Tuesday, November 4, 2014

Anchoring Connections at Bay Windows

Source: Astor Windows's Photo Archives

A bay window projects on the outside of a building as shown on the picture above.  The most common type we find in Miami is called canted bay windows, which have a flat front and angled sides.  Bay windows became very popular during the Victorian architectural era and hold their appeal today.  When performing remove-and-replace jobs of existing homes in Miami Beach, Miami Shores, Coral Gables, South Miami and other non-incorporated Miami areas built in the 40's, 50's and 60's, we come across these types of windows.

Issue At Hand

There are typically two structural issues we encounter when replacing old bay windows for new impact windows: 

First, because these windows are set outside of the building envelope, the window header is most probable a wood build-out.  This condition was designed and built prior to establishing the High Velocity Hurricane Zone requirements.  As a result, the window header might not be designed and anchored appropriately to windstand the lateral loads exerted by hurricane-driven forces.  This is a problem for us.  Installing impact-resistant windows requires anchoring to either the main structure of the house or to members that are capable of transferring the loads to the main structure of the building. 

The second issue has to do with the connection between the window frame and the existing steel posts.  Existing bay windows have round metal posts (shown in gray in the illustration below) joining together the center window with the two flanking units.  Impact windows' frames must be installed to flat substrates, which is not the case when anchoring to a round post.  Hence, when presented with these conditions, the window contractor needs to make modifications in order to comply with the product approval of the window being installed.


We, at Astor Windows, have encountered the the above described scenarios several times.  For the missing header issue, we custom-fabricate a steel header (previously designed by a license structural engineer) anchored to the main structure.  For the second issue of the round post and flat window frame connection, we have fabricated a continuous u-channel aluminum (or steel) wedge anchored or welded to the existing posts.  This wedge solution has been designed by a license engineer and fabricated by Astor Windows's industrial welding technicians.  Refer to 3D illustration below for details.

Source: Astor Windows

Source: Astor Windows

Thursday, October 2, 2014

Designing Structures to Provide Full Support to 3-Track Door Systems

Designing Structures to Provide Full Support to 3-Track Door Systems Impact-Resistant Sliding Glass Door
Source: Astor Windows's Photo Archives

This article is intended for design professionals who plan to specify sliding glass doors with three moving panels on three independent tracks. A three-track system allows for wide openings with unobstructed views when all panels stack on one end behind each other. It is important, though, to understand that heavy-duty, three-track configurations could measure more than 8 inches in depth. As a result, door tracks can extend beyond tie beams' and columns' depths, which presents a problem: Structural substrate must provide full support to the door tracks.

The table below provides dimensions for four sliding glass door systems rated for impact resistance and approved by Miami-Dade County. On one column we show the nominal track width, assuming NO screen rail tracks. On the other column, we present our estimated jamb or tie beam necessary depth to appropriately offer full support to the sliding glass door system.
Door System 3-Track Width
excluding screen track
Recommended Minimum
Column/Tie Beam Depth
PGT SGD770 7.140 9.5
PGT SGD780 9.323 11.5
CGI SGD150 5.921 8
CGI SGD560 8.625 11.5
Disclaimer: Astor Windows and Doors cannot be held responsible for the accuracy of these dimensions. These article has been written for illustration purposes. A formal analysis must be presented by Window/Door Contractor.

It is important that architects and structural engineers learn about these dimensions before they finalize their designs for new structures.

