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Old house_cement ceiling/subfloor Recommending Jackhammering out.

We have just begun some work on our older house.

Our contractor is correcting supports to floor beams/joist in the basement of our old house. In the house's oldest section, he found cement in the ceiling (or the first floor subfloor. That cement is about 3 inches deep and is supported by very old wood plant subflooring. I understood him to say that he has not seen cement used in a ceiling with a basement underneath before. He says because the cement is in contact with wood that it is not up to code and he needs to jackhammer all of it out. Further he cannot guarantee what will happen cement and to our upstairs doors and windows, if he continues with installing jack posts in this area. Some of the cement was exposed/without wood subflooring support, had been chipped away and did crumbled when they begain installing jack post in that area. The rest is hidden behing the plank subfloor and the condition right now is unknown. He estimates the area with cement is about 12' by 12' which would on the first floor is one small room, wall and closet space between the small room and another room.

I understand from another members post (in Victorian bath remodel) that cement or 3" mortar over wood subfloor while maybe not common is not unheard of, and that he had found it in houses from the 50's and 60's.

Does anyone else have more information or experience with this old construction method? Why was it used?

Is there a difference between 'cement' 'mortar' and "rock lathe"? all of which seem to have been referred in various posts discussing "cement" in second story subflooring in older homes.

Does the cement need to be jackhammered out? What does that involve? What other potential other issues does removing it cause? What additional repairs may we likely face if the cement is removed?

If jackhammered from the basement, the old wood plank will be destroyed..is that lose?

If it needs to be removed from above, that involves removing old hardwood flooring (a selling point for us for the house) and walls of the closet and room..less of a lose?, unless we want to reconfigure the rooms upstairs?

Any thoughts, information, suggestions, ideas of what we should be thinking about or asking will help.


Re: Old house_cement ceiling/subfloor Recommending Jackhammering out.

Is there a difference between 'cement' 'mortar' and "rock lathe"?

Cement is generally a fine powder and mixed with water will set and harden ---- addition of sand and you have mortar.
Mix rocks or stones ( aggregate ) with cement and water you have concrete.

Rock lathe is basically gypsum board or what bis commonly referred today as drywall. It replaced the old wood lathe used for plaster walls and ceilings.

It's unclear what you have concrete or mortar.

It was a common enough practice back in the day for a mud base consisting of a fairly dry mortar base sometimes 2-3 inches thick used for tiles ----- lots of old shower bases were made this way.

It's difficult to say from here what the situation is ----- perhaps that room was a bathroom at one time.

Re: Old house_cement ceiling/subfloor Recommending Jackhammering out.

Concrete floors and ceilings are still commonly used today but primarily in commercial buildings in this country but also in residences in Europe.

Todays code would require PT wood if it is in contact with concrete but it wasn't always so. Unless the concrete is severely cracked or disintegrating I would not jack hammer it. New steel or PT supports can be installed.

By the way if he calls it cement I would be suspicious of his credentials.

Re: Old house_cement ceiling/subfloor Recommending Jackhammering out.

It just occured to me this could have orginally been a cold room in the basement.
This hasn't been done around these part in decades ---- even then it wasn't too common around here though I believe it still is being done around various parts of North America.

Generally speaking if this is a concrete slab it may have been part of an exterior entrance with the slab being the porch so to speak. The space under this in the basement would have a concrete ceiling ( the slab for the exterior porch ) and was used for cold storage and possibly for coal ( if there is a sealed up opening for the chute ).
The wood planks would have been used for the forms with temporary supports underneath used during the concrete pour. After the concrete cured the temporary supports would be removed and likely the planks would remain.

This room would then be separated from the rest of the basement by a wood wall often built with the same 1X6 planks used for the subfloor and / or wall sheathing -------- a door made from the same materials built on site.

Perhaps over the years someone decided to close this area in and made the room that is currently there.

This is all a guess sight unseen.

As far as jack hammering this out .........
If it's done from underneath ---- let's just say ------- I'm glad it's not me doing it.

Sounds to me they may have to temporarly support the slab and jack hammer a section out then install permanent floor framing ---- then do another section and so on.

Now with the hardwood floor above likely resting on the slab chances are there are going to be issues so you might prepare yourself for some major repairs or replacement of the hardwood.

Again sight unseen over the internet and based on the description by Chauncey ----- this is just a guess.

Re: Old house_cement ceiling/subfloor Recommending Jackhammering out.

Thanks all for your thoughts and ideas and info on the differences of cement, mortar etc.

canuk, thanks for the idea of exploring this area's use as the orginal cold room or coal area. This is in the oldest area of the house...much older than even a few decade. There is does appear to be what I looks to be a sealed off coal chute near by and possible old, now covered, opening for a chimney nearby. The brick in this old section changes where the concrete ceiling stops, so it could have been a seperate room, albeit now any wall in that area is gone. While of a more recent decades, but still 50-60+ years ago, we have been told that previous owner (s) stored kegs of wine in the basement.

Again thanks. It will help as we investigate it more.

If you or others have additional thoughts, I am interested in hearing more or other thoughts.

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