How Did I Run a Chimney Pipe Through Two Floors?

I ran a Class A insulated chimney pipe straight up through two floors and the roof of my two-story log home. The system uses UL 103 HT-listed twin wall pipe with 2-inch clearance to combustibles at every penetration, following NFPA 211. The full install took one Saturday, and the stove now heats both levels of the house.

Location: Vermont, USA
Kit used: Class A Chimney Pipe Kit - Vertical Roof Exit for Multi-Story Homes
Building type: Two-story log home
Stove: Medium wood-burning stove in living room

Why I Chose an Internal Chimney Pipe System

We live in a cold climate, and I wanted to retain as much heat as possible from the flue pipe. That's why I decided to run the chimney pipe straight up through the ceilings and roof instead of installing it outside along the wall. I found the straight-up twin wall flue kit on flue-pipes.com and it looked like a perfect match for our setup.

An internal chimney run has real advantages in cold climates. The pipe stays warm inside the heated envelope of the house, which means stronger draft, less condensation, and less creosote buildup. An external chimney cools down fast in freezing weather, which can cause draft problems and more frequent cleaning. For a two-story home, the internal route also gives you a taller chimney stack, which further improves draft.

Planning the Route

The biggest challenge was planning the exact route through the first-floor ceiling, upstairs bedroom floor, and attic. I used a plumb line from the stove collar to make sure I stayed straight through all three levels. Luckily, there were no joists or rafters in the way.

Per NFPA 211, Class A chimney pipe must maintain a minimum 2-inch clearance to all combustible materials at every penetration point. In a two-story home, that means you need to verify clearance at three separate levels: the first-floor ceiling, the second-floor ceiling, and the roof. If a joist or rafter is in the way, you may need to reframe - never reduce the clearance distance.

Always check local building codes and UL 103 HT compliance before you start cutting.

What I Needed

Here is what the kit included, plus the extras I used:

• Class A insulated chimney pipe sections (UL 103 HT listed, rated to 2100 degrees F)
• Ceiling support box for the first-floor penetration
• Firestop radiation shield for the second-floor penetration
• Stainless steel roof flashing (adjustable for roof pitch)
• Storm collar and rain cap
• Connecting stove pipe (single wall or double wall black pipe, from stove to ceiling support box)
• High-temp silicone sealant
• Plumb line, tape measure, hole saw, jigsaw, drill
• Lag screws for securing the support box to framing

Step-by-Step Installation

Step 1 - Cut Ceiling and Floor Openings

I used a hole saw to cut clean openings through the first-floor ceiling and the second-floor floor/ceiling. I framed out each opening with fire-safe material to maintain the required 2-inch clearance to combustibles on all sides. At each penetration, you need a properly sized opening that allows the support hardware to maintain this gap automatically.

Step 2 - Install the Ceiling Support Box

I placed the ceiling support box at the first-floor ceiling and secured it to the framing with lag screws. This box does two things: it carries the full weight of the chimney stack above, and it creates the fire-safe barrier at the penetration point. The support system is one of the most important parts of the installation.

Step 3 - Stack the Insulated Pipe

From the stove upward, I connected the adapter and began stacking the twin wall insulated pipe section by section. I passed each piece through the second floor and into the attic. At the second-floor penetration, I installed a firestop radiation shield to maintain the 2-inch clearance and prevent heat transfer to the floor framing. The pipe sections lock together with a twist-lock connection - straightforward and secure.

Step 4 - Seal the Roof

In the attic, I cut the final roof opening and installed the metal flashing, storm collar, and rain cap. I used high-temp silicone to make it watertight. The chimney must meet the 3-2-10 rule: at least 3 feet above the roof penetration and at least 2 feet higher than anything within 10 feet horizontally.

Component Specifications

How It Performs

The stove now heats both levels of the house, and the vertical flue provides great draft. I can already tell that running the pipe indoors helps radiate more warmth throughout the rooms. There's no smoke leakage and no creosote smell - the system works beautifully.

If you're considering a similar multi-story installation, I'd recommend reading about how to route chimney pipe through an attic and general chimney installation in a two-story house. Both cover details that will help you plan your route.

My Takeaways

Plan your vertical run carefully and double-check for clearance at each level. The installation took me most of a Saturday, but everything fit together exactly as expected. It feels good knowing the system is both efficient and safe.

A few things I would tell anyone doing a multi-floor chimney install:

• Use a plumb line from the stove collar before cutting anything. Even a small offset compounds over multiple floors.
• Every penetration point (ceiling, floor, roof) needs its own fire-safe hardware - ceiling support box, firestop, or radiation shield.
• The 2-inch clearance to combustibles is non-negotiable at every level. If a joist is in the way, reframe around it.
• An internal chimney run is more work than an external one, but the heat retention and draft performance are worth it in cold climates.
• If you're not sure about your route or pipe diameter, use the free chimney design service before you start.

More Real Installations

• Installing a Class A Chimney Pipe in My Shed
• Through-the-Wall Chimney Pipe in My Garage
• How Did I Install a Roof Exit Kit in My Cabin?

Ready to Install a Chimney Through Multiple Floors?

Not sure which kit or pipe diameter fits your two-story home? Use our free chimney design service for a custom recommendation within 24 hours. Or call us at 888-834-0880 (9 AM - 9 PM, 7 days a week). Browse our complete range of chimney kits and Class A chimney pipe.

Frequently Asked Questions

Can I run a chimney pipe through multiple floors of my house?

Yes. Class A insulated chimney pipe that is UL 103 HT listed is specifically designed to pass through ceilings, floors, and roofs. At each penetration point, you need proper fire-safe hardware (ceiling support box, firestop radiation shield) that maintains the required 2-inch clearance to combustible materials per NFPA 211.

Is an internal chimney better than an external one?

In cold climates, an internal chimney performs better because the pipe stays inside the heated envelope of the house. This results in stronger draft, less condensation, and less creosote buildup compared to an external chimney that is exposed to freezing temperatures. The trade-off is that an internal route requires cutting through each floor and ceiling.

What fire-safe hardware do I need at each floor penetration?

At the first ceiling penetration, you need a ceiling support box that carries the weight of the chimney and maintains the 2-inch clearance. At every additional floor or ceiling penetration above that, you need a firestop radiation shield. At the roof, you need a roof flashing, storm collar, and rain cap. All hardware must be rated for use with your specific pipe diameter.

How long does it take to install a chimney through two floors?

For a straightforward vertical run with no obstructions, plan for a full day. The most time-consuming parts are verifying clearances at each level, cutting and framing the openings, and working on the roof. If you need to reframe around joists or rafters, add extra time.

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