Installing a Tiny House Wall Exit Flue System

Please excuse our dust as this guide is under construction.  We'll be updating images and links on this page, and fixing formatting issues over the next few weeks.  If you have any questions about your install, please shoot us an email at support@tinywoodstove.com.

Before you begin:

  • Your flue design should be complete, and you should have all the required components on hand.  The install kit is the "base kit" that includes the parts that most everyone needs.  Since every structure is different, people need varying amounts of pipe in addition to the kit.  Consult our flue design resources (link) or contact us (link) for help desigining your flue system.
  • Your stove should be assembled and your hearth built.  Consult the Dwarf Manual (link) for instructions on your hearth, proper clearances, and heat shields.  Watch the unboxing video (link) for help with stove assembly.  If you're building in a mobile structure like a Tiny House on Wheels, the structure should be level before you start work. (Links to stove assembly, hearth design).

You Will Need:

  • Screwdriver
  • Ladder
  • Level and/or plumb bob
  • Wax pencil or sharpie
  • Tools to cut a hole in your exterior wall.
  • Fasteners to attach your flange to your wall inside and out, and to attach the tee support and wall support to the exterior of your structure
  • Latex or silicone caulk to seal behind the thimble flange on the exterior of your structure

You May Need:

  • Chop saw or angle grinder with a metal cutoff blade to cut single-wall pipe.
  • Sheet metal crimpers to adjust crimps.
  • Stovepipe screws if you're not using clamps to secure your joints.
  • Drill
  • Stud sensor

Step 1: Attach your stovepipe to the flue flange.

The first section of stovepipe needs to be sealed to the stove's flue flange with stove cement.  Since the stove needs a flue system to function, and both the stove cement and the stove's paint are heat cured (which can generate some chemical fumes), we recommend curing the stove paint and the cement outside, at the same time.

Cover the inside of your flue flange and the outside of the male end of your pipe with stove cement, and connect them together.  Use a bubble level to ensure that both your stove and your stovepipe are perfectly plumb.

Thoroughly clean off any excess stove cement before firing your stove.  It is very difficult to remove stove cement once it's cured.

Stovepipe screws are not required to secure stovepipe into the flue flange, but can be optionally added for additional security, or to hold the stovepipe in place until the cement cures.  If you choose to add screws, use three heat-proof screws evenly spaced around the flue flange, and drill pilot holes through the the flue flange and stovepipe before installing them.

Add additional sections of stovepipe to get at least 40" of vertical pipe, and build a fire in your stove outdoors to complete your initial cure according to the instructions in the Dwarf Manual.

Once your stove is cooled, move it back inside and secure it in place on the hearth.

Tip: If you're exiting through the wall directly behind the stove's flue flange before turning to vertical, it may not be practical to do an outside burn before installing.  Seal the first section of stovepipe into the flue flange as described in this step, and then ensure your structure is well ventilated when performing your first burn inside.

Tip: If you're connecting insulated pipe directly to the stove's rear flue flange, the inner wall of the stovepipe will need to be crimped to fit inside the flue flange.  We can do that for you prior to shipping your order, or you can do it yourself with a set of sheet metal crimpers.  Crimp the pipe only as many times as needed for the pipe to bottom out on the flue flange.  Over-crimping will make the pipe loose inside of the flange.  Apply the stove cement to the outside of the inner wall, and the inside of the flue flange.

Tip: If the pipe is very loose inside of the flue flange, a thicker stove cement might be helpful.  High heat furnace cement sold in a tub works well.  Try to find it in black for best results.

Step 2: Cut the hole through your wall.

The hole in your wall needs to be aligned with the pipe attached to your stove, and should be large enough to allow the center of the thimble to fit through the hole.

Determine the center point where your flue will penetrate the wall.  If you're exiting at a point above your stove, make sure the wall penetration is centered vertically above the stove's flue flange.  If you're exiting directly behind the stove before turning to vertical, make sure the center of the hole in the wall is precisely lined up with the center of the rear flue flange.

Mark the area around the center point where you'll need to cut material away to allow the thimble to pass through the wall.  You can separate the two halves of the thimble and use the thimble itself as a template for your cut.  The 4" thimble needs a 10" diameter hole, and the 5" thimble needs an 11" diameter hole.

Make sure the point you're putting your chimney through doesn't intersect with any studs, pipes, or wires.  A stud sensor can help to detect studs, but may not indicate the presence of wires or pipes.  If you're not sure, make a small exploratory hole in the interior wall first to get a look.

Cut out your hole in the wall with an appropriate tool for your wall material.  A scroll saw or reciprocating saw tend to work best for wood, while a sheet metal nibbler typically works best for sheet metal.

Inside of your wall, cut away any remaining insulation or other material in the way of the thimble.  Install both thimble halves from opposite sides of the wall and secure in place with fasteners appropraite for your wall material.  Insulation can touch the outside of the thimble, but there should be no insulation or other material inside of the thimble.

