This is not an exhaustive or a complete subject. It is likely to change over time, with edits, additions and deletions, and is simply a collection of my thoughts based on many years of experience. You should follow your instincts, and you must always seek your own professional advice.
This is a follow-up to an earlier Blog in October 2023.
Mid-September and the weather is changing. Even on days that might seem sunny and bright, the air temperature is dropping. Specifically, overnight air temperatures are dropping. It is days like this where there is a greater tendency to see morning dew on our cars. At the time of writing this Blog, my external hygrometer is showing 82% and there is condensation (dew) on the car outside. It did not rain last night.
Relative Humidity is also the critical data point inside our older buildings too. As the masonry cools, due to the lowering air temperature inside, as well as outside, we will now start to see a greater likelihood for condensation to be seen on windows in the mornings as well as old walls. This is exactly the same as the dew which appears on a car overnight.
On ground floor walls, this is frequently noted as being ‘rising damp’. It is more likely to simply be the visible signs of surface and/or interstitial condensation. As the building cools, the Relative Humidity does not change much and the importance of awareness of the Dew Point is increasingly needed by surveyors and occupiers.
It is of great importance that heating and ventilation is consciously managed, to the whole building. Avoid trying to paint over condensation, avoid the use of impervious products to walls, floor finishes and also externally.
There are other Blog posts on the consequences of high Relative Humidity in buildings and related topics.
Do not try to solve these issues by calling in for a ‘local builder’ or ‘damp specialist’ who will simply try to cover it up or sell a product or service which won’t help you.
Science is science. It is actually not that complicated. Understand your building and how it needs to perform and work with it, not against it.
Do not cover it or conceal any existing damp issues.
There is no such thing as a ‘quick fix’ where moisture in older buildings is concerned. Time and patience is needed.
Always follow the methodology in the JPS 2022.
Banner photo is from a FaceBook group, where a member of the public was seeking advice
Disclaimer: Anything posted in this Blog is for general information only and it is not in any way intended to provide any advice, legal or otherwise, on any general or specific matter that you can rely on. You should always seek your own legal and surveying advice.