Deck Post Spacing & Layout

Install Deck Framing Ch02 Step10 11 20220210 172656

Accurately transferring the deck post layout from your plan to the job site is critical. Learn how to use stakes and string to pinpoint the deck footings and establish the correct deck post spacing below.

Why is Deck Footing Spacing Important?

Footings support a deck's posts and beams and must be spaced and sized accordingly. To figure the deck footing spacing, factor in the size of the footing and beam, as well as the beam's span. In most cases, it's best to space the footings/posts no farther apart than 8 feet in the center. Installing a hot tub on a deck requires a structural engineer to calculate the required structural support to carry the concentrated load of the hot tub as well as review by your municipalities' building department before a permit is approved. Other heavy loads on the deck may call for more or larger footings and/or tighter spacing. Stairs should have footings at the bottom corners. For help determining deck footing spacing, enter your deck's measurements into this footing and beam calculator. Also, be sure to check with your local municipalities' building department for specific regulations given influences such as soil type in your area and total load minimums.

Deck Layout Method

For most DIY deck projects, batter boards, mason lines, measuring tape, and simple math are all you need to establish the deck footing spacing. Batter boards--two wooden stakes with a cross piece-work better than just a single stake. They stay in place better and the cross piece makes it easy to adjust the mason line stretched between them. Use scrap wood for batter boards or build them from 1-x 2-inch or heavier ground stakes. A 12-pack of 3-ft stakes costs about $12. Whether you connect the cross piece before or after setting the stakes is up to you. Avoid string or twine. Genuine mason line is stronger and doesn't sag.

How to Lay Out Deck Footings & Posts

Use these simple techniques to lay out the deck footings and establish the deck post spacing. The help of an assistant will improve accuracy and make the job go faster. Remember to keep your tape measure and layout lines level.

Tools and Materials

Layout work requires no special tools and minimal materials. Don't skimp on the mason line. It isn't expensive and gives a better result.

  • Tape measure
  • Mason line
  • Plumb bob
  • 4-ft level
  • Line level
  • Landscape spikes
  • Ground stakes for batter boards
  • Construction screws for batter boards
  • Survey tape
  • Ground-marking spray paint
  • Heavy hammer
  • Tubular cardboard form
  • Screw gun
  • Sawhorse or tripod

Step 1: Remove Debris and Prepare the Site

Call 811 or go to 811.com to have utilities located and marked before you dig. Next, clear the site of sod and plants. Fill low areas. Slope the ground to drain water away from the house. Don't add landscape fabric or crushed rock until the footings are poured.

Step 2: Use the Ledger Board to Establish Reference Points

Most decks are rectangular, and the ledger board forms one side. More precisely, the ledger board is a framing member and a handy reference point to locate deck footings. Start by transferring the reference points-the ends of the ledger board-to the ground. There are two ways: hold a 4-ft level plumb with the ledger board end or dangle a plumb bob from it. Either way, stick a landscape spike in the ground where the level or bob makes contact. Wrap the spike head with landscape tape so it's easy to see. Repeat this procedure at the ledger board's other end.

Step 3: Install Batter Boards

Pound in the batter boards at each location so that each cross piece is approximately centered over each spike. Using a level or plumb bob, transfer the location of each spike to the cross piece and mark it with a pencil. Next, measure out the length of the deck, add two or three feet, and install a batter board opposite the one at the house. (It doesn't have to align exactly because the cross piece allows adjustments.) Return to the house-side batter board, tie mason line at the pencil mark, stretch the mason line to the far set of batter boards. Repeat this procedure on the other side.

Step 4: Square Up the Batter Boards and Connect Them with Mason Line

With a helper, apply the 3-4-5 method-or the identical 6-8-10 method-to square the line to the house. Start by measuring along the house and mark 8 ft. On the mason line, mark 6 ft. Then measure the diagonal distance from endpoint to endpoint. Move the string left or right at the far batter board until the diagonal measurement is 10 ft. This indicates that the mason line is at a 90-degree angle to the house. Tie off the line at the far batter board and repeat the procedure on the other side. These two mason lines represent the outside edges of the deck's frame or rim joist.

Step 5: Locate the Front Edge of the Deck

To establish the front edge of the deck frame, measure along each mason line and put a spike in the ground at the correct length. Set up two batter boards two or three feet to the outside of the mason lines and stretch a mason line between them so that it aligns over the two spikes. Adjust the line so that it is 90 degrees to the two lines it crosses while remaining at the correct distance from the house. To confirm that your layout forms a perfect rectangle, measure diagonally corner to corner. The distances should be equal.

Step 6: Lay Out the Deck Beam Placement

From your plan, determine the distance from the house to the center of the first beam. Measure and mark that distance on the mason lines of each side using a pencil. With a plumb bob, transfer each mark on the line to the ground and place a spike there. Erect batter boards two or three feet outside the lines and stretch a mason line between them, just as you did to establish the deck's front edge. Square this new line to the side lines using the 3-4-5 method. The new line represents the centerline of the deck's first beam.

