Hi, we live in a house that is 41 years old and have just found out that the chimney was never built properly, the ch linner is exposed, causing smoke to go up the sides and into the house,

wouldnt think so after 41 years lol

Your builder may have caused damage as some do! if you didn't have any smoke before the builder,then hes done someting!!!!! You need a gas safe registered engineer for gas or a Heatas engineer if its solid fuel/wood/coal! to attend and do a few smoke tests,then view you chimney from the ROOF,AND LOFT!,and do a survey! they mite classify your chimney as ID Immediately dangerous, and you will have to have work done! if your chimneys bad you can have it lined, or re-sleeved with cement,cage and balloon technique! chimneys can breakdown over time with cracks so get it well looked at. if your builder is liable you must get him to put it right or down the solicitors you must go! Hope helps Kieran

41 years later is this some kind of a joke ?

Good luck with that.

I'm afraid after 41 years the liability would be down to you. Best to get the chimney tested and re-lined if necessary.