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Vapor Barrier Paint
You want to install hardwood flooring in your basement but hear you can't do that because of moisture problems so often found in basements. A vapor barrier can be the solution to that dilemma. And vapor barrier paint is one alternative for basement moisture problems.
Vapor barrier paint is yet another weapon in a homeowner's arsenal to fight against damage caused by water vapor. Vapor barrier paint is made by many paint manufacturers in different grades, as we will see. There may be reasons you can't or won't use traditional vapor barriers for your floors before installing wood or carpets in your basement. That's one cases when vapor barrier paint is great.
It is important to understand how water vapor acts in order to understand the uses of water vapor barrier paint. In a process called convection, warm air always moves toward colder air. Thus, during cold months, the warm air in your house is constantly seeking to escape outdoors. Warm air also expands, putting more space between its molecules compared to cold air. Expansion allows warm air to hold more water vapor. When this warm air encounters the cooler surfaces of your home, such as exterior walls, it cools down and contracts, squeezing out water that collects on the cool surfaces.
Underslab and in-wall water vapor barriers are designed to keep water out of your home. They defend against groundwater seepage, rainfall, and floods. But having water form inside of your home is also bad. It is here that water barrier paint plays a role in protecting your home's interior surfaces.
Water vapor barrier paint is often applied to drywall walls and ceilings in attics, where warm air tends to rise. Without water vapor barrier paint, the warm air would release its water inside of the walls and ceilings, where the water would saturate the insulation and framing. This water damage can render insulation useless and cause rot in structural members.
Not every household paint or enamel is an effective water vapor barrier, though. In order to qualify as water vapor barrier paint, a product must attain a Perm rating less than 1.0 under the ASTM D1653 Test Method for Water Permeability of Organic Coating Films. The lower the Perm number, the less water vapor the barrier paint allows to pass during a given amount of time at a given temperature and humidity. When shopping for water vapor barrier paint, ask for it by name and check the Perm rating which should be on the can.
Water vapor barrier paint is often sold as a primer, to be applied under a final coat of a different paint. The primer is generally sold in white. It can be colored to some extent without degrading its water vapor barrier properties. Usually, the can's label will tell you how many ounces of pigment can be added to a gallon of water vapor barrier primer. The instructions will also state the maximum surface coverage of a gallon, and whether one coat or two are recommended.
Water vapor barrier paint is also used directly on concrete floors. Products such as Aquapel, made by L & M Construction Chemicals of Omaha, Nebraska, penetrate porous concrete and chemically bond with it to seal out water vapor.
Water vapor barrier paint is not a substitute for other water vapor barriers when they can be installed. In some cases, such as cinder block construction, it is impossible to install conventional water vapor barrier sheeting behind exterior walls. In these cases, a high-grade (low Perm) water vapor barrier paint is essential.
Older homes in need of water vapor barriers are also good candidates for water vapor barrier paint. It would be a bad idea to try to pull back the insulation in an old home's ceiling and try to install plastic behind it. It makes much more sense to paint the ceiling with a good water vapor barrier paint.
Water vapor barrier paint complements other forms of water vapor barriers and can be a valuable tool in insulating older homes.
Comments
'm doing a radical renovation spec. house and built a passive solar room with a 6" concrete slab floor over 2" of styrofoam. I failed to put a vapor barrier under the styrofoam, and the inspector wants me to install a vapor barrier before the slate / tile floor. All the existing concrete floors likely have no vapor barrier, but I'm getting nailed on my addition. The Schluter DITRA underlayment has a vapor barrier, but it defeats the very effective heat sink I've created in the insulated concrete floor. Is there a paint that will act as a vapor barrier that I can install a slate /tile floor over? FYI The slab is about 10 inches above grade with about 4 inches of compacted gravel as a base. I need to give my engineer some instructions to add to my plans. Got any ideas? Thanks Chris in St. Louis
Chris Vatterott at May 21, 2008 08:47 PM
Could you further explain why you're being asked to put a vapor barrier down? You might want to read the articles I mentioned in the previous post (the underlined link). I hope some of those ideas help out.
The Flooring Lady at May 22, 2008 09:34 PM
We have a previously installed ceramic floor in our basement that is damp virtually all summer. Also, although our garage has floor drains, there is also seepage through the floor. We can't pull up the entire 1000 sq ft floor, but we have to get rid of the seepage. We are looking at ways to drain water away from the house, but need a plan to waterproof the ceramic floors.
