Lawrence:

Sometimes it is better to look a little closer. Take another look after a
rain and when the upper surface is dry. If there are cracks through the
suspended slab and/or if any protective membrane has failed,  you will see
water still dripping. It takes awhile to perculate through. In Michigan a
lot of road salts are used through the winter - snow or something like that.
If the salts penetrate the concrete the reinforcing steel will corrode and
there will be a major maintenance problem.

So, any water coming through? Is the protective membrane still in good
condition or is it time for a re-coat?

Ken Johnson,
Victoria, BC
----- Original Message -----
From: "Lawrence Kestenbaum" <[log in to unmask]>
To: <[log in to unmask]>
Sent: 06 April, 2001 12:37 PM
Subject: Condensation on concrete ceiling


> Most days, like today, I park my car in a semi-enclosed multistory
> building designed specifically for the mass storage of automobiles.
>
> Here in Michigan, as I think I mentioned, such a building is called a
> "parking ramp"; in other places, it's a "parking structure" or "parking
> garage"; in Canada, it's a "parkade".  There may be other terms.
>
> Note that the car parking areas are not actually enclosed.  There is a
> small parapet, and some railings, around each floor.  The floor plan is
> rectangular, but spiral in concept: As you drive along the main aisle
> around and around the building, you are ascending gradually to successive
> stories.  The ceilings are very low, so if your vehicle is significantly
> taller than the standard American full-size car, you might worry about
> getting stuck under a beam.
>
> One of the odd things about this particular parking ramp is the way it is
> affected by rainfall.  On one recent dark and rainy day, I drove into the
> building in the usual way, and was dazzled by how bright things were
> inside.
>
> New lighting, I thought.  But the sodium vapor light fixtures, though
> plainly much newer than the original building, show signs of having been
> there for a while.  The lighting had not been changed overnight.
>
> What changed was the reflectivity.
>
> Obviously, cars were tracking in water from the wet streets.  But that
> alone couldn't explain why the floors and ceilings all had such a glossy
> sheen.  The light from the headlights and the sodium vapor lighting was
> bouncing off the wet floors and the wet ceilings and the wet cars,
> creating a much brighter and seemingly more exciting environment than you
> normally see in such a place.
>
> >From the basement up to the highest floor, essentially every ceiling in
> the car parking areas (all unpainted concrete) were speckled densely with
> little droplets of water, like the surface of a cold Coke bottle on a hot
> Alabama afternoon.
>
> Meanwhile, in the little corner section which includes the elevators and
> stairway, where all the surfaces are painted, no comparable condensation
> was seen.
>
> Is this typical behavior for practically an entire unheated reinforced-
> concrete building to be (literally) dripping with moisture after just a
> small amount of rain? Or is this a symptom -- or cause -- of some deeper
> problem?
>
> ---
> Lawrence Kestenbaum, [log in to unmask]
> Washtenaw County Commissioner, 4th District
> The Political Graveyard, http://politicalgraveyard.com
> Ebay Page, http://members.ebay.com/aboutme/potifos/
> Mailing address: P.O. Box 2563, Ann Arbor MI 48106
>
>