Cold 3rd bedroom with sloped ceiling

[swebb99]

The 3rd room in my house is very cold and turning the radiator on in that room has little impact. The room is basically a box room and the roof sloped down over it meaning there is a slope in the ceiling. There is a small door in the room leading to a small stand up space again with a sloped ceiling and a larger space in the lower bit of the slope running along the backside of the bedroom. All spaces very cold.

What is the best way to sort this out. Should I be removing the plaster/lyme&mortar off the slope in the bedroom and associated box space and putting celotex or something similar in between the roof rafters (I dread to think about the dust from the mortar in the tiles!), then board out the ceiling slope again plaster. I assume some moister barrier would be required also and a air gap between insulation and tiles.

Is this something a decent builder/decorator could help with. I am tempted to do some of the work but think an expert would be better to finish the job with the professional and long lasting finish.

Cheers for any advice.

 

[John D v2.0]

First reduce draughts if they're excessive
Second you need to balance the radiator output with the heat loss. So more insulation eg insulated plasterboard or if you can insert it above without affecting the ventilation

 

[Diver Fred]

Either insulated plasterboard against the existing ceiling or 2/4inches of Celotex against the existing ceiling, then plasterboard and skim over the the Celotex. Maybe even 1/2inches of celotex on walls and plasterboard and skim. OOK you will lose a little out of the rooms but it will reduce the heat loss.

 

[garyo]

You should be able to access the slopey areas from above and then you won't need to disrupt the existing finish to the rooms - have a read of these similar threads - e.g. //www.diynot.com/diy/threads/dormer-bunglo-insulation.469948/
and
//www.diynot.com/diy/threads/loft-insulation-sloping-sections.473274/#post-3799081

 

[swebb99]

Thanks for the replies

I think the internal insulation is my best bet, however the corner of the door in to the box cupboard area is so close to the slope I'd have to consider this.

Would I need to consider cold bridging when using the internal insulation. I'd need to screw it to the existing lath and plaster I think and then i suppose plaster the edges.

At the moment the connection between the slope and the normal ceiling and the wall are are rounded, I'd really like straight sharp edges where the connections are.