Sunday, May 26, 2013

Permit Fees for Impact Windows and Doors

Untitled Page impact windows permit fees charged by municipalities
Homeowners planning to replace existing windows for impact-resistant windows always ask us how much permit fees will cost. The answer is not simple as each municipality has different formulas to calculate the permit fees.  To give our potential clients an idea of how much fees might be, we have looked at our accounting records.  The table provided below contains a short list of previous projects by municipality.  On this list, homeowners and our readers can learn how much our previous clients have paid for permit fees.  We have included the total project cost to provide a tangible point of comparison.  It is our understanding that project cost is one of the important factors municipalities use to calculate the permit fees due. In addition, they might use the square footage of glass replaced and the total number of different products installed (because they review each product approval).
Municipality Date Project Cost Permit Fee
City of Coral Gables 5/7/12 $17,800 $803.00
City of Coral Gables 7/13/12 $43,840 $1,244.27
City of Coral Gables 12/13/12 $22,329 $1,192.07
City of Coral Gables 2/12/13 $8,000 $294.64
City of Miami 2/29/12 $19,736 $172.84
City of Miami 1/27/13 $24,303 $194.44
City of Miami Beach 2/27/12 $23,948 $1,454.84
City of Miami Beach 7/27/12 $24,448 $565.64
City of Miami Beach 2/4/13 $89,600 $811.09
City of Miami Beach 3/20/13 $14,864 $477.65
City of Miami Springs 10/16/12 $15,690 $151.44
Miami-Dade County 2/15/12 $74,234 $151.04
Miami-Dade County 5/9/13 $14,284 $147.44
Town of Miami Lakes 7/2/12 $4,858 $111.94
Town of Surfside 4/5/12 $13,128 $481.98
Village of Biscayne Park 7/19/12 $4,390 $281.44
Village of Key Biscayne 12/20/12 $34,359 $3,157.45
Village of Key Biscayne 11/29/12 $7,743 $707.72
Village of Palmetto Bay 4/4/12 $17,955 $280.30
Village of Palmetto Bay 3/12/13 $10,285 $277.58
Village of Pinecrest 8/12/12 $21,975 $245.64
Village of Pinecrest 4/09/12 $35,000 $273.49
Village of Pinecrest 3/29/13 $21,975 $245.64
Source: Astor Windows and Doors Accounting
Important note:
Please understand that this list is provided for informational purposes only. Astor Windows cannot guarantee nor estimate in advance how much permit fees will be assessed in our future projects. We hope that this information proves useful during your research when in the market for installing impact windows and doors for your property.

Thursday, February 28, 2013

2010 Florida Building Code and the use of two methods to meet the energy-consumption guidelines

Photo of single-family home with impact windows and doors

After the 2010 Florida Building Code went into effect last March 15th, 2012, owners of new construction projects were required to comply with new energy-consumption guidelines, including maximum U-factor and Solar Heat Gain Coefficient (SHGC) values.

To comply with energy requirements, designers have two methods they can choose from:  the prescriptive or the performance path. 

Prescriptive Path
With the prescriptive or pre-determined path, designers must ensure that the proposed windows and doors have a maximum U-value of 0.75 and a maximum SHGC of 0.30.  Windows and doors must bear the label with the energy ratings independently confirmed by National Fenestration Rating Council (NFRC).  Section 402.3.2 of the code specifies that when the U‐factor varies between the fenestration products, the use of area‐weighted averaging is allowed to satisfy the U‐factor requirements.  Fenestration products missing SHGC labels are assigned default values from Table 303.1.3(3).

Performance Path
As an alternative to using the prescriptive path described above, designers can opt for employing the performance path to meet the energy preservation code.   With the performance path, designers need to use an energy compliance software tool approved by the Florida Building Commission.  This analysis only includes heating, cooling and service water heating.  Using this software allows architects or mechanical engineers to perform a trade-off between U-values and SHGC ratings.  When using trade‐offs from Section 405, the area‐weighted average maximum
allowed for fenestration SHGC is 0.50. Why is this trade-off important? To achieve low U-values,  insulated-laminated glazing is almost always needed, an option that is more expensive than just laminated glass. 

The information presented above is not intended to replace the code.  Equally important,  I cannot guarantee this information is completely accurate.  Instead, it is a quick reference for our potential clients who are designing new construction projects.  We want to ensure that they know they have two ways of meeting the energy requirements.  Hence, they should consult with the competent professional to ensure they can build cost efficiently.

For our potential clients, we provide the following information that could be useful when analyzing our proposal of windows and doors.

The Solar Heat Gain Coefficient (SHGC) measures how well a window blocks heat from sunlight. The SHGC is the fraction of the heat from the sun that enters through a window. SHGC is expressed as a number between 0 and 1. The lower a window’s SHGC, the less solar heat it transmits.

Facts about R‐values and U‐values
  • R values rate one single material versus U-values measure entire components.
  • R-values rate how much heat loss the material resists from passing through it.
  • U‐values rate how much heat the component allows to pass through it.
  • R-values measure how much heat loss passes through fiberglass insulation.  On the other hand,  U-values rate how much heat can pass through a window component (glass, air, aluminum frame).
  • The relationship between r-values and u-factors is R = 1/U.

