Add Support Columns
Transferring loads from attic to foundation. Support posts carry the weight of reinforced floors and modified roof structures down through your home's structure to solid footing.
Why Support Columns Matter
Converting an attic to living space often means increasing floor loads beyond what the original structure was designed to handle. Storage loads of 30-40 pounds per square foot become living loads of 50-60 pounds per square foot or more with furniture and occupants. Additionally, if you're removing collar ties or ceiling joists to create headroom, or adding dormers that change roof loading patterns, the structure needs new load paths. Support columns create those paths, carrying concentrated loads from attic beams down through your house to the foundation. Without proper columns, floors may sag, walls may crack, and the roof structure may spread outward. This is one area where structural engineering expertise is essential - column placement, sizing, and connections must be calculated precisely for your specific situation.
Tools & Materials You'll Need
Step-by-Step Guide
Review Engineer Specifications
Your structural engineer's drawings are the blueprint for column installation:
- Study column locations marked on floor plans for each level
- Note specified column size (4x4, 6x6, 3" steel, etc.)
- Review connection details for top and bottom of each column
- Check if new footings are required at foundation level
- Verify alignment tolerances allowed (typically 1/4" max)
- Understand load values being transferred
Critical: Never deviate from engineer's specifications without approval. Moving a column 6 inches to miss a duct or shifting to a different wall can create dangerous structural inadequacy. If site conditions require changes, consult your engineer first.
Verify Complete Load Path
Trace where loads will travel from attic to foundation:
Two-Story Home:
- 1. Attic beam to column top
- 2. Through second floor framing
- 3. Through first floor framing
- 4. To basement/crawl post
- 5. To footing on foundation
Check at Each Level:
- Posts align vertically (use plumb bob)
- Floor framing can transfer load
- No utilities blocking column path
- Wall cavities available if hiding column
- Adequate bearing at each connection
Planning Tip: Use a laser level to project column center points through all floors. Mark locations on subfloors before starting installation. This reveals any obstructions early.
Install Foundation Support
The load path starts at the foundation - ensure solid bearing:
- If new footing required, excavate below frost line (typically 36-48")
- Form footing minimum 24"x24"x12" or per engineer specs
- Install rebar grid (#4 bars, 6" grid typical)
- Pour concrete and insert post base anchor before setting
- Allow concrete to cure 7 days before loading
- If using existing footing, verify size and condition adequate
Basement Slab Note: Don't place columns directly on basement floor slabs - they're typically only 4" thick and will crack under concentrated loads. Cut through slab and pour proper footing beneath.
Set Posts at Each Level
Install columns from foundation up, working through each floor:
Basement/Crawl Space Post:
- Install post base on footing or pier
- Cut post to exact height (floor to underside of beam)
- Set post in base, check plumb on two faces
- Install post cap connecting to beam above
- Secure all connections with specified fasteners
Upper Floor Posts:
- Cut opening in subfloor if needed for continuous post
- Or install post cap/base assembly at floor level
- Align directly above post below using laser level
- Cut post to exact height
- Install with proper hardware top and bottom
Pro Tip: Use adjustable steel post bases where possible - they allow fine-tuning height and compensate for minor floor irregularities. Tighten adjustment after structure settles.
Connect to Attic Structure
The top connection transfers load from attic beams to column system:
- Install post cap sized for beam width and post dimensions
- Use structural screws or bolts as specified (not nails)
- Ensure beam sits fully on post cap bearing surface
- For ridge beam connections, use engineer-specified hangers
- Check that column is still plumb after tightening connections
- Verify no gaps between column top and beam underside
Common Connection Hardware:
- Simpson Strong-Tie CC or CCQ column caps
- Simpson ABU or PBS post bases
- 1/2" diameter bolts for heavy loads
- SD or SDS structural screws for lighter connections
Pro Tips
- ✓Use a temporary floor jack to pre-load the structure slightly before final column installation - this prevents future settling
- ✓Steel columns can be painted to match decor if left exposed, or wrapped with drywall on light-gauge steel framing
- ✓Plan column locations to fall within future closets or at room corners where they'll be least noticeable
- ✓Document column locations with photos and measurements - you'll need this for future remodeling or sales
- ✓Have inspector verify column installation before covering with drywall - corrections after finishing are expensive
Frequently Asked Questions
Do I always need support columns for an attic conversion?▼
Not always. Support columns are typically required when floor joists need reinforcement, when removing collar ties or ceiling joists, or when adding a ridge beam to create cathedral ceilings. A structural engineer will determine if columns are necessary based on your specific roof design, span lengths, and planned modifications. Homes with existing ridge beams or engineered trusses designed for living loads may not need additional columns.
Can support columns be hidden inside walls?▼
Yes, support columns can often be concealed within partition walls, but this requires careful planning. The wall must be wide enough to accommodate the column (typically 3.5" for 4x4 wood posts or 3" for steel columns). You'll need to coordinate column placement with your floor plan so walls align on each level. Building columns into closets, adjacent to door frames, or at room corners makes them less noticeable while maintaining structural function.
What's better for attic columns: steel or wood?▼
Steel columns (typically 3" or 4" round or square tubes) are stronger per square inch, allowing smaller profiles that take up less floor space. They're ideal when space is tight or when supporting heavy loads. Wood posts (4x4, 4x6, or 6x6 depending on load) are easier to work with, less expensive, and simpler to modify on-site. Your structural engineer will specify the appropriate material and size based on load calculations and local code requirements.
How do I know if my foundation can support new columns?▼
New columns transfer concentrated loads that may exceed what existing foundation was designed for. A structural engineer will calculate the point load and determine if you need new concrete footings. Signs that new footings are needed include: columns landing on basement floor slabs (not footings), existing foundation cracks, or calculated loads exceeding 5,000 lbs per column. New footings typically need to be 24"x24"x12" minimum, poured on undisturbed soil.