Step 7: Mark the Deck Footing Locations

From your plan, determine the distance between the outside edge of the deck frame to the center of the first footing along the beam's centerline. Mark it on the mason line. Determine the spacing of the other footings along the beam's centerline and mark those on the mason line accordingly. Transfer all these marks to the ground using a plumb bob and landscape spikes. Your plan should also specify the footing sizes (diameters). Buy a tubular cardboard form of the correct size and cut off a short section of it. Center the section over one of the spikes and coat the ground with spray paint. Do the same at other locations. Double-check all your measurements before you start digging.

For more detailed instructions on how to layout and space deck footings, please visit Trex Academy.

Hi, I’m Lindsey and I’m here with Devin. In this video, we'll be laying out our deck perimeter, marking our beam locations, and finally marking our footing locations. So, you've probably noticed the orange line that we have right here as well as these orange flags. So, anytime that you're going to be digging on your property like in our case. We're going to be digging the holes for our footings we need to know the location of our underground utilities. This service is only for public utilities like water gas electric phones or other communication systems. If you have private utilities like a well or septic system. A private company will need to locate those utilities for you. Okay so now we're ready to lay out the perimeter for our frame of the deck. Okay, what we're really looking for though is; we want to get the locations for our beams which is ultimately going to give us locations for our footings. All right. So, as we're doing this though the first thing, we need to do is we've already determined where our deck is going to be. So, for us, it's going to be about just a quarter inch maybe half an inch away from this piece of corner trim. So, what we want to do is, actually come about two inches away from that and that's where a frame is going to land. Why are we measuring two inches back when we know we want our deck pretty much right up against this trim? Right, this is the frame this isn't our finished deck, so we need to think about our finishing materials. Okay.In our case, that's going to be fascia and we also want to consider leaving some kind of a gap for airflow water to just flow through and also so that debris doesn't get trapped and end up rotting like we've seen previously. I gotcha. That makes sense. So, if we had measured all the way up against the trim to put our stake in then the deck would actually come out two inches farther than we want it to? Exactly. Which depends on what you want, maybe that is what you want, and you can totally do that but then you're gonna have to notch into that corner piece of trim. Just something you have to keep in mind so since we're not gonna be doing that extra work. and I think it's a nicer look. We're actually gonna be measuring those two inches away and that's gonna be the location for our frame. All right makes sense to me. All right. So, I’m gonna go ahead and make this mark. Okay. Okay right there at two inches. Now we wanna transfer that line down to our foundation because obviously, our stake isn't gonna be going in right here.Right. So, a great way to do that is to take a four-foot level. I’m gonna level this out and if you don't mind, I’ll have you make a mark by the foundation on it on the foundation.Perfect. Okay. All right, thank you. Okay, so now we're ready to drive in our first stake. We're just going to be following the same process on the next corner so let's go ahead and get this driven in. Get that hearing protection…you're way ahead of me.All right. So, we want to keep this as plum as possible. Looking good right there.Okay. [Hammers in stake] Ready to move on to the next one. Great, the next thing we're going to do is establish our corner stake. All right. [x2] So, I'm going to have you measure out 15 feet away from the house, and you kind of need to stay in line with the foundation, just roughly. All right. Uh, why 15 feet? The deck's only going to be 14, right? Right. Yeah. So, what you're going to see is as we start to string everything together this is just going to give us a little bit better flexibility. Okay. Got it there? Yeah. Okay. Perfect. [Walking] down towards you. All right. So, now we're a foot past the front of our deck frame. We're also going to go a foot over. And again, what this is going to do… So, imagine that we have a string going right here [Points from the corner of the house to 14ft point] Now that gives us the flexibility to move that string around. I see. [To] Make sure that it's square. Gotcha. Okay, so go ahead and go about a foot over. Could be more. Footage is just an arbitrary number. It could be two feet. All right. Good there. Okay. So, now we're past the front of the edge and we're over so we're gonna go ahead and put our stake there. Cool. We'll be doing the same thing on the other corner as well [Begins hammering the stake] So, we've got that front string in place but remember this isn't actually the perimeter of the frame of our deck. This is going about a foot beyond that. This is just going to be used so we can tie a string to the location of the side of our deck over here. [To] be able to square that with the house. Okay, so go ahead and loop that around this string. Will do… I'll walk it back to the house. There you go. Tied to that stake. Okay. Just hung up a little bit... Oh, there we go. [Got] caught a stick. All right. So, once I get this tied up, we're gonna be using something called the: Three, Four, Five, method. Since our deck is actually longer than five foot. We can double those numbers and go Six, Eight, Ten. Which is actually going to make our measurement a little more accurate. All right. Looks good. So, now