September 26, 2013 at 7:37 pm #154022September 26, 2013 at 9:09 pm #154041CalicoParticipant
L. O. L. (although I do feel bad for everybody involved in the project)
How many tons of pavers will be ripped out?September 26, 2013 at 10:39 pm #154040Tanya OlsonParticipant
No, I think these are permeable pavers, they just didn’t add the material, or didn’t use the right material, between the pavers to fill the gaps. I’m guessing the controversy is either about ADA compliance or that sand swept into the gaps would reduce the permeability.September 27, 2013 at 1:45 am #154039Mark LerchParticipant
I’ve never seen these in clay before but what it looks like to me is that the tabs are touching the other tabs on many of the bricks because of the haring-bone pattern that was chosen. It the bricks were laid with a running bond and offset instead the tabs would be creating a less awkward spacing between the bricks but would still allow drainage.September 27, 2013 at 1:56 am #154038
they installed the pavers upside down…..
this is not as easy as landscaping, green side up.September 27, 2013 at 2:08 am #154037CalicoParticipant
If installed the other way wouldn’t you still face the same problem with this type of paver in any pattern other than running bond? Even in this close-up I can see a few tabs that were chipped off to force the pattern.September 27, 2013 at 2:35 am #154036Andrew Garulay, RLAParticipant
They are upside down. The tabs are not supposed to be visible in the joint at the surface.September 27, 2013 at 2:43 am #154035Goustan BODINParticipant
Lol !October 9, 2013 at 6:16 am #154034
Allrightythen. This week’s challenge involves a lesson on the proper choice of materials for a particular location.
What the photo shows are a specific clay brick permeable paver system installed in front of a building on a major university campus. These pavers are also installed at other locations around campus, but not in as large an area as this.
Many of you had thought that the pavers were installed upside down, or that they may have been installed in the incorrect pattern, which are good guesses. As evidenced by the tell-tale striations in the surface of the paver, these are extruded wire-cut clay brick, so there is not a proper top or bottom as there is with most molded concrete pavers. The top and bottom are identical. And according to the manufacturer, this particular line of paver can be installed in both running bond and herringbone patterns. Calico had mention that several of the spacing tabs may have been chiseled off. They weren’t.
So, what’s the issue here? Look at this photo:
As you can see, the gaps between the pavers have opened up to almost an inch. In some places, the gaps were OVER an inch. We should all know by now that gaps greater than 1/2” aren’t looked upon kindly by the Americans with Disabilities Act as they can cause issues with wheels on wheel chairs and problems for those who utilize walking aids like canes. As well, this is codified in the International Building Code via the reference to the ANSI A117 standard which restricts “openings in the floor surface” to allow a sphere of no more than 1/2” to pass through a gap. Another aspect that is frequently overlooked in pedestrian intensive applications is the concept of “heel safe.” The ladies will know all about this one. If there are large gaps in any kind of pavement, especially with expansion joints, the thin heel on your expensive fancy shoes will all but certainly find it. You can get the heel stuck in the gap, break off the heel or at the very worst, twist or even break your ankle. Joints should be made as tight as possible, even without a joint filler present, because it will eventually come out. Most permeable pavers create a 1/4” space between individual units to provide a “fudge factor” on installation tolerances.
Now, I hear you asking “but isn’t the gravel in between the pavers is supposed to make those holes all nice, safe, and legal?” Well, yes and no, as this is still being debated. When the gravel is present some would say everything is fine, but if it settles or washes away, it no longer is an acceptable surface. Like so many other things, maintenance is key. I would also argue that the fill gravel is not a “firm and stable surface” to begin with as it is easily dislodged and can be a slip hazard in any decent quantity.
We now come to analyzing the material assembly in the first place. Because the design of this paver requires a high degree of precision, something that the extrusion process does not offer as the clay is still quite fragile until fired, and the process of stacking and moving has damaged the spacing tabs. As well, the uneven shrinking of the clay in the kiln may have had a factor in the inconsistent quality of the spacing tabs as clay brick can shrink up to 8% or more during the firing process. Combine that with the miniscule contact areas between pavers as a result of the paver’s design and the defects of the spacer lugs and you don’t have the requisite interlock to hold the pavers in place to keep them from shifting as these pavers have. Remember, permeable pavers do not have the fine sand base and joint sand which compacts and provides the friction to lock the pavers together, so generally, larger lugs are designed onto permeable pavers to provide interlock.
There are lots of products available in this category, and as professionals, it is up to us to determine the best material for the application. These pavers may be fine in a parking lot, but the design of the paver and the manufacturing tolerances make them less than ideal for pedestrian walkways. This product even within this category is not alone as there are a number of pavers that would have a similar problem. And just because the manufacturer claims the product is in compliance with the code does not mean that it will be in your application. One glaring example would be a company whose advertisement shows a gravel pathway, but their product only was tested for compliance with granite fines (stone dust). So the specifier is led to think their installation with pea gravel meets accessibility guidelines, but it doesn’t. As we have learned from the other posts in this series, you also cannot count on proper maintenance to be performed, so we must think ahead and try to design things that will need a minimum of maintenance, and better yet, no maintenance to remain compliant once installed. Once again, the wrong material in the improper spot can open you up to liability, and nobody wants that. There are a lot of options out there, be sure to explore them!
Look out for another “What’s wrong with this picture?” coming in the near future!October 9, 2013 at 11:46 pm #154033
Oh, and they’re ugly too.October 11, 2013 at 11:55 am #154032Andrew Garulay, RLAParticipant
This sometimes happens when one aspect of a design is valued more than is reasonable. It is a university in a time and place where political correctness and “being green” may be more highly valued than practicality. It may be possible that several people, maybe the designers themselves, pointed out that this would be a problem.
