Start with the damper
A closed or partly closed damper is the simplest cause. Open it fully and check it moves freely.
A stuck damper needs repair.
A cold flue
A cold chimney holds a plug of cold air that fights the fire at the start. Warm the flue with rolled paper held up to the damper before lighting.
A top-sealing damper also helps.
Blockages
Nests, leaves, a clogged cap or heavy creosote narrow the flue and block the smoke.
A sweep and a cap fix this.
Flue and chimney design
A flue too big or too small, a chimney that is too short or a rough smoke chamber all hurt the draft.
These need a professional diagnosis.
House pressure
Tight houses with exhaust fans, dryers and furnaces pull air down the chimney. Opening a window slightly can show if that is the cause.
Providing makeup air helps.
Wind and trees
Nearby trees, tall buildings and roof lines can push wind down the flue. A taller chimney or a special cap may help.
We assess the site.
Open the damper, warm the flue and light the fire hot, and call for a diagnosis if it still smokes.
