News Room : Archives : September 2012

 

Posts Tagged ‘method’

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Hidden Seam Failures? We Put Flashing Tapes to the Test

Saturday, September 8th, 2012

Flashing and air barrier seam tapes get buried deep in our walls where we rely on long-term performance without monitoring them. Are they doing their jobs?

Companies do their own more sophisticated testing, like this tensile test on ZIP Tape. The company has a whole video on its testing procedures, but it’s more fun to try this at home! 
Photo Credit: Screen shot from ZIP System video

NOTE: Read this whole series here.

Service life of tapes can determine the service life of an entire high-performance building assembly.

Performance testing of adhesives and sealantsused in our weather barriers is improving due to new field-testing research, as we’ve written about before. However, the improvements in testing haven’t reached a critical product area: pressure-sensitive adhesive (PSA) tapes used for sealing seams in flashing, housewrap, and generally creating continuity in air and weather barriers. “I am unaware of any work being done on this issue, either laboratory or field tests,” says Christopher White, of the National Institute of Standards and Technology (NIST).

The most commonly cited adhesion tests for pressure-sensitive adhesive (PSA) tapes are as follows:

  • ASTM D3330 – Standard Test Method for Peel Adhesion of Pressure-Sensitive Tapes
  • ASTM D903-98-04 – Standard Test Method for Peel or Stripping Strength of Adhesive Bonds
  • ASTM D1876-01 – Standard Test Method for Peel Resistance of Adhesives
  • ASTM D3654 – Standard Test for Shear Adhesion of Pressure-Sensitive Tapes
  • ASTM D3330 – Standard Test Method for Peel Adhesion of Pressure-Sensitive Tapes

But none of these tests is ideally suited for lab-testing high-stretch construction flashing tapes, and none go anywhere near testing under field conditions. And since just about all tapes are used in concealed weather and air barrier systems, we really need a field-service-life prediction test.

 “Workbench tests” of flashing tapes

So we took matters into our own hands—or rather, our own workbench. Lately I have been just sticking a slew of tapes on different building materials and gauging how hard it is to pull them apart.

My efforts got a lift in technical rigor when I was discussing this with David Gauthier, president ofVantem Panels here in Brattleboro, Vermont, a local structural insulated panel (SIP) manufacturer. David is always looking for gaskets and tapes to recommend with his panels. He said, “Hey, I bet we could use our tensile tester on the tapes!” (Van Tem uses a tensile tester to assess the strength of the bond between their skins—mostly OSB—and their foam cores).

What were we thinking?

We have no illusions that the testing we performed is up to the rigor of ASTM D3330—the list of how our testing is different from the standard Test Method A is at the end of this article.

“Trying this at home” at first involved some pretty unscientific conditions; trying to rip strong tape off stuff is fun but doesn’t tell you much!
Photo Credit: Peter Yost

There are a lot of key differences, so no conclusions should be drawn from this testing. In any case, not all manufacturers report D3330, so we needed to pick one set of conditions and run as many tapes as we had through that one. We hope this testing provides some suggestive information.

And here is a thought: maybe our “benchtop” testing will inspire (or anger?) some experts from PSA tape manufacturers or test programs to conduct some field or field-like service life performance testing. We’d love to see more manufacturers engage in testing along the lines of the Sustainable Building Solutions Test Facility Tremco has going, in partnership with the Department of Energy.

After all, if the sealant manufacturers have rallied behind the work of Dr. Christopher White at NIST on standardized testing for field service life prediction of liquid sealants, can’t the PSA tape manufacturers rally behind our humble work to develop some testing and data for the field service life of PSA tapes?

Some lessons learned from our testing

Here are some things we noticed based on our test results (click to download the spreadsheet).

