Excellent advice all. I was under serious time constraints and didn't get to see much of it before I had to proceed but I'm likely to do this again. My third time with vinyl flooring and I'm getting better but on some of these jobs I appreciate the value of the good ol' apprenticeship concept.

I use to think the ol' "jack of all trades, master of none" was cute but it's looking more and more like a curse. I mean I sorta have much of carpentry, door installation, and woodworking in general down but when the only available work or at least the work of a regular client who needs it is something else, oh well, soldier on.

When I finally got the old flooring off, I realized the subfloor in question was 3/4 ply with half and then quarter inch CHIPBOARD on top. Almost worse than particle board, which can at least be scraped and reused, more or less. Damn chipboard was coming up in big pieces rendering it junk. Luckily, the top 1/4 inch had been put down in a previous remodel, and not glued so it was easily removed.

My favorite lumber yard in Berkeley, Truitt and White, recommended an "engineered sub floor material" Matrixx brand - it's high quality plywood, exactly a quarter inch thick, 5 x 4 sheet, impervious to water swelling, supposedly. Around $26 a sheet. Only needed three sheets. I took out my second layer of 3/4 ply I was going to use and replaced it with half inch ply. It was still a 16th too thick, so I had to grind off that much, this on a piece about 5 x 3. Luckily, the glue under the first ply was a good guide, as soon as it was gone, I'd gone far enough. W/o that guide, would have been a ***** to take off a uniform 16th.

Put it in, put down the Matrixx with those high quality screws used for holding down hardy board, I forget what they're called, but they're good. Slightly broader head and double depth thread, they stay down nicely, and rarely strip out the wood. I used Fix-It-All, a sort of plaster of paris product for the seams and screw holes. Probably a lot like the product BC mentioned - it dries enough to sand in about an hour. Recommended by an old contractor guy at the lumber yard, guy has been around, said it doesn't shrink. You don't find that kind of help at Home Depot.

I had been in a hurry and bought the wrong trowel, the one they recommend for the same glue on carpet. The one for vinyl has smaller teeth and openings. It was late, I used the one I had and held it low, with many pulls this way and that. Came out OK but oh man, get the right trowel for the job. Too much glue leads to persistent pockets of wet glue under the vinyl which can distort and finally dry all weird. I had a 100 lb. roller so it came out all right, I had just slightly too much here and there.

I landed on my feet but this is harder than it looks.

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1986 300SDL, 362K
1984 300D, 138K