Typically in larger Victorian and early 20th century properties there was a room at the back of the house called the scullery. This was where a maid would do work such as laundry, washing up etc. Due to the amount of water from spillage and condensation, these rooms usually had solid concrete floors, as timber would rot very quickly under the damp conditions.
The scullery floor was often at a lower level (to stop flooding the rest of the property). If a damp course existed then the floor should have been built below it, however they were often raised later by adding a further layer of concrete to become an integral part of the house, and so often this extra level would breach the damp course. Although a new damp course may have been added, often it wasn’t.
Any such rooms that have manifested serious damp issues have probably been treated with a new chemical damp course, but there seem to be even more that just have a low level damp issue and although the damp doesn’t manifest very obviously, they are harder to heat and have higher humidity than is ideal.
This image shows a scullery floor that has been laid with modern vinyl tiles and you can see that there is a very small bump. This shows that even though the installers laid a typical epoxy membrane under the tiles, it has failed in a couple of spots, but too too seriously.
Even if it had not failed, then this type of damp proofing carried out by floor contractors can be a problem because unless they “tank” the room, ie continue the membrane a metre up the walls and replaster, the damp that is under the membrane will just spread out and go up the wall. Even if you go to the huge expense of continuing it up the wall, this is not a good thing to do in old houses with breathable lime mortar and plaster.
What are we going to do about this?
Basically we will monitor, wait and see. Currently it is very minor – there is no smell or signs of damp. In the long term it would be best to properly treat the damp, however the expense of this, especially if tiles have been fitted, seem to be prohibitive compared to the perceived benefits. But the extra humidity in the room can affect energy use, not just because the room itself is damp but because when they are heated, then warm moist air permeates the rest of the house and the overall humidity levels can be higher. This can then aggravate any condensation issues in walls.
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