  1. High-stretch tapes: All of our results are probably considerably lower than typical D3330 results. Consider this perspective offered by Forest Products Lab research chemist, Christopher Hunt:
    “Rate vs load. The faster you pull, the higher your load. Molecules relax over time, resulting in lower tensile load. If you pull slowly, the molecules have time to relax during the test. If you pull really fast, they don’t and so loads (as well as elongation before break) are less. How much difference is going 1″ per minute instead of 12″?  Probably not big for this product, I’d guess that going at the specified speed may increase load by 10%–50%—but that’s only a guess. All the tapes will probably have similar effect, but not exactly the same.”
    And since MOST of the tapes we tested had very similar stretch outcomes (2:1; see column J – “Travel Ratio”), that helps our habit of comparing the test results of different tapes. The notable exception would be the DuPont FlexWrap; it yields considerably lower tensile results but its stretch ratio was 14 compared to 2!
  2. Difference between initial peak and (column G) and 2-inch peak (column F). Again, FPL research chemist Hunt:
    “The first versus second inch phenomenon is likely because of elastic vs plastic deformation. The first movement is like pulling on a spring – it wants to go back.  But you pull the spring too far and you’ve got a curly wire that never goes back. The difference is that you have exceeded the elastic limit of the material, and yes, the force required to keep stretching typically is less once you’ve passed this point. That’s why the standard is written that way—they want data on the stretched out material, not how hard it is to get started.”
  3. “Aging” of specimens – Ken Levenson of 475 High Performance Building Supply cautioned us that the solid acrylic adhesive used by Pro Clima tapes needs more time than other tapes to fully develop its adhesive bond—at least a couple of hours. Our results seem to support this; compare rows 17 and 31. The “aged” UNITAPE had significantly higher results. Compare Tescon VANA tape in rows 29 and 34; they “aged” results are much higher as well.
  4. Smooth vs. rough side OSB – PSA tapes just don’t stick to the rough side of OSB as well as the smooth side, period. Trouble is, some building inspectors mandate that the smooth side be to the interior (so that they can see the grade stamp—always on the smooth side—after the structural sheathing is covered with other materials, WRB and/or claddings). This puts the rough side to the exterior, right where you are likely to be taping seams for an OSB air barrier or window opening flashing if your windows are going in before your WRB.
  5. Performance comparison of different types of adhesives – we need more data on this one, but the results suggest that acrylics demonstrate stronger adhesion than modified bitumen. We can’t really say much about the only butyl rubber tape, since its far greater stretch ratio makes its peak so much lower than the other adhesive tapes.
    At the same time, the builder group that I worked with in the tensile testing, expressed interest in the combined performance/cost of the various tapes. The Huber ZipWall tape (solvent-based acrylic), at $20 per 75-foot roll, nearly half the cost of the Siga and Pro Clima tapes (solid acrylic) was a clear winner with the builders.
  6. This is just baseline data. The builder group was quick to point out how “unreal” this “benchtop” testing was: what about applying the tape at 5ºF, or when the substrate is damp, or after 10 years of extreme temperature cycling in the building assembly? Could be the solid acrylic tape manufacturer claims of superior performance be worth the higher cost?

    We hope to follow up this baseline ideal conditions testing with more field-like conditions.

Be careful with tape and OSB: no tape sticks well to the rough side, so smooth-side-out is best for taping seams.
Photo Credit: Peter Yost

Our testing vs. ASTM D3330

For more background into our test methods, here’s a list of how our benchtop testing is different than theASTM D3330 Test Method A (tapes peeled at 180° angle to the substrate, as pictured, Section [1.1.1] in the standard).

  1. [1.4] High stretch at low forces – D3330 does not handle high stretch tapes particularly well; the high stretch can lead to high variability in the test results.
  2. [5.3] Comparing results of different tapes – the standard specifically states that the test should not be used to compare tapes; it’s mainly “for quality assurance use.”  (Say what? Why do manufacturers report D3330 test results or data available on their product performance?)
  3. [6.3] Panel (substrate): Method A uses a stainless steel panel as the substrate; we tested tapes on various common construction materials: A-C plywood (C side) andOSB (both rough and smooth side).
  4. [6.5] Adhesion tester – VanTem Panels’ tester is a constant rate extension (CRE) machine, but D3330 specifies the test rate at 12 inches per minute and the top speed of the Van Tem Com-Ten DFM5000 is just over 1 inch per minute, not a particularly good combination with our “high stretch” construction tapes. More on this above.
  5. [9.1] Width of specimens – Most construction tapes are 2 3/8-inches wide (60 mm); we decided to make ALL of our specimens this width.
  6. [11.3] “Aging” of specimen – The standard specifies that the test must occur within 1 minute of adhering the tape to the substrate. We had quite a bit of variability (up to one week…) in how “old” the adhesive bond was between the tape and substrate. More on this above.
  7. [19] Precision and bias – We did mostly single specimen testing, not even close to the number and tolerance for variation called for by the standard.

