TL;DR
Cleaning the firebox and hearth is a homeowner job; cleaning and inspecting the chimney is not. Ash must be fully cold -- embers can stay hot for days -- and it must go into a metal container with a lid, never a paper bag or a plastic bin. Book the chimney inspection before the first fire, because that is the part that prevents a chimney fire, and no amount of hearth cleaning substitutes for it.
Why the first fire of the season is the risky one
A fireplace that has not been used since spring has had months to accumulate problems that nobody has looked at.
Creosote from last season is still lining the flue. It is the tarry residue of incomplete combustion, it is flammable, and it builds with every fire. A season of it does not disappear over summer.
Animals move into idle chimneys. Birds, squirrels, and wasps all nest in flues over spring and summer, and a nest is both a blockage and fuel.
Debris falls in. Leaves, twigs, and roofing grit accumulate in an unused flue.
And the damper may have been left in a position nobody remembers, or may have seized.
A blocked or restricted flue pushes combustion products back into the room instead of up the chimney, and that is a carbon monoxide risk rather than a nuisance. This is the reason the sequence starts with an inspection rather than a broom.
What should you do before the first fire of the season?
Book a chimney inspection and sweep first, then clean the firebox, glass, and hearth, and test smoke and carbon monoxide alarms. Do not light a first fire on an uninspected flue. Creosote buildup, animal nests, and debris are all invisible from inside the room.
The chimney is a separate trade
This is the part to be clear about, because it is where people substitute effort for expertise.
Chimney sweeping and inspection is a specialist trade. A qualified sweep evaluates the flue liner, measures creosote buildup, checks the damper and the cap, looks for cracks in masonry and liner joints, and removes blockages. None of that is visible from a living room.
Have this done annually for a fireplace in regular use, and always before the first fire after a long idle period.
A gas fireplace or insert has its own service requirements and should be inspected by a qualified technician. Gas logs, pilot assemblies, and venting are not homeowner maintenance.
Wood stoves and inserts follow the manufacturer's servicing schedule.
Do not attempt to clean a flue with a chimney-sweeping log or similar product and treat it as equivalent to a sweep. Those products are marketed as an aid, not a replacement for inspection.
Cleaning the firebox
Once the chimney side is handled by a professional, the firebox is straightforward.
Wait for cold. Ash can hold live embers for several days after a fire looks out. This is not a caution to skip. Check with the back of a hand held above the ash before starting, and if there is any doubt, wait longer.
Use a metal container with a metal lid for ash removal, and put it outside on a non-combustible surface away from the house, deck, or fence. Never use a paper bag, a cardboard box, a plastic bin, or a vacuum not rated for ash. A household vacuum pulls fine ash straight through the filter into the room, and a live ember in a vacuum is a fire.
Leave a thin ash layer in a wood-burning firebox if you like, since about an inch helps a new fire establish. Remove the rest.
Scoop rather than sweep to start, so fine ash is not launched into the room. A shovel and a bucket beat a brush for the bulk of it.
Then brush the walls and floor of the firebox with a stiff brush and vacuum with an ash-rated vacuum.
Do not wet-clean firebrick. Water and masonry cleaners can push soot deeper into porous brick and stain it. Dry removal first, always. The general method is covered in fireplace and hearth cleaning basics.
Cleaning fireplace glass
Glass doors on an insert or stove develop a brown or black film that is baked-on combustion residue rather than ordinary dirt.
The classic approach uses the ash itself. Dampen a piece of newspaper or a cloth, dip it in fine white ash, and rub the glass. The ash is a mild abrasive that works on this specific residue, and it costs nothing.
Follow with a clean damp cloth and dry.
Never use an abrasive pad, steel wool, or a razor blade on fireplace glass. Most of it is a ceramic glass that scratches, and a scratched panel is a weakened panel.
Do not clean the glass while it is hot. Thermal shock can crack it.
Do not use an ammonia-based glass cleaner on a hot or warm panel, and do not mix cleaning products while working on a fireplace.
The hearth and surround
The hearth is the horizontal surface in front, and the surround is the material framing the opening. Both need matching to their material.
Brick and stone. Vacuum first, then clean with plain water or a pH-neutral cleaner. Related handling is in how to clean a brick patio.
Marble, travertine, or limestone. These are acid-sensitive, and vinegar or lemon etches them permanently. pH-neutral only, and test any product in an inconspicuous spot.
Painted or wood mantels. Dust, then wipe gently. Degreasers can burnish paint, so test first.
Tile. Standard cleaning, but check the grout, which absorbs soot and may need a soft brush and an oxygen-based product rather than chlorine bleach.
Soot on a wall above a fireplace is a sign of a draft or combustion problem worth mentioning to the sweep, not just a cleaning task.
The rest of the pre-season checklist
Test every smoke alarm and carbon monoxide alarm in the house, replace batteries, and replace any unit past its expiration date. This is the single most important item on the page.
Clear the area in front of the hearth. Nothing combustible within the clearance the manufacturer or code specifies.
Check that the damper opens and closes freely and that you know which position is which.
Store firewood outside rather than indoors in quantity, since stacked wood brings insects in.
Season the wood properly. Wet or unseasoned wood produces far more creosote, which is what makes the next inspection worse.
Pair this with the rest of the heating startup work described in heating startup dust and what to clean first and the register cleaning in how to clean vent covers and registers.
FAQ
How long should you wait before cleaning out fireplace ash?
At least several days after the last fire, because embers can stay hot inside an ash bed far longer than the surface suggests. Hold the back of a hand above the ash to check for warmth, and if there is any doubt at all, wait longer rather than testing it.
What should you put fireplace ashes in?
A metal container with a metal lid, placed outside on a non-combustible surface away from the house, deck, and fence. Never use paper, cardboard, or plastic, and never use a household vacuum, which both passes fine ash through the filter and risks drawing in a live ember.
How do you clean fireplace glass without scratching it?
Use fine white ash on a damp cloth or a piece of damp newspaper, then wipe with a clean damp cloth and dry. The ash is a mild abrasive suited to baked-on combustion residue. Never use steel wool, an abrasive pad, or a blade, and never clean the glass while it is hot.
Do you need a chimney sweep every year?
Yes for a fireplace in regular use, and always before the first fire after a long idle period. A sweep evaluates creosote buildup, the flue liner, the damper, and any animal nests or debris, none of which can be assessed from inside the room. This is a specialist trade, not a homeowner task.
Can you clean a chimney yourself?
Cleaning the firebox, glass, and hearth is a homeowner job. Cleaning and inspecting the flue is not, because the risks are creosote fires and blocked venting, and evaluating a liner requires training and equipment. Chimney sweeping logs are marketed as an aid and do not replace an inspection.
Should you leave ash in the fireplace?
A thin layer of about an inch is fine and even helpful in a wood-burning firebox, since it insulates the base and helps a new fire establish. Remove the rest, because a deep ash bed restricts airflow and holds embers longer than most people expect.
Getting a house ready for the heating season touches a lot of rooms at once. If you want the indoor seasonal reset handled while you book the sweep, get a quote or read more about house cleaning services.