Applying one of our thin coat render systems to the outside of your property is a great way to help stop penetrating damp. Penetrating damp occurs when water travels through the bricks of your home – it often occurs where there are porous bricks, damaged brickwork or some sort of building defect.
Penetrating damp can cause damage to plasterwork internally. Initially, this would manifest itself as stains on the internal walls, but if left untreated the plaster/paint will eventually begin to flake off. Likewise, another issue with penetrating damp is the damage caused to wooden fixtures and fittings. Over time, the water will cause the timber to rot and decay.
By applying our thin-coat render systems to the external walls of your property, you are essentially coating them with a protective barrier which prevents the ingress of water. However, while incredibly effective at stopping penetrating damp, non-breathable renders can actually exacerbate rising damp.
What is Rising Damp?
Rising damp is not the same as penetrating damp – it occurs when water is sucked up from the bottom of the wall by capillary action. Nowadays, every new property built will have a damp proof course (DPC) – this is a physical barrier that stops water being pulled up through the brick work – the damp proof course tends to be some sort of plastic membrane.
A DPC is not a new idea. In actual fact they are fairly common in properties built around 1900, but instead of a plastic membrane these DPC’s were often created using slate to form the barrier to stop water being pulled up the wall. The issue now is that in many cases these old slate DPC layers have been broken down over time, making them far less effective and increasing the property’s chances of rising damp. There are also many old properties that were never built with a DPC, and instead rely on evaporation through the brick work to get rid of the water being pulled up via capillary action.
The problem with putting a non-breathable render on the outside of the property is that evaporation of the water can no longer occur, so you are trapping the rising water in the walls. In this case the water will unfortunately continue travelling upwards, causing all the brickwork in the property to become damp.
Using a Chemical DPC before Rendering
We usually recommend our breathable renders to our customers, although to be honest even if you are using one of these breathable silicone or mineral renders, we would recommend installing a chemical DPC to ensure you lock out rising damp.
At EWI Store we offer two types of chemical DPC. The first is Dryzone – this is a cream that is injected into holes around the perimeter of the property. We also offer Dryrod, which are little rods that are pushed into the drilled holes. They both work in the same way though – the chemical is absorbed by the surrounding brick and mortar, creating a water impermeable layer.
Installing a chemical DPC is relatively simple – holes are drilled around the perimeter of the property at 120mm intervals. The depth of the hole should be 40mm less than the thickness of the wall – we suggest marking the drill bit with tape so that you drill all the holes the same depth.
Once the holes are drilled, you can either inject our Dryzone cream into each of the holes, or push the Dryrod sticks into them. The Dryrod sticks are probably a little easier to install – so if you aren’t too handy with DIY this is probably the way to go!
By installing a chemical DPC before rendering, you can be sure that you will be protected from both penetrating damp and rising damp.