Re: Moisture in exterior wall

[Guest guest]

Elevated moisture levels down low could be the result capillary action but I would presume there to be a vapor barrier between the earth and the concrete. An improperly installed vapor barrier could account for the moisture considering the presence of the canal and a likely high water table.

Another possibility could be splash-back from roof run-off. This would be likely if there are no gutters installed and there is drip edge running horizontally up above the areas being affected. Such splash back often causes dirt to be brought up with the splash and having it stick on the lower walls like road grime for lack of a better term. It would not be unheard of for there to be some constituency of mold development in darkened areas as well. Two story buildings only 10 feet apart are more likely to be shaded down low the vast majority of the time and that slows any potential drying.

I am not all that familiar with Florida building practices but I am assuming that the concrete block is hollow core? If so, that type of material would potentially dry faster when wetted than the solid concrete stemwall lower down. This has to do with the hygrid storage capacity of the two materials and temperature variations during warming cycles based on mass. The hollow block higher up would come up to ambient air temperature faster than the solid concrete and would receive more of a drying affect.

This brings up another point, are you sure the differences in moisture content you are getting with your Tramex is not just the result of two different densities of building materials? Does your dramatic moisture change take place where the solid concrete gives way to hollow core block wall construction? If so, perhaps the readings your moisture meter is giving has more to do with differing material densities than with actually moisture content?

In any event, the picture you included of the affected wall does not look to be very discolored at all but then that picture may just be deceiving?

Stojanik

Moisture in exterior wall

I am investigating a stand-alone two story town house in Miami-Dade county Florida. Home built in 2005, back of house is adjacent to navigatable canal. Concrete block walls, unsure if it is a built on footers on piling. (getting construction plans from building dept.). Each town house is seperated by about 10 feet from adjacent stand alone townhouse. There is noticble black dust present on the bottom two feet of the exterior wall on each side of the house and the adjacent townhouses of similiar construction. The black dust appears to be organic soil-like. The first floor slab is about two feet off the surrounding ground. The top elevation of the dust buildup on the exterior wall corresponds to the top of the slab. Use of a Tramex Moisture Encounter Plus moisture meter (set to plaster setting) shows elevated moisture on bottom two feet of exterior wall. Above the elevation of the dust build up the moisture m! eter is at zero. The drywall on the interior side of the perimeter walls does not contain elevated moisture. First floor is completely finished with marble tile.My client is doing a pre-purchase investigation, so I am limited in to using non-invasive methods of investigation. The concern is that this is a potential long-term moisture intrusion issue, which may have not had enough time to manifest itself in the interior, as the house is only one year old.My client is very mold sensitive and had horrible "sick home" experiance so we are concerned that this may lead to elevated moisture in wall cavities and IAQ nightmares. any thoughts or experiance with this type of situation would be appreciated. Refer to attached photo. Sherry, CMCSouthern Sciences, Inc.

[Guest guest]

From the photo, and the information you provided, it looks like the

cladding system can't dry in that bottom 2 feet. If it is traditional 3-coat

stucco, that is a moisture absorbing cladding. I notice in the photo that

the cladding extends into the grade. There is no place for the water to run

off and away from the building. You say all the other buildings read the

same on your meter. Do they all have the cladding running into the grade?

Also, if there was a drainage plane behind the cladding this would allow it

to dry out. The cladding wouldn't be in direct contact with the concrete

block so air could circulate between the two. The location also appears to

be a shaded area which doesn't help, but even in sunlight, an absorbing

cladding system such as stucco or brick will wick moisture up if in direct

contact with the grade.

Those are just some thoughts.

Zito

>

>Reply-To: iequality

>To: iequality

>Subject: Moisture in exterior wall

>Date: Wed, 10 Jan 2007 21:17:07 -0800 (PST)

>

>I am investigating a stand-alone two story town house in Miami-Dade county

>Florida. Home built in 2005, back of house is adjacent to navigatable

>canal. Concrete block walls, unsure if it is a built on footers on piling.

>(getting construction plans from building dept.). Each town house is

>seperated by about 10 feet from adjacent stand alone townhouse.

>

>There is noticble black dust present on the bottom two feet of the exterior

>wall on each side of the house and the adjacent townhouses of similiar

>construction. The black dust appears to be organic soil-like. The first

>floor slab is about two feet off the surrounding ground. The top elevation

>of the dust buildup on the exterior wall corresponds to the top of the

>slab. Use of a Tramex Moisture Encounter Plus moisture meter (set to

>plaster setting) shows elevated moisture on bottom two feet of exterior

>wall. Above the elevation of the dust build up the moisture meter is at

>zero. The drywall on the interior side of the perimeter walls does not

>contain elevated moisture. First floor is completely finished with marble

>tile.

>

>My client is doing a pre-purchase investigation, so I am limited in to

>using non-invasive methods of investigation. The concern is that this is a

>potential long-term moisture intrusion issue, which may have not had enough

>time to manifest itself in the interior, as the house is only one year old.

>

>My client is very mold sensitive and had horrible " sick home " experiance

>so we are concerned that this may lead to elevated moisture in wall

>cavities and IAQ nightmares.

>

>any thoughts or experiance with this type of situation would be

>appreciated. Refer to attached photo.

>

> Sherry, CMC

>Southern Sciences, Inc.

><< 3880NW168th.pdf >>

_________________________________________________________________

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[Guest guest]

Please advise your client not to consider a home this close to a waterway. Especially one that uses sheetrock.Its asking for trouble. Thats just my opinion.. as someone who is sick from mold..

[Guest guest]

Is it possible that the air conditioning cools the bottom couple of

feet of the inside of the house below the dew point, and that outdoor

moisture is condensing on the exterior surface, allowing dust and

airborn spores to adhere to the building?

I saw a similar sitation in Melbourne, Fl. The more conductive studs

were cooler than the insulated wall cavities, so darker streaks were

visible on them. The condition was most pronounced on the north side.

Temperature and RH data would might be helpful.