Hello again. Just chiming in for another update.
The new rendition of the J-pad is a bit more of an undertaking, but is essentially a complete raised floor of the entire studio room (10' x 11'-3") using the same principal and re-using most of the original items. And as luck would have it, will only require an additional $120 in materials to construct. There are however a few logistical and design challenges which I will be documenting.
Challenge 1 is innertube access for yearly / periodic inflation. Granted they hold pressure for quite a long time before needing a recharge (mine went 12 months), but a wall-to-wall platform can't be lifted and moved. In addition, the original isolation pedestal design sandwiched the innertube between solid slabs, thereby closing off any access to the valve stem. The attached image shows a simple arrangement of inexpensive paver bricks that are readily available from Lowe's for 56 cents each. They are 7.7" x 3.8", and when arranged as shown creates a 3.9" hand hole for top access to the valve. Note that the lower brick layer is arranged opposite to the upper layer, which allows them to overlap in a very structurally secure way. The bricks are epoxied together between the 2 layers to form a single, rigid mass.
The platform has an interrupted slat where it crosses over the hand hole, which will be covered by a simple access plate screwed to the top of the platform. Just reach down with a bicycle pump hose once a year and you're good.
Additionally, there will be a very specific construction sequence since it has to be built with the pedestals already in place. I'll be producing a builder's guide with photos. I won't be able to do a full set of plans since the dimensions are a function of the available space. I will however provide measured detail drawings that show critical areas.
More to follow in the weeks ahead. Cheers.
Respectfully,
Brian Jackson