Update on the Surfside Tower Tragedy

Since the collapse of the Champlain Towers South, the investigation of the catastrophe has been spearheaded by KCE Structural Engineers leading it. Here are some updates on what has happened since June 24th, 2021.

Less than a week after the collapse, Miami Beach City Manager Alina Hudak ordered inspections of 507 buildings that were close to or over 40 years old and near the beach front. Also, near the beach front Mayor Daniella Cava ordered for an immediate audit in Miami-Dade of all high-rise buildings older than 40 years old and taller than five stories, and all those built by developers Nathan Reiber and William M. Friedman. Associates Architects, Inc. (developer/designer of the Champlain Tower South). The building owners then had 21-30 days to provide documentation from a licensed P.E providing evidence that these buildings were safe for occupancy.

By August 17th, 2021, 9 buildings were of concern and 4 buildings have been evacuated due to unsafe conditions. Commissioner Michael Gongora is sponsoring a board discussion on the inspection process including the potential for earlier inspections of beachfront buildings and creating a reporting requirement for engineers/architects who discover structural deficiencies that pose a life safety concern.

Residents of Crestview Towers condominium standing outside the building as it was being evacuated.

Since July 1st, the NIST (National Institute of Standards and Technology) has been working on ensuring that information and evidence related to the collapse is identified, collected, and preserved for the current investigation. Currently Allyn Kilshimer PE of KCE Structural Engineers is leading the investigation. His experience includes investigating major events such as the World Trade Center attack and the Oklahoma City Bombing. The firm, KCE, contributed to investigating the attack on the Pentagon during 9/11 and the FIU bridge pedestrian bridge collapse in 2018.

Kilshimer is assessing the Champlain Tower North to have a better understanding on how Champlain Tower South was built and is also working on the collapse site to study the reinforced concrete, balconies, and pool deck waterproofing. Kilshimer has stated: “This investigation will take several months…. there will be several contributing factors.”

Unfortunately, 98 people have died and our hearts go out to their families and loved ones.

Author: Sofia Covelli

Luck Favors the Prepared

As the old adage goes, “Luck favors the prepared”. With us officially being in hurricane season, it is important to talk about a subject that most new homeowners (especially new to Florida) often overlook, impact rated garage doors.

Studies have shown that garage doors were the biggest and among the most common breaches in homes during a hurricane. Then positive pressures build within the home, and are additive to the suction pressures already active on the roof and walls. For a wood-frame, low-rise house typical of North America, once the envelope of the building has been breached by the failure of a garage door, the loss of the entire roof structure becomes much more likely. 

While, many regions in the U.S. do not require garage doors to meet high wind specifications, Florida basic wind speeds range from 120-180 mph for Risk Category II. ASCE 7-16 section 1609.1.2.3 goes into details about how wind loads apply to fenestration product ratings. Besides being wind resisting, many garage doors in Florida need to withstand impact from wind-borne debris. Large and small missile tests in accordance with ASCE 7-16 section 1609.1.2 are done before a garage door manufacture can be approved in Florida.

New garage doors can cost from $700 to $1,200. Many current home owners would rather retrofit their current garage doors, and if done correctly, this can be as effective against hurricanes as new garage doors on the market. With retrofit kits costing ~$150 (for a single garage door) and ~$500(for a double-door garage).

Whether you chose to buy a new garage door or retrofit your current one, investing in this can protect your home and valuables, saving you thousands in damages. Besides helping you save thousands; insurance companies often offer premium discounts to homeowners with a wind and impact rated garage door.

Author: Sofia Covelli

Should We Be Worried About A Potential Hurricane Elsa?

When it comes to hurricane preparations we don’t want to just “let it go” for the last minute. With Tropical Storm Elsa predicted to skirt the west coast of Florida from tonight until making landfall in the Big Bend tomorrow afternoon.

Lets’ not underestimate her, remember Katrina was at first a tropical storm that turned into a Category 5 quickly. She strengthened into a Hurricane two hours before making landfall near Hallandale Beach, then once again weakened into a Tropical Storm until it reached the Gulf of Mexico. Because of the warm water in the Gulf, Katrina began to rapidly intensify into a Category 5 Hurricane, devastating the New Orleans area which is still affected 16 years later.  

