Ask This Old House

Kevin

Almost 30 million American homes have an outdoor deck and for good reason. Having a deck can add value to your home and expand your living space, giving you a unique place to entertain family and relax with friends. On this special episode of "Ask This Old House," we'll walk you through the entire process of building a deck from start to finish.

Tom

That's good. That pulled it right in tight. Now, what I don't want to do is run a straight line with the lag bolts because I could actually split this with the weight of the joist.

Kevin

That's coming up next on "Ask This Old House." Expanding your usable outdoor space by adding a deck is one of the most commonly requested homeowner projects. A deck can create additional areas for cooking, entertaining, and relaxing. But if they're not built correctly, they can be unsafe and potentially dangerous. With the proper planning, a modest-sized deck can be completed in two or three weekends, depending on your skill level and the complexity of the design. Before tackling a deck build, it's important to check the local building codes as well as pull all the proper permits. Homeowners Melissa and Mark drew up the plans for this multi-level, 20-foot by 20-foot deck and used them to get the permits we needed. They also had to have their property surveyed before we could begin. The first phase of the project involves transferring the planned layout to the site and determining the location of the footings.

Tom

What we've done is, we've set up a series of batter boards on the outside perimeter of our deck, away from our deck. It allows me to position the deck or get a reference off of the house. So if I lay this string, and I've got one end attached to the foundation down there, on top of my batter board and I slide it until the string touches the foundation right there, I'm now in line with the foundation. Now we're going to use the batter boards to establish a parallel line off the back of the house, 20 feet out.

Mark

That's the size of the deck.

Tom

Right. Now you take the level, put it against the siding, and run a plumb line down. Melissa's going to measure from the level out.

Mark

Okay.

Tom

All right. 20 feet. I'll place a screw.

Drill whirs

Tom

Okay. Now we're going to do the same thing on this side. Okay. Now pull the tape tight. I'm going to pull the string tight. I can slide it along the batter board, bring in the string line to 20 feet, put a screw in there, and we'll be all set.

Drill whirs

Tom

These three lines that run parallel to the back of the house represent the support beams that are going to hold the deck. Each one of these support beams have to have posts under them. To locate where the posts are going to go, we divided them in half and put a piece of tape in the center. We also measured back from the outside of the deck 18 inches for the other post. That means that this beam will be cantilevered over this post. Now, the post has to sit on a concrete column. Now I'm going to mark for the column. Now, I suppose we could dig all these holes by hand, but that could take us a couple of days. To make life easier, I brought a small skid-steer loader with an 18-inch auger that will drill 48 inches deep. We rented this auger for the day for $400, which includes delivery and pickup. How we making out, Mark?

Mark

Pretty good. I think we're a little bit past 4 feet. I gotta tell you, though, I'm surprised that they have to be that deep.

Tom

Well, in this part of the country, the frost will actually go 4 feet deep, so the building code says we have to be a minimum of 4 feet. If the frost should get under this column, it'll actually pick the deck right up.

Wow. Tom

All right. Now we're ready to set our form. This is a 12-inch tube made of recycled paper. Now I want you guys to backfill it evenly around the perimeter, and I'll hold it so it won't move.

All right. Tom

Okay. Throw it in there gently now. Nice and easy. All right. All of our forms are set, but we can't fill them with concrete yet.

Melissa

Why is that?

Tom

Well, you need to call the building inspector, and he's going to come out and measure every hole to make sure we're a minimum of 4 feet below grade. Once he comes and signs off and says everything's okay, then you can get some concrete and fill them up.

Mark

Easy enough.

Kevin

Once the footings are poured and cured, work can begin on the structure that will support the deck. This includes the support posts, the ledger board, and the support beams that will run parallel to the house. All three of these are typically made from pressure-treated lumber and are installed at the same time to ensure that the deck is level. First, the support posts are secured to the concrete footings using a post-base connector.

Tom

So, I see you've pre-drilled a hole, and you put an expandable bolt into the concrete.