Clearly, our benchtop testing is VERY different than the standard and mainly about looking for some generalizations we might suggest from comparing tape test results. We don’t come anywhere near claiming ASTM D3330 results.

 

original post found here:

The Great Debate: Is Prefab Really Green?

Sunday, May 22nd, 2011

A Possible Hybrid Prefab and Site-Built Approach

What if you were to take the best of both prefab and site-built methods of home building and combine them into a hybrid approach to construction and home delivery?

First, let’s start by roughly defining what this hybrid method might include:

  • Quality, stock plans from qualified architects that meet local codes and can quickly receive zoning and building permit approvals.
  • Educated clients that understand they are not buying a fully custom home.
  • Prefab building envelope – SIPs, ICF’s & Precast Walls.
  • Internal prefab components made in local shops — interior framing, framing with electrical & plumbing, prefab kitchen/bath/utility pods.
  • Better scheduling and local subcontractor cooperation

Quality Stock Plans
The first place to start when trying to streamline and cut costs from any building project is with high-quality building plans from qualified architects.  If every detail down to the last sheet of drywall and bucket of paint is nailed down and proven out in each set of plans, it becomes much easier for a GC to provide the best price from his crew and any subcontractors that are hired for the job.  This can not be undervalued, since any uncertainty on the part of those bidding on the project will instantly up the quotes.  This is where prefab gets most of the efficiency gains in their process, by building exactly the same home over and over.  They know exactly how much material and how much labor goes into each home plan in their library of options.

Another point to make here is the need for plans to be developed or easily modified for any location in order to ensure a fast permitting process. Zoning and building permit acquisition can add months to a building project, so having a way to expedite this phase of construction can be a significant cost saver that should not be overlooked.

An Understanding of Semi-Custom by the Client
One of the big reasons that fully custom homes designed by architects are expensive is not necessarily related to the architectural firm’s fee. It has more to do with the fact that the client is choosing exactly what they want in terms of appliances, layout, and finishes. There is nothing standard about this process.  The GCs that bid on these homes will be forced to deal with any number of materials or construction processes, some of which they might be seeing for the first time.  They may not be able to get their normal discounts on preferred brands and the uncertainty in labor costs will add a healthy premium to their bids.  An experienced GC knows that there will be many changes during construction on these custom homes due to the owner changing their mind or inadequate documentation on the building plans, and they will pad for these changes in their budget.

What clients must understand in any prefab or hybrid method is that the more custom changes they try to make, the higher their costs will be.  There is not an abundance of quality prefab or stock plan options out there, which is one of the reasons everyone ends up wanting to customize so much.  If the stock plan industry grew, then there would be much more variety to choose from and less desire to customize.  In the end though, clients will still need to understand the cost to value ratio of customization.  Most customizations will probably add $0.50 (if any) in value to the home for every $2.00 in extra cost that is incurred to make that customization.

Prefab Building Envelope
Now that we’ve covered the planning phases of a lower cost hybrid home, we can get into the nuts and bolts of the structure itself.  The basis of the hybrid system proposed here is that prefab is good in the right places and in the right doses.

The best example of this concept is SIPs or Structurally Insulated Panels.  SIPs are wall and roof panels that are prefabricated in a factory and then delivered on a flat bed truck to be assembled like legos on the construction site.  The SIPs combine the framing, insulation, and exterior sheething all into one product.  The windows and door openings of a home can also be cut exactly to size with framing lumber attached so that they are 100% ready for the windows and doors to be installed on site once they are in place.  The product is superior to traditional insulation methods in that it offers higher R-values per inch and an overall tighter home envelope.  There is far less thermal bridging with SIPs and dramatically less air leaking out of the finished house.

The SIPs will often save slightly on material costs when all components are added together, especially compared to a full prefab house that requires up to 30% more lumber to withstand shipping.  The SIPs are also flat-packed, usually on one truck, which reduces transportation costs compared to prefab which will require multiple truckloads of modules to the site.  SIPs can be handled by a fork lift or lull on site as well as by hand, which eliminates the very costly expense of a full-sized crane and operator at the site (always needed in prefab).  The panels will go up in 3-5 days on a typical home which beats stick building by a long shot considering that the SIPs include insulation and sheething.

