- Insulate Your Walls
- Type of Wall Insulation
- Reflective Wall Insulation
- Bulk Wall Insulation
- Insulation in Metal Walls
- Air Infiltration
- Adding R-value
- Installing Wall Insulation
- Vapor Barrier
Insulate Your Walls
There are many good reasons to insulate your walls. Wall insulation helps lower total energy consumption, creates greater comfort levels for the building occupant and can reduce HVAC equipment requirements. Wall insulation is one of the most cost effective ways of controlling the outside elements. Wall insulation with a low emissivity reflective surface will reduce the amount of radiant heat that enters the home in summer by up to 97% and provide some winter thermal protection. Rigid or bulk insulation will keep convective heat inside in winter as warm inside air rises. Using the right kind and right amount of insulation will reduce the energy required to heat and cool the home. This can allow you to run your heating and cooling systems less which will result in them lasting longer. You can potentially reduce the HVAC equipment size and thereby save even more money. Properly installed reflective wall insulation will reduce the potential for wall condensation occurring on the interior surfaces causing mold, mildew, rot and dripping.
Types of Wall Insulation
There are two basic types of wall insulation products. Reflective insulation and bulk insulation in the form of blankets. Blown-in cellulose, spay foam, fiberglass or rigid board. Many homes, commercial buildings and metal buildings combine reflective wall insulation and bulk insulation to reach high R-value requirements and have a complete insulation system. In warmer climates it's a must to incorporate a reflective insulation to prevent the radiant heat transfer. Some reflective insulations such as Prodex Total controls both cold, heat and moisture.
Reflective Wall Insulation
Reflective wall insulation is made of two layers of reflective aluminum foil with a central layer of foam, plastic bubble or fiberglass. It is ideal for home, pole barn and metal building wall insulation. When installed with an airspace of one or more inches it reflects up to 97% of radiant heat while the central layer inhibits the convective flow of warm air. Once seams are taped, reflective wall insulation will also create a vapor barrier. While mass insulation products are made to resist or impede the flow of warm air, a reflective insulation reflects back radiant heat (primary source of heat- flow) from the sun so it does not penetrate the building. It also reflects back radiant heat inside the house so it doesn't escape. The concept is simple each unit of radiant heat energy that is reflected away from your home in summer and each unit reflected back inside during winter means less money paid in utility cost. If you're only incorporating a mass insulation, you're losing half the battle.
Heat moves through wall cavities by a combination of radiation, conduction and convection. Radiation is the dominant method of heat transfer. Research shows that control of radiant heat transfer is the core of a climate control system. Radiation accounts for 65-85 percent of all heat transfer through walls. Traditional fiberglass insulation attempts to trap expanding warm air and prevent it from escaping. A reflective insulation effectively blocks both radiation and the convective heat transfer in and out of the wall. Unlike fiberglass insulation, Prodex Total Reflective insulation R-value is unaffected by humidity, thermal bridging and compression.
Bulk Wall Insulation
Blankets or Batts - Blanket insulation is made of fiberglass, cotton, sheep's wool, or mineral wool. It will protect against the expanding and rising flow of warm air; thereby trapping your heat inside. R-values are roughly 3.2 per inch. Moisture, compressing and bridging will compromise its performance.
Rigid Foam - Rigid foam will not compress or absorb moisture like blanket insulation. Moisture lowers insulating values of blanket insulation. Its higher R-values per inch than batt makes it a little better for roofing insulation where space is limited. Polyisocyanurate board has an average R-value of 5.8 per inch.
Sprayed Polyurethane Foam - Sprayed foam is used on metal walls and roofs to seal air, moisture leaks and control condensation. Sprayed foam average R-value is 5.9 per inch. Unlike the other forms of insulation, sprayed foam is not a do-it-yourself option.
None of these bulk insulations prevent radiant heat transfer (The primary source of heat-flow).
Insulation in Metal Walls
The best metal wall Insulation will be reflective. Reflective or batt insulation can be rolled out over the framing before the metal wall sheeting is applied. Reflective insulation and spray foam can be added from underneath after the wall sheeting is in place. In colder climates a combination of batt insulation of batt insulation and reflective insulation can be used with the reflective wall insulation on the warm side of the building. Placing reflective wall insulation on the warm side will allow it to double as a vapor barrier and prevent moisture from getting into the batt insulation. Any of these insulation types will help dampen noise levels both inside and from the outside like the sound of rain or hail.
Condensation can cause major problems in a steel building. Water in contact with metals contributes to corrosion and can lower the their service life of the building. Collection of water on the can lead to dripping, staining, mold, mildew and odors. In addition, water or ice collected in fiberglass, paper or wool insulation seriously degrades both thermal performance and insulation service life.
All of these problems can be solved with properly installed insulation vapor barrier system on the wall. Even in only moderately humid climates, condensation can cause serious problems in an unprotected metal building. Building experts advise against using fiberglass insulation at all in humid climates. Instead they recommend reflective insulation - it will not get wet and have to be replaced like fiberglass batts. Reflective insulation acts as a vapor barrier or vapor retarder by limiting the passage of water vapor thereby preventing condensation within the insulation or on the interior surfaces of the building.
