When building a deck, the way the framing is designed has a big impact on strength, appearance, height, and overall cost. Two of the most common framing methods are drop beam and flush beam construction.
At ProTech Builders, we use both depending on the project. Here’s a clear breakdown of how they compare and when each one makes the most sense.
What Is a Drop Beam Deck?
A drop beam deck (also called a “beam below joists” system) places the support beam underneath the joists. The joists sit directly on top of the beam, transferring the load downward.
How it works:
- Beam runs below the joists
- Joists rest on top of the beam
- Posts support the beam from below
Pros:
- Stronger load support due to direct bearing
- Easier and faster to build (less precision cutting required)
- Typically more cost-effective
- Great for larger spans and heavier structures
Cons:
- Increases overall deck height (beam sits below joists)
- Less clean look from underneath
- Can limit use in low-clearance areas
Best for: Most standard decks, elevated decks, and projects where strength and efficiency are priorities
What Is a Flush Beam Deck?
A flush beam deck (also called a “beam in line with joists” system) places the beam at the same height as the joists, with joists attached to the side of the beam using hangers.
How it works:
- Beam sits flush with joists
- Joists are connected using joist hangers
- Creates a single, level framing plane
Pros:
- Lower overall deck height (great for tight elevations)
- Cleaner, more streamlined appearance
- Ideal for multi-level decks or step-down transitions
- Can allow for better alignment with doors or thresholds
Cons:
- More labor-intensive (requires hangers and precise layout)
- Slightly higher material cost (hardware + labor)
- Less direct load transfer compared to drop beam
Best for: Low-to-grade decks, tight height constraints, and higher-end custom designs
Key Differences at a Glance
Structure:
- Drop Beam: Beam below joists
- Flush Beam: Beam level with joists
Strength & Load Transfer:
- Drop Beam: Direct bearing (stronger, simpler)
- Flush Beam: Hanger-supported (still strong, but more hardware-dependent)
Height:
- Drop Beam: Taller overall structure
- Flush Beam: Lower profile
Cost:
- Drop Beam: More budget-friendly
- Flush Beam: Slightly higher due to labor and hardware
Appearance:
- Drop Beam: More visible structure underneath
- Flush Beam: Cleaner, more finished look
When Should You Use Each?
Choose a Drop Beam if:
- You want the most cost-effective and efficient build
- Your deck has plenty of clearance from the ground
- You’re building a larger or higher deck
- Strength and simplicity are top priorities
Choose a Flush Beam if:
- You need to keep deck height low (near grade or door thresholds)
- You want a clean, modern appearance
- You’re building multi-level or complex deck layouts
- You’re okay with slightly higher cost for a refined result
Our Take at ProTech Builders
Both methods are structurally sound when built correctly—the choice really comes down to design constraints and project goals. For most standard builds, drop beams are the go-to for their strength and efficiency. But when height, aesthetics, or layout flexibility matter, flush beam construction is a great solution.
Not sure which is right for your deck? Our team can help you evaluate your space, elevation, and budget to choose the best framing system for your project.
