How do you raise the height of lawn?

[#1]

There are two main options when it comes to increasing the level of your lawn. Both are best done in spring, summer or autumn as during winter your grass is typically not actively growing.

The first option is to simply bring in new soil, dump it over the existing lawn, level it and then plant new grass either from seed or using turf slabs. This would be a quicker process than the alternative approach below, but it would mean you would have to put the effort into establishing the new lawn.

The alternative, which would not be quick, is to add topsoil over the existing grass over the course of multiple seasons, allowing the grass to grow up through the soil as the level slowly rises. This would be a slower process, but the lawn would remain intact throughout.

Either option will work, with the priority being in different areas. 

You might like to check out How To Topdress Your Lawn and How To Lay Turf for some examples of these process. - JacobZ