Similar products to SIPs are precast concrete wall systems like Superior Walls that include insulation.  These walls can significantly reduce time in the foundation and basement portions of the build.  ICF’s or Insulating Concrete Forms is another alternative to SIPs or precast walls.  These are basically hollow blocks of Styrofoam insulation that can be linked together quickly and have concrete poured in the centers to form the finished structure.

Internal Prefabed Systems
The next suggested use of prefab in the hybrid model is not used very often in the US, but has been used extensively for years in other parts of the world.  Many good framers are able to prefab most interior walls, stairs, and even some floor decking off-site to speed up the installation process on-site.  This off-site framing can be done in a local workshop while the foundation is being set on a home and while the SIPs are being made in a nearby factory.

The next step in this concept would be to include electrical, plumbing, and gas line runs in these prefabbed walls to further reduce construction time on-site.  The building codes in the US make this very tricky, but the Swedes have been doing this for years with great success.

Lastly, the furthest development of this prefab interior component idea is to actually prefab entire kitchen, bath, laundry, closet, and utility assemblies at a local off-site location.  These small modules would not be subject to the strict structural requirements of larger prefab modules due to their size and the fact that they would not need to travel on highways.  They could be dropped right into the homes as the SIPs were going in place that could result in the vast majority of the home being assembled on site in only two weeks.  A good example of this type of system is the Copod designed and built by a company in the UK.

Advanced Scheduling and Building Team
Advanced scheduling and building is something that goes hand in hand with a good stock plan and a client that keeps customization to a minimum.  The successful tract home builders in the country that are building 80% of the new housing stock can teach us something about process (but certainly not architecture) in this step also.  They have their build schedules down to the day.

The way to reduce construction costs on site is to eliminate as many unnecessary delays in the schedule both with each subcontractor and in between each sub’s work on the site. This can be done by implementing the following:

  • A fully developed stock plan with no uncertainty for the GC
  • A qualified GC or Project Manager that can make and keep a good budget and schedule
  • A qualified GC or Project Manager that can reduce delays with local code officials and utility companies to a minimum
  • A team of quality subs with 1-2 backup subs in each field

This may sound like common sense to many, but in many custom and semi-custom homes, all of these factors rarely fall into place.  Many construction sites sit idle for weeks and even months as delays are experience with specific subs, in between subs or while waiting for local officials to inspect work that is completed.  These delays must be eliminated to reduce the on site build schedule from months to weeks on a hybrid house.

Advantages of a Hybrid Building Method

What are the potential advantages of this type of Hybrid method of building?

  1. Faster – A hybrid approach could easily reduce the total build time of a home from start to finish to eight weeks or less if properly executed.
  2. Less Waste – The use of SIPs to eliminate most framing waste, less transportation, no crane requirement and the use of a construction waste recycling company will result in less overall waste than than prefab or traditional stick built houses.
  3. LOCAL Labor – This is a big difference from prefab which uses remote labor to perform over 50% of the work.  There are SIPs manufacturers all over the country that make the same products and can enable 100% of the construction of a hybrid home to use local labor and contribute to the local economy.  In my book, this is a big advantage over prefab.
  4. More Energy Efficient – Better insulation, a tighter envelope and fewer thermal bridges from excessive framing equals a much more energy efficient home than any prefab on the market.
  5. Unlimited Designs from Unlimited Firms – Architects no longer need to develop a costly and time consuming relationship with prefab manufacturers or worry about marketing and selling their designs with the hybrid approach.  Many different plans from many different architects can be used in the hybrid system anywhere in the country.
  6. Cheaper, much Cheaper – Somehow I almost forgot this key point.  Bringing high quality residential architecture to “the masses” will be done by some type of hybrid building system like the one proposed here long before prefab will due to the significant savings in cost that will actually be passed on to the home buyer.

To Conclude . . . Finally

There are many amazing things being done in prefab, and if it weren’t for my self-imposed ban on mentioning specific companies and architects, I could name a bunch that I personally admire.  However, there are also a large number of misconceptions about the benefits of prefab that need to be discussed, and this post is simply trying to get that discussion started.  Are there points of dispute here?  Certainly. Am I perfectly correct in everything I have said?  Probably not. So, go to the comments and tell me what you think.

