Tyvek is not a vapor barrier nor is it a paper.

If you are looking for a vapor permeable air/weather barrier sprayed on exterior sheathing the following products are appropriate. The STO product can also be applied by roller.

1. Perm-A-Barrier VP Air/Vapor Barrier - fluid applied synthetic latex rubber membrane
by Grace Construction Products.
a. Primary Air Barrier Membrane: One component elastomeric membrane, spray applied.

2. Air Bloc 31
by Henry Company Inc., Cold Stream Road, Kimberton, PA 19442.

3. Sto Guard Assembly:
by Sto Corp., Camp Creek Pkwy, Atlanta, GA 30331
a.Sto guard mesh for joints and flashings
b.Sto Gold Fill for joint treatment.
c.Sto Gold Coat for the membrane

4. PROSOCO R-GUARD Assembly:
by PROSOCO, Inc., 3741 Greenway Circle, Lawrence, Kansas 66046.
a.PROSOCO R-GUARD Tape for joints and flashings
b.PROSOCO R-GUARD Fill for joint treatment
c.PROSOCO R-GUARD Spray Wrap for the membrane

I should add that there is no better air/weather barrier because there is no space behind the barrier for moisture to collect, it seals sheathing joints, there are no membrane joints, and it wraps into openings.

Home construction is incredibly slow to follow the lessons of commercial construction because home builders have little exposure to that information and look for simple solutions that untrained workers can install and that consumers expect or ask for. Also manufacturers of spray-on products consider the market for individually built homes relatively small and too dependent on advertising and brand recognition (plastic wraps are heavily advertised and display their names across a building which is why plastic wraps pushed asphalt saturated felt out of the market). However, Huber is making a dent on the market with their bright green coated ZIP sheathing (although the sheathing joints rely on the same old specious "tape it and forget it" philosophy).

Eventually someone will find a way to market the field applied integral air/weather barrier concept to consumers and it will quickly become the standard for custom home construction.

Depends upon just what this builder 'sprayed' on the wooden framework of your house.

Housewraps are not 'vapor barriers' and 'vapor barriers' should not be applied to the exterior of wood framed stuctures in most US and Canadian locations.

Tell us where you live (State and County/Province is enough) and exactly what product your builder used, and perhaps we can help.

Until then, anyone would only be guessing...

A vapor retarder membrane may be applied to the face of exterior wall sheathing in a cold climate if the membrane is covered by rigid foam insulation sufficiently thick to move the condensation/frost point out of the wall cavity and into the foam board on the coldest day of the year.

There is a practical rather than a theoretical northern limit because there is a practical limit to the amount of foam board that can be installed over sheathing and be protected by a cladding.

Enviro-Dri is a liquid weather resistant barrier intended to be spray-applied over residential sheathing and is made by Tremco Barrier Solutions.

A weather resistant barrier (WRB) is the underlayment required behind exterior cladding. In a conventional wall assembly in a cold climate the WRB should prevent water from entering from the outside but allow water vapor to escape from inside, sort of like a Gore-Tex jacket. Common materials are asphalt saturated felt, Tyvek, Typar and WeatherSmart.

The spray-applied liquid WRB's have the advantage of allowing no space between the WRB and the sheathing and has no staple holes, needs no tape at the joints and can be wrapped into the openings. It is superior to sheet membranes in all respects.

A vapor retarder/barrier allows no water or water vapor to pass and belongs on the inside face of the wall in a cold climate and on the outside face in a hot humid climate. That prevents condensation inside the wall in both cases and allows the wall to dry to the outside in a cold climate and to the inside in a hot climate.

For St. Louis, I would want a design professional to bless the final wall assembly design because of the extremes of climate (I was born there). This is not a region that can use the standard construction techniques used in the north and south (stuck in the middle ever since it applied for statehood). It might be a good place to use exterior foam insulation.

What is the exterior cladding?

Here is a link that might be useful: Enviro-Dri

First, I need to state that I work for Sto Corp., the manufacturer of StoGuard waterproof air barrier.

Macy earlier listed some of the manufacturers of spray on barriers including Sto. So I thought I would add my $.02 worth.

A quick definition: Air barriers are used to minimize air leaks through the wall construction. The use of an effective air barrier can reduce the risk of moisture condensation in the wall and provide energy cost savings.

Air barrier products can be both permeable and vapor barriers depending on the product. How to choose the right solution depends a lot on your climate. I suggest consulting a design professional for the final assessment as Macy stated.

The good thing about fluid-applied barriers is that there is no space between the barrier and the sheathing providing a layer of protection against moisture. Conventional sheet house wraps can come apart at the seams and leak at the staple holes.

For more information on fluid-applied air barriers, I suggest going to the Air Barrier Association of America (ABAA) at www.airbarrier.org.

Hope this helps.

From what I've seen, housewraps are more often than not applied incorrectly. Application is often left up to the carpentry contractor, who has little interest in it. Let alone, at complicated intersections, it's hard for anyone to figure out just what laps what and where. Besides, outside of several well-known brands, what passes for housewrap is often utterly useless.

For those reasons, unless it's specified, I sheathe with XPS, followed by 15 lb. felt. The felt is redundant, but the masons feel comfortable.

It seems obvious that sprayed housewrap will be more efficient than roll membrane wrap. But since price rules in spec and subdivisions I see it only as a premium alternative.

Here is a link that might be useful: Leaky housewraps