Before we delve into the “whys” we really should look at the effects of ponding water on the roofing system. Ponding water can have the following effects:
- additional loading to the structure
- additional time for moisture pathway to open and allow intrusion
- accelerated material degradation including reflectivity and sunlight magnification
- freeze/thaw pressure from moisture seeping into cracks
- insulation compression
- dirt and debris build up that can cause mold or plant growth
- safety issues - electrical or slipping and falling
- voids warranties
The effects of ponding roof can be a safety issue as well as a serious financial issue. If most roofers are aware of the hazards of ponding water then why are there so many roofs that do not drain well? What are the common causes for poor drainage?
- structural deck deflection
- weep hole’s on connected building sections too low
- no or poor structural slope
- poorly designed tapered insulation system
- cost cutting
- poor detailing
- drains/scuppers/gutters plugged
After walking and inspecting millions of square feet of roofing, I have come to the conclusion cost plays a sad, but significant role. I believe roofers feel cost pressure from owners that do not fully understand the ramifications. I will share some examples.
- A roof that has deck deflection issues, retrofitted for cost savings instead of torn off and the deflection was not addressed properly.
- I referred “poor detailing” but what I really meant was that the good detailing was too expensive and the standard detailing was used as it was ok in the book. (example of this, HVAC units that stop the flow of water drainage and needed to be raised and saddles installed to divert water around the unit - not done… not in bid or too expensive or a pain/time to disconnect.)
- Another one I hear is that Polyiso tapered insulation is to expensive and I can go with a 1/8” pitch, that should work.
- Weep holes, I can’t go above the weep holes, its too expensive to modify or change.
I understand the competitive world of bidding but I have some recommendations that can Keep Your Standards Up and Your Cost Down. I hear building owners constantly saying, “ I want things done right.”
RECOMMENDATIONS: Keep Your Standards Up and Your Cost Down
- Instead of using overpriced Polyiso, value engineer and use EPS for the tapered. - save money. Learn about cost saving in EPS
- Use 3/8” tapered as a minimum instead of standard 1/4” as it moves the water better and can overcome many of the detail or structural slope issues. Learn More
- Disconnect units and other projections for proper height requirements and proper water flow.
- Learn how to move weep holes which can offer the ability to increase insulation heights and have better drainage.
- Use EPS saddle and crickets to make sure water moves around units, projects and even between drains. Saddles can be a roofers best friend.
Many myths about rigid insulation have been spread over the years, especially concerning EPS. Some of these EPS myths refer back to an extinct product called bead board. Modern day Engineered EPS is so different and technologically advanced, it’s amazing some still get confused. EPS have made major advancements in chemistry, fusion, expansion, steam quality and TQM. Plymouth Foam, the leader in foam, has state-of-the-art proprietary manufacturing technology to make the product even better.
Lab and field research have lead to new conclusions about the two rigid insulations especially in below grade applications. EPS rigid insulation is certainly been found to be superior to XPS in so many ways. The following is just 12 reasons why.
1) Higher R-Value Retention:
EPS does not suffer from the same plight as XPS in regards to “Off Gassing.” XPS has blowing agents that initially give it a higher R-value, but these gasses escape over time, lowering the R-value.
Engineered EPS can be made in various densities and can achieve compressive strength up to 8,640 lbs/ft and flexural strength up to 10,800 lbs/ft. It is amazing that such a light product, that is 98% air, is so strong.
3) Moisture Management
EPS insulation is non-hygroscopic and does not readily absorb moisture from the atmosphere. Its closed-cell structure reduces the absorption of moisture into the insulation material yet it can readily expel any absorbed moisture.
4) 100% R-Value Warranty
Due to the R-value stability of EPS, Plymouth Foam offers a lifetime limited 100% R-Value Warranty. XPS offers a 90% R-value warranty.
5) No Harmful Chemicals
EPS does not have VOCs or other harmful chemicals in its product. XPS use of chemical HFCs has been deemed to have a high GWP.
6) Cost Advantage
R-value cost per inch is far less in EPS insulation vs XPS Insulation. Value engineering can be used to save $1,000s on projects.
7) Superior Bonding
Due to the manufacturing process, EPS and XPS provide a far different exterior surface. EPS cell structure provides superior bonding.
8) Made in USA - Made in Wisconsin
Plymouth Foam’s EPS is made in Wisconsin and brings jobs, reduces taxes and helps create a better economy for our state. Made in USA.
Engineered EPS is superior in customizing thickness, lengths, shapes, tapers, chases and can even have reflective laminates attached.
10) Smoke Development
ASTM E84 test method for burning characteristic show that typically EPS has a lower smoke development than XPS.