This may also be a case of politics where a local brick manufacturer was preferred or a politically connected manufacturer.
We don’t always have enough control of our projects to override the stupidity or the alternate agendas of those whom we work for. We also need persuasion skills to do that, but sometimes you just can’t win.
…. or it could simply be that the designers were that dumb.October 11, 2013 at 7:19 pm #154031
It isn’t necessarily that they are dumb (though that does happen). From my personal experience in interacting with lots of engineers, architects, and LAs on site issues, there is STILL a general misunderstanding or plain ingnorance of the ADA regulations. Some of it is unscrupulous contractors as I recently reported to a local mall who had some concrete work done. Sure, an architect will be able to rattle of the dimensional requirements of a compliant restroom, but once outside the building envelope they just don’t know. I’ve even had a senior civil engineer say “what’s ADA?” after I brought up that and entire proposed main street section of a residential development was terrifically out of compliance. Mind you, the design guidelines have been in effect since 1992.The same holds true for the International Building Code sections with engineers and especially LAs. The area between the inside of the buiding and the curb is like a no man’s land. Which is subject to both the IBC as well as ADA (IBC references ADA through ANSI specs.). The whole thing is still a huge mess, the design guidelines have always been outdated and clear as mud (equivalent facilitation clause anybody?) and really only enforced through litigation in the courts rather than being part of a building inspection to get a certificate of occupancy.
It is also a matter of having a deep understanding of the materials you specify, and how they are to be installed, and then actually inspecting the installation. As I had mentioned previously in the ‘answer’ portion, many are suckered in by advertisements claiming ‘ADA Approved’ (which cannot be, the ADA does not approve anything), or that they are compliant. Many even put up results from private testing done on the materials. You have to know what you are looking at. While the product may be fine in one form, in this case the concrete paver version of this same paver, or for one specific type of installation as I had mentioned with a gravel product being tested with fines rather than how most will use it, with pea gravel. But in another application or material type, it isn’t.
That is partly my goal with posting this series…to get my fellow LAs to get used to looking at these issues and really start paying attention to the very fine details.October 29, 2013 at 12:10 pm #154030Doug DaviesParticipant
I think it is important to note that this was an experimental paver system that the University was testing out with the manufacturer. There is a deeper story to these pavers than what is at face value. That said, they do need to fix the gravel as it is a compliance issue. Just an FYI about commenting on a project that you don’t get to the bottom of. Here is a link send to me by University staff to illustrate that the paver was in fact not installed upsideown. http://www.beldenbrick.com/pdf/brick-permeable-pavers-brochure.pdfOctober 30, 2013 at 4:36 am #154029
Thank you for adding a bit of context.
However, there is not one thing that I have been critical of that is not true with regards to this paver or its installtion. I also had purposely redacted the manufatcurer’s name, as I do with all of my posts. I also have spoken directly with the manufatcurer with regards to this particular product and its noncomplaince. I have no qualms with the manufacturer, and have used other products of theirs in the past, and will likely use them in the future. This particular product is also perfectly acceptable for certain applications, just not for pedestrian areas as it does not truly meet ADA requirements. As far as being experimental, these pavers have been around in different guises before they were installed at this location, so I’m not sure what the experiment was all about, but it is kind of irrelevant now. And since this project was installed, these pavers have been installed at other locations even though they have a glaring design flaw.
If this were an experimental system, it should not have been installed in such a prominent pedestrian location. And once it was found not to be in compliance, should have immediately been removed and replaced with a different type. The school is opening themselves up to lawsuits leaving these installed. Talk to the school’s attornies about ADA compliance and liability. It is a massive issue. Besides, I had looked at these very pavers for a commercial project I was working on and it took me all of about a minute to determine these are not suitable for pedestrian applications. Add up the gap measurements in their brochure (they equal 3/4″ for the molded paver, btw). And as for the extruded, even on their literature, the gap is listed as 7/16 when laid in a herringbone pattern. I don’t know about what you have been taught, but a 1/16″ tolerance when installing pavers to be in compliance is nearly impossible to acheive, especially with clay brick, as there are defects and the pavers will shift and separate a bit. 1/16″ is only the thickness of a quarter. And once you stack tolerances, that 1/16″ can add up and add up to be a significant number. Also in the brochure, with the running bond, they actually show the gap as 11/16″, which is 3/16″ MORE than the 1/2″ limit of allowable gaps in the paver. And yet they claim ADA compliance. The gravel used to fill the gaps should not be considered part of the firm pavement system, as it is not permanent, not stable, and all too often is washed out or settled, leaving the huge gaps in the pavement you see here. This is not just my opinion either, as this has been expressed in many professional circles who deal with these materials on a daily basis. It was even a topic of a panel at an ASLA convention where this notion was the consensus. In any circumstance, maintenance should never be relied upon in order to meet or keep compliance, because in the real world, it just doesn’t happen. Improper maintenance opens both you and your client to litigation, as that is how the ADA is enforced. These are also not “heel safe” whatsoever as the huge gaps, filled with gravel or not, can very easily catch a woman’s dress shoe heel and possibly cause injury. Another lawsuit. Why chance it when there are better alternatives?
I see by your profile that you are a student…these are the things you need to pay attention to when in professional practice. The right material for the right application in the proper place. And don’t always beleive the literature or sales people. Use your own judgement and common sense, do your own calculations, and when in doubt, look for something else.
Thanks again for the input.October 30, 2013 at 2:41 pm #154028
…and they are still ugly!
- You must be logged in to reply to this topic.