If my house is not on stumps, is it possible to install underfloor insulation?

If my house is not on stumps, is it possible to install underfloor insulation?

Certain types of insulation - like thermal breaks in a concrete slab - will need to be done during the construction of the house and can't be done thereafter. In general, retrofitting insulation to a slab floor is a difficult proposition (if it's possible at all to do so effectively).

Retrofitting insulation in stump and joist floors is much easier than retrofitting a slab floor (providing there is enough space).