Rising damp buildings may be defined as the upwards flow of moisture through a permeable wall structure, the moisture being derived from groundwater. This moisture rises through the pores (capillaries) in the masonry by a process loosely termed as “capillarity” which cause the masonry to act like a wick.
Rising damp varies in severity depending on of several factors including the level of groundwater, the pore structure of the masonry materials (brick, bluestone, sandstone, mortar etc…) and the rate of evaporation away from the wall surface. It requires treatment because it has a number of undesirable effects on the structure of the building. Like cancer in humans the longer it is ignored the more severe the consequence.
These two headings are often the cause of confusion. Rising Damp becomes Rising Salt Damp when salts are present in the soil and are drawn up with the moisture. In Australia Rising Salt Damp is particularly prevalent in South Australia where it is referred to as Salt Damp due to the high salinity in the soil. On the Eastern seaboard and in the West where the soil contains less salt it is more commonly referred to as Rising Damp.
How do you know if you have Rising Damp?
If any of these symptoms are in evidence then there is the risk of rising damp being present. However a process of elimination is required as other cause of dampness in buildings need to be eliminated as they require other remedial treatments.
1. Lateral Damp. This is where there is soil, dirt, or a garden bed, etc. which is higher than the inside of the wall where dampness is evident and is entering the masonry laterally. A cellar situation or walls built into the side of a hill are obvious cases where lateral damp would be the cause. Read More
2. Condensation. A common cause of dampness which can be identified even without a moisture meter if it is evident high up the wall especially over a metre high. Rising Damp normally does not rise above a metre in height. Read More
4. Falling Damp. Again, if the dampness is more evident higher up the wall, wait for a rainy day, the heavier the better, go outside and check the gutters and downpipes for evidence of overflow into the top of the wall. Read More
5. Leaking Pipes and Shower units. If the only walls to have evidence of damp are on the perimeter of a “wet” area such as a bathroom, laundry or kitchen then diagnosis by a plumber pressure testing pipes and checking shower units could eliminate the possibility of rising damp. Read More
N.B. Always consider the above as possibilities if the house is less than 40 years old.
Having identified the cause of moisture is rising damp then it needs to be treated by introducing a new damp proof course. Sanding back damaged walls and/or plaster and repainting, covering the wall with plasterboard and any other band aid remedy will prove to be both a waste of time and money as the problem would not have been resolved. There is some urgency introducing a new damp proof course at this stage as rising damp in masonry is like cancer in humans, the longer you leave it untreated the more serious the condition especially if salts are present as evidenced by white powder on the surface. The reason the salts cause so much damage is that they are continually moving. On dry days with low moisture in the air they contract then on wet days or days of high humidity they expand so they are continually expanding, contracting, expanding, contracting until the masonry starts to crumble and mortar turns to dust.
How long does this take? Who knows as there are many variables, it could be years or tens of years but it will happen unless treated.
In the big picture there are two ways to introduce a new damp proof course, mechanical and chemical injection.
Mechanical is where the operator removes 2/3 bricks at a time, introduces new plastic sheeting, replaces the bricks and repeats the process along the length of the wall.
Chemical injection is where damp proofing ingredients are introduced into the wall via a “carrier” by injecting into predrilled holes. Traditionally the carrier for many years has been a paraffin based solvent which is injected under pressure or by gravity feed.
Pressure injection, as the name implies, is where the solvent is pumped into the wall via rods inserted into the predrilled hole by using a motor driven pump.
Gravity feed is where the holes are predrilled at a 45% angle into the wall and open ended bottles with nozzles are introduced one to each hole along the wall and the solvent then poured into the open end of the bottle which then gravity feeds into the wall.
More recently cream carriers have superseded paraffin based carriers.
Safeguard Chemicals in England developed the first water based cream carrier “Dryzone” in 2000. Damp Busters (Australia) Pty Ltd introduced it into the Australian market place in 2003.
Australian History: Dryzone was originally offered to our major competitor in Australia and for whatever was rejected by them. We were, at the time, the new kids on the block, being incorporated in 2001, and contacted Safeguard, as they had not approached us, with a view to securing the Dryzone agency. Safeguard agreed to send us samples for testing and to say we were more than impressed with the results would be an understatement.
Previously to 2003 we had been using paraffin based solvents as were all other operators offering chemical injection. Within six months of introducing Dryzone into our range we gave away paraffin based solvent injecting and went solely with Dryzone.
Our major competitors denounced the cream technology claiming that it was not effective especially for Australian conditions. An interesting claim as rising (salt) damp is rising (salt) damp wherever it is found in the World and no more virulent than in English conditions. Now some years later the majority of those same detractors have now introduced creams into their own range none of which have tested to be as efficient as Dryzone which is now being sold in 12 countries around the World and has proven to be the World leading product for eradicating rising (salt) damp by chemical injection.
For us this has proven to be a “Pretty Woman” experience as we have the Australian agency for this premier product with hundreds of successful applications including heritage buildings with not one failure.
Dryzone is injected with a caulking gun by inserting the metal nozzle into pre-drilled 12mm horizontal holes drilled at 110mm centres along the lowest mortar course above ground. Using the same capillary action that the moisture in the ground used to invade the wall in the first place Dryzone slowly and evenly disperses to a 70mm radius around each hole along the mortar course and into the masonry over a 7 day period.
Safeguard have done it again and have now developed over the past 4 years the Dryrod system which supersedes Dryzone.
Dryrod Damp-Proofing Rods are the next generation treatment for rising damp. They provide a higher level of performance and quicker installation speed than any other rising damp treatment currently available.
Dryrods are 12mm diameter, 180mm length, fibre rods that contain a powerful water repellent. The patented, and BBA Approved, Dryrod delivery system ensures the correct dose of active ingredient is delivered to the wall every time, permanently eradicating rising damp.
No fuss, no mess, no stress.
The Dryrod Damp-Proofing Rods are simply introduced into a series of 12mm holes drilled into the lowest available continuous mortar course. No special equipment is required.
Once the damp-proofing rods are installed, they diffuse the active ingredient deep into the wall before it cures to form a water-repellent barrier. This prevents the damp from rising up the wall.
Number of packs required per 5m stretch of wall:
4½″ (110 mm)
9″ (220 mm)
13½″ (330 mm)
Number of packs per 5m
Full installation instructions can be found on our DIY page.
As the latest development in the treatment of rising damp, there are numerous advantages to using Dryrod Damp-Proofing Rods:
Naturally, homeowners want the most effective products available to be used to treat rising damp in their properties. Creating the best possible barrier to rising damp minimises moisture in the wall and blocks the build-up of ground salts.
For this reason, Dryrod Damp-Proofing Rods have been designed to form an effective damp-proof course in walls of all types and have been tested under conditions of up to 95% saturation, where it has been shown to outperform all tested competitor products.
This is important because no two walls suffering from rising damp are the same. In particular the physical properties of the mortar used to construct walls can vary considerably and this can have a significant influence on the effectiveness of any rising damp treatment.
Dryrod Damp-Proofing Rods are effective in a wide range of conditions, including: