steel or have a very thick hot-dipped double galvanized coating to protect against this corrosive chemical mixture. When building a deck near the ocean, salt spray or salt spray may enter the deck. The salt in the ocean water can also make the corrosion worse, so stainless steel fasteners must be used.

The Solution

Using through bolts is the best way to secure ledger boards in the house. These fasteners go all the way through the ledger board, the exterior of the house, and then through the horizontal joists or band plates inside the house. A washer and nut are placed on the machine thread at the end of the through bolt. Only when it pulls the structural joists or band plates inside together does the sill plate come loose and fall to the floor.

The best way to attach ledger boards is with special retaining anchors attached to the sides of the deck joists. These anchors fit into a similar anchor that is bolted to the side of each joist in the house. A galvanized, threaded rod connects the two anchors through the sill plate. This method is highly recommended by structural engineers to ensure that the sill plate does not fall off or come loose from the house.

Mistake #2: Attaching the beam to the support column the wrong way

You can have an outdoor deck with no posts and the joists just resting on a concrete-grade beam. By far, these are the safest decks. But most outdoor decks are four feet or more above the ground. Most decks have a beam at the end away from the house on which the deck joists rest. This beam then needs to be supported by posts that go all the way to the ground. Imagine that these posts are the legs of a table or chair. If the beam is not properly attached to the posts, it will rotate and fall off the posts. This error can lead to collapse.

The Solution

There are two ways to prevent a beam from rolling off a post. Most beams are made of two 2×10 or 2x12s. The beams end up being about 3 and 1/4 inches wide. You can use a 6×6 post and cut an L-shaped notch in it.

The crossbeam rests on this ledge for solid support, leaving the 2-inch post all the way to the top of the crossbeam. Then, you attach the beam to this long wooden tongue with through bolts. This is a tried and true method of attachment.

The second method is to purchase structural metal framing connectors, which are tested to create an approved and solid connection between the post and the beam. There are many different styles and designs to choose from. Make sure that the connector you are going to use is designed for the size of the wood you are going to use. Since metal connectors can get wet, make sure it is sufficiently corrosion-resistant.

Mistake #3: Using the wrong deck fasteners

It’s easy to make mistakes with the wrong deck fasteners. You’ve probably seen installers use nail guns to shoot nails through wood trim boards. A nail gun isn’t a bad idea, but it all depends on how resistant the nails are to corrosion. No matter how you decide to secure your deck, make sure you use deck fasteners that won’t rust. Many have a poor zinc plating coating that is too thin.

The Solution

You must first decide if nails are the best choice. Over time, nails often begin to fall out of the joists. Most of the time, screws will work better than nails, and screws rarely come loose.

Before you decide which fasteners to use, ask the company making the floor what they think is best. It is likely that a certain type of nail or screw will be needed. Keep in mind that if you use the wrong fasteners, the warranty on the flooring material may no longer be valid.

composite deck boards

You should also know that most nails that go into a nail gun have a thin layer of galvanized metal on the outside. In a very short period of time, these nails will begin to rust. Galvanized nails tend to break down quickly in this way.

Stainless steel is the best for screws and bolts. Next, you should choose fasteners that are double-dipped and hot-dip galvanized.

It is also a good idea to cover the tops of the floor joists with special joist tape, which makes it harder for water to enter through the holes in the fasteners. This tape is easy to use and can help keep the decking tight to the joists and protect them.

Mistake #4: Incorrect spacing of deck joists

Deck joists are much more widely spaced than you might think. This is especially true if you have an outdoor deck made of composite decking. The joist spacing between composite decking is important because it keeps the deck from sagging over time.

The Solution

Before you start building the foundation of your outdoor deck, stop and read the installation instructions for the deck. If you want to put the deck on a diagonal, you may be surprised to find that the distance between the joists needs to be 12 inches in the center. This is because the distance is shorter when you measure perpendicular to the joists than it is when you measure diagonally.

