Trying to design a deck for my house

[Satellite^Guy]

This summer has quite a bit of work planned for our home. We're replacing the windows and front door. We're pulling off the crappy particleboard skirting (it's rotting, you could poke your finger through it like wet cardboard) and replacing it with proper vinyl skirting. If time, energy, and financing allow, we're building a deck for the front of the house.

Sat^Gal and I sat down earlier and scribbled out the basic layout for what we want. It'll be about 14' long by 8' out. If I'm not mistaken, it needs to be free-standing, not anchored to the house. We can't put in dug posts, so it'll be put on deck blocks.

Okay, how to describe how the steps are integrated...
If you have the deck drawn, x=14, y=8. The house door would be at the top right corner. Cut out the bottom right corner of the deck x=42", y=36"
The 42" is the width of the steps, with 6" allowance for the railing to give 36" clearance. 3 steps would take 30", and the steps would end 6" short of the outer edge of the deck.

I know, a pic would describe it so much more easily, but I'm terrible at drawing on a computer.

How would you guys frame this up? I was originally thinking of cantilevering it at the 5' point where the steps start, but you can't cantilever more than 1/4 of the joist span, so that's out.

Is there someone who is able to draft this up?

[C2H5OH]

I can't draft that for you, and I'm having trouble envisioning what you're trying to do, so I can't help you with the framing, but those deck blocks look kinda dicey to me. They only have 1 square foot of ground contact, so that's gonna make for a rather high ground pressure if you're putting any significant weight on the deck, even a 300 pound human. How many are you using? What kind of ground are you putting them on?

I used to be a Civil Engineering Technician (AKA a construction inspector), specializing in subsurface structural shit. That I can help you with.

[Jaglavak]

Agreed. That's only 1/4 of a square foot. Start by digging down through the topsoil layer to mineral soil below. When I did a job like that a few years ago, I poured concrete pads 1 1/2 ft x 1 1/2 ft x 6 inches deep for a surface area of 2 1/4 ft2. With a # shape out of number 4 rebar embedded 3 inches deep. That's good for a couple of tons on pretty much any soil except sand or mud. I would have used 1 x 1 ft pavers with deck blocks on top, but was unconvinced about their breaking strength for the load I was expecting. But that would be a lot faster and should be fine in this case. Use liquid nails between the deck blocks and pavers. I used a water level to get the pads all level, but a string level would work too. And you'll still need a pack or two of those plastic door shims for final leveling.

I would frame up the rectangular part of the deck first. Then frame up the 42" x 5 ft landing off the big rectangle. Then hang the top end of the stairs off the landing and the bottom end on blocks. Typically you want a pier block every 4 ft. So for the big rectangle, 3 pads along the house, 3 down the middle, and 3 on the outer side. The center support beam is usually a 4 x 8 under the joists, to avoid having to make all those cuts. With four steps up it sounds like you've got enough altitude.

Hang the left side of the landing off that, so 2 more pads for the right side. And finally 2 pads for the bottom of the stairs. You typically use a short 4 x 4 post down to the pier blocks. Then sister upward with 4x4s for rail posts using 7 inch galvanized lag screws. Cut a slight angle on top of the rail posts to avoid standing rain water.

Use treated lumber and be no shit paranoid about the sawdust. This may sound a little funny but do not seal or paint the bottom side of the deck boards. No matter how fanatically you seal the deck, water will find it's way in. If there is no path to dry out it will get waterlogged and stay that way. Even treated lumber will bit the dust under those conditions. Some friends of mine used trex lumber to build a deck about 10 years ago and they are still quite happy with it. No splinters. However brace yourself for the sticker shock.

[Random Precision]

One really important note if you use treated lumber. The deck boards need to be laid down so that when they warp, they will crown and not cup. So when you look at the end grain of the deck planks, the tree ring patterns should be like a rainbow, not like a smile. From experience I have learned that this is very very important.

One way to avoid that issue is to use one of the composite deck materials like Trex instead of treated lumber. It doesn't warp, never needs to be painted and has a non-slip surface. It's made from recycled plastic and wood fibers. Online sources say it costs $30-$45 per square foot of deck compared to $15-$25 for wood, but the no paint, no maintenance aspects really make up the difference.

[Satellite^Guy]

Originally Posted by Jaglavak

Agreed. That's only 1/4 of a square foot.

I think you're misunderstanding these blocks; the 6"x6" is the size of the square hole in the middle for a 6x6 piece of lumber. I actually clicked on the wrong one, I'd be using the blocks for 4x4's. The block itself is 12".

Start by digging down through the topsoil layer to mineral soil below. When I did a job like that a few years ago, I poured concrete pads 1 1/2 ft x 1 1/2 ft x 6 inches deep for a surface area of 2 1/4 ft2. With a # shape out of number 4 rebar embedded 3 inches deep. That's good for a couple of tons on pretty much any soil except sand or mud. I would have used 1 x 1 ft pavers with deck blocks on top, but was unconvinced about their breaking strength for the load I was expecting. But that would be a lot faster and should be fine in this case. Use liquid nails between the deck blocks and pavers. I used a water level to get the pads all level, but a string level would work too. And you'll still need a pack or two of those plastic door shims for final leveling.