Mark

That's right.

Tom

And now you're going to use these metal brackets. They're gonna sit on top. And that bolts down like that. And there's a flat plate that goes on top of that. And that actually allows about an inch on top so that the wood's not sitting in the water when it rains out. And then we can make a connection between the top of our concrete and our wooden post. We reinstalled our line using our batter boards, which is parallel to the back of the house. We use the string line to dig our holes, to set our columns, and now we're going to use it as a reference to set our post base. At the bottom of the post base, there's a slot so we can slide it back and forth. So we'll set this first one right here. Okay. Now we're gonna put our washer and our nut on. I don't want to tighten it yet. Now I'm going to measure off of the string, see where we're at. It's an inch and a half. Okay. So now we know where we're going to set the rest of our post bases. So we can tighten this one down. Okay. Can put the flat plate on there. We'll go to the next one. We need to remove the first course of siding so we can attach the ledger board directly to the house. Now we want to replace this metal flashing that we just removed along the back with this self-sealing membrane flashing. And I want to make sure that it goes up underneath this row. All right. Now we're ready to install our pressure-treated 2x8 ledger board. So I've cut a gauge block out of a scrap piece of a 2x4. I've got the thickness that I have for my deck, plus a little bit of air space. Okay. Nail it off.

Melissa

Whereabouts?

Tom

Anywhere you'd like.

Melissa

All right.

Tom

There. I want to make the joist spacing 16 on center. All right, now we're ready to set our timber hangers on our line, but to get the right elevation and the right spacing, I've cut a gauge block, which will represent a joist. Put it in the hanger. Gonna tack that little tab right there in place. That holds the hanger. Straighten it out. Tack this one. Okay. Now we'll nail it off.

Nail gun firing

Tom

Now, we've nailed the ledger to the house, but that's not enough fastening. What we want to do is lag it to the house. We're going to use a 6-inch lag bolt. I'm going to pre-drill the ledger with a 3/8 drill bit. That's good. That pulled it right in tight. Now, what I don't want to do is run a straight line with the lag bolts, because I could actually split this with the weight of the joist.

Okay. Tom

All right? So now I'm gonna basically stagger my lag bolts. Up high, down low. Okay, Melissa, take the 2x8 joist and set it right in the hanger, the other end of the joists are actually going to sit on a beam right here. These are two 2x12s. They're gonna be 20 feet long, and they're gonna run parallel to the back of the house. This beam is actually gonna sit on a 6x6 post.

Mark

What'd you do to the post there?

Tom

Well, I actually took the post and I cut a rabbet in it so the beam will sit in it. And I actually cut the top of the post on an angle so that if any water runs through the decking, it won't lay on top of the post. Now, the trick into this whole thing is, the top of this beam has to be even with the underside of the joists, and it has to be constant to make it level right across. Now, the problem is, the cement columns are not exactly level and the beam has to be. Let me show you how I established this mark right here. It all starts right here with this laser level. This laser level is spinning a laser light all the way around the yard at a constant level. I can pick up that light anywhere in the yard with this receiver right here. When it sees the light, it gives me a constant beep. That means I'm level. Then I marked a line on my board level with the underside of the timber hanger. I then took my beam, and I measured down from the line to the bottom of the stick and I cut the stick off square. Now I can use this stick and use it as a reference off of my laser, put it on any of the posts and mark the underside of the board. And that's where I cut my notch.

Nail gun firing

Tom

Okay, let's put the second one up.

Nail gun firing

Tom

Now we want to make the connection between the post and the beam using these galvanized carriage bolts. Now we'll just tighten them up with our impact wrench.

Kevin

Now that the supporting structure is in place, the joists can be installed.

Tom

Now, the upper level joists will actually fit into the hangers that are mounted to the ledger board on the house. The joist then comes out and sits on top of this beam. On the surface of the beam, we've mounted more timber hangers. Those timber hangers are to accept the joists that are going to go over and sit on top of these two beams. Now, from the upper level, you're gonna step down one step to the lower level, and that step's gonna be a diagonal. So I can know where to cut my joist, I put a string line to show where the back of the step will be. Line my joist up with the line at the right position and that's where I'll cut them.

