Build it Once
In this article I’m going to break an average deck down into its main components and address them one at a time, giving you my tips and techniques to make sure you only have to build it once. Some of these methods cost a little more initially, but trust me, they will save you money in the long run! Let’s start at the bottom and work our way up.
A deeper hole and bell footings on the bottom of your forms provide a rock solid foundation.
Dig properly sized holes and fill them in with care to give block footings a stable hold.
Please …Overdo it
When laying the beams Shervill recommends to either increase the width of each beam or the quantity of beams to provide a solid platform to build on.
Ledgers Need Some Space to Breathe
Do your best to keep the ledgers slightly away from your home so rot will be less likely.
Don’t Stick to the Minimum
Frame on 12" centers and use 2x10" pressure-treated lumber. And blocking will go a long way to resist twisting.
Forget toe-nailing altogether and stick to these handy little helpers.
Slap on the Preservative
When you cut pressure-treated lumber, you expose untreated areas of wood. By applying a healthy coat of preservative (below) you will slow rot dramatically.
Waterproof Sooner than you Think
Shervill applies waterproofing before attaching the decking to stop rot where it’s most likely to occur.
Your new deck will be strong, long-lasting and, of course, gorgeous. Just don’t be afraid to get it dirty!
1. Concrete footings
Deeper is better: Your local building department will know the minimum footing depth required in your area. I suggest adding at least one extra foot of depth beyond the minimum to ensure you are below the frost line and avoid frost heaving. You will need a little more concrete, but going beyond the minimum is cheap insurance.
Bell-bottoms are in style! Even if not specified in your local code, it is a good idea to do a “bell footing” on the bottom of your forms. By making the footing wider at the bottom, you reduce the chances of frost heave even further, and the larger footprint means the weight of the deck is spread over a larger area, which reduces ground pressure at the bottom of the hole.
Manufacturers have made this easy with the introduction of plastic bell footings that attach to the bottom of cardboard tube forms. You just slip the footing onto the bottom of your tube and drive a couple of screws to hold it in place. You then place the entire assembly into the hole, backfill around your tube and pour your concrete.
2. Block footings
Some free-floating decks are built on deck blocks rather than footings. It’s important to note that even though these blocks look like they just sit on the ground, there is a considerable amount of work you need to do to the ground under the blocks before placing them if you want them to stay put. Frost and settling are the two biggest enemies when it comes to block footings, so minimize the chances of either affecting your hard work by following these steps. To start with, dig a hole at least twice the diameter of the deck block and a minimum of 1′ deep wherever a block will be placed. Fill that hole within 4″ of the top with granular A gravel, compacting it with a tamper as you fill the hole. Top the compacted A gravel with a good layer of limestone screenings or decomposed granite, again compacting as you go, and bring this packed material slightly proud of the surrounding ground.
The beams are truly the backbone of your deck; don’t be afraid to “overdo it” when building them. While your local code will dictate both the minimum lumber size and number of plies you must use, I prefer to go “up one” on either the number of plies (three layers instead of two) or the lumber dimension (2x10s rather than 2x8s), depending on the situation. Some people suggest putting plywood spacers between layers to aid drainage, but I prefer to laminate my lumber tight together and then cap it with a triple layer of 30lb roofing felt to prevent water from entering the laminations to begin with.
The ledger (the board that attaches to the house) is where 90 percent of deck failure occurs. The reason failure occurs here is due to water sitting against the house and causing premature rot. You will read all kinds of articles about proper flashing, etc. for attaching your ledger board, but for my own decks, I prefer not to attach the ledger to the house at all.
Ledgers are most often attached to the house because it’s easy and inexpensive. The house structure is already there. Why not use it? The truth is that if you are willing to put in the time and money, there is a better way to do it. On houses where it is feasible, I will dig down to the existing house footings and set 6×6 or 8×8 pressure-treated posts directly on the footings, cut them to length and notch them to accept a double or triple 2×10 beam spaced 1½ to 2″ from the house, and then capped with more 30lb felt. This beam now serves as the ledger to which the joists are secured. On houses where the footings are too deep for this to be feasible, extra concrete footings are poured beside the wall and the posts are rested on those. If required by code, the entire assembly is then bolted to the house with ½” galvanized threaded rod, nuts and washers passed through both the double ledger and posts. By building this way, the entire deck load is passed to ground rather than to bolts fastened to the house structure, and because the “back” of the deck is 2″ from the rim joist of the house, water collection and penetration are never an issue.
