In this installment of A-Z of Atlantis Damp Proofing & Timber Specialists, N is for Nitrates and Rising Damp.
In the vast majority of cases we use our experience and moisture profiling techniques to determine whether the dampness in your home is, in fact, rising damp. It could be from another source entirely. It could be a leak, condensation or penetrating damp. However, if you so wish we can confirm our findings. We do this through what is known as destructive testing. With destructive testing, we can see if there are chlorides and nitrates in the wall sample. Nitrates and Rising Damp are inextricably linked.
Damp is a salty business
A consequence of rising damp is that it brings with it up from the ground various salts, mainly chlorides and nitrates. These accumulate in higher concentrations at the surface of the damp section of an affected wall from where evaporation takes place. This links Nitrates and Rising Damp. The greatest concentration of these salts is towards the highest point that the moisture has risen. These salts are moisture attracting (hygroscopic). Even if the rising damp that originally introduced them has been prevented, the salts will remain. They have the ability to cause persistent damp patches and spoil decorations. Especially when the atmosphere is damp and humid.
Why focus on Nitrates?
We always focus on the presence of nitrates in our samples as chlorides can be present in tap water. We’re only interested in salts that have risen from the ground.
There are three conditions that must be present in your sample to identify that rising damp is present. They are:
1. As mentioned above, you must have a rising damp moisture profile. That is a profile (think pattern of moisture readings) that is wetter at the wall base but gradually decreases with height. The maximum height is usually up to 1.0-1.5m, but this can differ depending on factors such as the humidity levels in your home or the property’s water table.
2. Furthermore, you may wish that we prove that moisture is present at depth in the masonry and that it is not enough to take surface readings from the plaster work. We have a radio frequency mode on our high tech moisture meters, which can detect moisture at depth. We are also equipped to carry out destructive testing at your request. This will involve deep wall probes or a calcium carbide (speedy) meter to confirm this on site.
3. You will then need to confirm that nitrates are present in the damp apex of your moisture profile. This will involve doing on site analysis or us sending a sample off to the labs. A positive test for nitrates confirms that the moisture has leached up from the soil.
Salts analysis can be a very useful method of determining if rising damp is the cause of dampness. Therefore, we can provide this service if you request it as it provides a crucial aid to correct diagnosis. We also provide an off-site remote diagnostic service. By simply removing a small sample of your plaster or wall covering and sending it to our external laboratory, who then carry out salts analysis on our behalf and advise you if any are present.
Want to know more?
See our blog on Hygroscopic salts and then contact Jamie or Freya for an informal chat to see how we can help you.