NOAA has issued advisories to parts of the west coast of Florida and a Tropical Storm Watch is in effect for the Georgia Coast and some portions of the South Carolina Coast (where the storm may reach late Wednesday and early Thursday). Specifically on the west coast of Florida, a danger of storm surge is predicted for tonight and Wednesday. Like Katrina, Elsa has a potential to strengthen in the Gulf.

Katrina’s intensity when hitting Louisiana

Prepare for Elsa by making an emergency plan, knowing your evacuation routes, bringing furniture inside, charging electronics, and gathering necessary supplies. Although it is too early to know for sure that Elsa will become a powerful hurricane, it is better to be prepared than just going “into the unknown”.

Author: Sofia Covelli

Surfside Tower Tragedy

This blog post is in respect for the families and victims affected by the Champlain Tower South collapse. During such tragedies, it is important for us in the construction industry to evaluate and understand them in hopes to prevent future catastrophes. For further understanding we must delve into the history of the building, and some of the different ways a building could be damaged.

The Champlain Towers South was a 12-story beachfront condominium built in the suburbs of Surfside, Florida, consisting of 1-to-4-bedroom units (136 units to be exact) ranging from 1,200 to 4,500 square feet. The condominiums were built in 1981 by developer Nathan Reiber and William M. Friedman. Associates Architects, Inc. the architect for the project. Brieterman Jurado & Associates, consulting engineers were responsible for structural engineering and Jurado & Associates covering electrical and mechanical.

All structures require periodic maintenance to meet or exceed their intended life spans and to ensure structural integrity from exposure to the environment. Prior to the collapse a resident reported “a hole of sorts opening near the pool before the collapse”. Also, a valet attendant reported “that at least one car had to back out of the garage because the space was filling with water shortly before the building fell”. A previous maintenance worker, William Espinosa was quoted saying “saltwater would seep through the building’s foundation during particularly high tides…The water would just basically sit there, and then it would just seep downward…I’m talking about a foot, sometimes two feet, of water in the bottom of the parking lot, the whole parking lot.”

Facts and maps on the apartment building that collapsed in Miami, Florida. – AFP / AFP

The foundation and reinforced concrete elements are critical components of a building’s structural integrity. In the case of the Champlain Towers, the building site was located right on the coast, which can accelerate corrosion. The salt-laden air continuously deposits salt spray on the surface of concrete members. Concrete is inherently porous and salt spray can lead to concrete spalling.

Photos provided by Morabito Consultants, 2018 report on Champlain Towers South

Concrete spalling is a result of rusting in the embedded steel reinforcement bars when it is exposed to water and air. When exposed to these elements, the steel bars begin to oxidize which causes a volumetric expansion of the bar up to 6 times the original volume. The increase in volume imposing a significant expansive force to the surrounding concrete, can cause the concrete to delaminate, spall, crack, or break off. This allows for more air and water to penetrate the embedded bars continuing the cycle of corrosion. 

Concrete spalling is a major concern to any building, and when not taken care of, can have detrimental effects. It is important to have regular inspections and maintenance of a building and report damages to a qualified structural engineer.

Author: Sofia Covelli

Anchors Ahoy!

Who wants to see their home or business blown/floated off its foundation like a ship adrift? No one, excepting Captains Nemo and Ahab. So, let’s go over anchors and how they keep structures grounded.

Historically, bent anchors are common on jobsites, but headed anchors have a notable advantage over hook/J/L anchors. (Pictured below on the left) TIE MAX Edge Bolt anchor with 5,480 lbs allowable tension next to a common 1/2″Ø L-anchor with only 927 lbs capacity (about 6 times less strength):

According to ACI 318 Appendix D 5.3.5, AISC 360-10 equation J3-1, and ACI 318 17.1.3, a cast-in-place headed anchor bolt will tend to form a breakout cone with the concrete. However, L and J bolts have a tendency to slip-pullout of the concrete prematurely. Whereas headed anchors like the proprietary TIE MAX Edge Bolt anchor will reliably achieve the maximum tension capacity of concrete and form a predictable breakout cone.