11) Lower GWP
EPS, the safe insulation, has a lower Global Warming Potential than XPS. Transportation costs are usually lower also lowering GWP.
12) Recycle Accessibility
With over 200 EPS recycling centers in the United States it is easy to see that not only is it 100% recyclable, but it easy to do.
(Learn More about these 12 reasons)
As EPS continues to grow even more popular and gain market share, competitors have continued to spread these old myths. The bad news for them is these myths have been BUSTED. Numerous studies done around the world are proving that EPS is not only “the safe insulation” but that it holds its R-value better, is extremely durable, great in freeze-thaw cycling, has great drying potential and outperforms all other rigid foam insulations.
(Get the 12 Reasons Brochure)
You’re bidding on a project and EIFS (Exterior Insulated and Finish Systems) is specified in the building package. Who do you rely on that it specified, bid and installed correctly? Where does the buck stop?
EIFS has make huge advancements in technology, systems and installation details. The biggest advancement for our northern climates has been drainage or moisture management. Advanced design EIFS systems use a drainage cavity to move unwanted moisture out. This concept is monumental and removes many of the old design flaws with EIFS.
Here is where knowledge can lower your risk and pay off for you. Insist that your EIFS system only uses EPS insulation. Why?
Good building practices and todays advanced EIFS systems' goals are to discharge any stray moisture as quickly as possible. What about when that moisture finds its way into the insulation? Good Question! We know from studies that XPS (Extruded Polystyrene) insulation has a difficult time discharging moisture. Moisture in EIFS systems can cause serious system failures such as cracking, blistering, peeling paint, structural rotting and even mold. EPS (Expanded Polystyrene) insulation, on the other hand, has the ability to breath and release off moisture much quicker. In test situation, EPS also has the ability to hold most of its R-value, where XPS losses 48%.
EPS Moisture management is a great reason to insist on EPS insulation in your EIFS system but here are a few more:
- EPS can be made into a variety of shapes
- EPS can be made in various thicknesses
- EPS can be made in various densities
- EPS offers a consistent R-value
- EPS is the Safe Insulation - no harmful HFCs
- EPS is 100% Recyclable
- EPS is a Better Value and Lower Cost
This is one of those cases where a less expensive product is much better and can lower your risk.
Learn more about EIFS
The biggest concern of condensation and its effects can be quit worrying for building owners and construction professionals. Water that forms in a system can cause damage such as:
✓ Corrosion of metal panels and components which can structural weaken the system
✓ Degraded and wet insulation reducing thermal performance
✓ Mold and/or mildew growth that can increase health risks
✓ Insect infestation which can contaminate systems
Condensation tends to occur in noticeable quantities and cause problems at surfaces where there is a sudden change of permeance, which causes an increase in local relative humidity sufficient to create dew point conditions. Condensation in metal roofs can be caused by air leaks around units, holes in vapor barriers/retarders, gaps in insulation just to name a few and no system is bullet proof. “Moisture moves by several mechanisms, including bulk drainage, diffusion (absorption), surface diffusion (absorption), capillarity, osmosis and convection.”
Condensation can occurs on a hygroscopic surface, such as wooden sheathing or insulation, then moisture is absorbed, lowering the vapor pressure and increasing the vapor pressure gradient, driving more moisture toward that surface.
Picking an insulation that is resistant to moisture and help stop condensation is important, but no insulation is 100% waterproof. When Polyisocyanurate (Polyiso/ISO) or Extruded Polystyrene (XPS) gets wet, they dramatically loss their thermal effectiveness. Engineered Expanded Polystyrene (EPS) has the ability to resist moisture but when it get wet has the ability to expel moisture. Most metal roofing systems are not waterproof but rather watersheds. Therefore, air can travel and flow through the upper metal roof system allowing drying to occur. Learn More Here is the Secret: EPS is the BEST Insulation Solution for Metal Roofs because it can expel moisture caused by condensation. EPS's R-value will stay stable and be an overall better value.
View our Metal Roofing Products
Continuous Insulation, is defined as, “insulation that is continuous across all structural members without thermal bridges other than fasteners and service openings.” More important is the fact that Continuous Insulation increases R-value performance due to the non-interruption of wooden or steel studs.
“Furring out” a wall with studs or furring strips and then filling in the gaps with insulation is still a common method used on interior and exterior walls. Every stud used, lowers the R-value and thermal loss and/or thermal bridging occurs at this intersections. Advancement in understanding performance R-value through continuous insulation has lead to the importance of Gold-Wall. The advantage of Gold-Wall is not only a Continuous Insulation system, but it has the built in ability to allow for finishing attachments. These finishing attachments can be interior drywall or exterior clad siding like vinyl or steel. The possibilities are almost endless.
