control of condensation

October 4, 2006 5:06am CST
To control condensation top First of all, you need to ensure that the amount of moisture in the air is not excessive. Check the structure of the building: Check that the walls are not suffering from rising damp. Ensure that there is damp-proof course, that it is not bridged or damaged. A new damp course can either be installed by removing a brick at a time and inserting a physical DPC, or a chemical DPC can be injected into existing walls. The damp-proof course should be at least 6 inches above any outside concrete to avoid heavy rain from bouncing back up and soaking the brickwork above the DPC - consider lowering the outside surface where necessary. Check that any wall cavities are clear of rumble, debris can accumulate over the years and to remove it normally requires removal of a brick at each corner and racking the cavity clean. Where the dampness is restricted to one area and no other reason can be identified, it is a relatively easy task to check/clean inside the cavity. Check that all airbricks are clear, consider fitting additional airbricks to ventilate under suspended floors (modern practice is to fit a duct across the cavity so that the cavity itself is not vented). Older buildings may not have airbricks, consider fitting them if there are internal suspended floor. Consider applying a surface finish to outside walls to prevent rain penetrating them. Either a clear waterproofing finish which can be brushed on or a paint/textured finish which will cause most of the rain to run down (check that you are allowed to change the outside appearance of your house before you start doing so). Check the roof, make sure that it is sound and directing rain into the guttering, not into the structure of the building. Check the guttering and down pipes, make sure that they are carrying the water away and that there are no damaged/blocked guttering or drainpipes causing the external wall to become soaking wet. Check solid floors to ensure that damp is not coming up through it, if it is, you may need to introduce or replace a damp proof membrane underneath it (potentially a big job) or fit a more suitable floor covering. Check that there are no leaking water pipes or tanks within the house. Once you are happy with the structure of the building, look at your life style within the building: Try not to breath (NO - just joking !!) After a bath or shower, try to ventilate the room to the outside, not to the rest of the house - just opening a window (and closing the door) will help. Dry clothes out of doors or in a cool area of the premises - this latter suggestion may sound strange, it will take longer but less moisture will be held in the air at any one time. While drying clothes indoors, ventilate the room. When people come in with wet coats, hang them outside the living area to dry. A good reason for a porch. Try to increase the change of air in the premises - increase ventilation. Add forced ventilation/extraction to areas which produce a lot of moisture (kitchen, bathroom). Extractor fans are available with an air-moisture switch so that they operate automatically while the moisture in the air is above a set amount. Other units (more expensive/complicated) are available which remove the moist air but reuse the thermal energy which would otherwise be wasted. Consider changing the fuel you use, electric is the driest, paraffin probably the wettest. Consider using a dehumidifier - domestic types are now available and can remove a surprising amount of water from the air. If condensation persists after you have sorted out the basic structure of the building and your life style, there are still some other changes to try. In Britain, condensation will almost always occur with single glazed windows. The inside surfaces of these windows can be almost the same as the outside temperature, overnight in winter their temperature can drop below freezing; often the inside window sill will be awash first thing in the morning.
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