Spectrum will perform just as well as any CLD sheet on the market when built up to 3mm (2-3 coats) There is not much over spray, it shoots where you point it and is too heavy to float around the area to drift off onto anything else. Spectrum can also be brushed, rolled, or sprayed...Sludge can only be put on with a gloved hand or trowel and is meant for small spaces, nooks, and corners. The 30 sqft you have in the post will most likely cover the floor only, if you want to cover the doors and walls, you will need to add about 15 more sqft. I would also recomend using Luxury Liner Pro instead of LL+CCF as it is less gluing, less cutting, and Luxury Liner Pro performs better then the 2 products seperately as the CCF on the Luxury Liner Pro is much more dense then the Over Kill Pro. Use SAVE10SS at checkout and save yourself 10% off your order. Good luck with your build, here is a video of Spectrum being sprayed inside of a shop with 10's of thousnads of dollars worth of builds in the back ground, there is very little over spray: Spectrum Video