Reward Insulated Concrete Forms as a Vapor Retarder

September 1st, 2009 | Lets Get Technical!

Reward iForm wall acts as a vapor retarder.

• Vapor retarders are used to prevent condensation within walls.

• Reward iForm with an inside finish of gypsum wallboard painted with latex paint is adequate to prevent condensation within walls for buildings in the continental U.S.

• Avoid the use of

> Low-permeance wall paper such as vinyl on the inside surface
> Low-permeance and unvented exterior finish materials on the outside surface

Vapor retarders (also called vapor barriers) are used to prevent, or more correctly greatly reduce, water vapor (moisture) from moving through building materials and condensing on cold surfaces within the wall. The rate of moisture flow through walls by vapor diffusion is called permeance and is measured in perms.

Water vapor permeance of building materials. The water vapor permeance of the Reward iForm wall system with 1/2-in. gypsum wallboard varies from 0.2 to 0.3 perms depending on the wall thickness. A material or system with a permeance of less than 1 perm is generally considered “nonbreathable” and a vapor retarder.

Materials such as cast-in-place concrete, polyethylene, and aluminum foil qualify as vapor retarders since they are low permeance materials when joints are properly sealed; whereas fiberglass insulation and unpainted gypsum wallboard do not. Building materials have water vapor permeances from very low to very high. Actual values for a given material vary depending on the moisture content of the material.

Two commonly used test methods are the water method (wet cup) and desiccant
method (dry cup) methods in ASTM E962. Specimens are sealed over the tops of
cups containing either water or desiccant, placed in a controlled atmosphere usually
at 50% relative humidity, and weight changes measured. The change in weight
represents the rate of moisture passing through the specimen.

Water Water Vapor Permeance for Selected Building Materials

Vapor retarder placement. The location of a vapor retarder within the wall is just as important as its permeance. A vapor retarder should prevent moist air from entering the wall but also allow moisture that gets into a wall to escape. Two vapor retarders within a wall, or a “double vapor retarder” should be avoided since this would not allow the moisture between the vapor retarders to dry.

Reward iForm with an inside finish of gypsum wallboard painted with latex paint is adequate to prevent condensation within walls for buildings in the continental U.S. The concrete acts as a vapor retarder and does not allow moisture to pass through the wall. In winter, the painted gypsum wallboard and concrete prevent moist indoor air from condensing within the wall. In summer, the concrete prevents humid outdoor air from passing through the wall to the cool air-conditioned side. The concrete is allowed to dry either to the inside or outside. The concrete and expanded polystyrene (EPS) insulation in the Reward iForm are not compromised by being moist, and the iForm has no cavities for moisture to collect.

Since the Reward iForm acts as a vapor retarder, low-permeance finishes that do not allow the wall to dry to the inside or outside surfaces should be avoided. For this reason, low-permeance materials on the inside surface such as vinyl wallpaper should be avoided. Low-permeance and unvented exterior finish materials should also be avoided. Masonry or brick veneer should be vented and/or have weep holes. Vinyl siding or other exterior finish materials should have a permeance greater than 1.0 perms.

Continuity. A vapor retarder must be continuous to be effective. The Reward iForm Wall System provides this continuity. Sheet materials such as polyethylene can act as a vapor retarder in a frame wall system, but all joints between sheets of material must be tightly sealed. The concrete in the Reward iForm is continuous around the
building and does not have these types of joints.

Buildings with high humidity. The above recommendations are for temperatures and relative humidity’s found in typical buildings: indoor relative humidities may be as high as 35% in winter and 80% in summer.6 Special recommendations provided by a building scientist or other design professional are recommended for other
conditions or where an indoor pool, hot tub, industrial processes, or other high humidity applications are present.

Here’s the bottom line on the Standard of Sustainability. Save Time, Save Money and increase the comfortability of the building.

Due to manufacturing processes, EPS thickness, EPS type and the uniqueness of the Reward iForm, this analysis, information and report is only to be used with Reward iForm and is not to be used with any other ICF system

Green Building

Reward ICFs with painted gypsum wallboard acts as a vapor retarder to prevent moisture from condensing on cool surfaces of a wall.

ICF Construction

The New Standard of Sustainability. Tell the World.

hVapor retarder placement. The location of a vapor retarder within the wall is just as
important as its permeance. A vapor retarder should prevent moist air from entering
the wall but also allow moisture that gets into a wall to escape. Two vapor retarders
within a wall, or a “double vapor retarder” should be avoided since this would not
allow the moisture between the vapor retarders to dry.
Reward iForm with an inside finish of gypsum wallboard painted with latex paint is
adequate to prevent condensation within walls for buildings in the continental U.S.
The concrete acts as a vapor retarder and does not allow moisture to pass through
the wall. In winter, the painted gypsum wallboard and concrete prevent moist indoorVapor retarder placement. The location of a vapor retarder within the wall is just as important as its permeance. A vapor retarder should prevent moist air from entering

the wall but also allow moisture that gets into a wall to escape. Two vapor retarders within a wall, or a “double vapor retarder” should be avoided since this would not

allow the moisture between the vapor retarders to dry.

