Efflorescence patterns to diagnose water intrusion

[Gary Farnsworth]

NACHI article time, Kenton.

[William J. Decker]

Originally Posted by kshepard

Since it's a sign of moisture intrusion you should comment on the fact that there has been intrusion and look for evidence that it's ongoing. If it appears that intrusion is ongoing you should recommend locating the source (if you can't locate it yourself) and recommend correction.

The potential probelms to mention are human health: from excessively high levels of mold spores in indoor air, rust of metal components, wood decay and foundation undermining.

Efflorescence is not always an indication of a defect. Masonry, all by ityself, absorbs water and moisture. If properly built (capillary breaks, flashing, proper mortar type use) then efflorescence can be merely an indication of the natural drying process.

But, it can also be an indication of bad construction.

[Marcel R. Cyr]

Good information on efflorescence.
and check out Note 23 of BIA

Efflorescence in Brick Veneers

What is effloresence?
(source - BIA Tech Note 23)
Efflorescence is a crystalline deposit of water-soluble salts on the surface of masonry units. Efflorescence is generally not harmful to the brick - nor is it toxic or a health hazard. The main problem with efflorescence is that it makes an otherwise beautiful masonry structure quite unsightly
Efflorescence is usually white in color; however, all white stains on brick masonry are not necessarily efflorescence. Also, certain vanadium and molybdenum compounds, present in some ceramic units, may produce a green deposit, commonly referred to as "green stain". Occasionally, "brown stain" may occur, resulting from deposits of manganese compounds.
Under certain specific circumstances and conditions, it is possible for the crystals of efflorescence to form within the bodies of the units. When this occurs, it is possible that the pressure of crystallization and growth of the crystals may cause cracking and distress to the masonry.

[Kenton H. Shepard, CMI]

Originally Posted by gfarnsworth

NACHI article time, Kenton.

Good suggestion, Gary!

[Kenton H. Shepard, CMI]

Originally Posted by wdecker

Efflorescence is not always an indication of a defect. Masonry, all by ityself, absorbs water and moisture. If properly built (capillary breaks, flashing, proper mortar type use) then efflorescence can be merely an indication of the natural drying process.

But, it can also be an indication of bad construction.

I think the point the article I posted was trying to make is similar to what you've said. It's that the hydration process takes years to complete. During those years, masonry contains unhydrated cement that can be leached to thte surface as calcium hydroxide and appear as white chrystals.

Rob's out 'til next week but we should do an article on this and see if we can't make this subject a little clearer.

[Rob London]

http://www.nachi.org/efflorescence.htm


bam

[William J. Decker]

Originally Posted by kshepard

I think the point the article I posted was trying to make is similar to what you've said. It's that the hydration process takes years to complete. During those years, masonry contains unhydrated cement that can be leached to thte surface as calcium hydroxide and appear as white chrystals.

Rob's out 'til next week but we should do an article on this and see if we can't make this subject a little clearer.

Ken,

Call me or e-mail and I will send you a Power Point on this subject. Presented it, as a paper, at the InfraMation conference and have converted it to a state licensed CE class. We will be doing the class next Thursday during a chapter meeting.

Also, have you looked into the lime putty mortar material. The process there is carbonation rather than hydration. Used in older masonry (apparently, portland based mortars were not available here until 1930.

Hope this helps;

[Stephen P. Shockley]

Hi,

I had a house this morning where the block foundation around the front porch area appears to have efflorescence going on. One picture is from the outside of the front porch and the other two pictures are from the opposite side of that porch taken from the crawl space. Could this be caused by the stone slab sitting on top. There does appear to be flashing on top of the foundation wall from the picture in the crawl space. Also, I found out that this whole area where this house was sitting was flooded in the same year the house was built, 1999 (Hurricane Floyd). Could this have anything to do with the efflorescence? There were a few other places that had a little more of the same, but very sporadic. Also, any recommendations on how to write this up?


Regards,

Steve

[Bob Elliott]

Originally Posted by sshockley

Hi,

I had a house this morning where the block foundation around the front porch area appears to have efflorescence going on. One picture is from the outside of the front porch and the other two pictures are from the opposite side of that porch taken from the crawl space. Could this be caused by the stone slab sitting on top. There does appear to be flashing on top of the foundation wall from the picture in the crawl space. Also, I found out that this whole area where this house was sitting was flooded in the same year the house was built, 1999 (Hurricane Floyd). Could this have anything to do with the efflorescence? There were a few other places that had a little more of the same, but very sporadic. Also, any recommendations on how to write this up?


Regards,

Steve

Looks to me like a couple things going on there.

No vapor barrier on the dirt ,and possibly no water proofing treatment (or failed).

Is the crawl ventilated? Is that the only area with efflorescence?

Seems to be a common issue with CMU foundations I have seen but would report what I see,take a moisture level reading,and recommend a foundation waterproofing contractor.

[Marcel R. Cyr]

Good advice Bob.

