how long average deck lasts

How Long do Decks Last?


How long is a rope?

How long will a deck last?– That depends on how it is built!


How Long Does the Average Deck Last?

One deck will be dangerous from day 1, another will be trouble free for 50 years.  The average Pressure Treated or Red Cedar deck lasts about 15-20 years, but the stairs normally need repairs after 10 years. The average composite deck lasts about the same because they are built the same way. This is because many builders put composite or PVC decking on a standard frame designed for wood.

Building department (Code Compliance) is only a 10-15 year deck.

We can do much better… Read on to learn more about making decks last longer.

Tragic Flaws that will lead to early Deck Failure:

  • Spruce framing works well for building houses but spruce is just not a suitable species for outdoors. It will be rotten in a few years.
  • Unflashed ledgers secured to a wood-clad home will need ledger flashing to prevent rot from setting into the home. The rim joist within the home is spruce and if that is damaged it is an expensive fix. When moisture gets trapped at the rim it is a 5-year inevitability of failure.
  • Improperly built stairs are always the first thing to fail on a typical deck. Stringers get cut from larger pressure treated boards and sometimes they don’t seal the boards back up. This can be done with high VOC paint or joist flashing.
  • Poor footings become obvious within a few years, but it can always be fixed–though it will not be cheap! We use engineered helicals– even concrete footings are now obsolete.
  • Lack of lateral bracing will cause movement, which slowly affects the structural integrity of the deck.
  • Unflashed Beams – The new formulation of pressure treated lumber is not working as well as those of previous decades. When you put 3 boards together to make a beam, we are seeing rot within 5 years where it would take 25years for rot to set in previously.
  • Lack of Ventilation will cause a deck to rot out prematurely. Low decks, close to the ground that don’t let the air flow through the underside will rot in 1/3 the time of properly built decks.
  • Decking Not Spaced— is one of the most deleterious flaws we see. Not only does it cause the frame to rot prematurely on the top of the joists, but, wood decks will often grow mold and shed stain. Without spacing, decks never dry. Perpetually moist decks will rot prematurely.

5 Ways to Make Decks Last Longer

Joist and Beam Flashing Tape

If you have ever removed an old rotted deck you will notice that the end grains and tops of the joists are the first to rot. Also, when the beams are all nailed together tends to rot quickly as well. Use joist tape on all beams and joists. Stair stringers also rot quickly. Cover everything in joist tape to keep the stringers, beams, and joists dry to extend the life of your deck 2 fold. This means you will likely be able to change the wood decking 2 or 3 times over the life of the frame.

Helical Footings

Using concrete with or without a soil test is gambling. You never know what was there before. You could be building on what was a swamp or pond. The soil could be mostly backfilled and over time the footings may move. Movement means a deck that is not level or straight. Helicals are engineered and are guaranteed not to move ever.

PVC Decking

Wood decking will rot over time. You can protect the frame but the decking has always been something that will age prematurely no matter what you do to it. The best PVC Decking is made from PVC with an automotive plastic cap. That means it fades very slowly and is not susceptible to moisture the way many composite and wood decks are.

Give the Deck a Roof

If you can keep the moisture away from the deck it will last nearly forever!  Give it a traditional roof or a Louvered Roof to help your deck last longer.

Waterproof Frames

On many second story decks, we waterproof the deck with a membrane above the framing to help them last longer. This can often double the budget, however, you get a frame that will often last 50 years or more. Doing it once always makes sense for the highest long-term and resale value.

Steel or Aluminum Frames

A galvanized aluminum frame should last 30 years or more, and an aluminum frame may last 50-100 years. They haven’t perfected how to waterproof these decks yet, but for grade level decks it is a great solution. You can also increase cantilever distance using these materials.

Let it Breathe

Build in ventilation to help keep the underside of the decking dry and prevent rot. By spacing the decking and the skirting on near ground decks and leaving a couple of inches of space beneath the skirting, you can double the life of a deck.

Environmental Factors that Affect Decks

Dry Climates can extend the expected life of decks, however, it may be difficult to keep stain on. UV is hard on the exterior stain.

Wet climates like BC or in and around the Great Lakes are harder on frames and decking. In these areas, it is advisable to build in more durability to defer maintenance.  On the bright side, living near Toronto has given us a fantastic proving ground to figure out what works and what doesn’t!

The direction a deck is exposed to also affects durability. A deck that faces south will last longer than a deck facing west. A more sheltered deck will last longer as well. On the north or east side, you may have issues with surface mold.

All these factors go into deciding which materials and specifications are right for your decks.

For more information about building decks (click here)

Lawrence Winterburn

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