Air Infiltration - Air sealing and moisture control make a building more comfortable inside and save energy by making insulation more effective. A significant amount of moisture enters the walls through air leaks and capillary action from ground water below. When properly installed (over the studs), reflective insulation will act as an infiltration barrier thereby sealing the wall to reduce heat loss from expanding warm air and prevent water vapor in the air from entering the wall cavity. The US Department of Energy estimate that in a 100 sq. ft. wall, one cup of water can diffuse through the drywall without a vapor barrier in a year, but 50 cups can enter through a 1/2 -inch round hole. Sealing air leaks in estimated at 10 to 100 times more important that installing a vapor barrier.
Reflective insulation will serve as an excellent supplement to your current insulation to help you reach your desired R-value. Reflective insulation has a higher R-value per its thickness than any insulation on the market. The R-values of reflective insulations and mass insulations are based on the same fundamental equations.
The actual R-value of fiberglass insulation in your walls may be lower by as much as 20% due to wood framing. Wood framing that holds the insulation in place reduces its effectiveness. Wood conducts heat faster than insulation, a phenomenon known as "thermal bridging." Fiberglass sheets or "batts" in a 2-by-6 wall can be rated R-10 by its manufacturer, but the conductive effects of the wood framing would reduce this to R-8. Installing a reflective wall insulation over the studs solves the bridging dilemma. R-value (the measure of resistance to convective heat transfer) is *R7 (one layer) and *R9 (two layers) for Prodex Total in wall applications. It can be used as a standalone or in conjunction with mass insulation in colder climates to stop both radiant heat transfer and convective heat transfer.
Installing Wall Insulation
click for installation methods (wood studs)
click for installation methods (concrete block)
click for installation methods (metal building)
Proper installation is key to the effectiveness of an insulation system. Reflective insulation can be installed over, between or under the trusses. The key is to have an air-gap (1 inch or more) to optimize performance. As the space for insulation is usually small, a combination of rigid insulation and reflective insulation fits much better than using blankets. Both rigid and reflective insulation have much higher R-value per inch than other forms of mass insulation. In retrofit applications, install reflective insulation under the studs.
In colder climates, a vapor barrier should be placed on the interior or warm side of the wall. The US Department of Energy states that in some southern hot and humid areas, such as along the Gulf Coast and Florida, the vapor barrier insulation should be placed on the exterior of the wall. If you live in there (Gulf Coast or Florida) and want to add R-value and a radiant barrier to the interior, we recommend Prodex Perforated.
Moisture problems in basements have lead experts to recommend against using fiberglass insulation in basement walls and crawlspaces. The old standard installation of fiberglass batt insulation between framed stud walls on the basement interior with a vapor barrier over the studs in no longer recommended because of excessive problems with mold, mildew, decay and rot. to maintain its effectiveness, fiberglass must not be exposed to high-moisture conditions such as a damp basement. Moisture will negate the insulation R-value of fiberglass insulation and promote mold and mildew - This degrades indoor air quality. Select an insulation that will provide a vapor barrier, R-value and a radiant barrier.
I ordered 4 rolls of Prodex insulation plus double sides tape and seam cover tape from insulation4less. I received the order in less than a week. Everything was in good condition and the packaging held up well during shipment.
I chose the product because I thought I could handle installation myself. I am a 67 year old widow with zip experience in home improvement. Part of the basement on the house I purchased recently was needed waterproof paint and the upper 3 feet were the bottom of the framing for the house. Those three feet had some miscellaneous insulation tucked between the joists. Only part of the areas were protected and the materials used were many varieties of insulation partly covered with shower curtain liner material. It seemed an honorable attempt to insulate exterior walls (this is upstate New York), but the effort seemed rather haphazard and pretty unsightly. The insulation4less website contained a lot of useful information about how to select the right type of insulation, the properties of various Prodex products and instructions for many areas of a dwelling, As long as one observed the requirement to leave an inch clearance between other surfaces and Prodex, installation seemed pretty simple with the use of double faced tape, a staple gun and seam tape. It turns out that the material could be cut with utility scissors. Even as a rank amateur, I managed to install the Prodex over the top of the ugly materials that were in place. I have enough left over to insulate the garage roof when the weather turns a bit cooler. What prompted me to buy the material? Reflective on both sides: inside temp stays in, outside temp stays out. It provided a vapor barrier at the same time. Instructions were easy and the material could be installed by a ten-year old. I was also intrigued by the claim that, if used on the floor during construction of a dwelling, Prodex could act as a radon barrier. I had just spent more than I wanted on my old home to mitigate radon. Too late for my current home, but interesting!
US Department of Energy,
Wall Insulation. DOE/GO-1020000-0772. October 2000
"Insulation Fact Sheet". Table 2. Evaluating the R-values of Insulation Previously Installed in Existing Homes 2002
*Parameters of test: 24-inch on center 2" x 6" wood assembly. Test method ASTM 1116. Airspace of 2.64 inch on each side of product. Heat-flow direction horizontal. Interior side of product exposed. ICC-ES Recognized and Energy Star Qualified. Compliance with International and Residential Code (IBC) 2006 and 2009. Questions, please click to email or send to: sales5@Insulation4Less.com For suggested installation methods click install.