Attaching plywood sheets to wooden sub-floor under appliance

[HPDIY]

I'm re-doing my kitchen on a tight budget. I'm going to use laminate, but have been told by the company who sells it that as it is a floating floor I cannot install it under the kitchen appliances or units. As it will be quite thick (at least 12mm with laminate plus fibreboard) (and my plumber mentioned he had had problems when people had different levels of flooring as once he couldn't get a washing machine out due to the 'step'), I am thinking of getting plywood sheets under the units and appliances to raise it to an equivalent level. Then I would use the plywood as a 'wall' and do the laminate up to it- with the appropriate spacers / edges to allow for the laminate expansion. The laminate company says that would work perfectly.

My queries are:
1. do you agree that wood sheets will work for this scenario?
2. is plywood okay? What kind (structural? birch? hardwood?)
3. how would I need to treat the plywood?
4. how should I attach it to the current wooden subfloor (I don't know what it is made of - some kind of sheet) - screws, nails, glue
5. do I need to leave expansion gaps around it? how big?

I am particularly thinking of under the washing machine - my machine seems to vibrate a lot, and so I want the best kind of base for that.

Thanks so much for any time and assistance.

 

[ree]

1. any piece of board thats the correct thickness will do.

2. as above

3. you dont

4. a couple of nails or screws just long enough to hold it, say 25mm.

5. only at the front where it meets the laminate - 10mm-12mm is fine.

Remember to bring the laminate just under the cabinet plinth.

Remember to allow for this raise in height when setting out your units, and work top heights.

 

[HPDIY]

Thanks so much. that's really helpful. I'll get the boards cut and hopefully get it all put together soon!