Improving a thermal bridge created by a bike store

[WisteriaMews]

We have a bike store just to the left of our front door behind the wooden doors in the photo. It is recessed into the house with a bedroom above. The floor joists of the bedroom form the roof the the bike store and are well insulated with Kingspan between and below the joists. However, the interior walls of the bike store which are cold, effectively become the inside walls of one corner of the bedroom as they rise up through the building. They create a cold corner in the bedroom as there is no thermal break in the wall. Hopefully that makes sense as a description of the issue.

 

I was thinking of cladding the inside of the bike store with insulated plasterboard to try and improve the situation. I appreciate insulated plasterboard doesn't have the best performance, but I'm limited on space if I still want to fit bikes in the store (which I do). I could omit the plasterboard and use that thickness to add more insulation, but I think leaving raw insulation would get damaged. I'm also not sure it is advised to leave exposed Kingspan? We are also likely to sell in the next year (to fund the next self build) so want to do something that is DIY and not too expensive.

 

I had three questions I was hoping the forum could help with:

1. Does this sound worthwhile doing?

2. I'll add another photo below. There is a gas pipe, two meter boxes and a couple of other things which mean I won't be able to cover all of the bike store, probably around 80/90%. Would that still be worthwhile?

3. There is also a big steel over the door. Should I try to cover that or leave it exposed due to the condensation risk?

 

Thank you!

 

[WisteriaMews]

Attached are two more images showing the inside of the bike store and the steel above the door.

[Russell griffiths]

If you are selling next year then it’s not worth it, stick £20 extra on the gas bill and get it sold. 

[SteamyTea]

Make sure the door is weather tight, you only need to insulate the walls that connect to the house, and you can add extra insulation to the shed ceiling.

12 minutes ago, Russell griffiths said:

If you are selling next year then it’s not worth it, stick £20 extra on the gas bill and get it sold. 

That just leaves the problem there for the next owner, who may not bother to sort it.