How long to build St Paul’s Cathedral today?

Written by LetsBuild

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“If they built St Paul’s Cathedral today it would only take 2 years instead of 200.”

Now isn’t that a fascinating hypothesis? Before we go much further, we’d better have a look at the factors involved and, for now, we’ll ignore the question of land. We’ll just assume there is an available plot and that Detailed Planning Permission has been granted. So what factors do we need to have a look at? Finance is first, followed by material availability and ending with the availability of skilled labour.

Finance is no problem!

The original was built using money as it became available. Keeping it simple, this was mainly donations into the Church collection plate from the regular church-goers towards the end of their Services. Generally, they were very poor villagers who had barely two farthings to rub together, so cash came in slowly. That meant that work could only progress at a slow rate because the men working on the job had to be regularly remunerated.

Now for material availability:

St Paul’s Cathedral is built with Portland Stone. Portland Stone comes from the quarries on the little island of Portland, south of Weymouth. It has several quarries and the one which produced all the stone for the original St Paul’s Cathedral, Broadcroft Quarry, is still operating. Now bear in mind that the Dome of the Cathedral alone weighs 65,000 tons, it seems a bit optimistic that they could achieve the required output inside two years. Therefore we’ll assume that most of the other quarries are going to become involved. All of them will need additional plant to quarry the stone and then cut it to the required shapes and sizes. Once they had the plant installed they would need to increase their manpower to operate it. Five year apprenticeships? – and they can’t all start on the same day! Best guess would have to be an absolute minimum of ten years to get all the materials to site!

Last on the list is skilled labour.

We’ve already had a look at the guys that do the quarrying, but there another group who work there; the stonemasons. Have a look at the St Paul’s Cathedral and, inside and out, it is covered with carved stone! Now we did actually ask the quarries about this, but we got no reply! Obviously the question was too bizarre for them to waste their time, so we just have to guess again! Best guess here is that it will take 30 years to train the required number of stonemasons and another 20 years for them to produce all the pieces required.

Once all the blocks and carvings are on site we come up against another bunch of tradesmen; those laying the stone! That shouldn’t take too long to get them up to strength. There are plenty of brickies and dry-stone wallers who would love to do it. Getting these guys up to speed will fall well within the other time scales, so no worries there! But suddenly we hit another problem which has the potential for delay; settlement! The old folk wisdom, from the days when we used to build with the technology that has to go into our new St Paul’s Cathedral, is that we built to the height of a man and then walked away until next year to allow everything to settle! Remember the Dome alone weighs 65,000 tons!

We can’t expect to stick the whole thing up in a hurry and it not settle!

Rafting wouldn’t be a good idea probably; so much weight on the raft that it could well float away with our Cathedral on top of it. Suppose we could consider piling, but what size would the piles have to be to carry that kind of weight and how deep down would they have to go? Where is bed-rock and are there any caves or other weaknesses in it that may cause slippage? No, sorry; we’ll be a lot safer sticking to our 6 feet a year! And a year is the number – famously 365 feet high! That works out to be a build time of 61 years! There we have our answer! We couldn’t build St Paul’s Cathedral in 2 years; it will take us 61. But at least we don’t have to worry about whether or not we can get our material and labour up to speed! The limiting factor is just Mother Nature!

What’s your best guess? Closest to two years with decent explanation wins credo points!

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