Leveling an Asphalt floor advice

s_a_n_j

I think this is going to be a tall ask, but you never know :-)

Problem: We'd like to lay a wooden floor in the living room, however, it's to be layed over asphalt.
Current info:
1. Floor is flooring grade asphalt in reasonable condition, ie it's not damp but the cracks have been repaired, as the previous floor covering was carpet and the grippers they used was nailed!
2. The space is approx 36 square meters, uneven, with the difference between max and min level is 22mm.
3. I'm fairly competent at diy, and have the time at present, unfortunately there's not a lot out there on the web for my particular situation.

It seems most manufacturers only recommend a max of 6 or 10mm in total over asphalt. I think this is because they're covering themselves for the effect of shrinkage of the slc, pulling up the asphalt floor.

I've come to the following method, after speaking to various self leveling compound (slc) manufactureres:

1. Prime the floor, with suitable product for asphalt.
2. Use latex slc, to max of 6mm - 10mm, for the first layer, allow to cure
3, Prime the slc layer with suitable product for slc.
4. Repeat steps 2 and 3 till floor is built to recommended level.
5. Lay a water resistant/proof underlay to seperate the slc and an engineered wood floor to form a floating floor.

I'm just working on the principle that each layer of latex will reduce the effect of shrinkage as the layers go on. ie because each layer will add a bit of flexibility.

The reason for choosing an slc, as apposed to anything else is because of the depth required, most screeds/asphalt need min 20mm+ to form an unbonded layer. The other method is obviously to rip out the old floor and rebuild, not something I'm keen on doing!
I've spoken to a few screeders, who've recommended laying the slc in one go, with aggregate to push up the max limits. It could be my method is overkill, but I'm thinking it maybe safer?

The reason for resurfacing the floor is because we've raised the level of the hallway by adding limestone flags, so putting down carpet again isn't really an option. (And no, we weren't aware of the complications of leveling an asphalt floor, as it originally had carpet down, and seemed fairly level. You live and learn...:-))

I'm hoping that someone has either solved a similar problem and can recommend an alternative method with the products they've used or provide some advice/re-assurance on the proposed method?