Installing a Roof Exit Flue System in an RV, Bus, or Van

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 or contact us for help designing your flue system.
  • Your stove should be assembled and your hearth built.  Consult the Dwarf Manual for instructions on your hearth, proper clearances, and heat shields.  Watch the unboxing video for help with stove assembly.
  • Your vehicle should be level and wheels chocked.

You Will Need:

  • Screwdriver
  • Ladder
  • Level and/or plumb bob
  • Wax pencil or sharpie
  • Tools to cut a hole in your ceiling/roof.
  • Fasteners to attach your pipe boot to your roof, your roof support bracket to your ceiling or roof, and your ceiling trim plate to your ceiling
  • Silicone or urethane roofing sealant to seal the pipe boot flange to your roof

You May Need:

  • Chop saw or angle grinder with a metal cutoff blade to cut single-wall pipe.
  • Sheet metal crimpers to adjust crimps.
  • High-temp RTV silicone if using a metal flashing or a storm collar
  • Stovepipe screws if you're not using clamps to secure your joints.
  • Scissors to trim your pipe boot
  • Drill

Step 1: Attach stovepipe to 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.

If you're connecting insulated pipe directly to the stove's flue flange for an all-insulated chimney, the inner wall of the pipe 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 sheet metal crimper.  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 Stove Cement

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.

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.

Install Screws (Optional)

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.

Complete Outside Burn

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.

Step 2: Cut the hole through your roof

The hole in your ceiling needs to be aligned with the pipe attached to your stove (unless you're offsetting your chimney with elbows), and should be large enough to allow the insulated pipe to pass through without violating clearance to combustibles inside the ceiling.

Before cutting a hole in your roof, make sure your pipe boot will adequately cover the hole, and that you have all the materials on-hand to seal up the hole.  Also consult the directions on your roofing sealant and the weather report to ensure that conditions will allow it to properly cure (i.e. not too cold, and not raining).

Mark Your Center Point

Determine the center point where your flue will penetrate the ceiling.

If you're going straight up from your stove, you can use a plumb bob to locate the center, or shine a flashlight up through the stovepipe to project the location on the ceiling.

Finding level when working in a vehicle can be maddeningly difficult, since "level" tends to change slightly every time you move the vehicle.  Sometimes it's easiest just to reference the pipe's distance from nearby vertical walls at the top and the bottom to ensure the pipe is plumb relative to its surroundings.  Large deviations from vertical can negatively affect your draft, but fudging the angle by a couple of degrees to make the pipe look straight relative to a nearby wall is fine.

Roof Install Instructions Drawings-15

Mark Your Clearances

Mark the area around the center point where you'll need to cut material away to prevent clearance violations inside of your ceiling.  Insulated pipe needs 2" clearance to combustibles in all directions.

A 3" insulated pipe, which is 5" outer diameter, needs to pass through a space at least 9" in diameter free of combustibles.  A 4" insulated pipe needs a 10" space, a 5" insulated pipe needs an 11" space.

If your roof is pitched or curved, the hole required for a vertical pipe to pass through it will be oval.

Roof Install Instructions Drawings-06

In addition to the obvious combustibles like wood sheathing and paper vapor barrier, "fire rated" spray foam is also combustible and must be removed to 2" away from the pipe.  "Fire rated" materials are generally designed to block the spread of fire by burning slowly, but they will still burn if sufficiently heated.  It's generally best just to cut away everything within 2" of the insulated pipe.

Cut the Hole through the Roof

Make sure the area your pipe will pass through doesn't intersect with any structural supports, pipes, or wires.  If you're not sure, make a small exploratory hole first to check.

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

Above your ceiling, cut away insulation and anything within 2" of where the pipe will go.

Mark the center point for your roof penetration and drill a small hole through your roof at the center point.  Then, from the top of your roof, mark the sides of your cutout and cut the hole in your roof using an appropriate tool for your roofing material.

Noncombustible metal roofs like aluminum Airstream roofs or steel bus roofs can be closer than 2" to the insulated pipe (but shouldn't touch the pipe).  Cutting away less roof material can help ensure the hole isn't too big for the pipe boot to cover on a steeper pitch.  If you do cut noncombustible roofing material closer than 2" from the pipe, ensure any combustibles below the roof or inside the ceiling like insulation, vapor barrier, or wood sheathing are removed to proper clearances.

Add Shielding if Necessary

If your pipe passes through a cabinet or other large space before hitting the roof, the pipe in that area must be enclosed in a chase to enforce the 2" clearance around the stovepipe.  A chase ensures that people or combustible materials can't accidentally come in contact with the hot pipe.

Step 3: Install your stovepipe

With your ceiling prepped, you'll now build your flue system and attach your stovepipe to your structure.

Assemble Chimney Pipe

Secure the single-to-double adapter to the bottom of the 20" section of insulated pipe with a double-wall clamp.

If you're having trouble inserting the single-to-double adapter or another piece of insulated pipe fully into the insulated pipe above it, check the metal trim ring in the bottom of the insulated pipe.  The trim ring should be pushed fully into the groove that mates with the clamp around the joint.  If the trim ring is not fully seated, it may prevent the piece below from bottoming out.  Push the trim ring in until it is fully seated, and try assembling the pipes again.

Insert Chimney Pipe into Boot

Determine whether your pipe boot needs to be trimmed to fit your pipe.  The hole in your boot should generally be 20% smaller than the diameter of the pipe passing through it, which provides a snug, watertight seal with no additional sealants need.  Most pipe boots include stamped ridges with labels for various pipe diameters.  If necessary, use scissors to trim your pipe boot to the proper size.

