Building a deck? Read this first

Building a deck isn’t hard; the trick is connecting it properly to the house so it doesn’t collapse or damage the home.

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Building a deck isn’t hard; the trick is connecting it properly to the house so it doesn’t collapse or damage the home.

Q: It's time for me to build a deck. It'll be my first one. Each person I ask how to build a deck gives me a different answer. Surely building a deck can't be that hard. When you used to build decks for a living, what tricks did you conjure up to ensure the deck didn't collapse?

A: If I were to ask 10 of my master carpenter buddies how they would build a deck, I'm pretty sure I would get at least five different answers to specific questions about connections, framing methods, squaring techniques, deck-board spacing, railing connections and the like. In other words, choosing between construction methods is a gray area. It gets very cloudy when you discuss ways to waterproof the connections to the house.

It might be more useful to point out what not to do. (I'll also mention a few best practices I used when I was building decks on a regular basis.)

A few days ago I came across a deck project near my home. To my shock, the builder had attached the deck ledger board directly to the house's oriented-strand board (OSB) sheathing. There was no felt paper, no water barrier, nothing to prevent the rot of the OSB and, eventually, the structural framing members in the wall.

The builder also used regular, non-galvanized nails to attach the board to the house. These will rust. With today's treated lumber, you have to use special galvanized fasteners, as the lumber can have a high concentration of copper preservative that can cause a corrosive galvanic reaction if the steel in the nails comes in contact with water and the treated lumber.

Whether your deck design calls for two posts or 10, you want them to be centered on the concrete piers for aesthetic reasons as well as structural ones. The deck railing is often an extension of these posts, so these posts can be visible. There are many ways to get the posts directly centered on the piers. Over the years I gravitated to one method that worked perfectly each time.

When I started building a deck, I would frame the outer shape of the deck with the lumber. This crude box, whether a square or a rectangle, defined the outer edges of the deck. I would support this box in the air with temporary legs, making sure the box was level away from the house, level left and right and square. I then would install temporary diagonal braces on top of the frame to keep the shape perfectly square.

With the frame square and level, I could then use a plumb bob dropping from the outer corners to the ground to find where the corners of the deck above were in relation to the ground. It was then possible to locate the exact spot for the concrete piers and the post above, depending on how the plans called for the post to connect to the deck. There's always a little math involved, but it's not that hard to do.

This method works on just about every outdoor deck, except for those that are high off the ground. If that's what your situation is, no doubt you'll struggle. You may want to hire a professional to help you with this part of the job so you don't get hurt or waste time.

Understand that deck construction itself is not too hard, but it can be complicated. A wood deck can appear to be simple, when in fact it's a collection of small, complicated steps that go together to make the completed project. Your biggest concern needs to be how the deck connects to the house so that it doesn't collapse or cause damage to the home.

If you have any doubts, it pays to have the deck connections engineered. A residential structural engineer will draw a simple plan that shows how to make the connections as well as identify the proper metal framing connectors, the bolts, the correct concrete piers, etc. When you consider the amount of weight, the number of people who might be dancing on the deck one day, and the horrible things that can happen if the deck collapses, you'll quickly see that it's the best money you'll ever spend on the project.

Tim Carter is a licensed contractor. To view previous columns or tap into his archive of information and sources of building materials, go to www.askthebuilder.com. You can write to Tim Carter at P.O. Box 36352, Cincinnati, OH 45236-0352.

. TIPS

Deck dos and don'ts

• If you decide to connect the deck ledger board to the house, space it away from the side of the house with corrosion-resistant washers or bushings. Use through bolts that have a nut and washer on one side of the bolt. Never use lag bolts to attach a ledger bolt to wood on the house or into a masonry anchor. Lag bolts can easily pull out of the house.

• The height of the finished deck surface should be 2 inches below the finished level of the inside floor of the house. If you make the deck surface level, rain can find its way indoors fairly easily.

• It is your responsibility to know zoning and building codes for your area.

Building a deck? Read this first 03/27/09 [Last modified: Friday, March 27, 2009 4:30am]

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