Every Floor needs a Moisture Barrier!
Moisture is a major problem in New Zealand homes!
Excess moisture causes so much damage to building materials, floor coverings, furniture and our health. It’s not just “leaky buildings”, and not just older homes in the hills that have a problem with moisture.
First we need to understand construction.
Many floors do not have a basic moisture barrier layer of polythene underneath the concrete floor, commonly referred to as a “DPC” (damp proof coarse), and if they do it may not have been joined correctly (just overlapped) or it may have been damaged during the installation of the concrete or by ground movement since then. The other issue that can occur is when an addition is made to the building, the join between the new and the old DPC is not sealed.
What happens is when it rains (or irrigation) the ground gets wet, the moisture soaks into the soil and gravity causes it to take the path of least resistance in a downward and or sideways direction. If you are on the very top of a hill, you have less chance of a problem. If you are on the side of, or at the bottom of a hill you are in the danger zone for moisture ingress.
Another interesting point is that moisture will also travel upwards through osmosis, and if a heat source is applied. That heat does not need to boil the moisture either, consider the steam that rises off a road after rain. Therefore the path of moisture can be very tricky to follow and often moisture issues need to be addressed at both the source and the destination.
There are 2 major entry points for ground moisture into your home or building.
1) through the floor – if you do not have an adequate DPC, moisture will easily move through the pores of the concrete floor – as it is not possible to get back under the concrete floor to install or replace the DPC, then the best option is a moisture barrier.
2) concrete or block walls – if your walls retain dirt (have soil against them) and do not have adequate external sealing you have 2 options. Remove the dirt and seal the walls from the outside (and improve the drainage), or apply a moisture barrier on the inside.
Moisture barrier Vs Waterproofing.
It is important to understand the difference between a moisture barrier and water proofing. It has to do with the direction of the moisture.
A waterproofing membrane is designed to stop water or moisture entering a building through a substrate for the source side. We also call this the positive side. For example, if you waterproof the outside of a wall, it stops water getting into the wall and keeps the building dry. The water pressure is pushing the waterproofing against the substrate.
A moisture barrier work the opposite way. If you are unable to stop the moisture on the outside of the substrate (i.e you can’t dig out all the dirt behind you basement wall or under your floor), then the acceptable method is to stop it at the negative side or on the inside, before it can enter the room.
Because of the forces trying to push the moisture barrier off the substrate (wall or floor), specialist products must be used that provide excellent adhesion and are not effected by the constant presence of moisture. Standard paints and coatings will not do this job. Also proper surface preparation and repair is required.
A moisture barrier should be installed where ever you suspect a moisture issue.
Common signs you need a moisture barrier are
- A damp smell
- Mold on walls or ceilings
- A white powdery residue on floors or walls
- Carpet discolouring or rotting
- Damp patches or dark patches on concrete
- Boxes going soft on the bottom
- A rice paddy is growing in the basement
Moisture barriers also prevent issues with flooring products
- Timber floors are very susceptible to moisture, it can cause them to swell, discolour, warp and bow.
- Carpet gets damp and mold and mildew grow, it also rots
- Vinyl the glue breaks down and a moldy slime forms underneath
- Tiles the grout and glue break down and fail, tiles come loose and crack or dislodge
- Paint will bubble and peel off the floor.
Floor Masters are approved applicators of a number of moisture barrier products and can recommend the one that suits your situation best.