Insulate under floor of 1st floor?

In a standard-sized 3-bedroom semi-detached house where under the floorboards of the ground floor has been insulated and also between the floor joists of the attic (not the roof joists) has been insulated, is there any point in insulating under the floor of the 1st floor? i.e. under the floor of the bedrooms?

Thanks!

I would think the only benefit to it might be for sound insulation.
You could end up with there being a noticeable difference in temp between upstairs and downstairs. Say for example you have a fire lighting in the sitting room downstairs, the insulation between there and the room above will prevent the heat spreading upwards.

Smythe said:

In a standard-sized 3-bedroom semi-detached house where under the floorboards of the ground floor has been insulated and also between the floor joists of the attic (not the roof joists) has been insulated, is there any point in insulating under the floor of the 1st floor? i.e. under the floor of the bedrooms?

Thanks!

Click to expand...

The current thinking in this area is to insulate on a room by room basis rather than a whole of house basis so as only the rooms that require to be heated get heated.

However, as you might expected it does not get much support here in our 'temperate climate'

However, I always recommend it.

Heat rises, so if you don't insulate between floors, heat from the lower living quarters (in most conventional Irish homes anyway) will rise up through the floors to the bedrooms. People generally like the living quarters to be warmer than the bedrooms.

For houses with zoned heating controls it makes even more sense.

I'm now thinking perhaps it might be best to place something under the 1st floor boards for acoustic reasons which will stop noise from bare wooden floors upstairs. That is, instead of putting in the thermal insulation.

Something like:
http://www.isover.co.uk/products/acoustic-partition-roll-apr-1200?cat=internal-floors

Perhaps it may also to some extent reduce heat loss to upstairs.

Retro-Sound proofing in a domestic dwelling is a completely new level of hurt in comparison to insulation.

Sound as you know is transmitted by some medium, be it air or timber or walls, whatever.
Nobody hears you scream in space because....

So air leakage through the floor will carry sound. Airtightness is key so recessed down-lighters are out

The key to deadening sound transmission is to either
1: increase the rigidity of the floor/ceiling, to reduce its ability to act like a drum skin or speaker cone.
2: provide some material such as rubber or thick underlay, that will absorb the movement.

Trying to do it with the stuff listed in the link: waste of money and time for sound proofing.
as it it will be virtually impossible to get it done right, even if it is dense enough and thick enough.

The other problem with noise is that what is acceptable/not noticeable at 15:00 is not at 03:00