Original:

The Great Debate: Is Prefab Really Green?

Method Laundry Detergent’s Radical Innovation Wins International Design Excellence Award

Wednesday, July 21st, 2010

Say-hello-to-Method-laundry.jpg
All images via www.methodlaundry.co.uk

Along with the great news that Method Laundry Detergent has just recently been launched in the UK (yes our clothes are already cleaner) we hear that Method’s innovative pump action laundry detergent bottle has won the International Design Excellence Award (IDEA) for its behaviour changing design. Adam Lowry head Greenskeeper at Method is a passionate proponent of using good design to create change, which he blogs about here on these very TreeHugger pages, so he must be delighted that Method is being celebrated for excellent design work.

 

Method Smartclean Technology
Meothod’s laundry detergent is 8 times more concentrated than normal detergents due to some very clever chemistry, involving hydrophobic and hydrophilic molecules. The process was brilliantly explained to me by Method’s Chief Ripple Maker Louise Roper last week, but I would need some good props and pretty graphics (see below) to recount it properly to you now. In short the clever chemists, or Green Chefs as they are called at Method, have reversed the usual detergent technology of suspending surfactants in lots of water, by suspending a tiny amount of water in lots of surfactants, thus using radically less water and dramatically increasing the efficiency of the surfactant cleaning agent.

Less Detergent, Smaller Bottle
Method’s mega concentrated laundry detergent has many benefits which have influenced the design of the detergent bottle and reduced its impact on the environment. Less water in the detergent means more concentrated, which means you need to use less, which means a small amount goes a long way, which means you only need a small bottle, which means you can fit more on the supermarket shelf, which means you can transport more bottles in one go, which means reduced carbon emissions. Method’s relatively tiny detergent bottle, compared with the big brand laundry jugs, “the SUV of consumer products” as Adam Lowry describes them, supplies enough detergent for 50 washes. (The smaller 25 wash bottle is the size on sale in the UK.)

Method Laundry Detergent Pump
One of the biggest misconceptions in laundry detergent land is that the more soap you use the cleaner your clothes. Adam Lowry talks about this in his TreeHugger post The Overdose Dilemma. In fact more detergent is worse on several counts as it clogs up your washing machine, degrades your clothes and pollutes the environment.

So Method in house designer, or Chief Disruptor, Josh Handy was asked to design a bottle that helped people control the amount of detergent they use for each wash. The result is the innovative pump action bottle which only needs four pumps to get the right amount of detergent in your machine and which squeezes every last drop out of the bottle so none is wasted before you throw it in the recycling bin.

The whole design package
As was recently reported in Fast Company the IDEA judging panel believed it is not just the pump action bottle, made from 50% recycled plastic, that merited the design award but the product innovation as a whole package:

“To the IDEA jurors, the innovation isn’t just the detergent or just the bottle; it is the whole product. ‘Even though the pump structure is nothing new in cosmetic packaging, combining it with ultra-concentrated detergent prompted new consumer behavior that reduces both resources and water use,’ says Starbucks executive Fumi Watanabe, a judge in the packaging category. ‘Why hasn’t anybody done this before?’

What Method are still working on
Method are delighted that their laundry detergent is the first Cradle to Cradle certified laundry detergent available on the market, and that it is such a major improvement on other concentrated laundry detergent products, but they are aware that sustainability is an ongoing journey and that there is always further to go. Method laundry detergent is currently 95% plant based with the remaining 5% being made up of artificial preservatives which they want to source naturally in the future if possible.

Method would also like the bottle to be made from a higher percentage of recycled plastic, but for reasons of stability and efficient pump action function they haven’t been able to get to 100% in the first design iteration. At the moment environmental impact measurements show the award winning bottle design as being made from 36% less plastic, with a 35% smaller carbon footprint and using 33% less oil and energy, compared to a regular bottle of big brand detergent.

Innovation is embedded deep into Method’s business model and we’re looking forward to seeing what radical designs moves they throw out next.

Method laundry detergent is now available to buy in the UK from Tesco’s and Ocado and is soon to be available from Sainsbury’s and Waitrose in August

See the original post:
Method Laundry Detergent’s Radical Innovation Wins International Design Excellence Award

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