Elderly cat - how do I stop her pooing in the house

[differenttoyou]

We recently had a loft conversion done. Prior to that our 17 year old cat would quite happily take herself in to the garden. She has a specific spot in the garden that she always used as her toilet. During the building work the weather was terrible, rain, wind etc. The cat started to use the empty loft as her toilet. I thought it was because of the disturbance and the possibility that she didn't like the garden being so wet.

Eventually we put down a litter tray and kept it there until the work was finished. I took it away but she started to use the new room again so the litter tray went back down. A few days ago I removed the litter tray again and she is back to using my new bedroom as her toilet. She is refusing to go outside. I put her out in the morning and she almost immediately goes around the house and comes back in the cat flap. It is almost as though she is afraid of something outside.

Is there anything I can do to get her to revert to her previous habits short of keeping all the doors closed all day long and shutting her in the kitchen at night time?

She is old and cats like litter trays ,just keep the tray .

I wouldn't mind too much if I had somewhere to put it that was out of the way. At the moment it goes in the kitchen. I might look in to getting a covered tray. She currently uses an open one and spreads the litter all over the place.

No experience of this I'm afraid, but is there a chance she'll start going outdoors again once the weather improves and the rest of the family start spending more time outdoors? She might feel a bit safer...