How to Install a New Dryer Vent — Complete Guide (2026)

Good route planning is the most important step. The goal is the shortest, straightest path from the dryer exhaust port to an exterior wall — minimizing bends saves cleaning effort later and keeps you within the 35-foot equivalent length code limit. Identify the nearest exterior wall from the dryer location. Check what is inside the wall — use a stud finder and measure to avoid drilling through a stud, and verify with a short pilot hole before committing to the 4-inch cut. In two-story homes, check for fire blocking between floors that will require additional horizontal routing. If the only viable exit is through the roof, factor in the added cost and maintenance complexity.

Tools: 4-inch hole saw (slightly larger than nominal — a 4-1/8 or 4-1/4-inch saw allows for the duct to slide in cleanly), cordless drill, tin snips or metal shears, screwdriver, tape measure, level, caulk gun, and utility knife. Materials: 4-inch rigid aluminum or galvanized steel duct sections, 4-inch elbows (90-degree and 45-degree as planned), semi-rigid aluminum transition duct (4 to 6 feet) for behind the dryer, 4-inch exterior vent cap with backdraft damper, sheet metal screws (#8, 1/2-inch pan head), aluminum foil HVAC tape, weatherproof exterior caulk, and hose clamps.

Step 1 — Mark and drill the exterior wall: From inside the laundry room, locate the exit point on the wall (at least 12 inches above exterior ground level). Drill a small pilot hole through to the outside. Step 2 — Cut the hole from outside: Using a 4-inch hole saw, cut the exterior penetration from the outside-in (easier to control angle). Step 3 — Install the exterior vent cap: Insert the vent cap pipe stub through the hole from outside. Apply weatherproof caulk around the cap flange before pressing it against the siding. Secure with stainless screws. Step 4 — Run rigid duct inward: Attach rigid duct sections starting from the vent cap, working toward the dryer. Crimp the connecting end of each section to allow it to slide into the next; the crimped end should face in the direction of airflow. Secure each connection with two sheet metal screws and foil tape. Step 5 — Install transition duct: Attach semi-rigid aluminum flex from the wall duct inlet to the dryer exhaust port using hose clamps at both ends. Keep the transition duct as straight as possible — no kinks. Step 6 — Test: Run the dryer on high for 10 minutes. Check the exterior cap for full flap opening and strong airflow.

Every joint in the rigid duct run must be secured with two sheet metal screws (placed at 180 degrees from each other, not at a location where they would protrude into the airstream) and completely sealed with aluminum foil HVAC tape. Do not use standard gray duct tape — it dries out within a year and falls off. If you use screws to attach elbows, position them so the screw tip does not protrude inside the duct (lint catches on exposed screw tips). Joints should run in the direction of airflow — meaning the downstream fitting slides over the upstream fitting, so if the duct disconnects slightly, air still flows outward rather than into the wall cavity.

All residential dryers require 4-inch (nominal) diameter duct. Before finalizing your route, calculate the equivalent length: start with the total physical length of all rigid duct sections, then add 5 feet for each 90-degree elbow and 2.5 feet for each 45-degree elbow. The sum must not exceed 35 feet. Example: 15 feet of straight duct + two 90-degree elbows = 15 + 5 + 5 = 25 feet equivalent length — within code. If your calculation exceeds 35 feet, you need to shorten the run, reduce elbows by choosing a more direct route, or consider a booster fan (consult your dryer manufacturer — not all allow booster fans).

Hire a professional when: the vent must exit through the roof; the wall is brick, concrete, or contains fire blocking that makes drilling complex; the route requires running duct through multiple floors; the local building department requires a permit and inspection; or you are not comfortable working with sheet metal and power tools. HVAC contractors charge $75–$150 per hour; handymen charge $50–$80 per hour. Total professional installation cost: $200–$800 for new installation, $100–$300 for replacement in an existing duct route (Bob Vila / HomeAdvisor, 2026).