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Old 10-15-2012, 04:49 PM   #1
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White fluff on chimney under roof


I found some white fluff on the chimney bricks under the roof.
Their appears to be some water leakage after a rainstorm, the roof plywood planking appears to be slightly moist.

I read about dry rot, but why would it be on the bricks on the chimney?

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Old 10-15-2012, 05:57 PM   #2
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White fluff on chimney under roof


It is probably efflorescence from water leaking through or around the flashing or from a chimney with an improper cap. Water can also enter a chimney in small amounts through absorption or poor mortar joints.

The efflorescence can easily be brushed away, but it is an indication of slow long term water penetration that may or may not be detrimental.

Dick

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Old 10-15-2012, 06:23 PM   #3
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White fluff on chimney under roof


As previous post said,try brushing it away first,if that doesn't work this link will guide you in it's removal.



Various methods have been used in attempts to remove efflorescence from masonry structures. It has been found that when efflorescence is caused by soluble alkali salts, the salts will dissolve in water applied to the structure and migrate back into it. These salts would then reappear on the surface as the structure redried. It was learned accordingly, that the best way to remove these soluble salts was to brush the surface thoroughly with a stiff brush. Water, however, has been satisfactory for removing efflorescence from the face of concrete structures, since concrete is fairly well saturated with water. In fact, efflorescence in the form of alkali salts will be washed from the surface of concrete structures, if exposed to rain, over some period of time. If the coating is largely calcium carbonate or calcium sulfate, it adheres rather strongly and is difficult to remove by brushing. The practice developed in this case for masonry surfaces, has been to saturate the structure as thoroughly as possible with water, and then wash with diluted muriatic acid, followed immediately with an alkaline wash, then washed with water. The acid recommended is five (5) parts hydrochloric to one hundred (100) parts water, or twenty (20) parts vinegar to one hundred (100) parts water. The alkaline wash recommended is diluted household ammonia.
Much care must be taken in applying acid to Portland cement products. The acid will attack, not only the calcium carbonate and calcium sulfate efflorescence, but also other calcium compounds to produce calcium salts such as calcium chloride. It is, therefore, very important to neutralize the acid before it can attack other compounds.
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Old 11-03-2012, 12:44 AM   #4
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White fluff on chimney under roof


I have a similar problem in my basement, here are two pictures:


and


I just read some articles online and it seems that it's recommended that once you removed the efflorescence, you want to use some type of concrete sealer to seal it.. Any suggestion about what type of concrete sealer to use? Would QUIKRETE Acrylic Concrete Sealer (available from Lowes) or RadonSeal (found on youtube) work? Thanks!

Also, to prevent the efflorescence to come back again, after apply concrete sealer, is it a good idea to use products such as DryLok waterproofer on top of the concrete sealer? Or just applying the concrete sealer is good enough? I assume that DryLok Masonry Waterproofer itself is not concrete sealer? It looks like UGL has another product called DryLok Concrete Protector, any experience with this product? Thoughts or comments? Thanks again!

Last edited by ohman; 11-03-2012 at 01:39 AM.
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Old 11-03-2012, 07:12 AM   #5
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White fluff on chimney under roof


Is this what you are seeing?
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White fluff on chimney under roof-100_6216.jpg  
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Old 11-03-2012, 07:19 AM   #6
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White fluff on chimney under roof


I would not take the advice of applying any type of sealer on the brick. That may trap any moisture behind the brick and cause further problems. What you want to do is apply a water repellent...not a sealer.

Do you notice after a rain that the brick on the chimney is wet and stays damp for a few days before it drys out? Most people do not realize that brick and mortar are porous and will absorb moisture. I had the same problem with the efflorescence appearing on the chimney. My chimney faced the west side of the house and was completely exposed to the wind driven rain.

My remedy was to apply a water repellent from Prosoco called Weather Seal Siloxane PD(the PD stand for pre-diluted). After this is applied and the chimney gets wet, the water runs off the brick like a newly waxed car.

See the data sheet here:
http://www.prosoco.com/Products/d113...e-b0006e080476

But because the repellent will not prevent water penetration through
structural cracks, defects or open joints I also spent a few hours paying attention to all the mortar joints....both head and bed where there were any cracks in the mortar. So I bought and brushed on a product from Saver Systems called ChimneyRx® Masonry Crack and Joint Sealant.

http://saversystems.com/chimney-prod...-joint-sealant

look for hairline cracks in all the head and bed joints...see photos below
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White fluff on chimney under roof-100_6371.jpg   White fluff on chimney under roof-100_6373.jpg  

Last edited by hammerlane; 11-03-2012 at 07:26 AM.
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Old 11-03-2012, 07:25 AM   #7
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White fluff on chimney under roof


Go to the Brick Institute of America and read their technical notes: specifically notes 23 and 23A that deal with staining and efflorescence

http://www.gobrick.com/TechnicalNote...4/Default.aspx
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Old 11-03-2012, 11:05 AM   #8
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White fluff on chimney under roof


Quote:
Originally Posted by john_bry View Post
I read about dry rot, but why would it be on the bricks on the chimney?
Dry rot can go across and through brickwork to find new timber.
I have seen it many times under the floorboards on ground floors.
However in your case it is probably salts as stated in the other posts.
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