JES at July 10, 2008 09:54 PM
French drains around your house will go a long way to rid you of your moisture problems. A sump pump may be called for too, if the water table is really as high as it sounds it is.
The waterproofing your are contemplating (painting the tiles) may keep moisture out of the house, but it won't keep it out of the tiles. To preserve your flooring you need to first remove the water source and then put a layer down between the concrete and flooring.
You have a big project ahead of you, but it's important to do correctly and well so you don't endanger your health with mold and poor air quality.
The Flooring Lady at July 11, 2008 09:47 AM
I have cinder block walled daylight basement divided into two spaces; one an ex-hair salon with plenty of plumbing for a second kitchen that I want to rent as a effiency apartment, and the other space currently being used for laundry, storage with huge outside window and outside entrance door that later on would like to rent as yet a third rental space. FYI, I will rent my primary upper level as the 1st rental. This house was built in 1962 and the cinder block walls are leaching that white powder residue and while there is no obvious moisture, the walls have the exterior moisture that I suppose is pushing in and causing the residue flaking. What can I use as a barrier to prepare for either paint or wall covering to create these rental spaces?
Pam at July 25, 2008 04:47 AM
Hi Pam,
There are sealers made just for concrete. There are also paints made just for concrete, depending on what type you use, some are made to be barriers too.
The Flooring Lady at July 25, 2008 10:50 AM
We are looking at buying a lakefront cottage. Currently the crawlspace has no vapor barriers/protection. The dirt "floor" has small puddles, most likely from water seeping up from the clay ground. There are already rotted floor joists where they "sistered" in new joists next to the rotting ones.
The local Be-dry people gave us an estimate of over 16k to install a vapor barrier, humidistat, trenches, etc.
We simply cannot afford this, but we are in love with the rest of the house/property. I was thinking that adding in some fiberglass insulation with foil backing into the floor joists, then adding a layer of plastic (air barrier) on top of the insulation, and sealing it.
Would vapor barrier painting the sub-floor and joists along with the insulation be an effective and cost-efficient alternative?
Andrew at July 25, 2008 12:10 PM
Hi Andrew,
My first thought is........why should you have to foot the bill for this? I presume an inspector has been out to the house? Often, the mortage company won't let the house be sold in that condition unless the owner foots the bill (or at least most of it!) to have the property pass inspection so the mortgage company (bank) will lend you the money for the house. Of course, if you're paying cash, then that's all out the window but can still be negotiated, because anybody else who has the property inspected is going to face the same problem. Yes, 16G does sound reasonable.
I think the "stepped" approach is better for preventing moisture problems, though I am a bit concerned that there may be mold problems already under the house - a big 'yuck' factor - healthwise too. It's my opinion that the insulation is not the best choice as a vapor barrier. The Raven vapor barrier on the dirt will reduce the moisture in the joists and the house. Once you get the ground and foundation stuff dry then insulation is a good step.
FYI: Our home, which we also fell in love with, but needed work before the lender would agree to the loan, needed a vapor barrier in the crawl space - which the owner had to pay for. The lender also wanted the joists in the kitchen checked out since they seemed slightly soft. Turned out that the joists needed replaced, which led to new flooring and new lower cabinets/countertop because they were built into the house. It was a bummer that the old cabinets couldn't be salvaged - they were beautiful! Long story short, the owner had to pay for this, not us! We did pay for new gutterwork to be installed though - there's always some give and take in this kind of deal.
Best of luck and hope you get your dream home!
The Flooring Lady at July 25, 2008 09:59 PM
Forgot to mention, the house in question is a bank-owned, and they are refusing to pay or do any repairs, so we are asking them to take off the price of some of the major mechanicals.
Looking through some DIY sites, it looks like the best route (for our money) is to lay down some heavy duty tarp, place a real dehumidifier, use the vapor barrier paint, insulate, then put on the plastic, in that order, as we get money to do so.
Cost of supplies: $2500 Cost of doing it professionally: $16600.
Andrew at July 28, 2008 06:04 AM
Ewww......... I take it you got a written estimate or two to show the bank? That should motivate them to come down some.
I wouldn't think that a dehumidifier is necessary, so long as you have a vapor barrier put down - remember too, that it needs to go up the sides some too. That's usally put down before any insulation as well so that the insulation doesn't get soggy. If you have ventilation holes, keep them open, it really does need to breathe under there. We do close ours up in the winter though - and have screens over them to keep little critters from having access to under the house.
Good luck!
The Flooring Lady at July 28, 2008 10:00 AM