Use exterior grade silicone or latex caulk behind the top and sides of the exterior thimble flange and the exterior wall of the house to prevent driving rain from entering the wall behind the thimble.  Leave a gap in the caulk at the bottom of the flange to allow moisture to drain away freely.

Tip: The thimble is designed for 2x4 or 2x6 walls.  If the wall is too thin for the thimble, you can remove material from both sides of the thimble with an angle grinder to make it thinner.  If the wall is too thick, you may need to add additional 24 gauge sheet metal around the thimble to ensure clearances to combustibles are properly enforced.   The two sides of the thimble must overlap so that it's not be possible for anything (insulation, rodents, etc) to reach the inside of the thimble from the inside of the wall.

Step 3: Install your Stovepipe

With your wall thimble installed, you'll now build your flue system and attach your exterior chimney to your structure.

Assemble your stovepipe using a clamp at each joint to secure the pipes together.  Alternatively, three stovepipe screws can be used to secure each joint.  No cement or caulk is required or recommended at pipe-to-pipe joints.

Attach the cleanout cap (part of the insulated tee) to the bottom of the tee support bracket.  Attach the tee support bracket to the bottom of the tee.  Attach the two triangular brackets to the underside of the tee support bracket, and align the bracket so that the wall side of the supports are facing the same direction as the opening on the side of the tee (i.e. the "tee leg").  Attach the insulated pipe used for the horizontal run (typically a 10" section) to the side of the tee, and attach the single-to-double adapter to the other end.

Place the horizontal insulated pipe through the wall thimble from the outside of the structure, with the tee support bracket touching the exterior wall.  Verify that the inside of your pipe lands where you need it, and adjust the tee support bracket accordingly.  Then center the pipe in the thimble (there should be a small amount of space between the inside of the thimble and the outer wall of the pipe).  Using a bubble level to ensure the thimble is oriented perfectly vertically, and fasten the tee support bracket to the exterior of your structure.

Connect the remaining single-wall pipe from your stove to the 90 degree elbow connecting to the single-to-double adapter, using a single-wall clamp or three stovepipe screws at each joint to fasten the sections together.

The center joint of the telescoping pipe is meant to be free-floating and does not need to be clamped or screwed.

Single-wall pipe can be cut to achieve the length you need.  Cut the pipe with a chop saw or angle grinder with a metal cutoff blade.  You can use a single-wall clamp as a guide and a sharpie or a wax pencil to mark your cuts.  Cut the female end off and preserve the factory male end on the piece you're going to use.

You can cut the female end off a longer single-wall pipe and insert the top of the telescoping pipe inside of it to make a longer telescoping section.

Tip: If you find yourself trying to attach a male end of a pipe to another male end, or a female to a female, then one of the pipes is upside-down.  Single-wall and inner wall male ends point down (toward the stove) to contain condensing liquids or creosote inside the flue system.  Outer wall male ends point up, to allow rain water to shed outside of the flue system.

Tip: If you are installing a flue system on a structure that moves, you may want to plan your flue system so that you have a joint as low as possible above the roof line, which will allow you to detach the above-the-roof chimney parts for travel.  See: Detachable Chimneys for Mobile Wood Stoves.

Tip: If you're having trouble getting insulated pipes joints to bottom out, check that the metal trim ring on the end of the insulated pipe pushed fully into the groove that mates with the clamp.  If the trim ring is not fully seated, it may prevent the piece below from bottoming out.

Tip: The insulated pipe must extend far enough into the room to avoid a clearance violation from the single-wall pipe and the rear of the stove.  A heat shield is usually required for the standard wall exit configuration.  Ensure there is at least 18" clearance to combustibles from the single-wall stovepipe and the rear of the stove, or use heat shields to reduce the required clearance.

Step 5: Assemble your chimney.

Assemble your vertical chimney on the outside of your structure by connecting the insulated pipes together and securing with clamps.  Install the wall support bracket as high as possible on your structure, up to 6 feet above the tee support bracket.  If there is more than 6 feet of pipe above the tee support bracket and below the roof line, you should use additional wall support brackets evenly spaced, at least one every 6 feet.

Attach the roof vent to the top of your chimney.

If you are using an extended chimney support bracket, install the clamp on the pipe at least 3' above the roof line and no more than 5 feet from the top.  Adjust the arms of the bracket to reach points on the high side of the roof on either side of the chimney.  A 60 degree arm angle relative to the vertical chimney is ideal.  Secure the feet of the arms to the roof using appropriate roofing fasteners and roofing sealant.  We recommend applying sealant to the threads of each fastener prior to installing it, then burying the entire foot in roofing sealant.

Install the roof vent on the top of the chimney and secure with a double-wall clamp.

Step 6: Inspect your completed installation.

Ensure chimney is properly supported.  The roof support bracket should fully support the weight of the chimney.  If the chimney stands 5' or taller above your roof line, it should be reinforced with an extended support bracket.

Ensure every pipe-to-pipe joint has either a clamp or three stovepipe screws (except for the center joint of the telescoping pipe which is free-floating).

Check for clearance violations around your stove and your flue system.

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