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How to fix window condensation
12 February 2020

In this cold weather, you might notice that your windows may be ‘sweating’. This tends to happen when the temperature drops below about 4 degrees; you may find that water condenses on the window and eventually runs down to wet the frames and sills.

Condensation indicates that your indoor humidity levels are too high. Indoor humidity of 50-55% is an ideal rate to aim for during colder months; it is when humidity exceeds this point that water condensing on cold windows can become an issue.

Modern homes have tighter building envelopes and one result of this is that indoor moisture has less chance to escape. One way to check your indoor humidity is with a hygrometer. This will allow you to measure and track your humidity so that you can monitor progress and identify which solutions prove to be effective.

When you burn gas or propane, water vapour is released and so, if you make use of a fireplace in the winter, this can be one explanation for an increase in humidity levels. New homeowners may find that excessive humidity is simply the result of a new home drying out. Concrete, wood and other materials can take a year to acclimatise.

Even older homes may have this problem as building materials dry out after a humid summer. If this is the case, you will find condensation only occurs at the beginning of the colder season and will then tail off.

If you do notice that the problem is persistent it is wise to check for other sources of moisture; for example, ground moisture moving up through a concrete slab.

A dehumidifier will provide a temporary solution to condensation issues. It is important not to overlook condensation but to mitigate the problem as failure to act can lead to the growth of mould and mildew.

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