Materials: Most codes call for 2×8″ joists on 24″ centers as a minimum. This is another area where it pays to over build. Given the choice, I will frame on 12″ centers and use 2×10″ pressure-treated lumber. Overkill? Maybe, but the difference in cost is actually not that much and the resulting solid deck will resist flex much more effectively, keeping your fasteners tight longer. Also add blocking to the center of your span. Blocking is easy, inexpensive, and will greatly increase the rigidity of your deck as the joists are prevented from twisting.
6. Nails or screws?
I frame with hot dipped galvanized nails. Unlike “decking screws,” which seem to be popular with some, galvanized nails last years and years without rusting. I will occasionally use 3 ½” #10 coated screws if the situation warrants it (a joint that needs to be drawn together for example). As a rule, however, nails are better.
7. Attaching Joists to the Beam
Toe nailing is a no-no. The standard method of securing the joists in place on top of the beam is to “toe nail” them by driving a nail down through the side of the joist at a steep angle so it exits the bottom and enters the beam. While this is fast and easy, it opens a cavity for water to enter the joists and also pierces the waterproof cap we put on the beam earlier. I prefer to use small galvanized metal plates called “hurricane ties” to attach the joists. These little plates are inexpensive (less than 50 cents) and allow you to attach the joists to the beam by nailing to the side of the joist and the face of the beam, cutting the chances of water penetration significantly.
8. End cuts and Copper Chromate
Whenever you cut pressure treated lumber, you expose fresh wood that has not been treated with preservative, opening up a place for rot to begin. This is obvious as there won’t be the tell-tale green colour on the faces of the fresh cuts. Fortunately this is a quick and easy fix: Add your own preservative to your cut areas. Also labelled as “end cut preservative”, this is a chemical made expressly for the purpose listed above. Pour some into a can, brush it liberally on the cut areas and allow it to dry … too easy.
9. Waterproof your Deck Framing
Most people will spray a waterproofer on their wooden deck boards to prevent premature damage, but the deck boards aren’t where the rot is most likely to occur. Before I begin laying deck boards, I like to spray the bare framing down with a quality waterproofer, ensuring that it gets into every crack, crevice, seam and nail hole. This is another one of those steps that costs a little more, but think of it as added insurance. Remember, we only want to build this once!
10. Choosing Decking Materials
The decking is the area people spend the most time and money on. After all, it’s the part people see! What many fail to realize, though, is that the decking needs to become part of the overall deck system to get the longest life, and just “looking great” isn’t enough. Here are some tips to get the maximum life span out of your decking:
It sounds simple, but choose the best decking you can afford. Remember, your decking isn’t only the part that you walk on; it’s also the first line of protection for your framing. My first choice for decking is a PVC product sold under the name Azek, available through special order at Lowe’s or azek.com. Unlike composites, Azek does not contain wood fibre, it works like wood, is relatively light, and is very hard. Also, because it is essentially pure plastic, it allows me to attach the deck boards from the top down with stainless steel deck screws (my preferred method) without fear of damage due to water collecting in the screw holes.
If you are set on using wooden decking, consider some of the alternative woods available (such as Ipe) before placing your order. Some of these new woods last for years with little maintenance and can be a great choice. If you choose to go with the “old standby” choices of either pressure-treated lumber or cedar, strongly consider going with lumber that is a full 1.5″ thick as opposed to the 5/4 radiused-edge decking that has become so popular. Two-by lumber is generally higher quality, is definitely stronger and, in my experience, far outlasts the thinner decking.
11. Fastening Deck Boards
There are all kinds of hidden fastening systems now available, but I still prefer driving quality stainless screws down through the tops of the boards and into the joists. Why? Because by having access to the screws, individual boards can be removed easily should they become damaged or if access to the underside of the deck is required. One extra tip: if you took my advice during the framing stage and framed on 12″ centers, you can attach your boards by driving screws into every-other joist with no loss of strength. Screws driven on 24″ centers look great, and doing it this way reduces not only the number of fasteners required but also the number of pockets that water can collect in.
12. Let it Breathe
It’s best to leave the sides of the deck open to allow air to circulate. Letting air get under the deck will help remove moisture and prevent rot throughout the entire structure. This will also allow access to space under the deck for storage.
That’s it! With a little extra work and a small investment in better materials, you can build a deck that not only looks great but will be around to enjoy for a long time.
Ryan Shervill - [email protected]
When he’s not out enjoying the woods and water surrounding his home, you will likely find Ryan Shervill in his Penetanguishene, ON workshop building custom furniture for clients throughout North America.