         J/L BENT ANCHOR                                           HEADED ANCHOR

Besides choosing the right anchor, it is also important to understand what finishes should be specified. Corrosion is an important factor when selecting materials. Exposures can range from, interior dry service to an exterior ocean-front location. Typically, interior corrosion is slower and less severe while exterior corrosion is faster and more severe because of environmental factors such as moisture, acid rain, and chemicals. Dissimilar metals can also affect corrosion rates, see AISC table 2-7.

Regardless of which anchor you choose to fit your project; you can find all of these supplies at Fastening Specialists Inc.

Author: Sofia Covelli

What are P.A.F’s?

What are P.A.F’s? Well, they are most widely known in the construction world as powder actuated fasteners. First developed in the early 1920s by Robert Temple, they became commonplace in the construction world by the late 1940s. The power of powder actuated tools offers an efficient, reliable and safe method for many construction applications. Available for use with concrete, wood, and steel substrates.

Three different models of P.A.T’s (powder actuated tools) are commonly available; a single-shot, semiautomatic, and automatic.

Popular types of fasteners include drive pin and threaded studs. Drive pins are effective for permanent fastening while threaded fasteners are better suited for securing removable hardware.

The ICC-ES recently updated their Acceptance Criteria 70 for product evaluations of Fasteners Power-Driven into Concrete, Steel and Masonry Elements. These updates allowed for a wider usage of P.A.F’s on nonstructural systems.

Powder charges follow a color-coded system to identify application power. Browns, greens, yellows, and/or reds are used frequently for concrete, while yellows, red, and/or purples are frequently used for steel. Along with color coding, the higher the number, the greater the driving power.

A pro-tip is to never fasten into a hollow block because it can blow out a crater, leaving little material to grip the fastener.

A very common use for P.A.F.s are for fastening the sill plate of a wood frame into a concrete substrate. To avoid concrete splitting, fasteners should be spaced 3” minimum, the thickness of the slab should also be 3x as deep as the fastener penetration. Also, minimum edge conditions in accordance with the manufacturer specifications should be observed.

A center punch test is recommended to use since one can see whether the fastener point makes a clear impression in the material without blunting. If the fastener blunts the material, it is too hard, if it cracks or shatters, it is too brittle, and if the fastener sinks, the base material is too soft.
For all your powder actuated fasteners and other hardware needs contact Fastening Specialists Inc.

Author: Sofia Covelli


You should be dry and safe in the face of a storm.  While waterproofing design requirements are typically the responsibility of the Architect, issues with water infiltration often result in structural concerns.  So which roofing type do you think is best for high wind and coastal construction?  Is it 3 tab or Architectural asphalt shingles?  The ubiquitous clay tile roofing of south Florida?  Or 5V crimp or standing seam metal roofing?

I have personally witnessed asphalt shingles transform into lethal frisbees as far inland as Gainesville, FL during Hurricane Frances back in 2004.  Outside of my anecdotal evidence, FEMA has documented after the more recent Hurricane Michael “widespread poor wind performance of asphalt shingles.”  Before closing the book on this roofing material, it should be noted that many failures were due to poor installation which would have a likewise effect on all roofing types.  There are multiple options depending on wind speeds for asphalt roof shingles as tested in ASTM D3161 where Class A passes tests at 60 MPH and Class F passes at 110 MPH (and yes, I did not get those backwards).  Another standardized test method, ASTM D7158, rates shingle performance against up to wind speeds of 150 MPH.

And clay tiles? Those things are bullet proof, right? Wrong!  Clay tiles set with mortar have been shown to be particularly vulnerable at hips and ridges.  Often, loose tiles  become projectiles themselves, further injuring nearby structures.  These tiles also do not fair well under impact loads and are liable to shatter or crack upon impact by wind borne debris, later leading to leaks and eventually structural damage to sheathing or framing.  FEMA 499 Technical Fact Sheet No 7.4, Tile Roofing for High Wind Regions notes that “foam and mechanical-set attachment methods have historically performed better than applied using the mortar-set attachment method.”

