Serious Damp Issues

I've just returned from a short holiday in Venice - we had never been there before and it seemed like a good place to tick off our list of "must-do somewhen".  The whole place is 

fascinating, and it really takes a visit to understand how this small island (or rather a set of smaller islands) is set in a large lagoon with other inhabited islands around.  Much of the lagoon is very shallow and so is un-navigable by everything except the smallest boats, and it is not clear to the eye whether the sea is taking back the land, or the land is being reclaimed from the sea! Probably a bit of both, I fancy.

The Venetians have not helped their predicament by allowing very large ships to dock on the north side of the main island, i.e. the side furthest from the Adriatic Sea.  To accomodate these 100,000 tonne monsters (each with over 5,000 passengers!) they require to keep the waterway past St Mark's Square dredged to about 50 feet, which surely cannot help but encourage the town itself to settle gently?  We were told that most houses are so damp that the ground floor is not used, and there is often as little as a foot difference between the water and ground that we walked on!

Being seriously interested in old buildings and issues such as dampness, I took a lot of

photos which illustrate the problems they have.  I don't think these are attributable to rising damp (if it really exists!), but more largely due to the continually damp and corrosive atmosphere.  Anything close to the water will be washed frequently by natural or man made waves as well as the damp breeze, and so erosion is hardly surprising and is visible everywhere (photo left).

What matters, sadly, is that there has been much use of CEMENT (aaaargh!) and the effects of this are all too readily visible, especially where repointing has been done.

The next two photos on the right show all too clearly what happens when a lime wall is re-pointed with cement.  It might look fine to start with, but ultimately the brick (or stone) starts to spall (i.e. lose its surface) because of the continual presence of the water in the brick which should escape

via the pointing but cannot.  The upper photo is a classic showing how the brick recedes into the wall.

Cement is also used for rendering, with the result that it comes off in sheets.  The photos left and below show cement render just falling off a brick wall.

Another technical issue if the frequent use of stone in an unnatural bed, i.e. laid with the natural grain (due to being sedimentary) at right angles to the ground.  This encourages vertical splits and just looks wrong anyway, as shown left in a wall where there is also spalling brickwork due to cement pointing.

This sort of thing is evident everywhere, and I fear for the future of the buildings for this reason alone, never mind the rising sea levels.  Unfortunately they seem to have made their natural problems worse by their own poor maintenance practices.  However, on the plus side, they do have lots of lovely old buildings (right), even though most of them look in need of a bit of TLC!