Why Do I Need an Engineer Letter If My Door Already Has a Florida Product Approval?

Why Do I Need an Engineer Letter If My Door Already Has a Florida Product Approval?

Short Answer:
Even with a valid Florida Product Approval (FL#), many local building departments — especially in Miami-Dade and HVHZ regions — still require an engineer-certified wind load letter to confirm the door is appropriate for your exact project location. Here's why.

✅ Florida Product Approval vs. Site-Specific Engineering

What Is Florida Product Approval?

A Florida Product Approval means that the door (or window, or roof system, etc.) has been:

• Tested and certified for structural performance, impact resistance, and water infiltration.

• Verified to meet statewide Florida Building Code (FBC) standards.

• Assigned a unique FL number — for example, FL15498.2-R4.

So yes — it’s a great product, and it has been proven in lab conditions.

But That’s Not the Whole Story…

The Florida Product Approval system does not account for:

• Your specific project address

• Local wind speed zones (e.g., 175 mph for HVHZ)

• Building height

• Exposure category (e.g., open coastal land vs. suburban neighborhood)

• Wall zone pressure multipliers (e.g., zone 4 vs. zone 5)

• Size of the door or window opening

That’s where a licensed engineer (like us at WindCalculations.com) comes in.

🏗️ Why a Wind Load Engineer Letter Is Required

Building departments want to confirm that your specific door can handle the actual wind pressure required at your site.

An engineer letter does three things:

1. ✅ Calculates wind loads for your location using ASCE 7 and FBC 2023

2. ✅ Compares those loads to the door's tested rating (e.g., +75 / –83 psf)

3. ✅ Certifies compliance with the code — and signs/seals the results

It’s like verifying that a strong door is strong enough for your unique property.

📍 Example: How We Help

Let’s say you have a 38" x 82" swing-out wood door with Florida Product Approval FL15498.2-R4, rated for +75 / –83 psf.

At your Miami-Dade site, the calculated wind pressure (Zone 4, Exposure C) might be:

• Required: +66.71 / –72.63 psf

• Door Rating: +75 / –83 psf

✅ The door meets the requirement — but the engineer must certify that in writing.

This signed/sealed letter is then submitted with your permit application, so the building official can approve the install.

🔍 Florida Statute 553.842(5)

This rule allows for “engineered design” in lieu of product approval in some cases — but more importantly, it confirms that engineer letters are a valid and often required part of compliance.

You can read more here: Florida Statutes – Section 553.842

🧠 Bottom Line

Yes, your door may be Florida-approved — but every site is different.

Permits require proof that your door is strong enough for your conditions. Our engineer letter gives you that proof — fast, code-compliant, and stamped by a licensed PE.

🚀 Get Your Wind Load Letter Today

At WindCalculations.com, we’ve helped thousands of homeowners, contractors, and architects get engineer-stamped wind load letters within 1–2 business days.

We’ll take care of the code math — you just install the door.