A division of SEA Construction, Inc.

Truths and Myths About Weather-Proofing

Posted by Petalyn Swartalbert

Feb 3, 2014


Waterproof or water resistant

Part 1 of 4


"Sometimes it has seemed to me that I would give worlds if I could retain my facts; 
but it cannot be. The more I caulk up the sources, and the tighter I get, 
the more I leak wisdom." ~ Mark Twain


Back in time, when perhaps a larger percentage of our population was 'handy', the pros and cons of caulk's use appeared to be better understood. Why am I not surprised that it is an American author who is so familiar with the product's over-use that he finds it a perfect metaphor to explain the futility of using it for a job it can never do. 

Caulk, like WD-40, duct-tape, aspirin, and nail polish, has long been a member of that faithful arsenal of household standby(s). As relieved as we are to have them on hand in a pinch, they are typically not a long-term solution.

The term 'water-proof' was a daring claim dreamed up by marketers decades ago. We've modified that term a bit these days so that if your grandpa's water-proof watch was made in the exact same way today, it would likely only reach 'water resistant' status. 

The fact is, there's little out there that can truly claim that level of performance. And as it turns out, water-proofing something isn't always a good thing in the long run in terms of investment and durability. While you want your smart phone and your underground basement as water tight as possible, a house needs to breath. 

To make a home water-proof it would need to be sealed in every possible way, which causes seriously negative health issues beginning with carbon monoxide poisoning just from breathing. In an interesting way, a house is similar to the human body in that it is a container for multiple systems. These systems include but are not limited to air-flow, temperature control, and moisture control (damp proofing). The control function is at the core of good performance which, in order of importance means rain control, air control, heat control, and vapor control. You can certainly see why water-proofing doesn't belong in this conversation.

Take a look at The HardieZone® System: HZ10® Care and Maintenance Guide for the inside scoop on best installation practices.


building envelop systemsYour Home's Real Job

A home has to handle the exchange of vapor, moisture, and temperature in a way that is healthy for your family and for the long-term performance and durability of the structure itself. One of the fascinating ways to handle this is now a gold-standard for siding installers everywhere.

Forward-thinking researchers at James Hardie understood that water resistance (damp proofing) needs to happen with a seriously high quality membrane installed under the exterior siding. One interesting fact is that before 1978 and before the real home-developer boom, many houses where constructed without this moisture barrier. Seems astonishing to us these days, but it's true.

The roll of today's (highest standard) exterior siding materials -such as with James Hardie fiber-cement products- is to behave more like actual wood siding. For proper performance and longevity, the exterior product needs to fully respect the constant characteristics of moisture and rain, allowing for the highest possibility of dryness to occur in damp conditions. It seems counter-intuitive, but we don't want to get in the way of what water needs to do...finding it's lowest level and easiest escape routes. Understanding how water behaves means we make sure its happy in a way that keeps your home dry and warm.

This means that air must be allowed as much access as possible to the layer between the water resistant membrane below and the inner wall of the exterior siding material used. It also means that we never want to inadvertently block water's path out with something like caulk. It's a beautiful thing when we grasp how much thought and planing goes into the shelter we take for granted; that simple house we call home.


Here's What you'll want to Watch For

proper moisture proofing

Armed with this uncommon insight, you should be looking at your installer's caulk usage in a whole new light. When, due to either inappropriate caulking or improper installation, water is allowed to become trapped behind the siding, materials begin to breakdown at an accelerated rate. We've become accustomed to not seeing any space between siding joints because in the past caulk was overused, due to dated mass-building practices which left many homes vulnerable to moisture seepage from the outside in. That is, until the use of moisture paper became mandatory in California. But this 'band aid' practice of caulking any and every gap has, over time and generations, retarded our eye to the visual cue of a properly functioning envelope.

We no longer aesthetically accept those little 'spaces' between joints, nor are we aware that they are actually required for a healthy siding-system (one that is buttoned up with the proper moisture barrier beneath). To giveinto our previously uneducated eye is a big mistake in terms of current technology and advanced understanding of how a home functions properly in the background of family life. 

Here's a thought: check out your exterior now. 
If caulk is over-used, it may be that your home is one of those that have no (or is inconsistently clad with a) proper moisture barrier. Or it may simply mean that the installer at the time used caulk to camouflage other issues. 

So...just so we're clear, current technologies and best practices reminds both the qualified installer (us) and you (our favorite homeowner) that with the proper moisture covering beneath your outer exterior, there should be very few areas where caulking is needed. In fact, if you spy caulking anywhere, you should be asking why it was used there rather than why it hasn't been used more.

Tip: A poor use of caulk...
Caulk should never be used as an adhesive, "and therefore should not be used to bond materials together..."  

Next: Part 2 of 4
Siding Engineered for California Weather? What it means and why it affects maintenance and longevity.Read Part 2 HERE



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Steven and Petalyn Albert

S.E.A. & Peninsula Siding

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