June 20, 2012 32 Comments
Chances are if you have a deck in your backyard–even if it’s a newer synthetic deck–the underlying support framing is pressure treated wood.
Pressure treated lumber is cheap, readily available and using it is a no brainer for the average contractor. “I’m going to build a deck, I’m going to use pressure treated wood” they automatically think to themselves. I’ve built hundreds of decks using pressure treated lumber, but I started getting increasingly frustrated by it.
The wood being harvested these days from forests is “new growth” wood for the most part. This means the trees are relatively young before they are cut down. There are barely growth rings on lumber we get these days (you know the number of rings a tree has is an indicator of its age, right?) and the more growth rings, the denser the board and the stronger and straighter it will be.
Older lumber was much denser than the lumber we get today and was generally of a higher quality. Trees can only grow so fast and demand is high, so we get what we can get at this point.
Aside from the wood being “young”, the pressure treating process has been changed significantly in the last 10 years and chemistry used in the treating process has been cleaned up to meet environmental concerns. The lumber mills will tell you the new processes are better than the old ones, but ask any carpenter and they’ll all agree the new lumber is terrible. Not a little worse…Absolutely terrible in comparison.
I got tired of dealing with the unpredictable characteristics of pressure treated lumber. Sometimes it comes soaking wet, sometimes it’s dry as a bone. Sometimes the boards shrink a little when they dry out. Sometimes they don’t shrink at all. Despite our best efforts to frame a precise pressure-treated frame, we simply cannot control what the wood will do as it seasons or dries out in it’s final position as part of deck.
This unpredictability means that a deck can develop dips and dives, and deck boards attached to the framing move out of plane creating raised and ugly joints. It’s frustrating to see a beautiful deck compromised by the irregularity of inconsistent framing lumber six months down the road.
In a quest to always provide the best product to my customers, I’ve completely abandoned pressure treated lumber in all of our new deck projects in lieu of light gauge steel framing (LGS). Just a few of the benefits of steel deck framing are:
- Lighter in weight but stronger than wood
- Wildly increased joist spans mean less beams and less footings. This is a really big deal on raised decks with patios underneath.
- More design flexibility. If I need a longer span I can change the parameters of joist from gauge, flange width, and web depth. With wood, we are stuck with 2×8 through 2x12s.
- Perfect material. Every joist is made by a machine so there are no inconsistences from joist to joist like wood. Sometimes two wood 2x10s can measure up to a half inch differently!
- Perfectly flat, level and square decks. The consistency of the material means that everything is extremely precise.
- No shrinking, warping, twisting or shape changing.
- Very little waste. All the steel is delivered to the job site pre-cut so it just has to be assembled.
- When completed, it’s nearly impossible to tell the framing is not wood.
- Lack of knowledge or understanding of steel framing methods, materials and techniques
- Resistance to change because they are comfortable in their old ways
- Cost. Most think it’s more expensive than it is or too labor intensive. It can be more expensive and it can be more labor intensive in some circumstances but not all. Usually the minimal cost difference is well worth the value of the finished product.
- It’s not locally available. Nonsense! Light Gauge Steel framing is available everywhere. If there’s a commercial building in your town, you can bet it’s got LGS in it.