"The tenant is a working woman in her 50s who actually spends little time there." I think that's the clue.
The property (detached bungalow, meaning all interior surfaces interface with the outside) is intermittently heated - warm when the tenant is there, then allowed to cool down when she goes out. The cycling of this situation leads to condensation on the cooler surfaces, which then leads to cold damp walls, and an exacerbation of the problem. As the temperatures even out in the warmer weather of spring and summer, the condensation disappears.
The temperature should be thermostatically maintained to a minimum of about 15 deg C from the onset of cold weather, so that cold cycling does not occur. The use of ordinary (not heated) oscillating desktop fans to move air around within rooms helps to avoid cold spots developing on exterior walls, for instance, below and around windows.
Maintaining an even temperature in an adequately insulated dwelling should not be much more expensive in terms of energy charges than allowing the property to chill down and then rewarm to comfortable temperatures on demand, especially considering the latent energy released into cold walls when the condensation takes place, and the energy required to evaporate the water while maintaining the same cold temperature on the cold damp patches.
Furniture in room corners and against outside walls, and closets packed with clothes and boxes prevent ventilation of cold walls and lead to mould growth and spoilage of decorations. Avoiding these situations and the use of fans to circulate air can prevent the build up of damp, and subsequent problems.
Inadequately circulated air in conservatories can cause running condensation, and damp mouldy conditions. Here again an oscillating fan can prevent condensation from forming by evenly warming all the glass surfaces, preventing cold spots forming. Here again having the heating thermostated to about 15 deg C throughout the house should prevent the formation of cold, damp patches.
In the bathroom, if the areas wetted during showering (from direct splashing and condensed steam & vapours) are wiped with a shower cleaning product to remove and prevent beaded water on tile and glass surfaces, then the surfaces will not only dry cleaner and free of scale, they will also release much less water into the atmosphere within the house, which of course will require additional heat to evaporate, at the expense of warmth.
Even better if the surfaces are towelled while wet - mirrors and other glazed surfaces maintain their sparkle and black and pink moulds cannot take hold. Don't forget to dry the loo cistern and any cold water pipes. Too much ventilation can chill the bathroom by evaporative cooling.
If the kitchen has a vented extractor, always use it while cooking, but don't leave it running long after cooking has finished. Circulating extractors are good for removing frying or roasting oily vapours but do little for steam and water vapour.
After much trial and error, I find that black mould is best removed with supermarket thick bleach, undiluted, painted on with a nylon-bristled 1 1/2" paintbrush, and left to dry. Do not scrub the bleach in, just lay it on over the surface.
Bleach is acid (until the chlorine released reacts with cations), and will not damage most modern paint in the way that alkaline cleaners (including soap) do. Chlorine is an irritant to eyes and mucous membranes, especially the throat and lungs, so it is best that treated rooms are unoccupied for an hour or so after treatment.
Of course avoid dripping bleach on any materials or surfaces that may be damaged, including clothes and furnishings. Stuff I've treated includes vinyl emulsion and silk on plastered and papered walls, gloss, eggshell, satin alkyd paints, acrylic paints, varnished and untreated timber, bare brick and pointing, tiles and grouting, rubber/neoprene glazing seals, UPVC and silicone sealant. Silicone sealant is the hardest to remove all trace of black mould, and is best cut away and renewed.
The property (detached bungalow, meaning all interior surfaces interface with the outside) is intermittently heated - warm when the tenant is there, then allowed to cool down when she goes out. The cycling of this situation leads to condensation on the cooler surfaces, which then leads to cold damp walls, and an exacerbation of the problem. As the temperatures even out in the warmer weather of spring and summer, the condensation disappears.
The temperature should be thermostatically maintained to a minimum of about 15 deg C from the onset of cold weather, so that cold cycling does not occur. The use of ordinary (not heated) oscillating desktop fans to move air around within rooms helps to avoid cold spots developing on exterior walls, for instance, below and around windows.
Maintaining an even temperature in an adequately insulated dwelling should not be much more expensive in terms of energy charges than allowing the property to chill down and then rewarm to comfortable temperatures on demand, especially considering the latent energy released into cold walls when the condensation takes place, and the energy required to evaporate the water while maintaining the same cold temperature on the cold damp patches.
Furniture in room corners and against outside walls, and closets packed with clothes and boxes prevent ventilation of cold walls and lead to mould growth and spoilage of decorations. Avoiding these situations and the use of fans to circulate air can prevent the build up of damp, and subsequent problems.
Inadequately circulated air in conservatories can cause running condensation, and damp mouldy conditions. Here again an oscillating fan can prevent condensation from forming by evenly warming all the glass surfaces, preventing cold spots forming. Here again having the heating thermostated to about 15 deg C throughout the house should prevent the formation of cold, damp patches.
In the bathroom, if the areas wetted during showering (from direct splashing and condensed steam & vapours) are wiped with a shower cleaning product to remove and prevent beaded water on tile and glass surfaces, then the surfaces will not only dry cleaner and free of scale, they will also release much less water into the atmosphere within the house, which of course will require additional heat to evaporate, at the expense of warmth.
Even better if the surfaces are towelled while wet - mirrors and other glazed surfaces maintain their sparkle and black and pink moulds cannot take hold. Don't forget to dry the loo cistern and any cold water pipes. Too much ventilation can chill the bathroom by evaporative cooling.
If the kitchen has a vented extractor, always use it while cooking, but don't leave it running long after cooking has finished. Circulating extractors are good for removing frying or roasting oily vapours but do little for steam and water vapour.
After much trial and error, I find that black mould is best removed with supermarket thick bleach, undiluted, painted on with a nylon-bristled 1 1/2" paintbrush, and left to dry. Do not scrub the bleach in, just lay it on over the surface.
Bleach is acid (until the chlorine released reacts with cations), and will not damage most modern paint in the way that alkaline cleaners (including soap) do. Chlorine is an irritant to eyes and mucous membranes, especially the throat and lungs, so it is best that treated rooms are unoccupied for an hour or so after treatment.
Of course avoid dripping bleach on any materials or surfaces that may be damaged, including clothes and furnishings. Stuff I've treated includes vinyl emulsion and silk on plastered and papered walls, gloss, eggshell, satin alkyd paints, acrylic paints, varnished and untreated timber, bare brick and pointing, tiles and grouting, rubber/neoprene glazing seals, UPVC and silicone sealant. Silicone sealant is the hardest to remove all trace of black mould, and is best cut away and renewed.
