Repairing your brick chimney: Part 2. Flaunching and mortar fillets

Flaunching is a sloped mortar fillet which helps rainwater to run off and away from the chimney stack, applied to the oversailing course in this case. Using our Old House Project as an example, we cover what to look for, using lime mortar, how to prevent lime mortar staining brickwork and after care.
Other videos in the series:
1. Introduction: • Repairing your brick c...
3. Repointing: • Repairing your brick c...
4. Repair and replacement of bricks: • Repairing your brick c...
For further information on this topic, download our Advice Note on fireplaces, flues and chimneys: www.spab.org.u...
Have a question about an old building? Phone our free advice line on 020 7456 0916, Monday-Friday 9.30am-12.30pm or visit our website for FAQs on caring for historic buildings: www.spab.org.u...
With special thanks to Lynn Mathias. Filmed at our Old House Project St Andrew's in Boxley, Kent by
‪@photography.tuition‬ Music: Ed Cook Sound
Find out more about our Old House Project: • Introducing the Old Ho...

[@robertmcintyre4088]

These videos are excellent - thank you for sharing.

[@spab1877]

Thanks for watching!

[@Kajpaje]

Not clean the brick? The moss?

[@artform7325]

NHL5 for the flaunching? Is there a mix ratio to sand you recommend? Thanks

[@ryankirk2007]

Should have a up stand on the flaunting to minimise it cracking over time

[@PaddleDogC5]

Great bond for mortar over MOSS 😂

[@jodyroffe6976]

Clean the moss …seal surface with a pre grit …2 coats of mortar one scratch coat on day one topcoat on day two .. add waterproofer even to limerender stops the shrinkage and cracks ..finish with a proper float not a wooden one from 1920s

[@spab1877]

Hi there! If flaunching in lime it could still be done in one, that isn’t to say a scratch coat and topcoat wouldn’t work. Using a modern waterproofer on lime could compromise breathability. The reason for using a wooden or plastic float is to give the surface a texture that opens the pores to make it more breathable. With a lime mortar flaunching you can work it with a float the next day to close any shrinkage cracks as it tends to "tighten" up on day one, and then day two rework it with float. There are a number of methods that create the same result, the method used here is just one.

[@huskyfrank9058]

Why have you gone for lime mortar on the fillets rather than a sand and cement mix?

[@spab1877]

Hi there! We've gone for lime mortar because cement mortar would be too hard and doesn’t accommodate movement like lime does. Lime works in a more harmonious way with the softer bricks.

[@vollandt]

​@@spab1877 accommodate movement by de-bonding and crumbling over time I suppose?

[@paulripley4095]

Would not like to pay this bloke to fanny about slow does not mean a. Good job

[@paulripley4095]

At least clean the moss off hope your customer reads these comments and relise your boot