Recently ran into a home built in the 1920’s in an Irish neighborhood that I was told was called a “kinko” and was a typical type of construction in Irish neighborhoods in Brooklyn, NY at the time. It is a four story two family/two duplex with two separate entrances.
Between the 3×8 joists there was laid about 3″ of cindercrete supported by 1×6 T&G pine placed on furring strips. I have seen similar framing in deafened joists for mud jobs for tiling, but the cindercrete tops out a good 3″ below the deck level so I don’t think that was the intent. Since a lot of effort went into doing it, I would be interested in knowing it’s original purpose.
One thing I did notice is that because of this construction there is no cross bracing between the joists. I’m presuming that the mass negated the need for any, although I doubt that was its main intent.
Replies
AVR
In older (30's) baths that were tiled-usually mudset-they nailed a 1x2 down an inch or two and on the side of each joist. Across and in between the joists they nailed 1x sheathing to those ledgers. Most of the time, they hacked the top of the joist edge (chamfered). They then packed a sort of concrete (might be the cindercrete he mentions)down in and up above the joist tops maybe an inch-set the floor tile to that.
I'm surprised you've never had the opportunity to tear that out. I should be so lucky.
wrong image in my head
i got a different image in my head so it didnt click. Sounded to me like he meant it was done throughout te entire place under al flooring.
yes
When he said it resembled the under tile detail only thicker, the frightening thoughts of '30's bath reno's came flooding back in.
Cinder Crete between the Joists
I know about the mudset in deafened joists (a name for the champfering you describe), which I said was not the case. and which I have had the misery of tearing out in the past.
The cidercrete here is set on plamking 1-1/2" above the bottom of the joist and the c-crete tops out 3" below the top of the joist or thereabouts. Definitely not used as a prep for a mudset floor.
thanks bk
even tho we don't have the answer nailed down, it's nice to learn something every day.
Mortar was used in such situations for a variety of reasons. As suggested, if it's only in an area that is or likely was tiled in the past then it may have been part of a dropped subfloor mud job. But if it's around the entire house then probably not.
Sometimes mortar was stuck in various places to discourage rats. Sometimes mortar was used to anchor the ends of joists to keep them from warping. Sometimes it was used as a fire stop. Sometimes to deaden noise. Probably several more reasons.
And likely more than once mortar was used because "That's the way it's always been done here".
[But on re-reading your post I see that you appear to be describing mortar along the length of the joists, vs at the ends. I originally read it as being at the ends.]
[I'll posit that this area of mortar (is it just an area?) may have set over a coal furance at one time, and the mortar was insulation and fireblock.]
Cinder Crete between the Joists
In this instance the cindercrete was installed inside the joist bays throughout the floor and only at the floor between the two units, which may indicate that it was for fireproofing, although the plaster ceiling should have provided an adequate fire rating. The planking is set 1-1/2" above the bottom of the joist and tops out about 3" below the top. Maybe just a "belt and suspenders" approach.
Soundproofing might also be a possibility, although it is not effective at that. I'm not sure that souldproofing was all that much a consideratrion in a working class neighborhood of this type in the 20's.
My current project involves coming up with an affordable soundproofing installation so the landlord can sleep in bedrooms beneath the tenant's LR/DR/Kit floors, since the owner is not happy with the sound transmission through the current installation.
I'm a contractor who has worked in Victorian, Brownstone and late 19th and early 20th century buldings for over 30 years, this was a new conditon for me. Whence the post.
Thanks for your reply.
Look up posts by user Ted White, he had a bunch of helpful advice on this matter for you.
Sounds like firestop to me.
Ah so
Yes, I've run into those plaster block walls.
Even worse is the 1-1/2 scratchcoated and plastered metal lath hung on black channel iron partitions.
Try finding room for an electrical outlet in that!!!!
Thanks for the post referencing the Triangle Shirtwaist Fire. That sort of knee jerk reaction to the building codes makes a lot of sense and an historical perspective.
I had presumed that the plaster ceiling would have provided a sufficient fire rating, but the Chicago fire did put a hole in that arguement since plaster does fall apart,