One of the most common mistakes in that can be made in installing a Marmoleum floor covering is not choosing the right underlayerment and sturdy subfloor.
First the subfloor needs to be secured if working on a remodel. If you are working with ship lap subfloor or something that is over 20 years old adding few extra screws are nails in the floor joists firm up the floor.
Next choosing the proper underlayerment is key. In large areas such as living rooms, family rooms or commercial areas where there is alot of light or long expanses of material. In my personal opinion no less than 1/2 in plywood underlayerment over subfloor will do the trick.
Take for instance this brand new floor installed in West Seattle. The first installation of 1/4 in plywood underlayerment( over existing vinyl and underlayerment) was used and did not turn out so well. The plywood showed alot of the high and low spots and just was not that firm.
The customer was not happy with the install, so the 1/2 in scuff guard plywood underlayerment was used for the second install. This did the trick. The floor was solid, firm, and showed no signs of high or low spots or rolls in the floor.
With the proper care this floor will last many decades of wear and tear. It is sometimes helpful to remember that the finish is not the most important part of the job, its whats underneath that really matters. Take the time to discuss the choices you have with your contractor and when your new floor is in you can rest assured that whats underneath it is going to last as long as whats on top.