5 Things to Know Before Buying Foam Insulation Tape

If you’ve decided to use foam board insulation for your construction project’s exterior walls, you’ll also need an accessory to go with it: tape for the joints. 

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When putting together your building’s enclosure, your system is only as good as its weakest point. That’s what makes sealing the joints between rigid insulation boards so critical. This step keeps air and other elements from seeping through the cracks and into your building’s interior by performing as an air and vapor barrier.

There are many construction tapes on the market to pick from. Choosing the right one for your job ensures that your building’s wall systems can perform as intended. 

Learn more about the best tape for foam board insulation for your exterior wall applications below.

The Difference Between Construction Tape and Insulation Joint Tape

When shopping for the best tape for foam board insulation applications, you’ll need to choose between construction tape and insulation joint tape. Both types of tape are made of an adhesive and a backing material. The difference between construction tape and insulation joint tapes is in the material used for these two components.

Construction tapes are more versatile and can be used for multiple applications outside of just sealing insulation joints, including sealing windows and other penetrations. They can be made of rubberized asphalt, butyl, or acrylic. However, not all construction tapes can double as insulation joint tapes, so you’ll need to verify compatibility with your installation.

Insulation joint tapes are designed specifically and solely for sealing insulation joints for corresponding types of insulations and facers. This type of joint tape is usually made of an acrylic adhesive and features various backing materials—including foil, foam, paper, or BOPP film.

What Is the Best Tape for Foam Board Insulation?

To get the best of both worlds, look for an acrylic-based construction tape that is compatible with your insulation. Acrylic is an ideal adhesive for walls due to its properties of water and mold resistance, as well as adaptability to temperature changes. Other factors to consider when shopping for the best tape for foam board insulation include the following:

• Pressure-sensitive

• Water-resistant

• Mold-resistant

• Moisture-resistant

• Wide enough to cover the joint

• Tough, durable

• Compatible installation temperature range 

• Wide operable temperature range

Rmax R-SEAL Construction Tape

Rmax R-SEAL Construction Tape is specifically designed for use with aluminum-faced polyiso products, including Rmax Thermasheath®-SI and Thermasheath® insulation. It can be used for additional applications such as sealing around windows and door frames, patching, and more. The tape is 3” wide and comes in a 165-foot roll. 

The 3 mil acrylic-based tape is pressure sensitive for maximum adhesion. Additional reasons that Rmax R-SEAL is the best tape for foam board insulation include UV-resistance and weather-tight seal. This tough sealing tape can be installed at extreme temperatures from five below up to 180 degrees Fahrenheit and it is also effective in sub-zero temperatures as low as -40 degrees.

How to Apply Rmax R-SEAL Construction Tape

To install Rmax R-SEAL—first, verify compatibility by testing the adhesion on your material (skip this step for Thermasheath® and Thermasheath®-SI). Once you’ve confirmed compatibility, proceed with these steps:

1. Clean any dirt, dust, moisture, or other debris off your insulation with a dry cloth.

2. Center the tape over the joint or object that you’re taping (extend ¾” beyond the joint’s edge).

3. Affix the tape so that it is smooth and flat.

4. Cut the tape from the roll at the end of the joint with a utility knife. 

5. Flatten out any imperfections with a feathering tool or hand roller.

Rmax R-SEAL as Adhesive for Insulation Joints

If you’re looking for a foil-backed joint tape, Rmax R-SEAL is a construction tape that has superior conformability for taping foam board insulation joints. This 2 mil acrylic-based pressure-sensitive tape features foil coating plus a release liner for maximum adhesion even in cold conditions. This tape is 4” wide and comes in a 150-foot roll. 

How to Apply Rmax R-SEAL Tape

R-SEAL Tape is installed the same over insulation joints as standard R-SEAL. Clean the surface, tape the joint, and apply pressure for a good bond. Lastly, smooth out any wrinkles with a feathering tool.

If you are looking for more details, kindly visit Foam Insulation Tape.