Gold-Wall, with its built in surface attachment stud, can be installed easily to most type of masonry walls. Gold-Wall can also be attached to steel studs, wood framing or even OSB/Plywood surfaces. Gold-Wall comes with a high performance poly facer laminated to the moisture resistant EPS foam board which increases durability, fastener holding and impact resistance.
Gold-Wall may be perfect for your next Continuous Insulation project. Learn More
Foundation insulation may be easy to overlook as many building professionals may be going under to old adage, "if it ain't broke, don't fix it." The serious reality is that in cold weather climates any structure that has a foundation that touch soil such as basements or frost walls needs to viewed differently in regards to moisture management.
Foundation insulation can be used for a variety of reason but the most important is R-Value. This is where it gets interesting - what does Moisture Management have to do with R-Value? Its all about building performance in real world applications.
We can explore permeability and the Laws of Thermodynamics and go very technical but for now most people know that when insulation gets wet, the R-Value of the insulation is reduced. This lowering of R-Value is a performance issue.
A new way to view and understand foundation insulation comes from a moisture study. This study looked at the two most commonly used insulation for below grade - XPS (Extruded Polystyrene - pink or blue) and EPS (Expanded Polystyrene - white). Three relevant items of note come from that study. First, XPS lost about 1/2 of its R-Value below grade and EPS held almost all of its R-Value. Second, it was found and further studied that EPS takes on a little more moisture than XPS but EPS insulation has the ability to dispel it. Third, for some anomaly in physics, that we don’t quite understand, EPS even with moisture, tends to hold its R-value. (Learn More from the research)
So now that we know what happens to insulation below grade how does that all tie back into Moisture Management? If you are not going to 100% envelope or water proof your below grade insulation or below grade wall system, EPS insulation should be used 100% of the time. Remember, the goal of Moisture Management - keeping a building lasting longer and performing properly - Its all about performance. If you want your below grade insulation performing properly and its going to be left “unenveloped," the best Moisture Management choice is EPS.
R-value is more than the R-value per inch. Polyisocyanurate (ISO), starts out with a higher r-value per inch, but then the blowing agents escapes and the R-value is reduced. (learn more) Expanded Polystyrene (EPS) has a lower R-value per inch but can be make thicker to match any R-value requirement. EPS’s R-value increase in colder temperature while ISO decreases. Many would give ISO the edge because of R/inch, but taking into consideration overpaying for R-value that does not stay stable in lower temperature, the advantage has to good to EPS.
- Environmentally Friendly
- Design Flexibility
- Moisture Retention
Expanded Polystyrene, when compared to polyisocyanurate, certainly has more reason to be use in roofing. It seems over the last few years, many designer have lost sight of the purpose of insulation and the importance of R-value long-term. Some designer only considered combustibility and its superior importance, when in all likely hood this physical property will never ever be used. A feature such as long-term R-value, which performs daily in that system, or even moisture expelling capability, get lower considerations. When all of the major features of insulation are considered, EPS seems to be the clear winner.
Breaking away from the norm and thinking out side the box is what Lumber Sales & Products, Jackson, Wisconsin strived to accomplish. Using a wood stove and in-floor heating is beyond normal construction and took special design and engineering.
Instead of using the traditional pink or blue XPS insulation, Engineered EPS was used as the insulation beneath the concrete to dramatically help save energy. Not only does the EPS work better, but the cost savings was almost 30%. The cost savings for just the insulation was over $15,000. In addition, the saving on the supply lines, using EPS, was $7 per linear foot.
Often these types of projects are specified using XPS insulation because of the myth that EPS is not as good or somehow the hot water running through the pex will melt the insulation. The reality is EPS is a far better product in this application and the cost saving is just an additional benefit. Once the merits of Plymouth Foam Engineered EPS systems are reviewed, the substitution is usually welcome and accepted. Read the entire Job Profile
In high school, I remember watching the track team race around the track. One runner Peter, a farm kid, was fascinating to watch as he always grabbed the early lead. Peter always looked so fast but in the end he would typically finish in 3rd or 4th place. In that moment, early in the race, Peter looked like a world class athlete that would easily win gold at the Olympics. In those early moments, that frozen time, the measure of performance was perfect.