I might put those deck blocks on top of larger pavers, I haven't decided yet. I'm planning on using a homemade water level when I do the build.

Incidentally, the reason I'm going to use blocks is because I'm in a trailer park, and I don't think we're allowed to put permanent poured structures, unless it's an owned lot, which this isn't.

I would frame up the rectangular part of the deck first. Then frame up the 42" x 5 ft landing off the big rectangle. Then hang the top end of the stairs off the landing and the bottom end on blocks. Typically you want a pier block every 4 ft. So for the big rectangle, 3 pads along the house, 3 down the middle, and 3 on the outer side. The center support beam is usually a 4 x 8 under the joists, to avoid having to make all those cuts. With four steps up it sounds like you've got enough altitude.

Hang the left side of the landing off that, so 2 more pads for the right side. And finally 2 pads for the bottom of the stairs. You typically use a short 4 x 4 post down to the pier blocks. Then sister upward with 4x4s for rail posts using 7 inch galvanized lag screws. Cut a slight angle on top of the rail posts to avoid standing rain water.

Use treated lumber and be no shit paranoid about the sawdust. This may sound a little funny but do not seal or paint the bottom side of the deck boards. No matter how fanatically you seal the deck, water will find it's way in. If there is no path to dry out it will get waterlogged and stay that way. Even treated lumber will bit the dust under those conditions. Some friends of mine used trex lumber to build a deck about 10 years ago and they are still quite happy with it. No splinters. However brace yourself for the sticker shock.

This sounds like a good start to the plan. I hadn't thought of treating the 10 1/2 foot span on its own and adding the 3 1/2 foot landing and step to it. This seems like it might make it a bit easier to figure out. thanks.

[Satellite^Guy]

Originally Posted by Random Precision

One really important note if you use treated lumber. The deck boards need to be laid down so that when they warp, they will crown and not cup. So when you look at the end grain of the deck planks, the tree ring patterns should be like a rainbow, not like a smile. From experience I have learned that this is very very important.

One way to avoid that issue is to use one of the composite deck materials like Trex instead of treated lumber. It doesn't warp, never needs to be painted and has a non-slip surface. It's made from recycled plastic and wood fibers. Online sources say it costs $30-$45 per square foot of deck compared to $15-$25 for wood, but the no paint, no maintenance aspects really make up the difference.

We're really keen on keeping the initial costs to a minimum, but the reduced maintenance costs are definitely worth keeping in mind. We'll have to carefully weigh our options. That having been said, doubling the initial cost just might not be in the cards. My parents have a deck on their house that's been there long enough that I'm not really concerned about the longevity of a wood deck.

[Satellite^Guy]

Originally Posted by Satellite^Guy

This sounds like a good start to the plan. I hadn't thought of treating the 10 1/2 foot span on its own and adding the 3 1/2 foot landing and step to it. This seems like it might make it a bit easier to figure out. thanks.

After thinking about this for a bit, I decided to go 13 1/2' long instead of 14, as this would allow me to build the main rectangle at 10', instead of having to buy 12' lumber and wasting a foot and a half of it.

Random Precision, I looked at local prices for pressure treated vs composite decking. PT was on sale for $5.99 for 5/4 x 6" x 8'. The composite was over $40 for 12' lengths. That makes a difference of $150 vs over $700.
I think the wood just makes more sense for our situation.

[Khampelf]

Hey, Sat^Guy!

I can't help you with the deck, but It's good to see ya!!

[Satellite^Guy]

Originally Posted by Khampelf

Hey, Sat^Guy!

I can't help you with the deck, but It's good to see ya!!

Hey, Khampy! I'm always here, I just never have anything to say.

[Glazer]

That doesn't stop the rest of us.

[Random Precision]

Originally Posted by Satellite^Guy

Random Precision, I looked at local prices for pressure treated vs composite decking. PT was on sale for $5.99 for 5/4 x 6" x 8'. The composite was over $40 for 12' lengths. That makes a difference of $150 vs over $700.
I think the wood just makes more sense for our situation.

I agree, definitely not worth that much extra. If you use the 5/4" PT, be sure you run the support stringers no more than 18" apart. If you try to go much wider, the deck will flex between the joists when you walk on it. Learned this by the way my brother built his deck with 24" on center joists.

[Satellite^Guy]

Originally Posted by Random Precision

I agree, definitely not worth that much extra. If you use the 5/4" PT, be sure you run the support stringers no more than 18" apart. If you try to go much wider, the deck will flex between the joists when you walk on it. Learned this by the way my brother built his deck with 24" on center joists.

I'm going 16"oc. I thought that was the going consensus.

[Random Precision]