You should also pay close attention to the flooring requirements for the load-bearing surfaces under each end of each floor. On some composite decking, there must be 1.5 inches of bearing surface at each end of each floor. When you put two pieces of flooring on a joist, you may only leave 3/4 inch of space between them.

Mistake #5: Making it hard to get in or out

When you think about it, your deck is an outside room. You need easy access to your outdoor deck, just like you need easy access to every room in your house. You should be able to get in and out of your deck safely without anything getting in your way.

The Solution

Equally important is how to get off the deck. In an emergency, you may need to leave your house and walk out onto your deck. You don’t want anything to stop you from leaving the house. This means that there should always be a clear path on the deck and the steps leading off the deck should never be blocked. As with everything else, just use your head.

Mistake #6: No handrails or improperly installed handrails

Handrails and guardrails are a must-have safety feature on a deck. The building code is clear on the timing and strength of handrails. Most decks at ground level do not require handrails, but it is a good idea to have handrails on decks that are two feet or more above the ground.

Also, from a design standpoint, railings are often forgotten when building outdoor decks, which is a mistake in itself. Since railings are often one of the most expensive and dramatic parts of outdoor space, it’s important to take the time and consider your options early on. Railings are not only useful, but they are also part of the architecture of your home, just like shutters. They should match your home and showcase your personal style.

The Solution

Installing handrails on your deck requires a lot of skill. Avoid using square-headed bolts. Remember that the top of the handrail and the posts that hold it in place become leverage when someone pushes or leans on them. When many people are pushing on the handrail at the same time, the force can be so great that square-headed bolts will pull regular nails out of the wood faster than a pry bar can.

Through-hole bolts are the only approved way to attach handrails and posts to the deck substrate. A better way is to use special retaining anchors that are bolted to the sides of the deck joists and then fastened to the posts with through bolts. This makes for a very strong connection.

Nails should not be used in any handrail installation. Over time, nails tend to lose their ability to hold things in place. If the nails rust or lose their grip, pieces of the handrail can come loose from the post with little warning.

Pay close attention to all deck handrail requirements in the building code. Remember, the building code is a list of minimum requirements. You can always make something better than what is specified in the code. Plan for the future. Think about someone leaning on the handrail you plan to build next weekend 20 years from now. Will the handrail still be as strong as it was when you built it?

Mistake #7: Building deck post footings that aren’t strong enough

Deck post footings, also known as “floor footings,” are where the weight of the deck is distributed on the ground below the deck. Keep in mind that the strength of different soils is very different. Some soils are so weak that you can easily poke a stick into them. Some soils are so hard and strong that they are almost like rocks.

The Solution

Before you start digging a foundation for your outdoor deck, you should talk to your local building inspector if you don’t know much about the soil and its strength. You should ask the inspector the following questions.

  • How deep does the hole need to be?
  • What is the diameter or size of the hole?
  • How thick should the footing be?
  • Should I put rebar in the foundation to make it stronger?
  • Is it best for the footing to stick out of the ground and how high should it be?

When laying a deck foundation, remember that its bottom needs to be below the frost line in your area. Frost heave is real and it can raise a deck 4 inches or more. It is important to know how big or small the bottom of the scaffolding is. You want the concentrated load of the deck posts to be spread out on the ground as much as possible.

Most deck bottoms should be at least 8 inches thick and poured concrete posts should be at least 6 inches in diameter and sit on top of the bottom. Having 8″ or 10″ would be better.

Steel reinforcement is cheap and can give great strength to foundations and piers. You can use it with confidence. Don’t put treated wood deck posts in the ground. There are many stories on the Internet about treated wood posts buried in the ground that have rotted or been eaten by bugs. Stick the foundation of the deck out of the ground about 6 inches so the wood posts are not near any wet soil or standing water.

Mistake 8: Choosing the wrong deck trim material

Once you start planning your outdoor deck, you’ll need to thoroughly compare all of your deck materials. How you build your deck will depend on the deck material you use. Don’t assume that all types of decks are put together in the same way.