Kevin

With the upper-level joists in place, the lower-level joists can be installed in the same way. Blocking between all the joists will help keep them true and straight over time. Stair stringers were also added to give access to the yard.

Mark

We got a concrete pad down here that I poured.

Yeah. Mark

And I put this plate that's 2x12 on top that I J-bolted in.

Tom

Good, good.

Mark

And then I cut the stringers and anchored them to that with this angle bracket.

Tom

Mm-hmm.

Mark

And if you come up here, you'll see I used adjustable joist hangers to anchor them to the 2x12.

Tom

You put some carriage bolts in there. Doesn't look like they're gonna go anywhere.

Mark

No.

Kevin

When it comes to decking options, there are a lot of different materials to choose from. In recent years, composites, which blend ground-up wood and plastic, have become more popular because they offer good looks and minimal upkeep. But wood decking is the overwhelming choice for homeowners in the U.S.

Tom

You guys chose real wood. This is called ipe, also known as ironwood. It's very dense. It's a Brazilian hardwood. It holds up to the weather wonderfully. Over time, it will just age out to a nice silvery gray. But you guys wanted to have it stained.

Melissa

Yeah, we decided that we liked the look of the darker, richer stain.

Tom

And it is very rich. So what we did, we had the factory stain it. The benefit to that is they stain all the way around the board. If we were to do that in the field, it's a lot of work. Now, your deck is gonna be 20x20. That's about 400 square feet. So we ordered 450 square feet for waste.

Let's get started. Mark

Great.

Tom

To ensure that our deck boards run straight and parallel with the house, the first thing we did is snap the chalk line parallel to the house out the distance of the board. Now we're gonna take our board, place it on the mark. Because this wood is so hard, I need to pre-drill a hole. Drill a hole right through the board.

Drill whirring

Tom

Now I'm gonna attach the deck with this screw that's colored to blend with the finish of the decking. Now, our chalk line is straight, but our board has a curve to it. To straighten the board out, we're gonna move it out until it touches the line. Then I'll screw it off. If we do it all the way along the chalk line, the board will be straight.

Drill whirring

Tom

We've installed our first board straight across the back of the house using a screw through the face of the board. Now that we're far enough away from the house, we can start installing the rest of the decking using a different type of a fastening system, a hidden fastening system. We're gonna utilize the groove on the board by driving the nail through the groove into the structure below. Right here on the nail, this little piece right here, will act like a spacer. And this little piece right here actually holds the next board down, and you won't see any fasteners on the face of the deck.

Melissa

So are we putting those all in by hand?

Tom

No, we're actually using a pneumatic tool that is designed for decking. It looks a lot like a flooring hammer that you'd use in the house. It's as simple as that. Now I'll just work my way down the line. Okay. Now we're ready for the second board. Melissa, take the end of the board and line it up with the board that we just put in place. Got it there? All right. Now I'm gonna use the same mallet to drive the second board into the fasteners. Whenever installing decking, you want to think about where the end of the boards are gonna end up, like these butt joints right here. You always want to make sure that the end of the deck board ends up in the center of a joist, not in the center of a joist bay. You'll have no support. You also want to make sure you seal this fresh cut to eliminate any checking or cracking. Now you have to think about how you're gonna fasten these boards. If I nail these two boards right here, the chances of these splitting are pretty good, so I'm gonna use a different type of a fastener, a plastic biscuit, with two little spacers on the bottom. I'm gonna drive these into the slot, and we'll take a stainless-steel screw, put it right in there. This is the last deck board on our first level, and we can't use our hidden fasteners on this board, so we're going to have to face screw it just like we did the first deck board. On the side of the deck, we let the deck boards run long so we can cut them off, have a straight edge, flush with the rim joist. From the step down from the upper level to the lower level of the deck, you can see this pressure-treated framing right here, and you can also see the groove of the deck. I don't want to see either one of them. I want to hide them. So we're gonna use a piece of 1x8 ipe and put it up just like that. Now, the first thing I have to do is, I have to put a filler on the riser and it just so happens that a piece of ipe scrap wood works out perfect. So I pre-drilled some holes, and I'll screw it in place.