Thirty-six years later and I see the same thing happening in the rigid insulation market. Its like watching Polyiso, and XPS insulation running just like Peter, getting off to a tremendous lead regarding R-value, but then fading out at the end. That perfect moment in time is when that R-value gets measured and they look like superheroes but in reality they just “blowhards.” Pardon the pun as the blowing agent escapes and lowers the r-value. (LEARN WHY)
When it comes to below grade or roofing insulation, Polyiso and XPS start out with really good R-value numbers but they don’t last (LEARN MORE). Unfortunately, you pay for these early performance numbers, sometimes as much as 50% more. Paying for performance isn’t bad but not knowing that the product will fade out is a different matter.
The old idiom, “slow and steady wins the race” really holds true in insulation. EPS might start out slow (or lower r-value) but is consistent through its life and ultimately wins the race. Not only does EPS (Expanded Polystyrene) have a steady consistent R-Value but when compared with XPS and Polyiso, it also performs better in the field. XPS and Polyiso, when wet, hold the moisture and loss much of its r-value. EPS has the ability to hold its r-value and even expel moisture under exsiccate conditions.
Next time, when you’re looking to specify or install insulation on a project, remember that Polyiso and XPS look great at the beginning but EPS is the steady performer and the best value in rigid insulation. Your customer deserves the winner - EPS.
When installing a new roof, (new construction or replacement) an owner is faced with the role of Risk Management. Many building owners believe the serviceable life of a roof is directly related to the warranty. Roofing Manufacturers’ have seized upon these beliefs by selling “NDL (No Dollar Limit) Warranties” giving customers the euphoria of total protection. Are NDL Warranties worth it?
NDL warranties have a relatively high cost, at several levels. There is a cost per foot for the warranty and to qualify for the NDL, the “system” has to contain “everything” from the roofing manufacturer (screw, plates, insulation, etc.). Most roofing manufacturers do not make all the components in a roof system but rather put their name on them and mark them up.
This is where NDL warranties go sideways - “all the other components.”
According to Roof Warranty Research, roofs typically don’t fail because of washers or insulation. So if insulation and other components, rarely if ever, cause roof failures, why bundle them into a warranty? Does the NDL warranty guarantee the R-value of the insulation when it declines or gets wet? Would you be surprised if I told you they do not?
Maybe bundling all these other components in a NDL warranty offers better cost? When the Roofing Manufacturers bundles the other components, it ultimately places a double margin on “all the other components” - 1st mark up from original manufacturer and the 2nd mark up from NDL Warranty Roofing Manufacturer. Does this double margin reduce cost or add extra profit for the roofing manufacturer?
Interest fact, the roof installers lose their competitive ability to “shop” all the other roof components, driving the prices higher. So, NDL Warranties really take Value Engineering away from the roofer and the building owner! In reality, it really hampers the free market system in some ways.
So are NDL worth it? It has long been said, that roof warranties are written to protect the manufacturer not the owner and that the best warranty is the one that you never have to use. What is a building owner to do? I suggest saving money and take the advice of the roofing experts, make sure the roof is installed properly, do proper maintenance and faithfully monitor the roof through inspections - this is how you get longer serviceable life, not through a NDL warranty.
Early this year, the National Roofers Contractors Association, made a recommendation to it's members that Polyisocyanurate Insulation revise "its design in-service R-value recommendation to 5.0 per inch thickness." This declaration was the second time Polyisocyanurate's R-value was downgraded in the last 2 years. For some of us "Energy Aficionados," who understand the principles of insulation off-gassing, determined it was time to re-examine LTTR testing (View Technical LTTR Bulletin).
LTTR really looks at Long-Term Thermal Performance of insulation as 5 years. Do we expect a building to last only five years? How is 5 years a true quantitative analysis of R-value performance?
We do not replace insulation in a building every 5 years, why would we think that is long-term? Most building in the U.S. are built to last 50 years, some 100 years. Long-term R-value should be figured at 50 years… right? We know off-gassing continues to happen after 5 years. Let's re-evaluate what we are doing as an industry and modify Long-Term Thermal Resistance to at least 50 years.
The real question maybe why? and why another change after last year’s change? The answer is independent testing. According to research conducted by BSC (Building Science Corporation) and others, “the thermal performance of some insulation materials changes as they age. The R-Value of Polyisocyanurate decreases as some of the gasses … diffuse out and are replaced by air.” This is known by several names - Thermal Drift, Gas Replacement Process or Off Gassing.
What the research has shown is that unlike EPS (Expanded Polystyrene) Insulation that increases its R-Value when the temperature decreases, ISO Insulation R-Value actually goes down. Bottom line: In the north, when you need the r-value the most, its not there like we thought.
• If you need to use ISO - the BCS Recommendation is to use it in a “hybrid insulation approach” with a cold stable R-Value insulation like EPS.
• Try to substitute out ISO Insulation and use EPS or the New Neopor Plus Insulation.