Richard Greenland
Last week I wrote about wooden floors, this week it’s solid floors.
Solid floors in modern buildings are usually concrete or beam-and-block, though they may be covered by tiles, laminate, stone, wood or carpet. They should present no problems if properly constructed and there is no subsidence. If they are wet it’s usually because there has been a plumbing leak above floor level and they have yet to dry, or pipes below floor level have corroded because they have not been isolated from the concrete properly. This means taking part of the floor up to fix the problem. Cement is very alkaline and corrodes copper so all concreted-in pipes should have been placed in plastic sleeves.
Older houses with solid floors can present these problems plus many others. Before the 1960s or 1970s it was normal to lay concrete without a plastic Damp Proof Membrane (DPM) leading to rising damp. Floors should be carefully inspected for signs of damp. A damp meter is an inexpensive tool which is useful for this, but beware that they are just as good at reading condensation or spilled water as rising damp!
Rising damp is solvable by re-screeding the floor on DPM, or even painting the floor with bitumen although this isn’t ideal. Flagstone or tiled floors without DPM can be OK if allowed to breath (I have a flat with one and it’s no problem, but it’s somewhat elevated so the ground underneath is only slightly damp, never wet). If carpeted they will sweat and cause rot. A plastic sheet over the floor helps, but again is far from ideal.
Other types of solid floor in older buildings include lime concrete cast between steel joists. There may be no reinforcing at all besides the joists, which are usually about two to three feet apart, so they need checking for obvious cracks and the condition of the steel (corrosion). They can be very strong if in good condition. You won’t be able to lay cables or more importantly pipes in them without seriously weakening the floor. Waste-water pipes need a fall, so this needs careful planning if you are undertaking alterations.
Talking of pipes, I’ll cover plumbing and heating next week.
Al the best,
Rich
As you said “If carpeted they will sweat and cause rot. A plastic sheet over the floor helps, but again is far from ideal”
but so many people don`t know this
Congratulations!
If it helps save your carpet, I’ve done my job with this blog!
BW,
Rich