The age-old craft of timber framing has a number of advantages aesthetically, but let’s take a look at the facts about the longevity of using exposed beam construction
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The Longevity of Timber Framing
The following video gets into all the details of why post and beam construction tends to hold up well against a number of causes. You can watch the video or continue to read on for a basic breakdown of what causes construction to fail and how timbers react to these causes.
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The three primary causes of construction breakdown are these:
Fire
Wind/Earthquake/Natural Disasters
Decay & Rot
All of these factors can contribute to the destruction and eventual downfall of any structure. Current “conventionally-built” or “stick-built” framed homes are meant to last 50+ years according to current code. This is not necessarily a long-time, but land development, freeway construction and other causes often promote new construction and demolition of older structures.
1. Fire Damage
Exposed beam construction is resistant to fire in that it has a larger mass, which takes longer for fire to charr and destroy.
Code allows for areas that are built with at least 4×4 post and beam to not have sprinklers.
This is because it would take much longer for a home with post and beam construction to collapse than 2×4’s, which burn fairly quickly. Of course, the larger you go with post and beam size, the better resistance to fire. A technique known as “shou-sugi-ban” provides even more protection against fire, bugs and rot.
2. Wind/Earthquake
The method of exposed beam construction can stand up to wind and earthquake to a pretty good extent due to the fact that though posts are sturdy, they also have some flex that can move and then resettle.
Historic buildings with mud and wattle used as the infill in between timber framing will allow for movement and settling. Although not every timber structure holds up against earthquakes and severe wind, there are numerous examples of post and beam buildings that have stood for hundreds and even thousands of years!
3. Decay/Rot
Again, the size of timber posts and beams have more mass, and in the case of rot, they allow for a longer period of time before the post becomes unsound. Of course, rot is not desirable however, and there are a number of things that can protect against water decay and rot.
The most basic principle is to KEEP WATER OUT.
Modern flashing methods are getting better for keeping water off of the beams, but it’s not always perfect. Good sized overhangs and excellent attention to flashing will protect beams from the elements. Another essential is leaving a half-inch space between the post and the concrete or stone that it is mounted on. Often, building stone bases for posts can help in this regard.
By maintaining your timbers and applying stain periodically, you can have timbers that last for a long time!
So how long does timber framing last?
For any home designed and engineerer, they should always be built to last no less than 50 years. Timber Frames that are properly maintained and protected from moisture could last WAY longer. Perhaps hundreds of years!
Climate will play into that longevity especially.
Stable climates without too much moisture will be kinder to exposed beam construction. There are historical buildings that have lasted 500+ years.