Condensation in our Unheated Sunroom

March 20th 2003
Condensation in our Unheated Sunroom

Hi Shell,

We have a sun room built on to the end of our deck, facing south-east, windows are double glazed, it is attached to the house, roof is double plexi-glass. There is no heating in it. This past winter we have had so much condensation the roof was dripping onto the floor (carpeted) and the ledge under the windows was mouldy from the moisture running down the windows. We do not know who built this so have no recourse to a specific builder to answer our questions. How can we stop this condensation? We open windows to allow fresh air in when possible. What suggestions do you have?

Thank you,


Hi Frank

Sunrooms of your design allow the radiant heat of the sun to beat into the room. This heats moisture in the air and increases the amount of relative humidity. When the moist air is heated it will expand and look for a cold spot to condense on hence your condensation problem (moisture).

Where does the relative humidity come from you may ask? Well, moisture can enter the room every time you open the door out into the sunroom and also comes from air leakage from the heated living space of your home.

To remove unwanted moisture, I suggest you install an appropriate model of a Humidex dehumidifier.

To find out more about Humidex products, visit the Referral Network area of this website, click on Ventilation.

It's Just That Easy!