When the floor is above an unheated crawl space install insulation between the floor joists.
How to insulate a cold floor.
A floor with ducts also should be insulated with a continuous layer of thick rigid foam under the floor joists.
An excellent move is to insulate the ceiling.
However if you are going to spend a lot of time in your shed then you may want to insulate the shed floor to keep the shed from getting too hot.
In the cold climates even the lawn equipment needs to be protected from the extreme cold so i recommend to insulate the floor.
In warm climates you could get away without insulating the shed floor.
This protects the floor from the chill of the space below.
Hot air rises after all and it would be a pity to waste the warm air you are paying for your hvac system to produce by losing it through the ceiling.
The latest breakthrough product in the world of insulation does not degrade does not absorb moisture and will not act as a.
Insulate ducts and plumbing and put them close to the floor.
For decades the accepted method for dealing with cold floors over crawl spaces has been to insulate the floor joists the crawl space ceiling.
This needs to be done before a fitted carpet is laid as it will not be possible afterwards.
Ensure you insulate thoroughly but avoid squashing insulation material as this will seriously compromise its effectiveness.
Most homes require at least r 13 though homes in cold areas can benefit from more insulation.
Remember to seal all the gaps between the skirting board and the floor to prevent draughts.
If you have 2 inches of insulation your floor has an r value of 6 4.
However there are significant flaws to insulating the floor joist that prevent it from being a long term effective solution.
To prevent cold floors in this situation you can add insulation between the ceiling of the room below and the floor of the room above or you can use carpeting in the room above to help insulate.
Top tips for insulating a floor.
If hvac ducts are routed through the floor assembly the floor joists must be deep enough to install several inches of insulation under the ducts.