How to Hire the Right Ductwork Contractor in Kenya

Why Design Capability Matters More Than Installation Speed

Ductwork installation itself — cutting, joining and hanging sheet metal or duct board — is a fairly mechanical skill that many contractors can perform competently. What separates a good ductwork contractor from a mediocre one is the design work that happens before installation: sizing calculations, routing decisions, and understanding how airflow will actually behave once the system is running. A contractor who installs quickly but skips proper design is the source of most of the ductwork problems we're called in to fix.

Credentials & Experience to Look For

Sizing & Design Calculation Capability

Ask how the contractor determines duct dimensions for your specific project — a proper calculation balancing airflow and static pressure, not a rule-of-thumb estimate based on similar-looking past jobs.

Sealing & Balancing Practice

Confirm whether joint sealing and post-installation airflow balancing are standard parts of their process, since these details significantly affect real-world efficiency but are easy to skip without anyone immediately noticing.

Retrofit Experience

If you're adding or modifying ductwork in an existing building, ask specifically about retrofit project experience — routing around existing structures and finishes requires different problem-solving than new-construction installation.

Questions to Ask Before Signing

• How did you calculate the duct sizing for my project? A specific answer referencing airflow and static pressure calculation beats a vague reference to standard practice.
• Will joints be properly sealed, and how will this be verified? Leaky joints are one of the most common sources of lost efficiency in ductwork systems.
• Do you balance airflow after installation? Confirm this is a standard, documented step rather than an optional extra.
• What ductwork material do you recommend for my application, and why? The answer should reference your specific use case, not a default material regardless of application.
• Do you have experience with retrofit projects similar to mine? Ask for specific examples if you're modifying an existing building rather than working with new construction.

Red Flags to Watch For

• No mention of sizing calculations. If duct dimensions aren't referenced to a specific calculation, they were likely estimated rather than properly designed.
• No sealing or balancing step in the proposal. These details significantly affect performance but are commonly skipped by contractors focused purely on fast installation.
• Quoting without a site visit. Ductwork routing and space constraints, especially in retrofit projects, cannot be accurately assessed without seeing the building.
• No willingness to discuss material trade-offs. A competent contractor should be able to explain why they're recommending a specific material for your application, not just quote a default.

Getting Multiple Quotes the Right Way

Ductwork quotes can vary significantly based on material choice, sealing practice, and whether balancing is included — none of which are always obvious from a simple price comparison. Share the same building information and system requirements with every contractor you approach, and ask each one to specify material, sealing approach and whether commissioning/balancing is included in their quote. A cheaper quote that skips sealing or balancing isn't actually a fair comparison against one that includes them, even if the headline number looks more attractive.

What Happens After Installation: Support & Warranty

Ductwork itself rarely needs frequent servicing the way mechanical equipment does, but it's still worth confirming what happens if a performance issue is identified after installation — will the contractor return to re-balance airflow or reseal a joint under warranty, or is that treated as a separate paid callout? Getting this in writing before signing avoids an awkward conversation later if a room turns out under-served once the system is in daily use.