Thursday, May 3, 2012

New Energy Conservation Code in Effect

Untitled Page 2010 Florida Building Code - Energy Conservation
Effective March 15th, 2012, the Energy Conservation Code will affect the glazing of impact-resistant windows and doors for both new construction and retrofit projects. Projects approved after March 15th will need to comply with maximum U-factor and Solar Heat Gain Coefficient (SHGC) values as shown in the table below:
Product U-Factor SHGC
Non-impact windows and doors 0.65 or less 0.30 or less
Impact-resistant windows and doors 0.75 or less 0.30 or less

The code states that both new contruction and renovation projects must comply with the values presented above. However, for renovation projects, the code is up to interpreration by the local building official. The Florida Statute defines a renovation as construction that exceeds 30% of the assessed value of the property. Per this statute, retrofit jobs that do not exceed 30% of the value of the property may not be required to meet the values above. Nevertheless, it is important to consult with the building official having jurisdiction before making a decision one way or the other.

Monday, July 5, 2010

Impact Windows and Vinyl Frames

Our clients always ask us for impact-resistant windows that meet current Energy Star criteria so they can obtain the Federal Tax credit. The reality is that aluminum-frame windows do NOT meet this criteria. To accomplish the insulating ratings required by the Energy Star program, we need to use hurricane windows made with vinyl frames. Unfortunately for Miami-Dade residents, there is only a handful of Miami-Dade-Approved impact vinyl windows.

How can I find out the list of approved products?
To obtain information about which impact-resistant products are Miami-Dade County Approved, our readers can check the Miami-Dade's Building Code Compliance Office. For your convenience, we compiled the list of approved impact windows as of July 04, 2010. The list can be found below. It is important to understand that this list will change overtime as new products are being approved and older products reach expiration.

Manufacturer Awning Horizontal Roller Single Hung Double Hung Casement Fixed
AWP, LLC No Yes Yes No No Yes
Benor Windows No No No No Yes Yes
Custom Window Systems, Inc. Yes No No No No No
Galaxy Windw and Door, Inc. Yes Yes Yes Yes Yes Yes
Jeld-Wen, (FL) No Yes Yes Yes Yes Yes
Jeld-Wen, Inc(OR) Yes No No No Yes Yes
Kolde and Kolde Millwork Company No Yes Yes Yes Yes Yes
Megrame U.S. Windows and Doors, LLC No No No Yes No Yes
PGT Industries, Inc No No Yes Yes No Yes
Pittburgh Corning Corporation No No No No No Yes
Rgency Plus, Inc No Yes Yes Yes Yes No
Schuco USA, L.P. No No No Yes No Yes
Silver Line Bulding Products Corporation Yes No Yes Yes Yes Yes
Teeem USA, LLC No No No No Yes No
YKK AP American, Inc No No Yes Yes No No
How to read the list above
The table shows different window types and which manufacturer has a Miami Dade product approval for the specific type. Also, you can find a window manufacturer up and down the list. If you run across the table, you can find out whether this manufacturer has the window type approved.

Wednesday, June 30, 2010

Impact Windows and Bulding Permits

Do I need to pull a permit if I am only changing ONE window in my house and installing an impact window? Do I need to pull a permit even though I am not changing the location or the size of the opening? We have several clients asking these questions when they are thinking about replacing one or more of their existing windows. The answer is yes, you must pull a permit if you are replacing any exterior window or door.

Impact Windows and Wind Engineering
The Florida Building Code requires you to obtain a building permit to replace an existing window for an impact window (this rule also applies if you install a non-impact window). To obtain the building permit, you will need a wind engineering report, specifying what the wind loads are for each opening in the house. The impact window or door that you are purchasing MUST have a design pressure that exceeds the wind loads calculated by the engineer. Otherwise, installing impact windows and doors is pointless.

Do Impact Windows Have Different Ratings?
The impact windows that we install in Miami must have the Miami-Dade County Notice of Acceptance, or NOA. To check impact windows ratings, you could review the NOA of the specific window or door. NOAs will have a table showing the corresponding maximum design pressures for an impact window depending on the size and glazing option used. So, it is not enough for an approved impact window to be installed in your house without checking against a wind engineering report.

If the explanation above is not clear or you have additional questions, please contact me at carlos@astorusa.com.

Monday, April 12, 2010

House Passes Home Star Bill

US House of Representative passed the Home Star Energy Retrofit Act (H.R. 5019) by a vote of 246 to 161. The legislation would provide rebates to homeowners who renovate their homes with more energy-efficient windows, doors and skylights. To become law, though, the US Senate must approve the Bill.

