Utility Penetrations
Bringing water, natural gas, sewer, and low-voltage conduit through the house basement wall from the garage trench. Penetrations will be below grade through uncoated CMU block.
Utilities and Sizes
| Utility | Pipe Size | Sleeve Size | Notes |
|---|---|---|---|
| Water (PEX) | 3/4” | 2” sleeve | Allows for insulation around pipe |
| Natural Gas | 1” | 2” sleeve | Check with gas company requirements |
| Sewer | 3” PVC | 4” sleeve | Allows for fitting clearance |
| Low-voltage conduit | 2” | 3” sleeve | Future expansion capacity |
Recommended Approach: Core Drill + Mechanical Seals
For below-grade penetrations without exterior waterproofing:
- Core drilling creates clean, round holes that seal better than chipped openings
- Mechanical seals (Link Seals) provide watertight, adjustable, code-compliant penetrations
- Sleeves allow pipe replacement without re-drilling
Tools Needed
- Core drill with diamond bits (rent from Home Depot/local rental)
- 2” bit for water and gas sleeves
- 3” bit for low-voltage sleeve
- 4” bit for sewer sleeve
- Hammer drill with masonry bits (pilot holes)
- Level, tape measure
- Safety glasses, dust mask, hearing protection
Step-by-Step Process
Step 1: Plan Penetration Locations
- Space penetrations at least 8” apart (center to center)
- Avoid drilling through mortar joints if possible (weaker seal)
- Mark locations on both interior and exterior if accessible
- Verify no rebar or utilities in the way (stud finder with metal detection)
Step 2: Core Drill the Holes
- Drill pilot hole from inside using hammer drill (1/4” masonry bit)
- Verify exit point outside is correct
- Set up core drill with water supply (wet cutting reduces dust, cools bit)
- Drill from inside out - better control, cleaner interior finish
- Support the core as it breaks through to prevent blowout
- Remove core plug - may need to break out if blocks are grouted
Tips:
- Drill at slight downward angle (exterior lower) for drainage
- CMU cores are hollow - drill through face shells only (~2.5” each side)
- If block is grouted, drilling takes longer but seals better
Step 3: Install Sleeves
Use Schedule 40 PVC as sleeves:
- Cut sleeve to wall thickness + 2” (1” protrusion each side)
- Dry fit sleeve in hole
- If loose fit: wrap exterior with closed-cell foam backer rod
- Apply hydraulic cement around sleeve exterior
- Allow to cure 24 hours
Step 4: Install Mechanical Seals (Link Seals)
Link Seals are the gold standard for below-grade penetrations:
- Measure gap between pipe OD and sleeve ID
- Select correct Link Seal size (they come in ranges)
- Slide seal links around pipe before inserting through sleeve
- Position in center of wall thickness
- Tighten bolts evenly to compress rubber and seal
Link Seal Suppliers
| Supplier | Link | Notes |
|---|---|---|
| Ferguson | ferguson.com/link-seals | #1 US plumbing supplier, local branches |
| Maddock Industries | maddockindustries.com | Same/next day shipping, $54-459/set |
| USA BlueBook | usabluebook.com | 10-link belts, good pricing |
| Garlock (manufacturer) | garlock.com/link-seal | Official sizing calculator |
| CCI Piping | ccipipe.com/wrap-it-link | Wrap-It Link alternative brand |
Sizing Help: Use Garlock’s Link-Seal Calculator to determine how many links you need based on pipe OD and sleeve ID.
Note: Link Seals are industrial products - not typically stocked at Home Depot or Lowe’s. Order from plumbing supply houses or online.
Step 5: Exterior Waterproofing
Since there’s no existing waterproofing on the basement wall, add protection at penetrations:
- Apply hydraulic cement around sleeve exterior (if not done in Step 3)
- Apply waterproof membrane (Tremco, Henry, or similar) over cement
- Extend membrane 6”+ beyond penetration in all directions
- Consider full waterproofing the wall section while excavated
Alternative: Fernco Flexible Couplings
If Link Seals are hard to source, Fernco flexible couplings can work:
- Install sleeve as above
- Use Fernco reducer fitting inside sleeve
- Apply silicone between Fernco and sleeve
- Less adjustable than Link Seals, but widely available at Home Depot/Lowe’s
Code Considerations
Gas Line
- Must be sleeved through foundation (no direct contact)
- Sleeve must be sealed at both ends
- Vent sleeve to exterior if possible (prevents gas accumulation)
- Check with local gas company for specific requirements
Sewer
- Maintain 1/4” per foot slope minimum through penetration
- 3” minimum for toilet drainage
- May need cleanout accessible inside
Water
- Protect from freezing - ensure adequate depth below frost line (42” in Michigan)
- Insulate pipe within sleeve
- Consider heat tape if near frost line
Low-Voltage Conduit
- Seal to prevent water entry
- No special code requirements for pathway itself
Materials List
| Item | Qty | Est. Cost | Source |
|---|---|---|---|
| Core drill rental (1 day) | 1 | $75-100 | Home Depot/rental |
| Diamond core bits (2”, 3”, 4”) | 3 | $50-150 | Purchase or rental |
| Schedule 40 PVC sleeves | 4 | $20 | Home Depot |
| Link Seals (sized for each pipe) | 4 | $80-150 | Plumbing supply |
| Hydraulic cement (10 lb) | 1 | $15 | Home Depot |
| Waterproof membrane | 1 gal | $40 | Home Depot |
| Closed-cell backer rod | 1 pack | $10 | Home Depot |
Estimated Total: $290-485
Sequence of Work
- Excavate trench and expose basement wall
- Mark and drill penetrations from inside
- Install sleeves with hydraulic cement
- Run pipes through sleeves (before backfill)
- Install Link Seals around each pipe
- Apply waterproofing membrane to exterior
- Backfill trench in lifts, compacting each layer
Tips for Success
- Rent quality equipment - cheap core drills burn out quickly in CMU
- Have spare bits - diamond bits wear, especially in grouted blocks
- Work dry if needed - wet cutting is ideal but messy indoors
- Seal from both sides - hydraulic cement inside, membrane outside
- Photo document - before backfill, for permit inspections and future reference
- Test for leaks - hose water against wall before full backfill
When to Hire a Pro
Consider hiring help for:
- Core drilling if you don’t want to rent equipment
- Gas line connection (usually requires licensed plumber/gas fitter)
- Sewer connection to house main (may require inspection)
- If you hit rebar or unexpected obstructions
Related Documents
- Utilities & Conduits - Underground conduit runs from garage
- Mechanical Room - Where utilities terminate in garage