What is this flooring

[RickSab]

I came across a type of sub flooring I am unfamiliar with. It's a mortar type material, about 1 to 1.5 inches thick. Based on what can be seen in the basement it is over a wood subfloor and wood joists. Linoleum was laid right over this material.

I suspect it might be a fireproofing or sound proofing material. The problem is is has cracked and the floors are uneven.

This is a four unit multi family built around 1942.

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[Marc]

We've done a few structural floors that had a couple inches of fiber-reinforced concrete over 1/2 inch decking instead of just regular 3/4 decking. It was said to produce a very quiet floor.

This was the mid-80's though.

Marc

[John Kogel]

Or it could be leveling compound spread over the uneven wood subfloor in an attempt to level it. Could have been done any time, but in the last 20 or 30 years.

[Jim Katen]

Gypcrete.

It's used all the time in multifamily construction. It's generally pumped in and is self-leveling. If it's not mixed properly it can crack and crumble. You can replace the crumbling sections very easily.

[RickSab]

Thanks, I considered a leveling compound but the thickness was puzzling. It was the same level ah the plywood in the hall.

You guys have all been very helpful.

Thats why this board is the best.

[duomit]

Looks like cementitious self-leveler. How old is the floor? Why patch in hardwood?

[Rob Amaral]

Hmm... 1942?    Military base housing perhaps?? (I don't find buildings built in 1942 around Boston... though a few near the coast may have been)... I'd suggest they make sure the cementitious composite was tested for asbestos-content just to be sure...    Exactly where was this property?