In short, the Bill includes two types of consumer incentives:

1) Silver Star provides up-front rebates for specific energy-saving investments, including windows and doors. Homeowners receive up to $1,500 per improvement—capped at a total of $3,000 or 50 percent of the total project cost. To qualify, homeowners need to replace at least eight exterior windows or skylights, or 75 percent of the exterior windows and skylights in their homes. Not all windows meet the minimum requirements as they need to have special insulating characteristics: U-value and 0.30 Solar Heat Gain Coefficient no greater than 0.30. Skylights and doors, on the other hand, must meet 2010 Energy Star criteria to qualify.

2) Gold Star provides larger rebates to homeowners who conduct a comprehensive energy audit and implement measures to reduce energy use. Consumers receive $3,000 for a demonstrated energy savings of 20 percent, plus an additional $1,000 for each additional 5 percent energy savings—capped at $8,000 or 50 percent of the project cost.

Vinyl impact windows and doors meet these requirements. If you need additional information about this topic, feel free to write me an email at carlos@astorusa.com or leave me a comment below.

Thursday, March 11, 2010

Laminated Glass Used for Impact Windows and Doors

I always have people asking me what type of material is used in the laminated glass for impact-resistant windows and doors.  A typical laminated glass is comprised of one outboard anneal glass, an interlayer and an inboard glass. Two types of interlayers are commonly used:  Polyvinyl Butyral (PVB) and SentryGlas Plus (SGP).  

PVB interlayer is fabricated by Dupont under the registered brand Butacite.  This interlayer helps by retaining glass shards in case of breakage.  Dupont offers this interlayer in clear, translucent white and other solid tints.  In Florida, the translucent white is a popular choice when privacy is desired, such as in cabana bathrooms (bathrooms leading to a backyard or pool area).  This option is a nice alternative to obscure glass.

The SGP interlayer, also manufactured by DuPont, is more rigid and less likely to tear than PVB.  This interlayer permits less glass deflection, a good characteristics for hurricane zones.  As a result, impact windows manufacturers use SGP in their larger windows, or those windows designed for the highest wind zones.

If you need additional information not covered on this blog, feel free to write to me at carlos@astorusa.com or leave a comment in the form provided below.

Monday, February 1, 2010

Impact Windows and Condensation

You noticed "sweating windows" after you had your new impact-resistant windows and doors installed. First explanation that came to your mind was an improper installation by your window contractor. Well, it is most likely not the case at all. Generally speaking, condensation on the inside of the glass is a not a sign of defective windows. Instead, it is a symptom of a moisture imbalance (mainly excess humidity trapped) in your home.

Causes of Condensation
Lack of proper ventilation is the main cause of excess humidity trapped in a house.  The excess humidity is created by daily activities, such as cooking, showering, bathing, clothes washing and drying, as well as the use of humidifiers and unvented gas heaters.

It is important to point out that when you replace standard-glass windows for impact-resistant windows, your house will be significantly better sealed against air exchange (inside-outside circulation). This new condition accentuates the symptoms.  So, when you have brand-new windows installed combined with a house heating and cooling system not properly designed, or outdated, you will start to accumulate excess humidity inside your house during the winter months. When temperature difference between the outside (cooler) and the inside (warmer), you will notice how water drops will begin to accumulate on the glass surface of your windows. The amount of water will be proportionate to the amount of humidity trapped in your house.  Now, people ask themselves why this phenomenon appears in the windows.  The reason is that the glass on your windows and doors tends to have lower temperatures than other surfaces in your house.

Consequences of Condensation
If condensation is chronic in your house, then you have excessive humidity.  This excess moisture can have, and will most likely have, serious consequences, including mold and mildew development.  After these conditions are maintained unchanged for some time, you will notice that your personal property, especially clothing, will be damaged.  More importantly, the excess humidity can result in serious health threats.

Possible Causes with Solutions

Inadequate ventilation of windows: Try as much as possible to allow air circulation in and out of the house.  Keep window coverings sufficiently open during the day to allow proper circulation.

Cooking and dishwashing: Install vent stove range hoods and dishwashers ducted to the outside of the house.

Showers and Baths: Make sure that exhaust fans are installed in bathrooms.  These fans must be ducted to the outside of the house.

Ironing, washing and drying laundry: Install duct pipes which take the air to the outside of the house. 

If you have any questions or want to share additional information regarding this topic, drop us a comment below.