Installing a Tiny House Roof 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 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.  If you're building in a mobile structure like a Tiny House on Wheels, the structure should be level before you start work.

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 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.

Tip: If you're connecting insulated pipe directly to the stove's flue flange for an all-insulated chimney, 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 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.

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.

(Optional) Install Screws

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 vertically 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.

If you're installing your chimney through a standing seam metal roof, it's best to try to locate the base of the pipe boot in the flat area between seams.  It's possible to conform a pipe boot up and over a seam, but it's more difficult to create a watertight seal.

Before cutting a hole in your roof, make sure your pipe boot or metal flashing 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.  Alternatively, remove the stove's baffle and shine a flashlight up through the stovepipe to project the location on the ceiling.

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 (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.

Tip: If you roof is pitched, your cutout will need to be oval. 

Tip: In addition to the obvious combustibles like wood sheathing and paper vapor barrier, spray foam (including fire rated foam) and drywall (including fire rated drywall) are also combustible.  It's generally best just to cut away everything within 2" of the pipe.

Cut the Hole through the Roof

Make sure the area your pipe will pass through doesn't intersect with any joists, 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.

Add Shielding if Necessary

If you're using loose fill insulation that could fall into the pipe, or have more than a few inches between the ceiling and the roof sheathing, you may need to add some shielding inside the ceiling to enforce the 2" clearance around the insulated pipe.

If your pipe passes through a second story, a loft, or an attic, 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 chimney pipe to your structure.

If you are using a metal flashing, skip to step 4 and install your flashing first, and then return to step 3.

Tip: 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 Chimney

Assemble all of your insulated pipe with the single-to-double adapter on the bottom and the roof vent on top.  Measure the distance from the chimney opening to the point where your pipe will pass the roof line as determined by the 3-2-10 Rule, and mark that point on your pipe.  Remove all the parts above your mark to make it easier to maneuver your pipe.

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

Determine the proper position of your roof support bracket relative to the mark you just made and clamp it in place on your pipe.  The insulated pipe must drop low enough below the ceiling to avoid a clearance violation from the single-wall pipe below it.  Ensure there is at least 18" clearance to combustibles from the single-wall portion of the single-to-double adapter in any direction, or use heat shields to reduce the required clearance.

Fasten the base of your roof support bracket L-brackets to your structure to support the weight of your chimney.  Ensure your stovepipe is plumb, and tighten the bolts holding the L-brackets in place to hold your pipe in place.

Tip: The roof support bracket can be installed on top of the roof under the pipe boot, or on the ceiling above the ceiling trim plate, upside-down or right-side up, whichever makes the most sense for your installation.  It's generally best to install the bracket somewhere that leaves it accessible for future maintenance, so installing it directly under the pipe boot or flashing may not be the best option. If you do install the bracket under the pipe boot or flashing, you may need to trim the sides of the L-brackets and the top corner of the clamp with an angle grinder to get it to fit under the boot or flashing.  Do this before attaching the bracket to your stovepipe.

Tip: 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 adapter from bottoming out.

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 male 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:  Single-wall male ends should point down toward the stove to contain any condensing liquids or creosote inside your flue system.

Step 4: Create a watertight roof seal.

Your pipe boot or flashing 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 the ideal choice for flashing a non-porous roofing material like metal or rubber.  Pipe boots are generally not compatible with porous roofing materials like asphalt or cedar shingles, or slate or tile roofs, and a metal flashing should be used with those materials instead.  Hybrid pipe boots with sheet metal bases can be installed under shingles or tiles similar to a metal flashing, but do not need sealant between the boot and the pipe, and don't require a storm collar.

Installing a Pipe Boot

Ensure that the underside of your pipe boot flange 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).

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.

Install your pipe boot onto your insulated pipe with the metal side of the flange pointing up.  Push your flange down your pipe until the flange is fully in contact with your roof.  If your pipe boot has a square base, 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.  If installing over a seam on a standing seam roof cannot be avoided, pay special attention to the area up and over the seam to ensure that the boot flange is properly bent and secured to tightly conform to the seam.

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.

A storm collar is optional if you are using a pipe boot.  If using a storm collar, install the collar immediately above the pipe boot, and seal between the pipe and the storm collar with high-temp RTV silicone.

Installing a Metal Flashing

Your metal flashing should fit the outside diameter of your stovepipe, and the pitch of your roof.  The flashing should be layered with shingles or tiles to prevent water from penetrating under the flashing.  The bottom of the flashing should sit on top of the layer of shingles or tiles below it, and the top of the flashing should be covered with a couple of courses of shingles or tiles, and lay directly against the roofing underlayment.

New Roofing

Cut the hole for your stovepipe in your roof, then shingle or tile up to the roof hole.  Layer the flashing into the roofing, using appropriate fasteners to attach the sides of the flashing to the roof.

Seal over the fasteners and under the top and sides of the flashing with roofing sealant to prevent water penetration.  Do not seal under the bottom so that any water that gets under the flashing is able to drain away.

Seal the area between the stovepipe and the top of the flashing with high-temp RTV silicone.  Install the storm collar (required) immediately above the top of the flashing, and seal between the storm collar and stovepipe with high-temp RTV silicone.

Existing Roofing

Cut the hole for the stovepipe in your roof, then slide the top of the flashing under at least two courses of shingles to center the flashing over the hole.

Seal over the fasteners and under the top and sides of the flashing with roofing sealant to prevent water penetration.  Do not seal under the bottom so that any water that gets under the flashing is able to drain away.

Seal the area between the stovepipe and the top of the flashing with high-temp RTV silicone.  Install the storm collar (required) immediately above the top of the flashing, and seal between the storm collar and stovepipe with high-temp RTV silicone.

Step 5: Assemble your chimney.

Add any additional sections of insulated pipe to reach the height needed, securing each joint with a double-wall clamp.

Add Bracing if Needed

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.

Cap Your Chimney

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 completed installation.

Verify Chimney is 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.  The entire flue system should be sturdy and stable.

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).  Joints are not required to be airtight, only structurally secure.

Check Clearances

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

The stove requires 18" clearance from the back or 16" to the sides.  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 stove/pipe and any combustible materials.

Insulated pipe requires 2" clearance to combustibles in all directions.

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, or call us at 208-352-3417.

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