Last but certainly not least, metal roofing is a solid candidate for high wind installations.  According to FEMA “metal roof coverings appeared to perform better than other roof covering on buildings built to the Florida Building Code, [however] metal roof damage to some buildings was observed after Hurricane Michael.”  References like FEMA 499 Technical Fact Sheet No 7.6 can provide guidance on minimum roof slope requirements for hydrostatic vs hydrokinetic panels or additional fastening requirements near eaves.  Consult with your preferred design professional for proper specification of roof covering, attachment methods and adequate underlayment so that you can confidently state “you’re safe while under my roof.”

Author: Enrique Fernández, PE


Let’s not talk about lumber prices, it’s too early for that.  Instead, let us settle this argument once and for all.  Which is the best softwood lumber to construct with?  Is it Southern Yellow Pine (SYP) or Spruce Pine Fir (SPF)? This is a matter with structural, constructability and economic implications.

It’s best to begin at the beginning.  So let’s review an essential wood property.  Specific gravity is defined as the ratio of a material’s density when compared to water.  The higher the figure, the greater the density.  Anything above 1 will sink and everything below 1 will float.  As can be seen in the table below, the specific gravity of SYP is about 24% greater than SPF and 18% greater than DF.  The denser structure of SYP contributes to it outperforming other species in bending, tension and compression.

It appears that where strength is needed, SYP is the champ among these softwoods.  However, this increased density means greater weight per board.  The denser, harder wood may also prove to be more difficult to drive nails or start screws into.  If constructing an interior partition on an elevated floor, one could benefit from the increased workability and extreme light weight nature of SPF lumber.

To be clear, when SYP is needed for strength and therefore specified, it SHALL not be substituted with SPF.  A beam or compression member that has been sized using SYP will only have a fraction of its intended strength if built with SPF.  This can lead to life safety liabilities that no one wants.  Consult your local professional Engineer or Architect for any substitution requests.

Author: Enrique Fernández, PE

Expansion Anchors at the Edge

Like the old refrain goes, “there are only two kinds of concrete: cracked concrete and concrete that will crack.”  Engineers and builders do their utmost to limit and control cracking to preserve structural integrity and aesthetics by employing various methods.  We create control joints, construction joints, expansion joints, provide temperature and shrinkage reinforcing using welded wire fabric, fibers and rebar.  In synopsis, we go thru a lot of effort to mitigate cracking concrete.  So then, why would a builder ever expressly create a condition where concrete is likely to crack and compromise structural integrity?  This cementitious sin is more common than you might think, and the guilty party is often an expansion anchor installed in a close edge condition.

Expansion anchors inherently work by, you guessed it, expanding!  When installed, the expansion anchor is hammered into a predrilled hole in the concrete.  Then a wedge at the base of the anchor is drawn up thru a sleeve which expands against the drilled hole within concrete.  Naturally, this expansive force creates stresses within the concrete that must be resisted.  While concrete is a natural champ in compression, it is an abysmal wimp in tension.  So when these stresses need to be resolved near a slab edge, resultant forces can create splitting within the concrete that will likely propagate cracks extending out from the anchor.  These cracks can compromise the integrity of the connection and aesthetically ruin your slab edges.

However, there is a time and place for expansion anchors though.  They are widely available and an economic solution for anchoring within interior slab conditions or when set within minimum edge distances on foundations.  Specific anchors can vary based on the manufacturer, but for a typical 5/8” diameter anchor to achieve full capacity, the minimum edge spacing is usually 10”.  Some anchor manufacturers allow lesser minimum edge distances, down to 4-1/2”, but with significant reductions in capacity.  In the absence of manufacturer recommendations tested per ACI 355, the minimum edge distance of expansion anchors (displacement or torque controlled) must be checked for side-face blowout failure and cannot be less than 8 anchor diameters per ACI 318-11 appendix D8.3 and ACI 318-14 section 17.7.3.