Reward iForm with an inside finish of gypsum wallboard painted with latex paint is adequate to prevent condensation within walls for buildings in the continental U.S.

The concrete acts as a vapor retarder and does not allow moisture to pass through the wall. In winter, the painted gypsum wallboard and concrete prevent moist indoor

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5 in 1 Construction- Why Reward Insulating Concrete Forms Can Be Built so Efficiently

July 28th, 2009 | From the Field

5-in-1 Wall Assembly

Sounds like a sale as it sounds too good to be true. Sorry we are not running a buy 5 get 1 free or anything like that. Instead, we are trying to get out to the world the efficiencies of building with insulated concrete forms. Usually we talk about the owner benefits of green building, energy efficiency, added strength, etc. However, the inherent 5-in-1 properties of ICFs can really affect the builder or general contractor or trades involved in erecting a building, which ultimately will trickle down to the building owner by saving construction time, labor, or by affecting the bottom line of the building by reducing extra steps and materials!

The inherent five properties of a Reward ICF wall is that it encapsulates 5 different trades or processes or functions of a wall, all into one product – the Insulating Concrete Form. By building with an ICF you are completing the 1) Structural Wall, 2) Insulation, 3) Air Barrier, 4) Vapor Retarder, and 5) Furring – all in one step.

Structural Wall

This is the main core component of ICF walls. By stacking the forms, placing rebar to code, and filling with concrete, it serves as the Structural Wall and can be designed for any structural wall as needed.

Insulation

This is the Main “glamor” feature of Reward Insulating Concrete Forms. This is where it’s easiest to see the benefits of the insulated properties by energy savings alone. But as far as construction steps, NO ADDITIONAL insulation is needed for the wall, this is included as part of the formwork and stays in place. This also reduces labor steps by not having to take away any of the formwork. There is plenty of info out there on this – “Insulate” is in the name of our product!

Vapor Barrier

Let’s be clear here as some folks ignore this inherent benefit of building with insulating concrete forms, yet this can save you substantial amounts of costs- both on product and on labor. In fact, I’m going to bold it, center it, slap a different color on it, and put it on its own line.

NO VAPOR RETARDER IS NEEDED

The building codes require a vapor retarder if the permeance rating is 1.0 or greater, to prevent condensation within the walls. The water vapor permeance of the Reward iForm wall system with 1/2-in. gypsum wallboard varies from 0.2 to 0.3 perms depending on the wall thickness, substantially below the 1.0 requirement. This eliminates the need of applying another layer of material after the ICF wall is constructed.

See our research done on the permeance of Reward’s ICFs (product manual login required). FYI this info is owned and copyrighted by Reward Wall Systems, conducted by a third party research group.

Air Barrier

The solid monolithic concrete wall is the air barrier. By eliminating the need for an air barrier, again you eliminate extra materials, more layers and further costs. Once again we tested the air leakage by a third party, and it showed Reward ICF or solid concrete wall has no measurable leakage of air. (login required)

Now you see why in our R-Value discussion we stressed the importance of caulking and sealing, as you don’t have to worry about the wall itself to achieve an excellent air changes an hour rating. Did you get to read the post on the Reward house in the Parade of Homes in Lancaster County? Measured and recorded .03 ACH.

Furring

: Look at all that wood…poor trees

Furring is long thin strips of material (usually wood or metal) used to make backing surfaces to support the finished surfaces in a room. Furring refers to the backing surface, the process of installing it, and may also refer to the strips themselves. This is where saving our trees comes into play, as 2×4’s won’t be needed!

Reward Insulating Concrete Forms have embedded 1-1/4″ furring strips 1/2″ recessed in the foam every 6″, PLUS our double bridging H-corner bracket allows for tighter finish connections all the way to the edge of the corner and in more places for better attachment. Screw drywall or attach any exterior finishes directly to the ICF

: Notice furring strips embedded 1/2″ deep- 6 in on center

Smarter Way to Build

Hopefully I was able to elaborate enough to see how the 5-in-1 assembly will save you time and money. It makes the most (dollars) and sense to build with insulating concrete forms. It will increase your bottom line and the long term benefit of any building. Any of these claims Reward can prove. WE have done the research which is why we are the leading Insulating Concrete Form Manufacturer.