we can slide that back and forth. Again, just to make sure that we get square with their house. The first thing we're going to do is get that six-foot measurement. Give that to you [end of tape measure] and you're going to be measuring on the back side of that stake [Stake on the corner] I'll come down here. I'm going to make a mark at six foot. Okay. Now, that we've got that… I’m just gonna switch this around… All right. So now, we're looking for that eight-foot mark. Sure. I’m measuring away from the foundation of the house, and then just make a mark on the string at eight foot. All right got our eight-foot mark. Okay. Great. Actually, just stay right where you are. Okay. Because we've got our six foot, we've got our eight foot, and now we're looking for that ten foot. So, I'm going to put the tape measure right at that six-foot mark. I’m going to be using the tape part of the tape away from me so the part closest to you. Okay. You'll be using the same side, and what we're looking for: we want to line ten foot up with our eight-foot mark that we have on the string. [The tape measure hook is against the house and the case is on the string] Okay. So how do we look? So, we're just a little off. Okay. Looks like we'll have to move this line out just a hair. To… To get that on the mark. Perfect. All right make that adjustment. Okay. Let's see if we're any closer. All right. Okay, I'll just do the same thing. [I] got my tape at six foot. How do you look? Uh… we are perfect. All right. I like perfect. Yeah. Okay so now what that means is the side of our frame is square with our house. Okay? So, we just need to do the same process for the other side and then the sides of our frame are going to be square. Sounds good. [Music] [Music] [Music] [Music] [Music] Okay. So, now that we've marked the location of our beams with these strings. I think this would be a great opportunity to give us a little recap of everything we've accomplished so far. Absolutely. We've squared up the sides with the house, marked our beam locations as you just said, and we've done all that to get to this point of marking our footing location. Yeah, so we are finally ready for our footings. Okay so, our first post is gonna be right here but according to our plans, we actually have a cantilever of our beam one foot past our post. So, we're going to be measuring one foot away from the edge of our deck frame right here. Okay. And we don't want to be to the edge of our post we're going to be right in the center. So, I’m going to measure to the center of that post. I'll make a mark right here in our case that's fourteen- and three-quarter inches. All right. Right there [Points at the ground]. Okay so now what we're going to do we're measuring from the center of this post to the center of our next post. Okay. So, I'm going to give this to you. All right. I'm going to be measuring to seven feet and nine inches. Okay. So, we are at… seven, nine. Okay, great. Now, we're going to be doing the same thing seven feet nine inches to the center of our next post. Okay. So that's 15 [feet] 6 [inches]. A quick math going on, I like it. Yeah [laughs] yep. 15 6 and I see that we've got our utility right here, but we are more than two feet away. So, we should still be good right? Yep. We're in good shape. Great. All right, I'm gonna let go of this. All right. Okay. So, our last post location is gonna be really easy because it's gonna be flush with the other edge of our frame. So, we'll get that location marked. Then, we're going to do the same process on this beam right behind me here. After we do that, we're going to be extending all of these marks down to the ground just by using some paint. [It’ll] give us a nice mark and that's going to give us the center of our footing location. Okay so we've transferred that mark down to the ground but again this is marking the center of our footing locations. Now we're going to be finding the perimeter where our post hole is going to go. Okay. Okay. So, I think a great way to do that is to take a 12-inch concrete forming tube because in our case that's going to be the diameter of our holes. Right. Right, so we're going to slide this [tube] underneath. We'll be using this as a pattern. So as long as we line that up with the mark that we already have, again marking the center. Now if we just paint around or Inside, we'll have the location that needs to be dug out. This is great. So, if we didn't have this, would we just have to measure the 12-inch diameter? Yeah. It's exactly what you would do. You could take a 12-inch measurement put your six-inch right in the center and then do the same thing in two directions then you can paint a circle and dig that out. Again. It's fine, you can get pretty accurate with that, but I think this is a really quick way to do it, especially with two people. Now we can quickly throw it down, paint and then you'll move on to the next hole and we'll just keep moving that way. I like it. Okay. All right. Let's go ahead and paint this first one. Safety first. Right. Yep [put] those glasses on. Okay. Here we go [Music] All right. Look at that. Perfect. Now we know exactly where we have to dig out for our first footing. We're going to be doing this entire process again for the middle deck and for our lower deck all the way on the end. Okay so now that we've got all the locations for our post holes marked our next step is going to be to come back and dig the holes for our footings. So, you can go to trex.com/academy where you can find a video on that and a whole lot more covering the entire deck building process. Thanks for watching!

Start the Deck Layout & Spacing Process Today

Batter boards are inexpensive and easy to make. Plus, the math is basic. Time to find your footings!

To find decking materials, use our Find a Retailer tool. To find a contractor, use our Find a Builder tool.

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