SuperFOIL SF19+ in an unheated loft space

[MikeJH]

An elderly friend of mine had her loft space boarded up many years ago with minimal insulation beneath the boards. It is unheated.  She would like to improve her house insulation and has been advised to have SuperFOIL SF19+ fitted on the internal side of the roof.

 

The loft space is not air tight and cold air draughts will be entering near the eaves. Consequently, we are unsure whether fitting SuperFOIL SF19+. will have any worthwhile effect on reducing heat loss from the living area of the house. Can anyone advise on the wisdom of proceeding with this form of insulation? 

SF19 SUPERFOIL | Green Guard

[JohnMo]

A loft space is supposed to be well ventilated. The floor of the loft is insulated to keep heat in the house. Adding insulation at the roof line does nothing except waste money.

 

Best way is to insulate is take floor boarding up insulate ceiling with about 400mm of insulation then use floor board risers and reinstate floor - if you really need to. Use as an opportunity to get rid of stuff that maybe been up there for decades.

 

Keep the eaves ventilation open.

[Nickfromwales]

4 hours ago, MikeJH said:

An elderly friend of mine had her loft space boarded up many years ago with minimal insulation beneath the boards. It is unheated.  She would like to improve her house insulation and has been advised to have SuperFOIL SF19+ fitted on the internal side of the roof.

 

The loft space is not air tight and cold air draughts will be entering near the eaves. Consequently, we are unsure whether fitting SuperFOIL SF19+. will have any worthwhile effect on reducing heat loss from the living area of the house. Can anyone advise on the wisdom of proceeding with this form of insulation? 

SF19 SUPERFOIL | Green Guard

The foil will do the square root of zero. It will likely cause problems tbh.

 

There is no quick fix, as above, the flooring needs coming out, at least 200mm of insulation, 300mm is plenty, (some say that after 300mm the weight of the top layers of insulation crushes the lowest layer rendering it ineffective), and board over. The most important thing is to leave a gap at the eaves so air can flow over the insulation, and it absolutely must NOT touch the felt / membrane of the roof. This needs particular care and attention, vs some numb-nuts pushing in as much as they can and asking for cash.

[saveasteading]

7 hours ago, MikeJH said:

wisdom of proceeding with this form of insulation? 

It is upmarket bubblewrap . OK for a garden shed but I wouldn't advise it in a house.

[MikeJH]

Thanks to all for your advice. It has been very helpful.