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Question DetailsAsked on 4/6/2014

With a chimney leak causing exterior brick efflorescence (white powder), is it mandatory that it be removed prior t

applying a chimney saver sprayed on?

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2 Answers


Well, if you don't the sealer will be sealing the efflorescence where it exists, not the mortar and brick/stone, so it will not work as well - especially if it is light and fluffy, not just a lime stain. if just a thin lime stain, then probably will not hurt much, but it will now be under the sealer, so will be very hard to ever get off in the future.

I would say not removing it would not be the most workmanlike way to do it, but would make me jump up and down either, if looks are not an issue. Sort of like sealing grout without cleaning it first - probably better than nothing, but not best practice.

Answered 6 years ago by LCD


Saversystems the manufacturer of Chimney Saver Masonry Repellent states that the surface should be washed prior to application to ensure the best surface for absorption of the repellent. That will insure that you get the warranty for bthe product. Effloresence is salt and lime that is being extruded from the masonry from hydrostatic pressure and gravity. Long term exposure to moisture has created the problem. Once the effloresence powder is removed, a lime stain may remain. This stain should not effect the masonrys ability to absorb the repellent and once exposed to sunlight should prevent future absorption of moisture for 10 years. Chimney saver is NOT a sealer but a repellent that is vapor permeable( it allows the brick to breathe) and the natural evaporative process can continue to relieve the masonry of internal moisture once applied. The lime stain removal may not be possible without possible damage to the brick. The lime is likely not just on the surface but is coming from within and may be persent below the surface layer of the masonry. Sand blasting may remove it but not guaranteed. Restaining the bricks with a brick color stain is a common soultion for a variety of discolored brick issues. Chimney Saver is the best product for stopping moisture absorption in masonry chimneys. It is important to address leaks from the top down, starting with the masonry crown. This might be done with a crown coating applied to the sand mortar on the top of the chimney, then wash exterior and apply Chimney saver repellent to the exterior veneer. One gallon covers up to 100 sq. feet, depending on how thirsty the bricks are.

Never apply a sealer to a masonry chimney as it can cause spalling and a host of other freeze/thaw cycle problems.

Thanks for the question. Should you need other professional chimney help you can contact David Lamm, The Classic Chimney Sweep in Raleigh NC. 919-782-2879

Answered 6 years ago by David Lamm

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