Thread your pipe boot onto your insulated pipe with the metal side of the flange pointing up.  If your pipe boot has a square base and your roof is curved or pitched, it's best to orient the corner to the high side of your roof (i.e. like a diamond, not a square), which will give you better coverage and help to shed water away from the flange.

If you are using the recommended detachable chimney, attach the driving cap (sold separately) to the top of the pipe with a double-wall clamp, and adjust the pipe boot so that the top of the boot is just below the bottom of the clamp.  This will ensure you have the shortest possible chimney stub when the detachable chimney is not deployed.

Roof Install Instructions Drawings copy-17

Install the Roof Support Bracket

Assemble your roof support bracket by attaching the L-brackets to the sides of the clamp using the provided bolts.

The roof support bracket can be installed upside-down or right-side up, on top of the roof under the pipe boot, on the ceiling above the ceiling trim plate, or anywhere in between.  The two most popular options are pictured.  Install the support bracket wherever makes the most sense for your installation.  Adjust the position of the bracket until you are satisfied with the placement of the insulated pipe through the roof, and then fasten the bracket to your ceiling.

It's often best to install the roof support bracket on the ceiling to leave it accessible for future maintenance.  For instance if the pipe is damaged by hitting a tree branch and needs to be replaced, it would be easier to do so if the bracket was not buried under the pipe boot.

If you do install the bracket under the pipe boot, you may need to trim the bracket to fit with an angle grinder.  Complete any cutting of your bracket before installing on the pipe to avoid accidentally damaging the pipe.  (1) The sides of the L-brackets may need to be cut to fit under the pipe boot flange.  (2) Depending on the roof pitch, the top corner of the clamp can sometimes interfere with a pipe boot, which can be resolved by flipping the bracket upside-down, or by trimming off the offending corner.  

If you are not using a telescoping pipe to make your final connection, you may need to assemble your single-wall pipe before securing your insulated pipe through the roof.

Build Your Connector Pipe

Connect the remaining single-wall pipe from your stove to the single-to-double adapter, using a single-wall clamp or three stovepipe screws at each joint to fasten the sections together.  No cement or caulk is required or recommended at pipe-to-pipe joints.

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.

Each piece of Tiny Wood Stove pipe has a top and a bottom.  Since the pieces will only fit together in one direction, maintaining the proper orientation is usually straightforward.  If you find a piece won't fit because you have a male-to-male or female-to-female end, something is probably upside-down.

Single-wall male ends (and male inner walls of insulated pipe) should point down toward the stove to contain any condensing liquids or creosote inside your flue system.  Male ends of insulated pipe outer walls should point up to help shed rain water outside of the pipe.  Note that the orientation of the insulated pipe inner wall is opposite the orientation of the outer wall.

Step 4: Create a watertight roof seal

Your pipe boot is critical to keeping water from penetrating your roof.  A properly installed pipe boot or flashing should provide decades of reliable service.

A high-temperature silicone pipe boot is an ideal choice for flashing a non-porous roofing material like metal or rubber.  For installation in a vehicle, the flexible seal of a pipe boot handles even severe bumps and vibrations without compromising its seal.

Pipe boots are generally not compatible with porous roofing materials like asphalt or cedar shingles, or slate or tile roofs, but those types of materials are typically not used on vehicles.

Installing a Pipe Boot

Ensure that the underside of your pipe boot flange (the surface that will touch the roof) and the top of your roof where the flange will sit are clean and dry. Consult the directions on your roofing sealant and the weather report to ensure that conditions will allow it to properly cure (i.e. not too cold, and not raining until the cure is complete).

Verify that your boot is oriented properly.  The metal side of the boot flange should be on top.  If your pipe boot has a square base and your roof is curved or pitched, it's best to orient the corner to the high side of your roof (i.e. like a diamond, not a square), which will give you better coverage and help to shed water away from the flange.

Apply sealant to the underside of your pipe boot flange, then fasten the flange into place with fasteners through the flange and into the roof.  Fastener spacing should be approximately 1" apart, and fastener type is dictated by the roofing material.  Rivets work well for sheet metal.  Pan head stainless screws work well for both metal and rubber roofs with wood sheathing behind them.

The boot flange needs to tightly conform to the surface of the roof.  Fasten from the center outward, and avoid stretching or pinching the boot while fastening.  If installing on a corrugated roof, ensure you have a fastener at the belly of each corrugation to prevent the boot from pulling away from the low spot.

Seal around the perimeter of the pipe boot flange, and over top of each of the fasteners.  Remove any excess sealant.

No sealant is required or recommended where the pipe meets the boot.

Roof Install Instructions Drawings-09

Step 5: Assemble your chimney

Install Remaining Chimney Parts

If you are using a detachable chimney, remove the driving cap and install the extra 20" insulated pipe using the same clamp.

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

Trim Your Ceiling

Install the ceiling trim plate on the ceiling around the insulated pipe.  For pitched ceilings, install half of the plate on the low side of the ceiling first, then install the other half on the high side, overlapping the previous plate.

Step 6: Inspect your installation

Verify Chimney is Supported

Ensure chimney is properly supported.  The roof support bracket should fully support the weight of the chimney vertically, as well as laterally.

Verify Joints are Secure

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 Clearances

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

The Dwarf stove requires 18" clearance from the back or 16" to the sides. Third party stoves may require different clearances, so check your user manual or contact the manufacturer if needed.

Single-wall pipe requires 18" clearance to combustibles. These clearances can be reduced by up to 2/3 with a proper air cooled heat shield between the heat source and any combustible materials.  Insulated pipe requires 2" clearance to combustibles in all directions.

Larger clearances are always acceptable.

Questions?

If you aren't sure about any part of your flue installation, please get in touch!  We are here to help however we can.  You can contact us by email at support@tinywoodstove.com, call us at 208-352-3417, or use the contact form below.

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