I worked in a Block Manufacturing Plant many moons ago and have this to share if it helps.

Soluble salts, metal salts, which migrate with moisture to masonry surfaces (brick, block and mortar) – a controllable problem.

White powdery stains on the surface of brick and block pose a significant problem in many locations due to the make up of concrete block and the cement mortar products used in wall construction.
In regard to cement hydration and permeability of cured mortars, it is possible to reduce the cause of the problem and the resulting unsightly visible deposits.

Difficult to remove architecturally displeasing, often acid washing does nothing to remove the stains.
In most cases, the use of water in the cleaning process just adds to the problem. Block production mixes are usually classified as Dry Mix or Low Slump using a very low W/C (water to cement ratio).

This will range from calculating the only the use of moisture content of sand in the mix, up to a .3 W/C ratio.

This is because most produced block must exit the mold machine within minutes of being formed and remain free standing until cured and stored on pallets.

Due to the low W/C ratio of most concrete block, cement in the block is rarely adequately hydrated. This causes the block to be susceptible to moisture activated hydrates moving to the surface of the block and re-depositing as a white chalky stain as the moisture evaporates.

The use of exterior block coatings such as Thoroseal Foundation Coatings, or equivilant, will provide the protection of exposed Concrete Masonry Block and help prevent unsightly stains and efflorescence.
You are right about the interior, without the dampproofing on the block and vapor barrier on the ground surface, the block will continue to wick up moisture and the chemistry begins again to form the efflorescence or stains as we see.

Hope this helps.

[Stephen P. Shockley]

Bob,

I thought I had just replied to this, but something happened and all of my response disappeared on me...

Anyhow, to answer some of the questions in your reply, the crawl space did have a vapor barrier, however, it was pulled away from the foundation in several places around the perimeter. I don't believe any sort of water of water proofing treatment was ever used on it. I don't think many of the builders around here do that at all, at least not that I'm aware of. There were quite a few vents in the foundation around the perimeter of the home, (just not in that photo). There was one other small place where I saw some more of the same, but for the most part everything was concentrated to being around the front porch.

This was a modular built home by Nanticoke Homes in Delaware. It was set on that foundation back in 99'. I was told that soon after the home was put up, this whole area of the Delmarva peninsula was sitting in water, which was why I was wondering if this could have had something to do with the efflorescence. My other concern was perhaps it might be coming from water running off that slab floor and down around into the foundation wall. We've had an enormous amount of rain here over the last 6 months.

Makes sense that the efflorescence from the crawl space side could be due to the vapor barrier being pulled away from the foundation wall, because the only other place I had seen it was at a lower course of blocks near the soil level.

I think I will go ahead and defer this to a foundation water-proofing contractor as you suggested, just to be on the safe side.

Marcel - Thanks for the post on efflorescence. Very helpful.


Regards,

Steve

[Bob Elliott]

Originally Posted by sshockley

Bob,

I thought I had just replied to this, but something happened and all of my response disappeared on me...

Anyhow, to answer some of the questions in your reply, the crawl space did have a vapor barrier, however, it was pulled away from the foundation in several places around the perimeter. I don't believe any sort of water of water proofing treatment was ever used on it. I don't think many of the builders around here do that at all, at least not that I'm aware of. There were quite a few vents in the foundation around the perimeter of the home, (just not in that photo). There was one other small place where I saw some more of the same, but for the most part everything was concentrated to being around the front porch.

This was a modular built home by Nanticoke Homes in Delaware. It was set on that foundation back in 99'. I was told that soon after the home was put up, this whole area of the Delmarva peninsula was sitting in water, which was why I was wondering if this could have had something to do with the efflorescence. My other concern was perhaps it might be coming from water running off that slab floor and down around into the foundation wall. We've had an enormous amount of rain here over the last 6 months.

Makes sense that the efflorescence from the crawl space side could be due to the vapor barrier being pulled away from the foundation wall, because the only other place I had seen it was at a lower course of blocks near the soil level.

I think I will go ahead and defer this to a foundation water-proofing contractor as you suggested, just to be on the safe side.

Marcel - Thanks for the post on efflorescence. Very helpful.


Regards,

Steve

That stuff is very porous and of course it is going right through.

All about it being flashed or drained and sealed.
just needs the right combination and hard for a typical Inspector to fully determine.
IR would of course help determine issues somewhat but it obviously coming from top,sides and bottom.High humidity does not help in a crawl though it may be a good thing it is vented as I personally would also recommend a Mold inspection .

I know someone that has a dehumidifier running 24 hours a day with a similar issue with a walk in concrete floor slab.

They are not going to pay for digging out the exterior sidewalls and having a moisture barrier put in.

Sure you could parge coat the inside for temporary relief,key word being temporary.

I am sure some of the other guys have more to add later as I usually see concrete pour foundations around here unless they are 100 years old in which case it is stone that bleeds through the mortar.