Treatments & Repair

What are damp-proof membranes?

Damp-proof wall membranes are created out of high-density polyethene (HDPE) or polypropylene. The thickness of the sheet is around 0.5 mm.

The moist confirmation film is basically used to make a hindrance between a solid subfloor and everything that is laid over it. This will cause the solid not to contact the wood, earthenware or quartz tiles, cover or rug. The primary point of this boundary is to keep dampness from going between the solid and the material made laid above it. DPMs can help with existing soggy issues, yet can likewise avoid future sodden or dampness issues also. On the off chance that you are introducing rug or parquet wood over cement and there is no soggy sealing, there will probably be issues later on.

How do damp-proof membranes work?

Due to the fact that damp-proof membranes are made from high-density polyethene or polypropylene, they are unaffected by moisture and moisture vapour. This will create a stud formation, which will look similar to bubble wrap, which will create cavities known as air gaps that will allow moisture to evaporate from the wall without restriction.

The different types of damp-proof membranes

Physical DPMs for concrete floors

Physical damp-proof membranes are usually faster and more efficient to install than using damp-proof coatings. This is because they can be installed on top of already damp surfaces. The drawback is, however, they will always require a separate floor covering on top of them as well as special attention when it comes to the floor or wall that is being maintained.

Dry base liquid applied DPMs

The benefits of these are that they can be applied to damp floors directly to create a damp-proof barrier, and will not raise the floor level. They are extremely easy to apply. Brands include dry base ECSC poxy floor coatings and dry base liquid applied DPM.

When should damp-proof membrane be used?

As soon as you notice damp or find evidence of salt on your walls, you will need to identify the cause of this before dealing with it. After the initial issue that was causing the damp is fixed, removal of old plaster and any surfaces that have deteriorated is recommended.

How is damp-proof membrane installed?

DPMs can be installed internally, with hardly any or even no surface preparation. Yet, installing a damp-proof membrane incorrectly can cause costly water ingress in the future. The damp-proof membrane should always be used as well as a damp-proof course in outer walls in order to ensure there is a continuous barrier to water. Without this, damp-proof membranes will be less effective.

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How do I know if my property already has damp-proof membranes?

You can quickly check whether a DPM has been laid down by discovering the levels of moisture in your floor. This can be achieved by using an approved handheld moisture meter. You will need to make sure them moisture meter has been approved and tested so that you know your readings are accurate.

Acceptable more moisture content levels can be a personal thing and generally speaking, guidelines can vary. However, if the moisture content of your subfloor rises above the manufacturer’s guidelines for the floor covering you have chosen, you are probably going to have to lay down a damp-proof membrane. This is the only way to be certain you are preventing moisture passage and problems with damp. Even if the moisture content is below the manufacturer’s recommended level, it may still be a good idea to invest in the damp-proof membrane in some cases. It’s always a good idea to future proof your home.

Do damp-proof membranes go above or below floor insulation?

Damp-proof membranes go below the insulation. Insulation should always be laid above the DPM. This way the concrete is protected, and so is the insulation. Without the DPM going below the insulation, there can be a risk of moisture damage, and this would degrade the insulation over the course of time.

What can cause a damp-proof membrane to fail?

In modern buildings, the causes of damp-proof membrane failure are less common. This is because they are usually built with durable plastic damp-proof membranes. The problems that can cause damp-proof membrane failure usually relate to moisture and damp rising up through the ground to the top of the concrete. So, due to the fact that new houses have membranes laid on to sand binding before concrete is applied, failure will not be an issue.

What is the difference between the damp-proof membrane and damp-proof course? In general, damp-proof course or DPC is applied at basement level, in order to restrict the movement of moisture through surrounding walls and floors. Knowing which material you need for DPC will require a comprehensive survey of your home. This is because a variety of different factors can influence which material is best, including climate and atmospheric conditions, the nature of your structure and the reasons for which DPC is needed.

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The types of material for DPC

Flexible materials

These can be materials like bitumen felt. Felts may either be hessian based or fibre/glass-fibre based, flexible plastic sheeting, such as polyethene sheets. And more.

Semi-rigid materials

These can be materials such as mastic, asphalt, or even a combination of various materials or layers.

Rigid materials

These materials will consist of first-class bricks, stones, cement concrete, slate, and so on.

Damp-proof membranes are membranes implemented to prevent the transmission of moisture. For DPC, DPM may even be used. DPMs are moisture inhibiting foil that is 100% watertight. Damp will be starved because of this and unable to flourish, as it will not be able to penetrate the membrane.

DPM and DPC can both be extremely efficient and effective in treating issues with damp. If you suspect you may have a problem with damp, you can contact for a variety of damp-proofing and rising damp solutions in London and the South East England areas. Your first port of call can be the only one you need. Southern Damp Proofing also offers a wide range of high-performance, effective and cheap damp-proof membrane is to prevent the transfer of moisture and the ingress of damp into buildings.
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Must I remove the plaster before applying the membrane?
Depends. If you have a cement render, your wall is made of hard, good sand and can withstand the drilling, then you don’t have to remove it. However, if you your wall has Bonding plaster and Gypsum, then you have to remove it.
Can I use a Membrane if my wall is old and rough?
Absolutely. If your wall is loose, uneven, or out of line, a timber 'stud' frame will hold the Membrane in place.
When is a Membrane used?
Usually below the ground like in a cellar or basement. But it can also be used above the ground in cases of ‘salts’ problem, stained chimney breast or a cold wall.