[homeholic37]

A family of three living in a family home on a windy hill.

Now that I want to convert the loft in to a brand new (kind of) aparmtent for myself, we've added a room, a bathroom, a kind of studio kitchen bedroom.

the area is big, so the heating and cooling will be an issue. My dad insisted on putting isolation material on the ceiling.

The ceiling is currently just wood, that is under the roof tiles.

Is is really necessary or can i just get away with it?

Thanks

 

[chandler48]

You use the term "loft". Is it a loft or an "attic"? Most "lofts" are finished. If it is an attic, it may be well served by using polyisocyanurate foam in the rafter bays. Otherwise you need to maintain an air space above your insulation for air to move from the soffit vents to the ridge vents, which usually results in inferior insulation quality.

What type of "isolation" material did he put on it? If you can't migrate heat/cool from your existing system, you may want to consider a mini split unit dedicated to that area only.

 

[ChuckTin]

Simple answer is yes. But ...
First, be warned, you need to consider venting and circulation for moisture. That moisture will want to condense on a cool surface, usually the inner face of the roof decking.
If the rafters are showing measure them to see if they're 2x4 or 2x6. With 2x6es you can put 2" foam sheets between the rafters and still have air space between them and the decking.

 

[Nealtw]

You would like to have or make the rafters the size of a 2x12.