The Solution

Two main types of deck materials are used in today’s society.

  • Natural wood
  • composite decking materials

Both types of materials have good and bad qualities. To help you make a decision when comparing wood and composite decking, it may be helpful to write down a list.

Most of the time, it is easier to cut and fasten natural wood. Still, some wood products from the rainforest are hard enough that you must drill a hole for each fastener. All wood decks need to be cleaned and sealed from time to time. The best way to clean a wood deck is to use certified organic oxygen bleach. Never use chlorine bleach because it breaks down the lignin that keeps the wood fibers in place. Wood will also lose its natural color when bleach is used.

Cleaning and sealing a wood deck takes a lot of work. If you’re lucky, you may be able to use a sealer for up to three years. Natural wood is also difficult to handle because it can chip. If you or someone you care about has sensitive feet, consider this.

outdoor composite decking

Composite decking requires very little maintenance. You may only need to lightly scrub it once a year with plain soapy water to remove airborne dust and a thin layer of algae. Composite decking never needs to be sealed.

Composite wood decking is very easy to install. The nice thing is that the boards are all the same and there are no knots, warps, or cracks to deal with. The best composite decking materials have special fastener systems that ensure that the flooring is spaced correctly and looks good for a long time. These fasteners take more time and work than nailing with a nail gun, but the results are worth it.

Whichever type of flooring you choose, don’t forget to put protective tape on the wood beams and joists of the substructure. With these tapes, water cannot enter the planks through the holes punched by the fasteners. Over time, water can cause cracks in the wood and loosen the screws that hold it in place.

Mistake #9: Not putting in the right flashing

Waterproofing is an important part of a deck that many homeowners and first-time builders miss. Many times it is not set up properly, or not set up at all.

Deck flashing is the piece of material used to catch water and send it to the exterior of the home. Flashing can be made of many different materials such as pure copper, steel coated with zinc or a rubberized synthetic membrane.

The Solution

To properly install flashing, you need to know a lot about physics. You will soon learn that you need to solder the joint between the two pieces of flashing so that it will work properly. When making flashing, copper is the easiest material to solder.

Don’t expect to use caulk to seal the joints in the flashing. Caulk is not a long-term catch material. Most caulks are quickly destroyed by the sun’s ultraviolet (UV) rays.

Remember, most synthetic membranes should not be left in the sun for long periods of time. Read how to install it to make sure the material will stand up to the sun’s rays.

You need to know why kick-out sheets on metal flashings are important. The capillary attraction of water is stopped by the kick-out elbow at the edge of the flashing. You don’t want the water droplets being pulled back under and up the flash, which is the result of capillary attraction.

Mistake #10: Not getting the right building permits

In the United States, almost every city or town requires a permit for a deck. When applying for a permit in some states, the engineer must also stamp the construction plans. In some cities or towns, even if you have a permit, that doesn’t mean the deck will be inspected. Before you start making plans for your deck, you should ask the building department about this.

You also need to make sure your deck plans comply with local safety and building codes. It is very important to understand setbacks and easements, especially in communities with covenants and restrictions. The fines can be high and the wait can be costly. Building a home without a permit can also make it difficult to sell your home if a potential buyer or home inspector finds that the local building office has no record of the permit.

The solution

Getting a permit and following the rules for deck building in your area can help prevent accidents and other problems from occurring. For example, you may find out early on that your deck doesn’t comply with zoning rules. Can you imagine spending all that money and time building a new deck without a permit, only to find out you had to tear it down or make it smaller because you didn’t get the right permit in the first place? This happens every year to people who want to do it themselves. Don’t let it happen to you!

Also, if you are a member of a homeowners association, you need to know what their rules are. Associations can place restrictions on the types of materials you can use and require you to use certain styles of railings and balusters. Do your homework. Seek guidance. Talk to neighbors who have been through the process before.

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