Duravent DuraTech chimney planner

5"–8" all-fuel chimney · parts from catalog DV_DT_CT-001E (Aug 2026)

These answers are an example: a one-story ranch with a wood stove. Replace them with your own measurements.
How to measure
  • Heights start at the floor the stove or fireplace stands on.
  • Positions are at the chimney's center: the middle of where the hole will be.
  • One exception: the distance to the ridge is measured from the chimney's uphill (higher) side, because that is where the roof is closest to the top of the chimney.
1 Appliance Information

The chimney must match it.

ft in

Stove height with legs or pedestal.

Top of the fireplace unit.

From your manual Optional

Look in the venting or chimney section of the installation manual. Leave anything blank that the manual doesn't state. Where the manual and Duravent differ, the planner uses the stricter value.

ft

Measured from the top of the flue collar to the top of the chimney.

ft
Your layout Fill in the installation below.

Many manuals have a height table by number of elbows, tees, horizontal run and elevation. Find the row that matches and enter its minimum height above.

An offset is a pair of elbows around framing. DuraTech allows 2.

in

Often a note on rear or wall venting, e.g. "min. 24 in vertical rise".

in
2 Chimney Configuration
ft in
ft in

Measured in the second-floor room, from its floor to its ceiling where the chimney passes.

Not needed for the parts list: the chimney goes from this room straight out the roof.

in

From the stove room's ceiling to the second floor's surface. Usually 10"–14".

Where it comes out

A chase is a framed box around the chimney above the roof. The roofer flashes the chase, so no roof flashing is needed.

Does the chimney go straight up?

An offset is a pair of elbows that shifts the chimney sideways to clear a joist, rafter or ridge beam. DuraTech allows up to 2. The shifts listed are the ones Duravent's elbow chart makes, so pick the one at or just above the shift you need; a smaller shift than the chart's smallest can't be built.

Height available is the vertical room where the jog happens, for example from the top of the ceiling joists to the underside of the rafters. With Auto, the planner uses 15° elbows if they fit and 30° if not. The line under each offset shows the shift, the height it takes and what's left over.

in

Whole wall: drywall, framing, sheathing and siding or brick veneer with its air gap.

ft in
in

Level distance from the collar's center to the inside wall. Counts as horizontal run.

in

2"–6", set by the tee support.

ft in
ft in

Highest point a wall strap can attach, usually the eave.

Offsets on a through-the-wall chimney, for example to get around an eave, aren't supported yet. The planner runs the chimney straight up the outside wall.

Does the chimney go straight up?

An offset is a pair of elbows that shifts the chimney sideways to clear framing in the chase or a rafter. DuraTech allows up to 2. The shifts listed are the ones Duravent's elbow chart makes, so pick the one at or just above the shift you need; a smaller shift than the chart's smallest can't be built.

Height available is the vertical room where the jog happens, for example from the top of the ceiling joists to the underside of the rafters. With Auto, the planner uses 15° elbows if they fit and 30° if not. The line under each offset shows the shift, the height it takes and what's left over.

Floors or ceilings the chimney passes through

Height of each above the fireplace's floor.

2b Chase Information
ft in

From the floor the appliance stands on up to the top of the chase framing. A chase built on the roof starts at the roof, so its top is higher than the roof height in section 4.

in
in

Duravent's chase top flashing is a square of about 18¾" to 21¾", depending on chimney size. A bigger chase needs a cover made by a sheet-metal shop; the parts list will say so.

Use what your inspector or plans call for. Duravent requires at least 6" from the chase top flashing to the bottom of the cap under every choice, and the roof and anything within 10 ft are always checked too.

in

6" or more. The planner rounds up to whole pipe sections, never down.

3 Attic Information

The attic is where the chimney gets its attic insulation shield and where an offset usually goes, so the planner needs to know how much open space is up there. Measure in the attic, directly above where the chimney's center will be.

Where your tape measure starts
ft in

Straight up to the underside of the roof boards (sheathing), not to the bottom of a rafter.

in

Actual size: 2×6 = 5½", 2×8 = 7¼", 2×10 = 9¼", 2×12 = 11¼".

in

Usually ½" or ⅝". Plaster ceilings run about ¾"–1".

underside of roof boards chimney center top of joists J top of drywall C D ceiling below

4 Roof Information

Rise in inches per 12" of level run.

ft

Measured level from the chimney's uphill (higher) side, its outer wall, to the ridge. Leave blank if more than 10 ft.

Height of the roof where the chimney comes out

The chimney's height is measured from this spot, so the planner needs to know how high it is.

ft in

From the stove's floor level up to the top of the roof edge (the eave). Outside, measure from the ground and adjust for how far the floor sits above it.

ft

Measure on the ground, from below the roof edge to below the chimney's center. Include the overhang.

in

Sheathing plus roofing, usually about 1" for shingles. Added to the attic measurements in section 3 to reach the top of the roof.

ft in

From the stove's floor straight up to the top of the roofing at the chimney's center.

stove's floor A B roof height at the chimney
Roof height = A + B × pitch. On a 6/12 roof, every foot of B adds 6".

Anything else within 10 ft of the chimney

A dormer, an upper roof, a gable edge. The chimney must be 2 ft higher than each.

5 Chimney Options

Sets the cathedral support box height.

Site elevation

Thinner air draws less, so high-altitude chimneys usually need to be taller. Below 2,000 ft, leave this unticked.

ft