8R Value sufficient for this basement ceiling?

[Babugaa]

Hi all.

I have recently bought a Victorian house, and am coming to learn its various foibles!

 

One of them has been a basement (full footing of the house), which generally sits at 8degrees. On the whole, the temp of the exposed floorboards of the Ground Floor is 1.5 to 2degrees colder than the temp of the air at waist height in the same room. The cold convection makes it feel like there's a very cold draught coming up under your legs when sitting down on an evening.

 

The basement ceiling had zero insulation when I bought it, but I am in the process of installing:

 

100mm PIR board

80mm Batt insulation

Vapour Barrier membrane (2 way breathable)

 

It comes to about an 8 R Value. Whilst I know this will 'help' in terms of extra insulation, and removing draughts/air moisture, I am trying to find a calculation on whether this will stop the afore-mentioned cold transfer.

 

Basically, is there a way of seeing if an 8R Value ceiling is enough to stop an 8degree basement making an 18degree ground floor from feeling cold?

 

Thanks!

[JohnMo]

If you divide 1/R you get the U value.

 

U value is W/m2.k.

 

You can then calculate how much heat transfer occurs.  k is just the difference between the two temps, upstairs and down. So say 20-8=12.  M2 is the ceiling area.

 

1/8= 0.125.

Let's say 50m2

And 12 degrees

 

W = U.m2.k = So about 75W or 1.8kWh per day will be lost to the cold space.

 

Your insulation value better than most homes.

[Redbeard]

Are you installing the insulation from the top (lifting the floorboards) or below?

[Babugaa]

 

Thanks for the rundown John.
The equation itself looks straightforwards, though the underlying math of the constituent parts is a bit beyond me. I'll try to bone up on it.

 

RedB, I'm insulating from below.