Rain being drawn through windows on new build.
We have almost finished building our new home on a ridge line in rural Victoria, Australia.
The house was architect designed and, due to its location (highest point of ridge) it was designed with a cyclone rating. The house is built on stumps, and approximately 1 meter off of the ground. We encountered a storm within the past few months, with high winds and rain. During the storm the western (weather facing) windows and doors were all subject to water penetrating the window frames causing water damage inside the house. We observed the incident and it appeared that water was bubbling in through the window frames and under the window and door seals, almost as though it was being suctioned inside.
Since the first large storm and damage there have been three more incidents similar in nature, only when rain is accompanied by high winds.
The window company have returned and replaces seals, and sealed corners where water was getting in however it has continued to happen. The window company ensure they have fixed the problem and they are cyclone rated windows.
Given the position, no plinth boards across the bottom of the house allowing wind under the house also could the house have a negative pressure issue causing a vacuum type effect?
Is there anything else that could assist with reducing internal pressure?
If you have rain coming in below windows and doors I would suspect that to be an installation issue rather than a window manufacturing defect, especially if the window company just replaced seals and that the windows are rated for cyclones. A depressurized house will draw air into a home (and moisture if it is humid outside), but given that the problem only happens when you have high winds and driving rain I just can't see it being the source in this case. But it doesn't really matter what the source is, because there are enough openings in the building envelope so something went wrong somewhere.
Windows are built in the controlled environment of a factory, where the quality of installation is up to the person installing it. To get an idea of how it might have gone wrong, see how it should be done right, check this page and video -
DIY window installation for best performance and durability
There you will see a window installed in a way that it would be extremly unlikely for water to penetrate. There is far more room for error when it comes to installation, but also, from what you say it was coming in ‘under’ the doors and windows. Please clear up one point if you would – is the water infiltrating between the window and the framed roof opening? If it is a new build then you should have a warranty. Have you discussed this problem with the company that built it? I think in order to find the problem, you could do a blower door test to find leaks in the building envelope. Blower door testing intentionally depressurizes a home for the expressed purpose of finding exactly such leaks.