Avoiding trapped moisture in timber windows is highly important for the overall durability and life expectancy of the product. Some manufacturers place significant investment into the research and design of their products in a bid to improve timber window life expectancy and overall performance.
All windows are susceptible to a significant threat from trapped moisture. Water is often able to penetrate external glazing seals at various 'weak points' of the seal. On a timber window, this moisture can become trapped and lead to significant failings over time relating to the paint finish and in worst case scenarios, the timber could rot.
A method used by some manufacturers of high performance timber windows is to include an angled slope that's steep enough to shed water in a short space of time before it's able to penetrate any seals. This minimum slope is integrated into all horizontal surfaces where moisture could become trapped, helping to provide an insurance against the possibility of paint damage or timber rot.
The minimum slope is often fitted to both ventilation and drainage beads to all bottom glazing rebates. A good timber window design will allow any moisture that does penetrate external seals to dry out, or in more extreme cases drain out via the provision of angled slopes.
This simple yet highly effective design innovation is vital to the overall performance of timber window products. Not only does this process help to preserve the paint finish and avoid timber rot, it's also able help prevent double glazed units from failing where condensation can appear between the two panes of glass.
Some manufacturers will take great care in the design and innovation of their timber windows, however, others may not. It's often recommended to check the full specification of timber window products before you make any investment and pay close attention to the weatherproofing of such products.