Smoke Chamber Repair and Parging: What You Can Do Yourself
The smoke chamber is the area above the fireplace damper, between the firebox and the flue. In many older fireplaces its brick walls are stepped and rough. Parging means coating those walls with a refractory mortar so they're smooth, sealed and insulated. Some products go on by hand, others need a sprayer, and the job is harder than it looks. Everything below ships with No Sales Tax in any state.
Quick answer: smoke chamber parging products
- Trowel or hand pack: HeatShield PriorFire Formula 51, $161.99 for 30 lb.
- By hand, trowel or grout bag: Chamber Safe, $136.99 for 30 lb.
- Parged or troweled: Chamber-Tech 2000, $124.99 for 30 lb.
- Sprayed by a professional: HeatShield Cerfractory Foam, $258.99 for 25 lb, with Adhesion Promoter, $60.99.
All ship with No Sales Tax.
What does a smoke chamber do?
It funnels smoke from the wide firebox into the narrow flue. If the walls are stepped (corbelled) and rough, it's harder for smoke to flow smoothly, and they're harder to clean. Saver Systems and the makers of these products say a parged chamber improves performance and safety, and reduces the heat that gets through the walls.
Saver Systems states that a proper installation of Cerfractory Foam meets IRC and NFPA 211 requirements for parging and smoothing corbelled smoke chamber walls in residential fireplaces.
What can you do yourself?
Be realistic. The chamber sits above the damper, so you're working overhead through a small opening, and the surfaces must be properly cleaned and checked first. Have a certified chimney sweep inspect it before you buy anything, especially if there's any glazed creosote or loose brick. Hand-applied materials are possible for a competent owner on a chamber you can reach. Spray-applied Cerfractory Foam needs a smoke chamber sprayer and a compressor, so it's a professional job.
The materials compared
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| Product | Size | How it goes on | Coverage |
|---|---|---|---|
| PriorFire Formula 51 | 30 lb | Parged, troweled or hand packed | See the instructions |
| Chamber Safe | 30 lb | By hand, trowel or grout bag | 6 sq ft at 1", 4 sq ft at 1 1/2" |
| Chamber-Tech 2000 | 30 lb | Parged or troweled | Ask us |
| Cerfractory Foam | 25 lb | Sprayed, professional | See the data sheet |
To work out how much you need, add up the area of all four walls of the chamber. A chamber with 18 sq ft of wall would need three 30 lb buckets of Chamber Safe at 1" thick.
How the job goes
Always follow the instructions for the product you bought. The Cerfractory Foam data sheet shows the general order of work.
- Clean it. All tar, glazed creosote and soot must come off the chamber walls. If normal sweeping won't do it, rotary sweeping equipment is recommended. See our guide to the best creosote remover for glaze.
- Inspect it. Look for cracked or loose bricks, loose or missing mortar, and obstructions.
- Protect the room. Remove the damper plate if you can, and cover the firebox floor and hearth. Mix outdoors.
- Dampen the walls. Lightly wet them just before you start, with no standing water.
- Work from the top down. Start next to the flue liner and work down, covering all four sides.
- Let it cure. Allow 24 hours with natural air flow, and protect the repair from freezing until it's dry.
- Condition it. With Cerfractory Foam, burn a small conditioning fire after the 24 hours and keep fires small for 5 more days. Excessive heat could turn any leftover moisture into steam.
- Keep the rain out. Install a rain cap to protect the repair. See how to measure for a chimney cap.
Small surface cracks or crazing may appear after curing or use. Saver Systems says these are of no functional concern for Cerfractory Foam.
Frequently asked questions
What is smoke chamber parging?
It's a coat of refractory mortar applied to the smoke chamber walls to smooth, seal and insulate them.
Do I need a sprayer?
Only for Cerfractory Foam. PriorFire Formula 51, Chamber Safe and Chamber-Tech 2000 go on by hand or with a trowel.
What is Adhesion Promoter for?
HeatShield Adhesion Promoter replaces part of the mixing water in Cerfractory Foam and HeatShield flue sealant, to improve bonding and strength. One gallon mixes ten 25 lb pails of Cerfractory Foam.
Can I use ordinary mortar?
Use a product made for the job. The materials here are refractory, made to handle the heat in a smoke chamber. Flue Goo II dry mix can also be used to parge smoke chamber walls.
Related guides
- Best creosote remover: which type to use
- How to clean a chimney yourself
- Chimney crown repair: seal the cracks yourself or rebuild?
All smoke chamber products are on the chimney repair and waterproofing page. Questions? Email info@stovesource.com or text 1-888-866-8206. Every product ships with No Sales Tax in any state.