I've only recently heard about this technique, but have never seen it. Bill, our contractor, hasn't seen anything like it either, even in doing this type of work on these types of houses for 30 years.
The finished floor in "Katie's Room" has been removed. Somewhere along the line the finished floor suffered some serious water damage and was not salvageable. Under that is the sub-floor you see pictured.
One of the sub-floor boards has been removed to reveal a 4-inch layer of what appears to be a dry mix mortar made of of stones and hard packed sand with some sort of binder. Then there's another sub-floor on top of the joists.
Apparently this was used as mass to attenuate sound between the floors of the building. I've heard this was common in old European construction, but haven't heard of it being used here in the US.
If you look closely at the picture, to the left of the hammer and running horizontally under where the missing floor board used to be, you can see the old pipe for the gas lights that were original to the house.
Yup, variations of this method were common in Europe, although I've never heard of any binder being used, typically it's just compacted dirt and debris (sometimes containing up to half bricks, torn work clothes, shoes and who-knows-what-else).
ReplyDeleteThere were essentially two different installation methods. The simpler variety uses a false floor between the joists for the fill and the subfloor/finish floor is nailed down on top of the joists. The more elaborate version (which seems to have been used mainly or even only in Austria) has two layers of subfloor with the fill in between.
The difference between this and a completely hollow floor never ceases to amaze me!