Key Points of Using a Good Quality Tape for Foam Board Insulation

You’ll know you’ve got the best tape for foam board insulation when your construction tape has these attributes:

• Excellent adhesion 

• Easy to work with

• Easily cuttable in the field

• Flexible

• Durable

• Long-lasting

• Adequate coverage

Rmax is the Superior Construction Tape for Insulation Joints

We’re seeing a material shift, literally. There’s a sweeping wave of synthetic, fabricated materials being used more frequently in construction, and this is a paradigm shift in construction. Leading the pack are changes in how we insulate.

Read on to learn more about the pros and cons of Rigid Foam Sheathing in high-performance building.

Rigid Foam as an Insulation Strategy

Rigid foam sheathing is a form of insulation — continuous insulation, to be exact — that’s applied to the exterior of the building. Continuous rigid insulation is a construction solution that provides a thermally efficient building enclosure. Rigid insulation sheathing is made of a rigid plastic foam that is typically sold in 4×8- or 4×10-footboards. The boards are available in several thicknesses and R-values; 1-inch and 2-inch thicknesses are common. Rigid insulation provides thermal protection and it can also serve as an air and moisture barrier.

There are three primary types of rigid insulation: expanded polystyrene (EPS), extruded polystyrene (XPS), and polyisocyanurate (polyiso). EPS and XPS are thermoplastics, which are non-cross-linked polymers so they are susceptible to deterioration in high temperatures (BSC ). Polyiso is a thermoset, which is made up of cross-linked polymers so it has a much higher melting temperature. While properties can vary among specific products, XPS and polyiso tend to be higher density, higher R-value, and lower permeance than EPS.

When rigid foam insulating sheathing is installed on the exterior walls of a home, the foam can serve as a drainage plane, taking the place of house wrap for time and cost savings. To serve as a drainage plane, the seams in the foam sheathing must be properly taped with sheathing and flashing tapes to provide continuity of the drainage plane at joints between panels. The tapes must be durable enough to prevent ingress of water at panel joints for the life of the system. Sheathing tapes and sometimes flashing tapes are also needed to integrate the top edge of diversion flashings (head flashings, flashings over penetrations, step flashings, kick-out flashings, etc.) with the drainage plane.

Rigid Foam and Building Codes

Because of its thermal properties, rigid insulation is being called for by certain codes and programs. ENERGY STAR(TM) requires that rigid foam or insulated siding be installed over walls if they are metal framed (ENERGY STAR ). ENERGY STAR also requires that rigid foam sheathing or insulated siding or a combination of the two be installed to a thickness of ≥R-3 in Climate Zones 1 to 4 or ≥R-5 in Climate Zones 5 to 8 (ENERGY STAR ).

Continuous rigid insulation also provides an effective solution to thermal bridging. Thermal bridging occurs wherever assembly components with low R-values (such as wood or steel) span from the interior to the exterior of the building. In traditional building construction, while the wall cavities are filled with insulation, there is no insulation at the window frames, door frames, studs, top plates and bottom plates; together this framing comprises nearly one-fourth of the wall area. Rigid insulation can be attached to the exterior side of the framing to provide a continuous insulating layer that reduces thermal losses through thermal bridging.

3 Benefits of Rigid Foam Sheathing

More effective insulation
With R-values ranging from 3.6 to 8.0, rigid foam sheathing has much better insulation per inch than other materials (i.e. plywood has an R-value of 1.25 and fiberglass batts have an R-value of 3.14). This is especially critical in preventing damage (such as mold and rot) to framing and walls in areas with extremely cold or damp climates. Since rigid foam is applied on the outside it also prevents thermal bridging. Thermal bridging happens when there is a loss of heat due to an interruption in the insulation by a material that is more conductive. This typically happens when interior insulation intersects things like stud frames or electrical boxes.

Better at controlling moisture When it comes to controlling moisture, rigid foam serves two functions. It protects the wood sheathing or framing from any rain or water that leaks in under the siding. And it warms the interior sheathing or framing enough to prevent moisture accumulation from the heated interior air in the winter.

