| Adkins Construction Co | Jerry A Adkins | adkinsconstructionohio@gmail.com | (530) 510 7192 | GC, remodel, ADU | Redding · Shasta County | — | — |
| Adkins Trees | Adkins Trees | — | (530) 357 3116 | Tree | Anderson · Shasta County | — | — |
| Adrian Renaud | Adrian Renaud | — | (530) 538 1614 | Other | Redding · Shasta County | — | — |
| Advanced Electric Service | Terry Allen Shafer | — | (530) 780 8161 | Electricians | Anderson · Shasta County | — | — |
| Advanced Plumbing And Electric | Jeffrey Lynn Bradford | — | (530) 949 1359 | Electricians | Redding · Shasta County | — | — |
| Advanced Roofing Solutions | Michael Arthur Roberts | — | (530) 248 3437 | Other roofers | Redding · Shasta County | — | — |
| Advanced Seamless Gutters Solutions | Advanced Seamless Gutters Solutions | — | (530) 980 6555 | Other | Redding · Shasta County | — | — |
| Advantage Construction | Christopher Joseph Verhougstraete | — | (530) 736 3535 | GC, remodel, ADU | Anderson · Shasta County | — | — |
| Advantage Electric INC | Tom Joseph Hiscocks | — | (530) 605 3955 | Electricians | Redding · Shasta County | — | — |
| Adventure Construction & Remodel LLC | Christopher Allen Nicholson | — | (443) 821 6768 | GC, remodel, ADU | Redding · Shasta County | — | — |
| Advisor Construction | William Daniel Jannsen | office@advisorconstruction.com | (530) 356 7055 | GC, remodel, ADU | Redding · Shasta County | — | — |
| Affordable Electric Service | Michael Lee Freude | — | (530) 209 9053 | Electricians | Redding · Shasta County | — | — |
| Affordable Video Surveillance Systems | Affordable Video Surveillance Systems | — | (530) 610 4391 | Electricians | Redding · Shasta County | — | — |
| Ahern & Sons Plumbing INC | John Francis Ahern | — | (530) 221 7495 | Other | Redding · Shasta County | — | — |
| Ahlberg's Construction Co | Matt Derek Ahlberg | — | (530) 365 5216 | GC, remodel, ADU | Anderson · Shasta County | — | — |
| Aim High Enterprises | Raymond Bryan Di Giuseppe | — | (530) 227 3596 | Electricians | Redding · Shasta County | — | — |
| Air - O - Service | Jack Albert Jr Sanders | customerservice@airoservice.com | (530) 221 4691 | HVAC | Redding · Shasta County | — | — |
| Air Care Heating And Air Conditioning | Michael James Williams | — | (530) 941 9576 | HVAC | Cottonwood · Shasta County | — | — |
| Air Experts | Air Experts | — | (530) 241 0815 | HVAC | Anderson · Shasta County | — | — |
| Air Pro Heating & Air Conditioning | Michael Edward Kranz | — | (530) 524 2226 | HVAC | Shasta Lake · Shasta County | — | — |
| Air-o Service | Daniel Carver Sr Hoeppner | customerservice@airoservice.com | (530) 221 4691 | HVAC | Redding · Shasta County | — | — |
| Aireco Heating & Cooling | Aireco Heating & Cooling | — | (530) 510 7362 | HVAC | Millville · Shasta County | — | — |
| Airflow Dynamics LLC | Justin Charles Nelson | — | (530) 355 1242 | HVAC | Shasta Lake · Shasta County | — | — |
| Akers Home Improvements | Akers Home Improvements | — | (916) 852 1976 | GC, remodel, ADU | Redding · Shasta County | — | — |
| Aks Construction INC | Eric Nels Stahl | — | (530) 357 3336 | Pool | Anderson · Shasta County | — | — |
| Alan Kent Delashmutt Painting | Alan Kent Delashmutt Painting | — | (530) 949 7599 | Windows, patio, painters | Lakehead · Shasta County | — | — |
| Albert F Naticchioni | Albert F Naticchioni | — | (530) 245 1944 | GC, remodel, ADU | Redding · Shasta County | — | — |
| Alcala Landscape Design | Alcala Landscape Design | — | (530) 806 6311 | Windows, patio, painters | Redding · Shasta County | — | — |
| Alcon Engineering | Araiza Victor Vazquez | m.congedo@alcon-engineering.com | (650) 315 3342 | Other | Cottonwood · Shasta County | — | — |
| Alex Voorhees | Alex Voorhees | alex@alexvoorhees.com | (530) 410 2089 | Other | Redding · Shasta County | — | — |
| All About Air | All About Air | — | (530) 364 8434 | HVAC | Anderson · Shasta County | — | — |
| All Aspect Tree Service | Trevor D Cyphers | trevor@allaspecttreeservice.com | (530) 410 6168 | Tree | Millville · Shasta County | — | — |
| All Floors | All Floors | — | (530) 921 9037 | Other | Redding · Shasta County | — | — |
| All Good Hardwood Floors INC | Anthony Sergio Gonzalez | — | (530) 262 1192 | Other | Redding · Shasta County | — | — |
| All In 1 Tree And Timber INC | Aaron Lee Peterson | — | (707) 272 7387 | Tree | Cottonwood · Shasta County | — | — |
| All Out Fire Protection & Construction INC | Ronald Paul Zega | — | (530) 227 4739 | GC, remodel, ADU | Redding · Shasta County | — | — |
| All Plumbing & Drain Solutions | All Plumbing & Drain Solutions | — | (530) 275 5105 | Other | Redding · Shasta County | — | — |
| All Seasons Landscape Maintenance | All Seasons Landscape Maintenance | — | (530) 515 6197 | Windows, patio, painters | Redding · Shasta County | — | — |
| All Seasons Roof Coatings | Elmer Gene Woolard | — | (530) 243 1148 | Other roofers | Redding · Shasta County | — | — |
| All State Fencing | All State Fencing | — | (530) 710 6496 | Other | Redding · Shasta County | — | — |