Yes, this is a post about running a dryer duct and rerouting HVAC vents. Before diving in, some context: by the time Monday’s post went up, David the framer had finished framing our new laundry room by adding the final wall (the one with the door to the hallway).
He also framed the wall that will hold the frosted door to the current storage area/future TV room. I shot the photo from this angle to avoid the plastic sheet that’s keeping attic heat out.
Here’s a full shot of the completed framing. I propped the door in place to illustrate how far it swings into the room — at 8′ deep there’s plenty of clearance for the washer, dryer, and cabinetry.
This post focuses on some of the smaller but essential tasks we completed before drywall could begin. They’re not glamorous, but they matter. Below are three key jobs we finished, along with photos to help anyone tackling something similar.
First up: the dryer vent. For proper dryer performance and safety, a vent should generally be no longer than 25 feet, with about 5 feet subtracted for each 90-degree elbow. Our old setup had too much length and too many turns, which reduces airflow and increases lint buildup.
Placing the dryer on the back wall of the new room brought us closer to the exterior, but our first routing plan still had too many turns. We realized a better path was available by running the duct under the attic stairs, which required cutting a new hole through the exterior wall. Not fun, but necessary. Later I’ll explain why we routed up the wall instead of out under the stairs.
To make space under the stairs for the 4″ vent, I used a Dremel Sawmax to cut the plywood top along the step joist, allowing me to reattach it later. Then I used a reciprocating saw to remove a 4″ section of the 2×6 so the duct could rest there.
I planned to reuse the existing metal duct pieces since they were in good shape. I disassembled them, cleaned lint using a long-bristled brush and a Shop Vac, then reassembled the sections. When reconnecting, make sure crimped ends face the airflow direction so air doesn’t leak around the seams. I sealed all joints with metal-faced duct tape (not cloth duct tape).
With the sections fitted, I ran the duct under the stairs and up the back exterior wall, securing it with steel hanger straps. I cut a portion of the bottom pipe down with metal snips, leaving it slightly long until the room is more finished. Painter’s tape covered exposed edges to avoid cuts while working.
Next I made the new hole in the exterior wall. I drilled a pilot hole from inside to make sure the new exterior opening lined up with the duct. Outside, I used a 4-1/8″ hole saw to cut through the siding; stopping at the hardboard, I finished the cut from the inside to avoid extra ladder time. The inside pilot hole helped ensure alignment.
With the full hole cut, I installed a new exterior vent hood that matches the old one. Sherry painted it to match the siding before I installed it so the ladder work would be quicker. I sealed the back of the hood with a ring of silicone caulk and fastened it to the siding.
We chose a higher exit point on the wall rather than under the attic stairs to avoid placing the vent just above a lower roof section, where lint would collect on the shingles. Aligning the new vent with the old kept the exterior look balanced until we patch the old opening.
Inside, I trimmed the duct that protruded and connected a semi-rigid duct to the vent, securing it with metal-faced tape and another bead of silicone caulk. Then I reattached the piece of stair I had removed, leaving the laundry room ready for the dryer once it’s installed.
Quick note on the floor: the new laundry room floor was lower than the adjacent hardwoods, so we built up the subfloor. I planned for 3/4″ subfloor, 1/2″ cement backer board for tile, plus tile and thinset to match the hardwood height. To transport materials I rented a Home Depot truck, which made moving 4×8 sheets much easier.
I trimmed and fit two 4×8 sheets of 1/2″ OSB subfloor into the room, glued and screwed them down to reduce future creaks, then prepared for the backer board and tile.
Now onto HVAC: this new laundry room had no supply vent, despite the main trunk being close. After researching and watching tutorials, I felt confident to add a vent. Home Depot sells an “Add-A-Vent” kit that includes materials and instructions; I bought it, then returned it after realizing I already owned several items and could source the rest more affordably. One useful component is the Speedi-Boot for nailing the ceiling register between joists.
The nerve-wracking part was cutting into the main HVAC trunk. I traced the collar location, removed the insulation, and exposed the metal trunk. For cutting the metal I followed a video technique: puncture with a screwdriver, then cut the circle with metal snips. It worked well with the tools I had.
I installed the collar into the cut, bending its tabs so it gripped the trunk metal, and sealed the connection with foil duct tape. Then I attached insulated flexible duct from the collar to the ceiling register, securing it with zip ties and duct tape and supporting it so there were no kinks that could restrict airflow.
I left the cardboard dust shield in the ceiling register until the room is ready for full service, but I briefly turned on the A/C to confirm the new supply works — and it did.
This wasn’t the most glamorous update, but getting the dryer duct, exterior vent, subfloor, and HVAC supply in place cleared the way for drywall. We’ve already started hanging drywall, and the space is finally beginning to look like a room.
I’ll share drywall-hanging details once that stage is complete. We have book photoshoots this week so laundry room mode is paused for a bit, but at least we managed to do laundry at my parents’ house so we won’t smell for the shoot.