The default direction decking runs on an attached deck is parallel with the house. A few reasons for this are deck framing construction, water runoff and appearance. Decking running parallel to the house is beneficial structurally, aesthetically and costwise.
Let’s think through the benefits of running decking parallel with the house. There are three main reasons construction, water runoff and appearance. Before we get started, a freestanding deck beside a house, decking does not need to run parallel to the house. Also, decking running parallel to the house may be the most economical direction, but there are several other options for decking direction.
Running decking parallel to the house is easier for construction
The standard attached deck is supported with a ledger fasten to the house and a parallel beam. The beam is appropriately spaced from the house based on the deck’s size and joist span. Joist hangerred from the ledger and resting on or hangerred from the beam running perpendicular to the house. The decking running parallel to the house, lying on perpendicular to the joist.
This basic design is the most economical deck design. Requiring the least amount of material to support the decking. Decking can span the greatest distance running perpendicular to the joist. With the rim joist attached to the house becoming a ledger, you only require a single beam away from the house to support the joist. A simple design, using the least amount of material, saving the most money.
Decking running parallel to the house ensure water drains off the deck to the ground
Decking needs to slope away from the house or be gapped to prevent water from running into the house from the deck. But a level deck or one slightly sloped towards the house with decking perpendicular to the house the rain can run the length of the decking to the house even if the boards are gapped. But if the decking runs parallel to the house, the water runs-off the deck through the gaps parallel to the house. Minimizing the amount of water getting to the house.
I discuss deck slope and water runoff in greater detail in another article. If you would like to learn more, click here. Short of it is, gapped decking parallel with the house diverts the most water away from the house.
Decking running parallel to the house is aesthetically beneficial
Yes, beauty is in the eyes of the beholder and some wonderful decking designs that do not run parallel with the house. But the simplest is rows upon rows of decking leading up to the house. Standing in the yard looking back to the house. It’s is nicer to look over rows of decking than looking down the length of the decking.
Lines of decking define space
Decking running parallel to the house makes the deck look wider and blends the deck into the house. If the decking runs perpendicular, the deck looks long and extending far out, away from the house.
Often the house siding also is running the width of the house, and parallel decking reflecting this pattern. Taking on the appearance of a reflection of siding on a lake as the decking. As humans, we often enjoy consistency. Too much variety with lines is interpreted as chaos, something we all feel uneasy about.
Decking should run parallel with the stair treads
Often the deck is the bridge between the house and the yard. We walk over the deck from the door to the yard. With the door opposite of the stairs on the deck. Providing an efficient path to the yard. Not required on exterior decks, but inside your house, hardwood must run parallel with the stair treads or have a border that does.
This is for safety to make us aware of the step visually. Our eye is unconsciously noticing the lines along the planks and looking for the edge. Where boards are running perpendicular with think of it going on endlessly not looking for the edge. Again, not all stairs our opposite of the door but commonly are. Having the decking running parallel to the house help for stair safety.
If stairs are on the side of the deck, it’s a good idea to picture frame the deck. The picture frame provides and parallels the deck board to the treads while protecting the perpendicular decking.
Bringing us to a few more decking design options
There are many more decking layout options then parallel and perpendicular. Different layouts will create a different feel on your deck. Also, features will increase cost with additional labour and material required to support the decking. Here is a diagram of eight popular decking layouts. If you would like to see more of there designs, click here to go to their website.
One note about these diagrams. Most decking needs to be supported at 16″ (400mm). Decking not run perpendicular to the joist increase the distance the decking runs. Meaning any pattern except for perpendicular decking requires a reduction in joist spacing. Increasing the number of joists needed. This fact is not shown in these diagrams.
Decking Layout Summary
Decking running parallel to the house is the most straightforward and most economical, but there are other options for decking. The decking direction will impact the feel of the deck, and I hope the one that you choose makes your deck, an enjoyable outdoor living space.