What are the realities of working with tape in Mid-Atlantic Region? How do mixed climate zones affect tape application and performance? What is the future of SIPs and tape? Is expandable tape a reality? In a recent conversation with Al Cobb, President of PanelWrights, we gained an insider’s take on residential building in this climate zone, and went behind the scenes on tape, SIPs, and deep energy retrofits.
Al Cobb is a SIPA Master Registered Builder, and his company, PanelWrights, provides full-service SIP Sales, SIP Design, and SIP Installation for commercial and residential projects. He also happens to be Director of SIPschool, a program that provides training and consulting in all areas of SIP manufacturing, design, and construction.
Clearly, he is passionate about education. But Cobb is also driven by how energy efficiency is impacting construction, and he talked at length with us about how all of these things impact tape.
“Tape has to be put on at the right time, in the right fashion, and you have to select the right type of tape – then you’ve got to get it on the right side of the assembly and know where in the world you’re building. It’s not a one size fits all,” Cobb began.
Tape Tips for the Mid-Atlantic Region
ECHOtape: So let’s talk about the where. PanelWrights builds everywhere from North Carolina to West Virginia, to Maryland. What lessons from these climate zones do you have?
AL COBB: As a builder, you should always be thinking about vapor, and warm side and cold side. Avoiding condensation is the trick. The vast majority of the country is mixed climate. On the East Coast, you have a huge swath of states that are difficult to build in because of this mixed climate, where homes need both heating and cooling. General climate conditions also shift in the span of a few hundred miles.
If you’re in an area where heating systems are not required due to climate, then tape to the outside. In a mixed climate zone, you get into areas where you’re almost better off to take the extra effort to seal the interior of the panel or assembly, and ensure you get it done right in the middle of the wall or roof, so you don’t need to apply tape unless a blower door test indicates a trouble spot.
Where tape may be required, a safe rule is to go inside in heating climates, and tape to the outside in cooling climates – so in Pennsylvania, you’d go inside, on the Gulf Coast, tape to the outside. Anywhere north of Pennsylvania, its almost always a given to have to tape on the interior.
I also look at the type of joint I’m dealing with. If it’s a joint that might shift and move over time or has components like lumber that can change based on climate and age, then let’s tape it. If it’s my building, I might tape the inside of the roof panel, as the roof to wall connection is notoriously leaky. The ridge is also critical because of stack effect, especially up north.
Let’s take our time and make sure it’s perfect.
That’s the ‘where’; how about the ‘when’ for tape installation?
The when is all-important. Too frequently, a SIP roof is set, and then the builder wants to tape the roof and ceiling before the structure is watertight. Guess what? That sequence is wrong, and water finds its way into the joint and the tape, preventing drying so that it puddles up and the joint becomes moisture laden. The mantra for installation: At the right time, in the right fashion, on the right side of the assembly. If you go in thinking that moisture is an issue you have to confront and spend the time and money to make sure it has a robust capacity to dry.
What are the most common mistakes you see in tape application?
Far too often contractors don’t pay attention to a clean surface. That’s important. And I also find we are far better off when we pay attention to temperature. Some tapes are more susceptible to external conditions than others.
The State of Tape
What advances are you seeing in tape products? Are you seeing tapes used differently on the job site today?
Tape manufacturers have created PSAs that really stick beautifully. Some of the more advanced tapes are now vapor-permeable. You would think that this is the golden chalice, to stop air but allow drying. It’s all about drying. If you can get an assembly to dry out, you’ve got a good assembly. Let’s quit trying to keep water out, and instead spend more time trying to figure out how to let it out. Murphy says it will get in – it could be vapor coming from the basement, from the sky, from an indoor sauna, from plants, etc. Let’s figure out how to make assemblies so that drying is completely understood and the structure has a greater capacity to dry. This is where tape becomes a hindrance, unless you go with high-end tapes that are designed to be permeable and allow moisture out.
What about SIPs and tape?
When structural insulated panels (SIPs) came out with tape in the 1990s, it was a hard rubber tape that didn’t stick well. We would routinely come back and see tape was hanging off the panels a day after installation. Newer tapes have release paper and an adhesive bond that make them easier to apply, so you don’t have to use a primer if the surface is relatively clean. You should use a roller or putty knife to really press that material on and ensure it actually stays stuck. Today I see problems because installers simply push in the tape with their hand and say, “Hey, it’s stuck!” They don’t realize the difference in application with a roller versus just slapping an adhesive tape on with their hand.
When training ensures the proper design and installation, a SIP envelope can meet all the consumer’s expectations. SIPs provide lower energy costs, reduce our carbon footprint and provide a safer, cleaner and structurally superior building system. Pre-planning in a SIP build is an important part of the process. You need to be considering issues such as proper HVAC sizing, sealing strategies, electrical issues. The R-value benefits provided by SIPs are significant, but unless you’re installing these panels correctly you might as well just leave your windows open.
And energy efficiency and tape?
A facet that has really dictated what’s going on is the airtightness of a structure. In everything from Passive House standards down to code minimum, tape has become a belt and suspenders approach to getting a properly sealed system. Tape really came on scene in the mid-1990s. It was introduced to address failures in assemblies and envelopes where internal sealing was not done per manufacturer recommendation. However, when you have an energy efficient structure with low air movement, with no air, there’s no way to dry, and condensation can accumulate and cause moisture issues. This has bit a lot of builders who lacked an understanding of the impacts of heat, air, and of building science.
SIPA came up with a method to put tape on as a vapor barrier. The tape is put on the warm side, so that whether or not you seal the assembly properly, tape located on a warm side will prevent moisture-laden air from coming in contact with a cold surface which results in condensation. This was relatively successful, but there are still builders and installers pulling in many directions at once, even within the SIP industry. Some people say no tape is needed, if internal pieces are sealed correctly. If we put tape on we do prevent drying in a certain direction. I believe if a builder is conducting blower door tests done regularly, and if they show an assembly is tight, then putting tape on it can only potentially trap moisture that wants to get out.
Adhesive tape is a double-edged sword; it can be our best friend in an assembly that’s not as tight as we want it to be. When put on right, it prevents air from traveling in the wrong direction, and it all works really well. When put on wrong it traps moisture and ruins the whole system.
So what’s next… what’s the future of tape? What product or innovation would you most like to see?
Expandable tape! There’s a huge debate between sealants and foams. What’s better? Mastics or expanding foam? You can go to a manufacturer who uses one and you’ll hear about failures in the other; both groups point fingers and claim they’re the best solution.
A number of people have come up with expandable foams; the same recipe could be applied to tape – you unroll it, put it in the joint, and it fills the void and seals it up. Foam is difficult to work with right now for installation. This tape would need some type of internal methodology allowing it to expand on a delay and fill voids, and it would move us away from expanding foams.
Any last thoughts?
After all is said and done, the very best solution is an educated installer who knows the best fit for each joint, whether it is tape, foam, or a different solution. You shouldn’t be limited to stay within a manufacturer’s system. In the real world, joints are different than what manufacturers proclaim – in the lab, it may have gone one way, but in the real world conditions can be so different. We need to have a toolbox with all the tricks, all the sealing options at our disposal, and have the knowledge on how to use them and why certain solutions are a best fit.