We have a problem with steamy windows on our home. What can we do?

Property Clinic: The issue of condensation can be addressed by repair or replacement

It can be frustrating for the house-proud homeowner to clean the windows inside and out and still have a mist on the glass

We live in a three-bed bungalow. All is in good condition and the walls and roof have extra insulation. The windows are teak-framed and double-glazed. Two of the larger ones have started to get condensation between the panes. Would you advise new triple-glazed uPVC windows or new panes? Would the benefit of low maintenance and possible energy savings be worth it? Lastly, would planning permission be needed if new windows are installed? We’re retired and intend to continue living here.

Pat McGovern writes: It must be very frustrating for the house-proud homeowner to clean the windows inside and out and still have a mist on the glass. The good news is you don't have to replace the window, only the glass. Teak windows, probably iroko, look very well and have a relatively long lifespan once maintained, so I'm sure you will get many more years out of them.

The sealed double-glazed unit comprises two panes of glass with a gas-filled cavity which gives it its improved thermal (and sound-proofing) performance. However, the double-glazed units do fail in time and will require replacement. Holes and gaps can form in the seals around the perimeter, allowing condensation (mist) to form within the unit. The reasons for the seal breaking down can vary from the age of the unit to a manufacturing defect or the use of cleaning chemicals that damage the seal over time.

There are three options to consider.


The simplest and cheapest thing to do is replace the failed double-glazed units, as there are only one or two of them. You may have to do this a number of times over the life of the windows.

The second option is to have them repaired. This is done by specialist companies that repair the unit by removing the moisture and resealing the window; however, this option is not cost-effective.

Your third and final option is to replace the faulty double-glazed units with triple-glazed units, however, you may be limited by the size of the rebate in the frame to house the glazing unit. An enthusiastic carpenter could rout out a deeper rebate but this takes time and the cost of doing all this versus the cost of new modern units has to be considered. That said, there are now glazing companies specialising in slimmer, highly efficient glazing units.

The windows aside, I note that extra insulation has been provided in the walls and roof; care should be taken to ensure that adequate ventilation is provided in the property. It is important to consider the nature of the dwelling construction and the level of ventilation when upgrading insulation and replacing windows, particularly in older properties.

You generally don’t need planning permission to change windows if maintaining the existing openings; however, the original planning permission for the dwelling may contain conditions relating to the finishes, or a condition may specify that the dwelling is to be constructed in strict accordance with the lodged plans. You should check before you consider uPVC windows.

My advice: If you are a conservationist at heart, keep the teak frames and replace the double-glazed units with as high quality a unit as the existing frame rebates permit.

Pat McGovern is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland, scsi.ie