Project: Timber window replacement project in 2008 in Auckland
Background: Mr and Mrs S had single glazed timber windows in their house. The window sashes were rotten and did not close properly so they had draft. They come to us for a quote to replace the timber windows. They had a tight budget.
The solution: We visited their house and found that while the window sashes were not good the existing timber window frames were all in good condition. The cost effective solution was to insert new PVC-U windows into the existing timber window frames. With the exiting timber window frames kept, there would be no need of jamb liners for the new PVC-U windows. Mr and Mrs S happily accepted this solution.
The existing timber window frames at the bottom is slopped down on the outside and window flange was put in under the bottom PVC-U frame to cover up the big gap at the bottom.
Small 3mm to 5mm gaps between the PVC-U window frame and existing timber frame were allowed for tolerance. Those gaps were sealed by silicone as shown below. The photo below also shows the 40mm wide flange at the bottom of the PVC-U window frame which covers the gap between the PVC-U window frame and the existing timber frame at the bottom.
Alternative way to seal the gaps between the PVC-U window frames and the existing timber window frames is to glue the PVC-U window flanges on to the PVC-U window frames. Following photo shows the finish taken from another project in Christchurch.
Please note that this is a cost effective solution but the existing window frames must be in good condition otherwise the timber window frames have to be removed for complete window replacement.