We live in a loft space that is around 14 feet tall, not quite high enough for two regulation 7.5 foot living spaces. We added a 7.5 foot space up high and to maximize the clearance underneath, we built a very thin floor.
The floor is 4 1/8 inches thick (actual measurement) and it spans 16 feet. Gives us enough headroom underneath to be able to walk around down there.
It is made with the metal forms that are typically topped with poured concrete in office buildings (trade name is Verco). Instead of concrete, on top of the Verco is a glued and screwed layer of 1 inch OSB “plywood” (I think it stands for Oriented Strand Board). The edges of the Verco sit on angle iron that is bolted to really thick beams turned sideways. We sanded, putty filled and then polyurethaned the OSB.
If you live in California, building a floor in this way is now part of the state approved allowed uses of building materials (you can contribute to our unexpected engineering costs if you feel generous).
We needed a very thin floor and we are very happy with the results. The only gotcha was that the verco sheets are crimped together and then welded together and then welded to the angle iron. Welding is no big deal except it is on pre-galvanized steel (unhealthy fumes) and the inspector needs to watch the welding. Otherwise it was pretty easy to install.
Kee
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Many years ago (early 80's) I worked on the construction of a 49 floor high rise building that used metal deck with concrete topping. My understanding was that the concrete contributed significantly to the overall strength of the floor structure. Something about composite strength. If you had glued and screwed osb to the top and bottom, you would have created a form of a torsion box, whuch has quite a bit of strength. But I'm a little surprised to hear that Calif approved what you describe.
The OSB acts as the compression member in place of the concrete. When we designed it, we modelled it after what we had seen elsewhere. Turns out what we had seen had been built without permits so ... we got to create and submit all the engineering details and calculations to the state so that the city would approve it. It added 6 months to our construction schedule.
Kee
Saw an interesting show once that demonstrated an European (Swedish?) floor system that was a simple glue-up of dimensional lumber--imagine gluing up a whole bunch of 2x4's on their wide edge to make a large panel which becomes the floor. Had a pretty good span and also had the benefit of being the final finish for both floor above and ceiling below. I bet the sound transmission was really something, though. No dancing in high heels above the master bedroom!
So, anyone have an idea how far you could span with a glue-up of this sort, with the common wood species used in NA for 2x4 lumber?Close enough for government work
our neighbors across the hall did that for their bedroom floor. They are spanning 12 feet no problem. The glued and (nailed or screwed) the 2x4s as they installed them one by one. Then they sanded the top flat and sealed and finished it. It is a very stiff floor.
Neither our verco/OSB floor or their 2x4 floor is quiet underneath. You can hear people walking. But, if you are fitting a floor between an upper and lower limit, these work fine.
Kee
Roger, max span for your floor is 12' as the trees being harvested now are only about 15' from root to crown? Joe H
Still there? contributions?
Hello Kee,
We have a similar space which would be well served with a thin floor. If you still have enineering calcs and construction specs and details, perhaps we could help defray some of your expenses of 12 years ago?
Please respond if you read this, and we can go from there.
Thanks for your post, and hope you see this message,
Kim