The Building Envelope
Rick De La Guardia
Author of "Engineer to Entrepreneur: Success Strategies to Manage Your Career and Start Your Own Firm", President and Founder of DLG Engineering, Inc., avid photographer and over 20 years of work experience in the forensic investigation, design, analysis, consulting and inspections of residential, commercial and retail building envelope components.
Tuesday, February 25, 2014
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Sunday, January 27, 2013
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Rick De La Guardia
President and Founder of DLG Engineering, Inc.
Saturday, June 30, 2012
The answer to those questions is not a simple one and it will vary from municipaliy to municipality and from region to region.
If you focus on the entire State of Florida, the answer would have to be no to all three questions. If you focus on South Florida, generally speaking, especially Miami-Dade and Broward Counties, the answer would be yes to all three questions.
The discrepancy in the answers to the above questions is only natural since you have to have experienced the devastation first hand in order to properly appreciate the urgency and desire to change. There is a constant and intense struggle between South Florida and the rest of the state with respect to implementing and enforcing what we have learned. South Florida has implemented a safe code whereas the rest of the state has not. South Florida has implemented strict product control whereas the rest of the state is attempting to weaken that control.
If we have this intense struggle in the State where hurricane codes are the strictest and most advanced, and there is still tremedous lack of implementation and enforcement, how do you think the rest of the hurricane prone regions stand as far as hurricane preparedness??
Not good, I would have to guess...not good!
Wednesday, October 5, 2011
Rick De La Guardia
Friday, August 26, 2011
1. The afffects from wind load are being considered in most cases but the affects of windborne debris have not been given due attention from our northeastern neighbors.
2. Installation of windows, doors and storefronts are being installed in substrates that are not adequate to transfer those forces to the main building structure...such as improperly attached wood bucks, inadequately designed metal stud framing, excessive shimming of anchors.
3. Envelope products are being sold and installed without proper engineering and testing.
4. Products that are properly engineered and tested are being installed improperly and with disregard to the testing and design limitations.
5. The impact resitant glass types on installed products are sometimes being substituted with cheaper, weaker glass.
6. Many municipalities approve building envelope shop drawings and calculations without proper review just because it contains an engineers seal. You would be surprised how many signed and sealed shop drawings and calculations I have reviewed,, that have been prepared by seasoned engineers in which I have found gross misinterpretations or even disregard for the code.
7. There exists a lack of awareness from architects and structural engineers on the intracacies of designing the building envelope and on the product approval process.
8. There is a misconception that the glass on impact resistant products will not break during a storm. In fact, the glass might very well break but if installed properly will not separate from the frame.
9. There is a serious lack of knowledge with many of todays building inspectors regarding interpreting and enforcing approved shop drawings.
10. There is much work needed to bring shop drawings up to par with being an adequate representation of the product approvals and the specialty engineers design intent.
11. There is rampant fraud and lack of oversight in the hurricane mitigation inspection process performed for the insurance companies.
I could seriously go on and on but will stop by saying that it will not be until an Andrew or like storm hits a major metropolitan area that these issues will start being addressed. Let's hope and pray that the time is not now for the sake of our northeastern neighbors.
The answer to the question, in my opinion, is.....NO!
Saturday, December 19, 2009
This means that these two Counties have stricter design requirements then the rest of the state.
The minimum (hurricane) wind speed that one must design for is 146 mph in Miami-Dade and 140 mph in Broward. This wind speed is the same for all buildings and not to be confused with the design wind pressure which varies from building to building.
In order for a manufacturer of windows and doors to be able to sell their product to the public it must comply with the above Code requirements, be tested and receive a product approval or Notice of Acceptance (NOA) from Miami-Dade county.
Just because a product has an NOA does not mean that it can be used everywhere. The product comes rated at a certain wind pressure that must be equal or greater than what the architect or engineer has determined is the design wind pressure for your home.
The tip here is: MAKE SURE THAT, BEFORE YOU BUY WINDOWS OR DOORS, YOU ASK TO SEE A COPY OF THE NOA AND CHECK THAT THE RATED WIND PRESSURE FOR THE WINDOW IS SUFFICIENT TO MEET THE DESIGN WIND PRESSURE FOR YOUR HOME.
1. Determine the design criteria (applicable code).
2. Identify the specifications for the project provided by Architect or Engineer.
3. Confirm project design wind loads.
4. Review shop drawings & calc's for compliance w/ code & project specs.
5. Review product NOA's or State approval documents.
6. Perform inspection to confirm product and installation.
Things to look for:
1. Proper wind load factors and tributary areas.
2. Adherence to limitations of product NOA's or State approvals.
3. Allowable stresses of steel and aluminum.
4. Allowable load of anchors including (edge, spacing & cantilever reductions)
1. Check product for compliance with NOA's or State approvals.
2. Check glass type & interlayer.
3. Check anchor types and shimming including substrate conditions.
Thursday, December 10, 2009
1. Annealed glass is your basic non-impact glass type. It is used in applications where the required wind load is not so high and safety requirements are not a concern. When annealed glass breaks, it breaks in sharp chards.
2. Heat Strengthened glass is also a non-impact glass. It undergoes a "heat treatment" that increases it's strength to twice that of annealed glass. It is used in similar applications to annealed glass but where the required wind loads are much higher. When heat strengthened glass breaks, it also breaks in chards.
3. Tempered glass is your basic impact glass. It undergoes a more aggressive "treatment" that increases it's strength to four times that of annealed glass. It is used in "small missile" impact applications typically installed 30 feet or higher above ground and in safeguard applications. When tempered glass breaks, it breaks into very small cubes.
4. Laminated glass is your typical impact glass. It is a combination of two (usually) of the three previously mentioned glass types that are "laminated" together with an interlayer between them. It is typically used in "large missile" impact applications installed up to 30 feet above ground. When laminated glass breaks, it breaks based on it's glass type make-up but is held in place by the interlayer...similar to a car's windshield.
1. What County is it in? The Florida Building code, 2007 edition identifies Miami-Dade & Broward Counties as being in the High Velocity Hurricane Zone therefore subject to stricter code compliance.
2. Is the County in the Wind Borne debris region? This encompasses all areas where the design wind speed is 120 mph or greater OR 110 mph if the design area is within 1 mile of the coast. The wind borne debris region requires impact protection or impact resistant products.
3. The glazing product most have either a State of Florida OR a Miami-Dade County product approval.
4. Local ordinances: Some municipalities require compliance above and beyond the Florida Building Code requirements. Check with the local building department prior to design. Example Coral Gables (Miami-Dade County) does not allow light gage framing as exterior walls. Some coastal municipalities require turtle friendly glass specs to be used to prevent disorientation of turtle hatchlings.
5. Inspections: Some municipalities require a special inspector form to be provided prior to issuing a permit.
These are just a few of the unique requirements of designing a project in Florida.
Wednesday, November 25, 2009
There is a mis-conception that impact glass will not break during a storm. That is not entirely true. Impact glass is very resistant to wind loads and should not break due to wind load during a storm but may break when hit by wind borne debris. Should the impact glass break, you now have to replace the impact glass therefore adding a long term cost.
Which brings us to the point about convenience. With Impact systems you do not have to run around and hang/close shutters every time there is a storm warning.
It's cost or convenience, barring locations that don't allow shutters or where impact systems are not required, if you choose cost, go with a non-impact system and shutters, if you favor convenience, go with the impact glass.