Can Internal Moisture Cause Timber to Rot?

So you’ve made sure every crack and pentration on the external cladding is sealed, so the house won’t leak… right?

Not so. Sure, the external cladding may now be all sealed up and water tight as a navy submarine, but is there a possibility that moisture can still get into the timber frame of the house? Yes… if there is no wall cavity system, most definately… especially if you don’t have a system in place to expel the trapped moisture.

How is the moisture getting into the wall if the house is ‘sealed’?

Recently I found this topic on a forum which talks about the basic theory of how moisture ‘penetrates’ walls, even when you think your home is water tight. I thought this summed it up nicely…

internal moisture extract

(Did you take note of the last sentence of paragraph 2? Nice analogy!)

In summary, if a wall can’t breathe (i.e cavity system), then it’s only a matter of time before moisture does what it does best to timber… rot.

If you fix cladding directly onto timber, and then you also cover the internal side with gib board, then what you are actually doing is creating a vaccuum. What  happens next, is that the local plumber comes along and fixes a pipe bracket through the plaster which will eventually release and create a small hole. Then what happens?

Here’s what… the outside air pressure is greater than the internal wall pressure, therefore the water gets sucked right into the tightest of holes and penetrations. Got kids? Make sure they dont slam their pushbikes up against the plaster cladding and penetrate it… same effect… in goes the water!!

As a result of many plaster homes leaking, some people will only buy old weatherboard or brick & tile homes… you know, then ones that have been standing for 50+yrs, but wouldn’t get a CCC under the new building code  🙂 . Hmmm.

Did they build with internal gutters back in the good old days (Common design issue associated with leaky buildings)? The basic issue here is that if the gutter leaks, it goes straight down into the wall… and it can’t escape because there is no cavity for it to exit. The only thing standing in the way of the water is untreated timber! Ekkk.

Here’s an interesting fact: Just about every builder I speak too says “I tried to warn the authorities that untreated timber wouldn’t work”. So why did they go ahead and build with it? Because they could, and it was cheaper etc etc. Lets not get into the ‘who’s at fault’ debate… we’ll leave that to the ‘experts’… and no doubt the experts will be the ones that created the problem in the first place (cough).

95% of plaster home owners when asked “Would you buy another plaster home?”, say “NO”. This is based on my own survey whilst inspecting homes, it’s not an official statistic. You can join the dots on the meaning of that one.

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