Foundation Waterproofing for Chemical Sensitivities

Understanding the Challenge

When you have Multiple Chemical Sensitivity (MCS) or chemical sensitivities, choosing foundation waterproofing becomes critical. Traditional asphalt-based products like Watchdog can off-gas for years, potentially affecting indoor air quality even when applied externally. Let’s explore safer alternatives that still provide effective protection.

Why Asphalt Emulsions Are Problematic

Watchdog and Similar Products:

• Petroleum-based asphalt emulsions
• Strong odor during application
• VOC off-gassing continues after curing
• Can migrate through concrete over time
• Sensitivity reactions reported years later

Health Concerns:

• Headaches and dizziness
• Respiratory irritation
• Skin reactions
• Long-term exposure concerns
• Indoor air quality impacts

Important Distinction: Damp-proofing vs Waterproofing

As Riversong correctly noted: “Asphalt emulsions are damp-proofing only, not waterproofing.”

Damp-proofing:

• Resists moisture vapor
• Not effective under pressure
• Typical asphalt coatings
• Minimal protection

True Waterproofing:

• Resists water under pressure
• Bridges small cracks
• Provides lasting protection
• Required for basements

Safe Alternatives for Chemical Sensitivities

1. Polyethylene Membrane Systems (RECOMMENDED)

As Armando Cobo suggested, these are excellent low-VOC options:

Delta-MS/Delta-Drain:

• High-density polyethylene (HDPE)
• 60-90% recycled content
• Zero VOCs after installation
• No chemical off-gassing
• 20-30 year warranties
• Creates air gap drainage

Installation Notes:

• No adhesives required
• Mechanical fastening only
• No chemical exposure
• Can install in any weather
• Immediate protection

Cost: $2-4 per sq ft installed

2. Crystalline Waterproofing

For New Construction:

• Added to concrete mix
• No surface application
• Zero VOCs
• Permanent solution
• Self-healing properties

Brands:

• Xypex (additive)
• Kryton KIM
• Penetron

Note: Ensure concrete mix has no chemical additives that trigger sensitivities

3. Latex-Based Sealers

UGL Drylok (Water-Based):

• Latex formula available
• Lower VOCs than solvent-based
• Must specify water-based version
• Allow full cure before occupancy
• Best for interior application

Limitations:

• Still contains some VOCs
• Requires reapplication
• Not true waterproofing
• Better as backup system

4. Bentonite Clay Systems

Natural Clay Waterproofing:

• Sodium bentonite clay
• Completely natural
• No chemical additives
• Swells to seal
• Self-healing

Forms:

• Panels (cardboard backed)
• Spray-applied
• Trowel-applied

Considerations:

• Must stay continuously wet
• Not for all soil conditions
• Professional installation required

Products to Avoid with Chemical Sensitivities

High-VOC Systems:

• Solvent-based asphalts
• Rubber-modified asphalts
• Coal tar products
• Polyurethane liquids
• Solvent-based acrylics
• Hot-applied systems

Hidden Chemical Sources:

• Adhesives for membranes
• Primers and prep coats
• Crack fillers
• Joint sealants
• Protective coatings

Best Practice Approach for MCS

Recommended System:

1. Exterior: HDPE dimpled membrane (Delta-MS or similar)
2. Drainage: Proper foundation drains
3. Interior: Leave concrete bare or use zero-VOC sealer
4. Backup: Good site drainage and grading

Installation Timeline:

• Install membrane immediately after forms removed
• No waiting for chemical cure
• No off-gassing period needed
• Can backfill immediately
• House can be occupied sooner

Critical Details for Success

Membrane Installation:

• Overlap seams properly
• Terminate above grade correctly
• Protect during backfill
• Integrate with drainage system
• No chemical sealants at seams

Drainage Requirements:

• Foundation drains mandatory
• Free-draining backfill
• Proper slope away from house
• Sump pump if needed
• No waterproofing works without drainage

Indoor Air Quality Considerations

Even Exterior Applications Affect Indoor Air:

• Chemicals migrate through concrete
• Stack effect pulls air through foundation
• Soil gases carry VOCs
• Long-term off-gassing occurs

Protective Strategies:

• Create air barrier on interior
• Use ERV/HRV ventilation
• Maintain positive pressure
• Seal all penetrations
• Monitor indoor air quality

Cost Comparison

System	Initial Cost	VOC Level	Effectiveness	Lifespan
Asphalt Emulsion	$	High	60-70%	10-15 years
HDPE Membrane	$$	Zero	95%	30+ years
Crystalline	$$$	Zero	99%	Permanent
Bentonite	$$	Zero	90%	25+ years
Latex Sealer	$	Low	70%	5-10 years

Questions to Ask Your Contractor

1. Experience with low-VOC systems?
2. Can they source HDPE membranes?
3. Will they avoid all chemical adhesives?
4. Do they understand MCS concerns?
5. Will they document all products used?

Red Flags to Avoid

• Contractor dismissive of chemical concerns
• Insistence on “standard” products only
• Claims that exterior application is safe
• Unwillingness to provide MSDSs
• Push for quick/cheap solutions

Making the Decision

For New Construction:

1. First choice: HDPE dimpled membrane
2. Second choice: Crystalline admixture
3. Third choice: Bentonite clay
4. Avoid: All petroleum-based products

Key Points:

• Drainage is more important than coating
• Mechanical systems beat chemical ones
• Plan for long-term health
• Document everything used

Working with Your Contractor

Communication Strategies:

• Provide written requirements
• Specify prohibited products
• Require product submittals
• Get everything in writing
• Have MCS-safe alternatives ready

Contract Language:

“No petroleum-based, solvent-based, or high-VOC products shall be used for foundation waterproofing. Only approved low-VOC or zero-VOC systems as specified.”

Alternative Approaches

For Extreme Sensitivities:

1. Raised foundation: Minimize below-grade space
2. Slab-on-grade: Eliminate basement
3. Crawlspace: Easier to ventilate
4. Interior drainage only: Manage not prevent

Supporting Systems:

• Excellent site drainage
• Deep roof overhangs
• Gutters and downspouts
• Impermeable landscaping
• French drains

Long-Term Considerations

Maintenance Without Chemicals:

• HDPE membranes need no maintenance
• Drainage systems need periodic cleaning
• Avoid chemical drain cleaners
• Use mechanical cleaning only
• Monitor for settlement

Future Repairs:

• Plan access for maintenance
• Document system installed
• Keep extra materials
• Maintain contractor contacts
• Photo document installation

Success Stories

Many MCS sufferers have successfully built with:

• HDPE membrane systems
• No reported sensitivities
• 10+ years symptom-free
• Indoor air quality maintained
• Peace of mind achieved

The Bottom Line

Your chemical sensitivities are valid and must be respected in construction choices. HDPE dimpled membranes like Delta-MS provide superior waterproofing without chemical exposure. While slightly more expensive initially, they offer better protection and zero VOC exposure - a worthwhile investment in your health.

Professional Resources

• Chemical Sensitivity Foundation
• Building Biology Institute
• HDPE Membrane Systems
• Crystalline Waterproofing Options

Next Steps

1. Reject the Watchdog proposal
2. Request HDPE membrane quote
3. Ensure proper drainage design
4. Get everything in writing
5. Trust your health concerns

For chemical-sensitive waterproofing solutions in Toronto, call (437) 545-0067.

DrySpace Waterproofing - Healthy Home Solutions Since 2008