The Simpson Strong-Tie MPB88Z Moment Post Base is a purpose-engineered connector designed to provide moment resistance for wood columns and posts. Its innovative sleeve design encapsulates the post and prevents it from rotating at its base when lateral loads are applied at the top - giving specifiers and contractors greater design flexibility while reducing the need for bracing and creating more unobstructed views. This off-the-shelf solution has been engineered and tested to eliminate the time and expense of designing, calculating, and ordering custom-fabricated parts. Built from heavy-duty 12-gauge steel with a ZMAX galvanized finish, the MPB88Z is ready for demanding exterior and treated-wood applications where corrosion resistance is critical.

Key Features

• Code-required 1 in. post standoff: Internal tabs keep the post elevated above the base to help prevent rot from standing water and ground moisture.
• Concrete embedment indicators: Stamped indicators and internal tabs clearly identify the required concrete embedment depth for accurate, confident installation.
• Template attachment holes: Strategically placed holes simplify installation by allowing direct template attachment.
• Obround trim attachment holes: Optional obround holes have been added for conveniently attaching trim material.
• Drainage and inspection holes: Additional holes at the embedment line allow standing water to exit and provide a point of visual inspection.
• One-piece design: Streamlines installation by reducing complexity and the number of components needed on the job site.
• ZMAX galvanization: Provides extra corrosion resistance for exterior and treated-wood applications.
• 12-gauge steel construction: Heavy-duty material ensures structural integrity under demanding load conditions.
• SDS screws included: All required 1/4 in. x 3 in. Strong-Drive SDS Heavy-Duty Connector screws are included in the package.

Specifications

• Model Number (MPN): MPB88Z
• Post / Member Size: 8x8
• Steel Gauge: 12-gauge
• Finish / Coating: ZMAX Galvanized
• Installation Fasteners: 1/4 in. x 3 in. Strong-Drive SDS Heavy-Duty Connector Screws (included)
• Country of Origin: United States

Approved Applications

The MPB88Z Moment Post Base is specifically designed to resist rotational forces at the base of wood columns and posts where lateral loads are applied at the top. Its moment-resistance capability makes it well suited for applications where bracing must be minimized or eliminated for aesthetic or design reasons. The ZMAX finish makes it appropriate for:

• Exterior wood column and post connections to concrete foundations
• Applications involving ACQ, CA, or other preservative-treated lumber where standard galvanized finishes may not provide sufficient corrosion resistance
• Structures requiring enhanced lateral load resistance without additional bracing systems
• Projects where unobstructed sightlines are a design priority

Also available for 4x4 and 6x6 posts.

What's Included

• 1 x Simpson Strong-Tie MPB88Z ZMAX Moment Post Base (8x8)
• 1/4 in. x 3 in. Simpson Strong-Tie Strong-Drive SDS Heavy-Duty Connector Screws

Frequently Asked Questions

What post size is the MPB88Z designed to fit?

The MPB88Z is specifically designed for 8x8 wood posts and columns. Simpson Strong-Tie also offers the MPBZ moment post base in sizes for 4x4 and 6x6 posts if a different post dimension is required.

What hardware is included, and what is used to attach the post?

The MPB88Z includes 1/4 in. x 3 in. Simpson Strong-Tie Strong-Drive SDS Heavy-Duty Connector screws. These screws are used to attach the post to the base during installation.

Why does the MPB88Z have a standoff inside the base, and how high is it?

Internal tabs inside the MPBZ provide a code-required 1 in. post standoff. This elevation keeps the bottom of the post raised above the base, helping to prevent rot that can result from standing water and ground moisture.

What makes the ZMAX finish suitable for exterior and treated-wood applications?

The ZMAX galvanized coating provides extra corrosion resistance compared to standard galvanization, making the MPB88Z well suited for exterior installations and applications involving treated lumber where exposure to moisture and corrosive chemicals is a concern. The connector is also built from heavy-duty 12-gauge steel for added durability.