To expect builders to fix damage

[howmanyusernames]

Having a loft conversion done, builders are lovely. Have noticed a few marks that paint can fix, and now a few cracks that we can fill (albeit begrudgingly).
But last week I noticed the dining room carpet (where it meets the kitchen door) is frayed and doesn’t even meet the door edge now. This is due to their excessive hoovering at the end of each day (which is really kind) but it’s meant the carpet has been damaged. They also hoover with just the tube bit and almost scrub the carpet to get the bits up.
AIBU to expect them to fix this (although not sure how you ‘stretch’ a carpet?) or pay for a replacement?
My OH says it’s ‘just one of those things’ but I don’t expect to pay tens of thousands for a new loft room and then pay more to repair the damage caused to the rest of the house!

Can’t you buy a wider metal strip to cover the frayed part? I don’t think you can hold the builders responsible for this. That said, they should have covered all the carpets that would be affected for the duration of the build and charged you for this.

Show them and ask them to suggest a remedy but asking for a new carpet is VVU.

They put dust sheets down but bits still go on the carpet. It’s probably about 2 inches away from the runner, so not sure they go that wide, do they? It’s also a wooden one so I could ask them to make and fit a new one maybe?

You need to get a carpet fitter to stretch it back to the threshold and replace the strip. It's just what happens when it gets pulled off the strip for whatever reason. I'd just sort it myself but It's up to you if you want to risk upsetting them over It!

That’s probably best. There is a sort of super strong cling film that they can use to protect the flooring which you could ask them about, it stays down for the whole build. I’m slightly struggling to see why the dining room is affected by a loft conversion.

Do we need a diagram?

They put a lot of the building materials in the back garden, so to get to them they have to come down from the loft, and through the dining room and kitchen. They put the dust sheets on the landing, stairs and on the downstairs ‘walkway’ they use, it bits still come off that which is why they hoover each day.
They also only have 1 week left (been here for 6 weeks already) so probs a bit late for that sticky stuff!