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View Full Version : A concrete ceiling in a basement??



John C Ritter
09-16-2010, 10:27 PM
Hi folks! I was hoping someone has seen this before and had some insight into why they built it like this, because it’s a bit of a mystery to me. This house is 100 years old, brick construction over rubble foundation walls, suburbs of Philadelphia, PA. It’s been added onto over the years more times than I’m able to count. It’s a long and narrow multi-family building now, with nooks and crannies, and numerous interior foundation walls in the basement, plus I-beams in various spots.

In the basement, there are two good-size sections (each probably 15’ x 15’) that have a concrete ceiling, about 6" thick and reinforced with rebar. All the rest of the sizeable basement has wood joists and the underside of the wood sub floor as its “ceiling”.

Why would they have gone to the trouble to pour a suspended concrete slab above a basement? (They then added wooden joists on top of the concrete slab to lay the main floor’s subflooring, so it’s not like they went with concrete because the carpenter called in sick that day.)

It just seems like a suspended concrete floor could be so problem-laden (weight, crumbling) that I don’t know why they’d have chosen that route. I’m wondering if it has something to do with what was there, and when, during the various add-ons. (In both houses I’ve seen this in, they were in sections of the basement that could conceivably have been below outdoor space at one time, but then the concrete pour should be on the earth, without any basement below it...)

Anybody have any thoughts on why they went this route in these sections?

While I also love leaving a good mystery for “those generations who come after“, I’m just not seeing the reasons they did this…

Thanks!
John

Bruce Breedlove
09-16-2010, 10:38 PM
What decade does the basement date to? If it is the 1960s the basement could have been built as a fallout shelter.

John C Ritter
09-16-2010, 10:50 PM
mm, overall the basement's much earlier than that. The building is about 90-100 years old. Had a coal cellar/chute up front. And some evidence of knob-and-tube (now deceased). Building was added onto often over the years, but I'm sure the basement wasn't dug out as an after-thought.

This isn't a separate room or anything, just 2 sections of the basement out of probably 7 different sections at least. Sections are delineated by brick columns or by an interior foundation wall, since the building was added onto so many times. The sections mostly just flow into the adjacent section.

Jim Luttrall
09-16-2010, 10:54 PM
Another thought is maybe it was part of the all concrete houses that were tried around 1914. Seems like Henry Ford was involved in a machine that was supposed to revolutionize home building like he did cars.

Beyond the Model T: the other ... - Google Books (http://books.google.com/books?id=_6IYAC2qfNwC&pg=PA76&lpg=PA76&dq=ford+concrete+house&source=bl&ots=IrBi8mQNdB&sig=C7ZY3ejZli7u-wOkQqQ_FeMf5CM&hl=en&ei=ggGTTOaKHMSBlAer-IynCg&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCAQ6AEwAg#v=onepage&q=ford%20concrete%20house&f=false)

Darren Miller
09-17-2010, 10:37 AM
That looks like some heavy mesh, not rebar in the one photo.

Philip
09-17-2010, 10:49 AM
It could have been under a concrete wrap around porch. Most coal pits have concrete ceilings.

Art Dotson
09-17-2010, 11:27 AM
John, is the room above now or could have been a parlor or library or the like with a sunken terrazo floor that's been leveled back up with the rest of the house now?

Art Dotson
Construction Code Services, LLC
permitexpeditors.com (http://www.permitexpeditors.com)

John Kogel
09-17-2010, 11:30 AM
I don't suppose the space above was ever an attached garage? Can you post a view of the outside?

John C Ritter
09-17-2010, 09:58 PM
I don't suppose the space above was ever an attached garage? Can you post a view of the outside?

hmm, possible but most of the concrete pour is 4-5" below grade, which wouldn't be useful for a garage floor.



John, is the room above now or could have been a parlor or library or the like with a sunken terrazo floor that's been leveled back up with the rest of the house now?


Actually, they tore up the subfloor over one of these sections today because there was some moisture infiltration and wood rot. Interestingly, there was a rectangular section along the rear wall of the room where the concrete had been poured up to grade level. (That pad is maybe 3' by 8'.) The rest of the room's concrete was recessed down, so that the 4-5" high wooden joists were needed to bring it to grade.

(In the pictures, it's where the sawhorses are standing that's the grade-level pour; the rest of the room -- the whole portion to the front and also wrapping around the grade-concrete portion -- were poured low with wood joists added.)

As I look at the pictures, it occurs to me that the room we're photographing was possibly once outside space that became the site of a later addition connecting the front and rear buildings. (Because 2 of the rooms to the front have remnant windows that peer toward this room.)

So I guess it's possible that the 3'x8' pad marks the front-facing entrance to a rear building, approached from the back door of the original front structure.

Does anyone know if it might have been common practice to use a suspended concrete pour where you had a Bilco door entrance into the basement?


(What you're seeing between the joists is the top of the basement's concrete ceiling, but parts of some bays were partially filled with dirt/debris.)

Markus Keller
09-18-2010, 06:31 AM
Don't know about Philly, around here though ... concrete ceilings are common in basement rooms when that room is under an old entry way, stairs or what was originally designed as an outdoor space.
Our typical basement cellar room has a concrete ceiling. It sits under the entry porch room that was most likely originally and open porch room. Previous owners added windows and a door so it is now enclosed.
I've seen many such rooms and ceilings in typical bungalows from the 20's

H.G. Watson, Sr.
09-18-2010, 09:23 AM
Exposed reinforcement mesh, bar, ties, rods in cementious structure is never a good thing, as seen when not fully encased presence of moisture and air it quickly corrodes/deteriorates - and compromises structurally.Didn't see that mentioned (rusting exposed reinforcement metal, one of last photos on first post) in quick scan of the string, that in and of itself is reason to question structural integrity/worthiness and call for a specialized, professional consultation/evaluation.

Also not seen mentioned, some electrical issues, bundling, unsecured, unprotected small guage wiring cables exposed, etc.

Unconditioned/unheated basement areas with alcoves with exposed to outdoor "concrete" ceiling slabs, or stoops often were used as a heatsink/collector/store solar gain - to house indoor well-heads, french drains, municipal water main to maintain above freezing temps without benefit of mechanical heat source to protect from freezing. material outdoors often dually served entrance to home - solar gain quickly de-icing, promoting snow melt. Very popular in time period which compensated for drafty, uninsulated or poorly insulated construction, and oversized/burdened/inefficient heating systems.