Drill whirring

Tom

Now, we mitered both ends of the 1x8, and we sealed the end grain. Now I want to hold it into position, keeping it flush with the top, lining up my outside corner, and I want to pre-drill for a screw.

Drill whirring

Kevin

When it comes to railing systems, homeowners have an almost unlimited variety of styles and materials to choose from. In this case, the homeowners went with a custom-made railing using the same hardwood used for the decking.

Tom

We've pre-drilled the holes right here for our lag bolts, and we're gonna use 5-inch lag bolts, one in each hole. And I've actually marked the location on our structure where each post will go. Now, Melissa, I'll hold it in the position if you want to start it. Now get it started, and then I'll plumb it up at the level.

Melissa

Okay.

Drill whirring

Tom

Okay. Now let's see. You get another one on the bottom there. Now let me see if it's plumb first. Okay. Right... Right there, Melissa.

Drill whirring

Tom

Now we're gonna start installing the railings. Give you the top one. Got it right there, Mark? Now, this post has a little bit of a curve in it, so we need to pull the post back. To do that, I'm gonna use this strap right here and ratchet it back into place. Now just give that a little tap. Good. Little more. Good. Now go there. Okay. Now the dovetail will hold it together. In the design of the deck, we decided to put two posts in the corner.

Yeah. Tom

To fill that gap, we have to put a railing in, so we made two pieces of 2x4. We mitered them, and we're gonna slide them into the dovetail. Okay. Let's take that one over there, Mark. Tap it in.

Mark

That's a nice fit.

Tom

Okay. Take that drill, and we'll put a stainless-steel screw right in there. I pre-drilled the hole.

Drill whirring

Tom

Looks good. Nice and tight. And now we'll do the one on the top. Now, the dovetail joint is very strong this way and this way, but it's not this way. It's a sliding dovetail. To stop that from sliding, we're actually going to drive two galvanized pins right in the corner, in the top of the bottom rail and the bottom of the top rail.

Mark

Here you go,

Tom. Tom

Thanks. Okay. Now what we're gonna do is, we're gonna build each baluster section in place here on the table, and then we're gonna install it as a unit. Now, lots of times you see the balusters spaced equally between the posts, but you guys have a different idea. You want to start with a baluster about 4 inches away from the post, then a 2-inch space, then a 4-inch space, a 2-inch space, a 4, and so on down the line. So what we did is, we took the sections, we divided them equally in the layout that you wanted. We mark two sticks. These are the nailing sticks, one at the top and one at the bottom. Hold it there. And now our balusters will be positioned perfectly, top and bottom. Now, I'll just pin them. This is a 1-inch, 18-gauge nail. Anything longer, it'll bend 'cause the wood is so hard. Four in the top, four in the bottom. All right. Now let's slide our first section in. Got it there? Well, guys, the rain held out just in time for us to finish the deck. What do you think?

Mark

This is tremendous.

Melissa

I'm blown away. It's amazing.

It is a great deck. Mark

Yeah.

Tom

Well, there's one thing left that I want you to do. I want you to put these blocks on the top of each one of the posts.

Mark

I think we can do that.

Kevin

Whether you build it yourself or hire a professional, a properly built deck can expand your usable outdoor space for years to come. Next time on "Ask This Old House," we'll examine the plumbing system. We don't want to see it, hear it, or smell it, but understanding how your plumbing system works can save you a lot of money.

Man

You want to make sure that that water has somewhere to go. Otherwise, the pan is just gonna fill up, and you're gonna have water problems anyway.

Kevin

We'll let you know what to look out for and what you can do to keep your system running properly and prevent costly damage to your home.