Refractory Relining & Repair

Brick ovens fail predictably, and most of it is repairable without rebuilding. A reline typically costs a fraction of a replacement and buys years of service — and the earlier it is caught, the wider that gap gets.

Most of the ovens we reline were built by someone else, frequently by someone no longer around. We do not need the history to assess it. The structure tells us what was used.

What goes wrong, and why

Hearth wear and spalling

Cooking floors take direct flame, thermal shock from cold dough, and years of a steel peel scraping across them. Eventually tiles spall — fragments flake off leaving pits. On a dry-laid floor that is a morning's work to replace. On a mortared floor it is a much larger job, which is why we lay ours dry.

Spalling can also mean the wrong brick was used. Ordinary building brick spalls as a matter of course under oven conditions and will keep doing so. The difference between brick types is worth understanding before you pay to fix it twice.

Failed castable

Ordinary Portland cement loses its strength above roughly 300 °C. Used in the hot structure of an oven it does not fail immediately — which is the trap — but it fails predictably. Crumbling or powdery joints, particularly near the mouth, usually mean the wrong binder went in.

Wetted insulation

The most common cause of an oven that used to hold heat overnight and now does not. Water gets in through a failed rain cap or porous render, and saturated rockwool does not recover. The dome may be entirely sound; the oven simply bleeds heat.

This one is worth catching early because it is cheap relative to the fuel it wastes. How insulation actually works.

Flue problems

Creosote build-up, a collapsed liner, or a cap that has failed. Symptoms are smoke rolling back into the kitchen and a fire that will not establish.

Which cracks matter

Every brick oven cracks, and most of it means nothing. The distinction we draw:

• Normal: fine hairline cracks in outer render; stable cracks that appeared early and have not changed; fine crazing on the hearth surface.
• Not normal: cracks that grow season by season; cracks you can see light or smoke through; crumbling or powdery edges; bricks that have moved relative to each other.

The word doing the work is stable. Photograph and measure anything you are unsure about — if the width is the same next year, it has found its equilibrium. The full diagnostic guide.

What a reline involves

Stripping back to sound material and rebuilding the affected layer. Depending on what the survey finds, that can mean replacing worn hearth tiles, cutting out failed castable, removing and renewing wetted insulation, rebuilding a section of dome where movement has occurred, and making good the render.

And then curing it again, because fresh castable carries water exactly as a new build does. We run that schedule ourselves.

Reline or replace?

Reline is usually right when the dome geometry is sound, the structure is stable, and the problem is wear or a compromised layer. That describes most ovens we are called to.

Replacement makes more sense when the dome profile itself is wrong — an oven that never baked properly will not start because you relined it — or when ordinary building brick was used throughout and will keep failing, or when the flue can never be made to draw from that position.

We will tell you which, and we will tell you plainly. There is no point relining an oven that was built wrong, and no point replacing one that needs a morning's work.

Getting an assessment

Send photographs of the dome, the hearth, and the outside, along with what has changed — slower to heat, will not hold temperature, higher fuel use, visible cracking. That is usually enough for us to tell you whether it is a repair, a reline, or a conversation about replacement.

Across Kenya the survey is free. An annual inspection under our servicing schedule catches most of this while it is still cheap.