Answers to Deck Questions #2

deck under construction
  • 5-40 hours
  • Intermediate
  • 500-5,000

Q. I am building my first deck this weekend and had a few questions to prepare. It is a new home, and currently has a 10 x 10 concrete patio on the back of the house. We are building a 14 x 16 deck over the top of this patio. I have two questions: Will I need to rent equipment to dig into the concrete for a support post, or will the boards span this width? Second, what do I do about the approximately three feet of lawn that surrounds the patio? The deck will be covering this, so will I need to dig up this sod or use some other method to kill the grass?

A. With 22" of difference between the slab and the deck, you can leave the slab in place and don't have to cut into it at all.

Through bolt the ledger to the wall of the house, assuming that you can get under the house to put large washers or steel plates and nuts on the bolts. Use joist hangers (Simpson LU26's or larger, depending on the size of joists you opt to go with) on the ledger. With the deck projecting 14' out from the house, go out six feet - you will have a beam there - and another at 12' out from the house. Some of the beam at six feet will be over the slab. Anchor AB, ABA, ABE, or similar standoff bases to the slab where the posts will be. Once the beam is beyond the slab, you will dig footing at whatever depth your local code calls for. How deep is determined by the frost line where you live, if one exists.

The beam at 12' out from the house is not going to be over the slab at all. Dig footings. Set CB44's or PB 44's in the top of each footing, or set pier blocks. Your posts will attach to those. Digging out the sod and laying landscape fabric or black plastic (two layers of six mil minimum) and covering it with rocks will eliminate the need to mow under the deck.

elevated deck on side of a house

Q. I have an elevated deck off the back of my house, which gets no sunlight underneath, resulting in absolutely no grass growth, which turns into mud when it rains. Here's the problem: My septic tank is under the deck, so I am limited to what I can put down to where I can still dig up my tank to get it pumped out when needed. Got any ideas of what I can place down but still allow easy access to the septic tank? I was thinking mulch or gravel of some type?

A. Dig up the tank lid and install a riser so the lid is on grade. Then use landscape fabric and mulch or stone. Many folks enclose beneath the deck area with lattice or other material and use the space for lawnmower and lawn equipment storage or a potting shed.

Q. I'm attempting to build my deck this weekend. I currently have an existing ledger board and need to extend it. Would I be able to run the extension lower than the existing ledger and put the floor joists on top of the new ledger and use hangers on the existing ledger so the decking will be level?

A. No, you need the joists to butt into the ledger, not sit on top of it, so that the joists won't twist. Another option would be to not use an attached ledger for the portion that you are extending. Instead, add a girder within two feet of the wall on piers, let the new joists sit on that, and use a rim joist along the house wall that the joists butt into. Extend the girder under the first two or three existing joists so that you can get the new portion level with the existing.

Q. I want to attach a two foot high or so vinyl privacy lattice on top of my existing deck rail. The deck rail is standard 2x6 all the way around. My real concern is 1) will it be sturdy enough and 2) installation. I thought of using a router on 'top' of the rail and inserting lattice, or attaching it to the back or outside of the rail with screws. How far apart should support pieces be, and do I have to cut into sections and slide into the support, or can I screw right into the lattice and support strip?

A. Make the privacy "fence" separately, and screw it down to the top of the deck's 2x6 handrail. My suggestion would be to purchase some cedar 2x4's and router your notch in them. Not only would the cedar be easier to router, but also the whole thing could be made in modular pieces, which would be easy to make and install, and all of it could be easily removed someday without ruining your handrail.

Cut your vinyl lattice into 2' x 8' pieces, and put the notched 2x4's around them like a picture frame. Then you can just set these sections on top of the handrail and screw them down. You will probably have to cut some 2x2's and install them vertically to keep the whole thing from spreading in the middle, and to keep the vinyl from flexing in the wind. The only thing that would make this very secure is if the deck is small with lots of corners, because that stuff is going to want to blow over.

If someone thought it was sturdy (like handrails are supposed to be) and leaned against it, they could go right over. Making the thing safe and secure looks like the real challenge. I think we'd need to see a picture of the handrail to make any specific suggestions in that regard.

In order to make it secure, my first thought would be to cut a 1 1/2 x 3 1/2 hole in your handrail so that you could drop in and sister a 2x4 along each of your handrail posts (which I'm assuming might be 4x4's?) so that it extends up two feet above the handrail. If you did that, it would probably be easier to forget the modular idea, and cap those 2x4's you sintered with a 2x4, and then just hold the lattice in place with some 2x2 "stops" on each side of the lattice.

worn deck boards

Q. I have a wooden porch that was painted and is now quite worn. I used a heat gun to remove the old paint and was thinking of doing a tinted stain or repainting. I was just looking at This Old House Magazine and saw a porch that had slate instead of wood boards. Can I do this on a wooden porch or is this only something I could do on a concrete porch? I'd assume I'd need to put down some plywood or concrete backer board. Are there any other issues to consider like weight? Is this just a bad idea and I should just go buy some paint and call it a day?

A. Slate or tile over a wood sub floor inside is one thing. Do not do it over a wood sub floor on an exterior porch.

Q. We have a sundeck over our carport. We replaced the plywood sub floor and are going to hire contractor to lay rolls of vinyl. We are confused about thickness, and so many different opinions from contractors: 40 mil, 55 mil, and 60 mil. What about fabric-backed versus plastic backed? Can anyone give us his or her experience? Does it tear easily from patio furniture?

A. All man-made manufactured products from solid wood to engineered wood, plastic laminate, vinyl or other products require year-round moisture, humidity, and temperature control. Vinyl floor covering in an exterior installation on a sundeck is not an option. If you want to install a floor covering over the sundeck, you will need at least 16" joists on centers, concrete underlayment board and frost-proof tile (quarry). I don't know whom you've been talking to, but you need to talk to some more folks before you proceed with the project and sink your checkbook into a project set for failure. You need to consult warranty info regarding installation and maintenance. You need to address installation and maintenance issues to maintain the warranty.

Q. I have a leaky deck over our carport. My plan is as follows: Replace existing plywood with one-inch plywood, tape and seal, place Durarock over that set with thinset, then put tile/brick on top. Will this give me enough water proof protection or will I need something between the tile and Durarock?

A. Just make sure that your joists can support the weight of Durarock and tiles. If you have a sturdy joist system, and Durarock and exterior grade plywood beneath provides a flat surface for tile, then you are good to go. You will need a frost-proof tile such as quarry tile. If the tiled area is accessible as a deck, you will need to seal grout and tile periodically to prevent staining.

Q. I want to put some decking on my drive, but the tarmac is not level. Does anyone know how I make it even before I can build?

A. If you're building an elevated wood deck above an asphalt drive, then you need to address the leveling issues in the construction of the deck.

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