Better at preventing air leaks
When sealed with proper techniques and a suitable adhesive, rigid foam is an excellent air barrier. The same principle mentioned above that prevents thermal bridging also applies to air transfer. Unlike house wrap, which works to prevent infiltration (air coming into the building) but is poor at stopping exfiltration (air moving out of the building), rigid foam is able to do both.

Disadvantages of Rigid Foam 

Must be installed properly to limit air leaks and act as a weather-resistive barrier
Rigid foam does not require specialized equipment to install it but you do need to follow strict seam-sealing procedures to meet code.

Less structural strength than plywood or OSB sheathing
If rigid foam sheathing is used on top of wood sheathing, this doesn’t matter. However, if you want to use rigid foam in place of wood sheathing it needs additional bracing to prevent racking.

Slightly more expensive
Adding a layer of rigid foam on top of plywood or OSB sheathing will increase the cost of the project. However, this is just a short-term, fixed cost. Rigid foam often pays for itself with lower utility bills over the long term. And it may put off or prevent costly work to repair rot in walls or framing.

Installing Rigid Foam Sheathing

When using foam insulation, you’ll need to decide whether you intend to use OSB in addition to the rigid foam to serve as the building sheathing or if the rigid foam layer will itself serve as the sheathing, and you’ll need to determine what will serve as the drainage plane and where this layer will be. These decisions are determined somewhat by climate.

• Extruded polystyrene (XPS) and foil-faced polyisocyanurate (polyiso) are high-density rigid-foam insulations that can be used as exterior insulation and are generally approved, per Building America(SM) to be used as a drainage plane if the joints are sealed.
• Insulation sheathing membranes rely on tape to complete the air barrier; the tapes should be applied on a clean, dry, warm surface.
• For the rigid insulation to be used as a water-resistive barrier, the vertical plane of the exterior face of the sheathing must be as smooth and continuous as possible.

The lowest cost, highest performing rainwater management strategy is rigid polymeric foam sheathing with sealed joints (Lstiburek , ). There is an existing construction challenge of sealing the joints in rigid polymeric foam sheathing in a reliable and durable manner to prevent water ingress.

Best Practices for Taping Rigid Foam Sheathing 

The Building America Solution Center has the following builder guidelines for taping rigid foam:

1. When rigid foam is used as the weather-resistive barrier and/or the air barrier, tape all seams using manufacturer-recommended tape per the manufacturer’s instructions. Wipe the surface of the foam with a clean dry cloth before taping to ensure good adhesion by removing dirt or oil residue which is common on foil-faced polyiso.
2. When rigid foam is used as the weather-resistive barrier, apply flashing shingle fashion around all openings for doors, windows, etc., to reduce bulk moisture intrusion and air infiltration.
3. Center the tape over the joint to cover the fasteners. Fasteners located in the center areas of the boards do not need to be taped. Use a shingle fashion technique when taping joints. Avoid taping during extremes in temperature; install tape per the manufacturer’s instructions, which is generally between 15°F and 120°F.
4. Apply pressure along the entire surface for a good bond. Remove all wrinkles and bubbles by smoothing the surface and, if necessary, repositioning.

When working with any new material, you have to make sure you have enough available surface contact. We’re seeing applications where tape works well with synthetics, but we’re also seeing materials that offer a very imperfect surface to bond to. As new materials are introduced, and airtightness remains a critical requirement, the industry needs a pressure-sensitive tape that’s going to bond quickly to rigid insulation and stay that way.

Which is exactly why ECHOtape launched our new, next generation seaming tape.  PE-M is a proprietary high-performance building tape, made from an advanced polyester backing, which makes it extremely strong and easy to apply. Available in red, silver and white, it is a versatile product used in a wide variety of building envelope sealing applications, including cold weather applications.  As excited as we are about PE-M, ECHOtape R&D team is continuing to develop additional seaming products to meet the needs of a rapidly changing building industry, products that will adhere to a wide range of building materials and surfaces including house wrap, exterior, and rigid insulation, sheathing, vapor barriers and a variety of underlayments.

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