What are Post Base Anchors?
Post base anchors are structural connectors that attach a deck or dock’s support posts to a concrete footing or slab. They position and secure the post, transfer bearing loads into the concrete, and keep wood elevated to reduce moisture wicking. This category includes full post bases, half post bases, and post caps/end anchors used to connect post tops to beams or guard framing.
Why 316 Stainless for Decks & Docks?
- Maximum corrosion resistance in coastal, splash, and chemically aggressive environments.
- Long service life in exterior applications with treated lumber and repeating wet/dry cycles.
- Clean appearance for visible deck hardware and premium builds.
Types of Post Connectors You’ll Find Here
- Full Post Base Anchors – Sit under the post and fasten through side flanges; primary choice for anchoring posts to concrete where uplift and bearing need to be addressed.
- Half Post Base Anchors – Compact base plates used at intermediate posts or rail posts where loads are lower and access is tight.
- Post Caps / End Anchors – One-piece, two-piece, and adjustable caps for connecting the top of a post to beams or guard framing.
Selection Guide
- Post size: Choose the model sized for your 4×4, 6×6, or 8×8 post.
- Load demand: Use a full base for primary support posts; half bases suit light/intermediate duty.
- Adjustment: Pick adjustable caps when you need field alignment of beams or guard framing.
- Fasteners: Use stainless concrete anchors (wedge/sleeve/epoxy set) into cured concrete and stainless screws/bolts into the wood post—follow the fastener quantity listed for each model.
- Environment: Prefer 316 stainless for coastal, pool, and de-icing exposure.
How to Install a Post Base Anchor (Overview)
- Layout & drill: Mark the base location on cured concrete. Drill the hole with a hammer drill and carbide bit sized for your concrete anchor.
- Set the anchor: Install a stainless concrete anchor per its instructions (wedge, sleeve, or epoxy-set).
- Place the base: Position the base over the anchor and seat it to the slab.
- Attach hardware: Add washer/nut to secure the base to the slab. Plumb the post, then fasten through the base flanges into the wood with the specified stainless fasteners.
Note: Post bases restrain the bottom of the post and transfer bearing and uplift within their ratings. They are not designed to resist overturning moments by themselves. Follow local codes and the product’s fastener schedule.
Post Base Anchors - Specifications
| Post / Column Size: | 4 x 4 | 6 x 6 | 8 x 8 |
| Manufacturer Part Number: | PAU44 | PAU66 | PAU88 |
| Simpson Part Number: | ABU44 | ABU66 | ABU88 |
| Dimensions (Width): | 3-9/16" | 5-1/2" | 7-1/2" |
| Dimensions (Height): | 5-7/16" | 6" | 7-3/16" |
| Dimensions (Length): | 3" | 5" | 7-1/16" |
| Bearing Load (Lbs.): | 6775 | 16005 | 24900 |
| Uplift Load (Lbs.): | 2535 | 2380 | 3185 |
| Material: | 316 Stainless Steel | ||
Half Post Base Anchors - Specifications
| Post / Column Size: | 4 x 4 | ||
| Manufacturer Part Number: | D44 | ||
| Simpson Part Number: | BC40 | ||
| Dimensions (W): | 3-9/16" | ||
| Dimensions (H): | 2-1/2" | ||
| Dimensions (L): | 3-3/8" | ||
| Uplift Load (Lbs.): | 565 | ||
| F1 Load (Lbs.): | 750 | ||
| F2 Load (Lbs.): | 750 | ||
| Steel Gauge: | 18 | ||
| Material: | 316 Stainless Steel | ||
Not recommended for fence posts or other unrestrained (not fixed or fastened at top) applications. These anchors are not designed to resist overturning (moment) loads.
Common Applications
- Deck and dock support posts on concrete footings or slabs
- Stair landing posts and guard posts (as part of an engineered connection)
- Pergolas, pavilions, and exterior structures where wood-to-concrete connections are required
Pro Tips for Best Results
- Drill to the correct diameter and depth for the chosen concrete anchor; clean the hole before setting.
- Use stainless fasteners with stainless connectors to avoid galvanic corrosion.
- Keep wood elevated above the slab where the base design provides a standoff—this reduces rot risk.
- Follow the specified fastener count into the post and slab to achieve listed capacities.
Post Base Anchors — FAQ
Do post bases replace the need for hold-down hardware?
No. Post bases provide bearing and uplift resistance within their ratings but are not designed to resist overturning moments on their own.
What concrete anchors should I use?
Use stainless wedge, sleeve, or code-approved adhesive anchors sized per the installation instructions. Match anchor material to the stainless base.
Can I use these for fence posts set on top of a slab?
Not recommended. Fence posts are typically unrestrained at the top and subject to significant moment; these bases are not designed for that condition.
When would I choose a half post base?
Half bases are used at intermediate/light-duty locations with limited loads and access where a compact plate is preferred.
What’s the difference between a post base and a post cap?
A post base anchors the bottom of a post to concrete. A post cap ties the top of a post to beams or guard framing and is not used at the slab.