Architects, engineers, contractors, and do-it-yourselfers may be asking themselves right now, “Ay bendito! How can I attach a sill plate at an exterior wall to my slab without wedge anchors!?!”  The limitations of expansion anchors (wedge and sleeve anchors) noted above preclude their use in exterior wall applications near slab edges.  Well, despair not, you can always specify a cast-in-place anchor like the TIEMAX Edge Bolt which has higher holding power and is specifically designed for close edge conditions as little as 2”.  Also, if you need is a post-installed solution, then there is always the drill and epoxy TIEMAX Stud or the Large Diameter Tapcon that comes in many sizes and flavors.  These are all available from Fastening Specialists Inc:

Author: Enrique Fernández, PE

Glazing Protection

Do you sit outside during a hurricane?  Not likely, even if you are invited to a hurricane party.  So why would you allow a hurricane into your home or business by not protecting windows, doors and openings adequately?  Luckily, there is guidance for glazing protection recommended, or in some cases mandated, by the Code for hurricane prone areas.  These approved products and methods can keep the storm outside and even incidentally protect your home or business from an errant brick launched by a not so peaceful protestor.

Impact resistant windows can be costly but offer permanently in place protection that does not require last minute installation and allows a view to what is happening outside.  Their construction can be a laminated glass/film assembly or fenestration made of polycarbonate that is 200 times stronger than glass.  Impact testing for such assemblies against large and small missiles is covered in ASTM E1996-20 Standard Specification for Performance of Exterior Windows, Curtain Walls, Doors, and Impact Protective Systems Impacted by Windborne Debris in Hurricanes.   “Missiles” can range from a small steel ball weighing as little as 0.1 ounce to an 8 foot long 2×4 lumber board launched at 80 feet per second.

Impacted windows are then tested against hurricane wind pressures per ASTM E1886 Standard Test Method for Performance of Exterior Windows, Curtain Walls, Doors, and Impact Protective Systems Impacted by Missile(s) and Exposed to Cyclic Pressure Differentials.  This ensures that impacted windows continue to perform throughout the storm event.  For homes and businesses located within 3000 feet of the shoreline, window frames are typically made of vinyl or fiberglass to mitigate corrosion and provide a durable assembly.  It is obviously important to attach these windows per the manufacturer’s approved recommendations which typically include provisions for pressure treated wood bucks and stainless steel anchors, like those pictured below and available from Fastening Specialists Inc.

Alternatively, shutter systems are also available for opening protection.  These function independently from the windows and doors they protect from missile impact, but do not typically protect against cyclic wind pressures which will need to be resisted by the door or window itself.  Shutter systems come in many forms including roll-up, accordion types, corrugated panels, etc.  Some require installation prior to the storm event and others are in place permanently, but must be operated to be set in the closed position.  In the event that a system is electrically operated, these units should be able to be manually overridden in the likely event that there is a power failure.  Some systems offer translucent or clear panels that allow a view to the outside and light to pass into the structure during a power outage.  Lastly, the minimum glazing protection permitted by the Code is structural wood panels no less than 7/16” in thickness and spanning no greater than 8 feet.  The minimum fastening schedule for this type of protection is also specified in the International Residential Code section R301.2.1.2.

Garage doors are a common point of failure in the structure’s exterior envelope.  These are very large openings that can increase internal wind pressures substantially if failed.  Roof sheathing can be peeled off from the combined forces from within and without the structure.  Use the appropriate roof sheathing fasteners to mitigate this risk as covered in a previous blog, The Rise of Roof Sheathing Ring Shank Nail.  Additionally, impact and wind pressure rated garage doors are increasingly available from a myriad of manufacturers and should be specified for designs in hurricane prone areas.  As evidenced, elevated internal pressures can often lead to significant structural failures locally or throughout the building.  Interestingly, the Code used to allow for the design of these elevated internal pressures in lieu of glazing protection, but since has been repealed due to significant material losses as a storm enters a building.  Fortunately, with regards to this, the times are a changing, as described in more detail by a previous blog addressing the updated wind code adopted in the Florida Building Code 2020.  Consult your local professional structural engineer for the enduring design of your next project.

Author: Enrique Fernández, PE