If you are familiar with modern building practices, you may already be well aware of the importance of having a vapor barrier underneath your finish siding when building or modifying your home.
A vapor barrier under siding helps keep moisture from getting into your home’s walls. It stops water from rain or humidity from causing mold, rot, or damage. This barrier protects your home’s structure, helps with energy efficiency, and keeps the inside of your house dry, safe, and comfortable.
What many of even the most seasoned of home builders may be entirely unfamiliar with, however, is what I believe to be perhaps the best and most effective vapor barrier known to date.
Those who are familiar with it may hesitate in recommending/utilizing it due to its price point, but there is, literally, not a vapor barrier system around which can compete with the way this particular vapor barrier maneuvers around moisture challenges that many of our homes come across.
The name of the product is ‘Prosoco’.
Prosoco (not to be confused with the sparkling Italian wine ‘Prosecco’), to be fair, is what I call it.
Prosoco is actually the name of the company that makes the system (sorta kinda like when people refer to facial tissues as ‘Kleenex’).
The actual system that Prosoco makes is called R-Guard, which includes liquid-applied vapor barriers. These are sprayed or rolled onto the surface of a wall. Once they dry, they form a tight, flexible seal that blocks out water but still lets the wall “breathe.” This means it stops water from getting in, but also allows any trapped moisture inside the wall to escape. That’s REALLY important for keeping a home dry and healthy.
Here are a few reasons why Prosoco’s vapor barriers stand out:
1. Seamless Protection – Since they are applied as a liquid, there are no seams or gaps where water can sneak in.
2. Strong and Flexible – The material moves with the house, so it doesn’t crack over time.
3. Works on Many Surfaces – Prosoco vapor barriers can be used on wood, concrete, brick, and other materials.
4. Long-Lasting – These products are made to last for years, helping your home stay protected for the long term.
5. Energy Efficiency – By keeping moisture out and air from leaking, they help lower heating and cooling costs.
What made a believer out of me was a project I was involved with a number of years back on Cuttyhunk Island in Buzzards Bay, MA.
On this particular project, a VERY reputable island-area builder had built a home for a client in-line with modern building standards AND with superior building materials.
With the location of this particular home however, this did not seem to matter.
Being situated on a hill on an Island and fully exposed to the elements – seemingly every time a wind-driven rainstorm occurred, the home would leak like a sieve and water would pour in from what felt like every crevice.
Enter ‘Prosoco’.
The client had a contractor flown in whom his family had used to build homes all over the country.
The client found out about me, and I was invited as an expert to help work through things at the home and ended up being totally enamored by this new approach which I had never seen used before.
After removing the existing siding system and vapor barrier, the contractor applied the Prosoco, with I’m sure me giving him a variety of inquisitive looks, but – no more leaks were to be had moving forward.
To say I was impressed is a SIGNIFICANT understatement.
Recently I was called to the aid of a similar situation for a new home build on the water in Quincy, MA and I knew exactly what to recommend to the client.
Besides being fun to say, Prosoco is a vapor barrier that although still not very well known in this region of the country and a bit of an investment, is a product that without a doubt is worth its weight in gold if you are looking for what I believe to be quite simply the best option as a vapor barrier when navigating through a home new construction project.
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