Guides
Plain-English background to the numbers behind the calculators — how to measure a fireplace opening and flue, how the 1/10 flue rule works, the 3-2-10 height rule, chimney liner types compared, the NFPA 211 inspection levels, creosote stages and chimney-fire risk, when to repair vs rebuild, tuckpointing vs rebuilding, when to reline, masonry vs factory-built chimneys, gas vs wood fireplaces, cap & damper basics, and how chimney draft works.
How to measure a fireplace opening & flueHow to measure a fireplace opening and existing flue correctly, so the 1/10 rule and your liner order land on a real size — with a worked 34x27 example.How the 1/10 flue rule works (round vs rectangular)The 1/10 rule in plain terms: a round flue at least 1/12 of the opening, a rectangular one at least 1/10 — why round wins, and how to convert between them.The 3-2-10 chimney height rule explainedHow tall must a chimney be? The 3-2-10 rule is the larger of two clearances: 3 ft above the roof, and 2 ft above anything within 10 ft. Worked example inside.Chimney liner types compared: clay, stainless, cast-in-placeClay tile, stainless or cast-in-place? What each liner costs, where each wins, and how to pick for a reline or an appliance conversion — with a comparison.What the NFPA 211 inspection levels mean (1, 2, 3)Level 1, 2 or 3? What each NFPA 211 chimney inspection covers, when the code triggers a Level 2 camera scan, and why the situation sets the level.Creosote stages 1-3 and chimney-fire riskCreosote builds in three stages, from brush-off soot to hard glaze. What each stage looks like, why Stage 3 fuels chimney fires, and what removal takes.Signs your chimney needs repair vs a rebuildWhite staining, spalling brick, a cracked crown, a leaning stack — how to read the signs and tell a small repair from a full rebuild before you get a quote.Tuckpointing vs rebuilding: when repointing is enoughRepoint the joints or tear it down? How to tell whether tuckpointing will save a chimney or you are paying for masonry that needs a rebuild, with cost math.When to reline a chimney (and what it costs)A cracked flue, an appliance conversion or an oversized chimney all call for a reline. The triggers, how liner length is measured, and a worked 24-foot cost.Masonry vs factory-built chimneysBrick-and-mortar or a metal prefab? How masonry and factory-built chimneys differ in cost, lifespan, repair and install — and which suits a new fireplace.Gas vs wood fireplace basicsReal flame and wood to haul, or a switch and instant heat? How gas and wood fireplaces differ in install, venting, running cost and upkeep — before you pick.Chimney cap & damper basicsA cap keeps water, animals and sparks out; a damper seals the flue. How to size a cap so it does not choke the draft, and throat vs top-mount dampers.How chimney draft works (height, temperature, stack effect)Draft is what pulls smoke up — it grows with chimney height and the hot-cold temperature gap. What strengthens it, what kills it, and why it is theoretical.How to estimate tuckpointing cost (the joint takeoff)Three different things get quoted as a linear foot of tuckpointing. How to take off joint footage on a chimney, convert a per-square-foot rate, and price it.Chimney clearance to combustibles: the 2-inch air spaceA factory-built chimney needs a 2-inch air gap to combustibles all the way up. What that air space does, how to frame for it, and where it gets closed off.Firebox repair vs replacement: which one you actually needFirebox repair or replacement? The decision ladder from repointing joints to a new refractory panel, with the brick-count crossover and a worked example.Clay flue tile sizes: nominal, actual and what fitsClay flue tile sizes are nominal, not actual. How to find the inside area you really have, what each standard size supports, and how to read a rectangular flue.