How much does the cathedral weigh?

I believe this question might have been inspired by the movie “Up”

When I was a newly-qualified tower guide I tried to learn the core facts and figures, but fortunately someone has nailed them to the model of the cathedral.

So if we add up the Chilmark, Purbeck, Tower/Spire, Lead, Timber, and an allowance of 75 tonnes for the stained glass plus another 50 tonnes or so of random artefacts (stalls, pulpits, altars etc) we get around 86,000 tonnes or 86 million kgs.

One litre of helium can lift about 1g (making a small allowance for the weight of the balloon itself) so to lift the cathedral you would need 86 billion litres of helium, or a balloon approximately 550m across.