I would be interested in any advice or hints about a series of damp problems in an old Victorian house.
The property was built in 1870, is over four floors and was previously used as a bakery, shop and boarding house. The bakery was built into the basement, with a floor and coal store, a small corner shop on the ground floor and four small bedrooms on the first and second floors. The property is unusual in its layout and the deeds indicate that it was purposely built as a bakery on a corner plot of land to service an expanding Deleted town.
When I moved in, the property was quite damp and it was clear that this was not just from being unoccupied for a few weeks. After removing many layers of vinyl wallpaper, lifting up carpets etc, the property immediately warmed and the in places wet walls quickly dried. Removal of concrete plaster also helped as did unblocking the vents between the groundfloor floorboards and the basement ceiling at the front of the property. This wall had become dry.
However, the wall at the back of the basement remains damp. One airvent has been concreted over and the extension of the basement under what is now the backyard has been concreted over, probably recently. Underneath around a foot of concrete is what was probably a flour store and is outside the walls of the property. The render in this back wall is in part crumbling. I also discovered in the corner next to this back wall a well which was presumably used to provide water for the oven or even baking. I have emptied the well with a pump but the water slowly returned to the previous height within 2-3 mms. I assume that the water comes from the water table and was carefully channeled by the builder. The well has been constructed. Part of this back wall is also in fact sheer rock and is sometime inevitably damp.
I don't think that the damp problem has worsened in the past two years but I'm concerned that there is no airvent at the back of the house. The concrete floor of the backyard appears to be higher than what was previously there so may be covering any natural ventilation that was almost certainly built into the property. The working hypothesis is that the moisture is not a problem per se but is not being allowed to escape naturally due to this concrete floor.
Fortunately this concrete floor outside slopes down into a drain so at least any rainwater does not collect.
One idea is to drill a series of holes in this concrete floor next to the property. Since the water runs away from the property to the drain, any rain water should not drain through them (or maybe they could be blocked in some way) and allow air to pass from the basement out of the back of the property.
In addition, I will try and unblock the one airvent still visible at the back of the property.
Based on the information above, any more ideas or suggestions welcome.