8 Inch Exterior Wood Stove Chimney Pipes

Shop 8in Exterior Class A Systems

Key Takeaways

• 8in is for higher-output stoves and appliances with an 8in flue collar. Do not step up from a 6in collar to gain draft.
• An exterior run is a complete system: single-wall or double-wall connector inside the room, then Class A insulated pipe from the wall outward and upward.
• The tee with clean-out cap at the base is what makes sweeping an outside chimney easy.
• We supply one curated, fully matched line, so every part on this page fits the next one.
• Free flue-design help is available before you order, and returns run 14 days, no questions asked.

What Size Exterior Chimney Pipe Does Your Stove Need?

Match the pipe to the stove's flue collar, not to the room, the height or a hunch. If the appliance leaves the stove with an 8in collar, you run 8in all the way to the top. If it leaves with a 6in collar, the whole system is 6in, and our 6in exterior chimney range is the right shelf. Oversizing cools the flue gases, slows the draft and builds creosote faster, which is the opposite of what a bigger stove needs. The US store stocks Class A in 6in and 8in, so the decision is usually made for you by the appliance plate.

6in vs 8in: How To Decide

Single-Wall vs Double-Wall vs Class A

Three different products, three different jobs, and mixing them up is the most common ordering mistake we see.

• Single-wall stove pipe: the black connector inside the room, from the stove up to the wall. The simplest of the three to build and the lowest priced, but also the hottest on the outside, so it needs the most space around it. Stocked in 6in and 8in.
• Double-wall connector pipe: the same in-room job with an air gap, so it can sit closer to a wall and keeps flue gas warmer. Stocked in 6in.
• Class A insulated chimney pipe: the chimney itself. Insulated between two stainless walls, and the only one of the three allowed to pass through the wall and run outside.

On an exterior 8in install you will normally own two of them: a connector pipe in the room and Class A insulated chimney pipe from the thimble out.

Clearance To Combustibles

Clearance is the number your inspector checks first, and it belongs to the product listing rather than to a rule of thumb.

Class A insulated chimney pipe, when UL 103 HT-listed for wood-burning, maintains a minimum of 2 inches clearance to combustibles per the standard listing. Always verify the exact clearance specified by the manufacturer's UL listing for the specific product.

Practically, that means the wall thimble and the outer stack keep their listed air gap to siding, framing, soffits and eaves. Do not pack insulation into the thimble to close a sloppy hole. Cut the hole to the thimble, not the other way round.

What Is In A Complete 8in Through-the-Wall System

1. Stove pipe adapter from the appliance collar to Class A
2. Wall thimble sized to the pipe, sleeving the wall penetration
3. Tee with clean-out cap at the base of the outside run
4. Base wall support carrying the weight of the stack
5. Insulated Class A lengths to reach the required height
6. Wall bands at the spacing the system calls for
7. Termination at the top of the stack

Everything on this page comes from one product line, so the parts lock together without adapters bought from a second brand. If you would rather start from a pre-built configuration, the through-the-wall chimney kit gathers these components in one place, and the full kits hub covers roof and attic routes.

How Much Does An 8in Class A Through-the-Wall Chimney Cost?

Prices sit on the product listings on this page and change with the catalog, so read them there rather than from body copy. The honest framing is the comparison: doing a standard install yourself instead of paying for labor saves the larger share of a project like this, and a metal Class A stack costs a fraction of building a masonry chimney of the same height. Component count drives your total more than any single part does, so the taller the stack and the more offsets, the more it comes to. Our chimney installation cost guide sets out what parts and labor each contribute. Ask us for a parts list before you buy and you will not pay for a length you do not need.

Chimney Height On An Exterior Run

An outside stack still has to terminate at the correct height above the roofline, and on a low-eave building that is often more pipe than owners expect. Height is governed by its own national rule, and we keep the full requirement on the dedicated chimney height guide rather than summarising it here. Work out your termination height first, then count lengths, because doing it the other way round is how people end up one section short on installation day.

Installation Requirements

The route matters more than the tools. Keep the horizontal section short and level or slightly rising, land it on the tee, then support the vertical stack from the base and band it to the wall at the stated intervals. Keep the whole run clear of gas meters, vents, windows and overhanging eaves. Fit the thimble so the pipe is centred with its listed gap on all sides.

Plenty of our customers do the physical work themselves and have it inspected. Our warranty asks that the system is installed according to the supplied instructions, whether the work is carried out by the owner or by a contractor, so fitting it yourself does not reduce your cover. The full terms are on our warranty page.

Can You Use An 8in Chimney For Both A Stove And A Fireplace?

One appliance per flue. An 8in Class A chimney can serve a wood stove or a fireplace insert, whichever one is connected to it, but never both at the same time on a shared flue. Two appliances on one chimney interfere with each other's draft and can push combustion products into the room. If you have a stove and an open fireplace, each needs its own system.

Insulation, Steel And Temperature Rating

The insulation between the two stainless walls is what keeps flue gas hot enough to draw properly and keeps the outer wall safe to sit near combustibles. On an exterior chimney it does even more work than indoors, because the whole stack is in the cold air. A warm flue means stronger draft, less condensation and slower creosote build-up. Our Class A system is 304 stainless and rated for 1000°F (538°C) continuous use.

Maintenance And Cleaning

Sweep at least once a season, more often if you burn softwood or damp wood. An exterior system makes this easy: open the clean-out cap at the bottom of the tee, brush down from the top, and the debris drops where you can collect it. While you are up there, check the wall bands, the storm collar seal and the termination for corrosion or nesting. Burn seasoned wood only, and if you live in the Puget Sound area, check the local burn status before you light up.

In the Puget Sound region (King, Pierce, Snohomish, Kitsap counties), the Puget Sound Clean Air Agency (PSCAA) issues Stage 1 and Stage 2 burn bans during forecast PM2.5 air quality episodes. Stage 1 prohibits the use of uncertified wood-burning devices; Stage 2 prohibits all wood burning except where a wood stove is the home's sole adequate source of heat.

Common Problems With Exterior 8in Chimneys

• Weak draft on cold starts: normal on an outside stack. Warm the flue with a small kindling fire before loading.
• Too much horizontal run: every extra inch sideways costs draft. Keep it as short as the wall allows.
• Undersized support: the base support carries the stack, not the thimble. Fix it into solid structure.
• Mixed brands: joints from two systems rarely seal properly. One matched line avoids it.
• Oversized flue: an 8in chimney on a 6in stove runs cool and sooty.

Warranty, Returns And Delivery

We back the Class A system with a limited lifetime warranty: 100% of the original purchase price for the first 15 years, and after this period replacements are offered at 50% of the original price, for as long as the original consumer owns the system. Returns run 14 days, no questions asked. Orders ship from the nearest warehouse, with small orders often going next day and up to 5 business days for larger shipments.

Talk To A Specialist Before You Order

Send us your stove model, wall construction and roof height and we will design the flue for you at no charge, part by part, so your first order is the right one. Call 888-834-0880 or use our Expert Advice service.

Need more information?

• Frequently asked questions
• Wood stove pipe installation guides
• Expert advice