How do you treat damp in an old house?

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how do you treat damp in an old house

In this article, we’re going to be looking at how you can treat damp in an old house. We’ll discuss the importance of diagnosing the cause of your damp. Following this we will give an overview of common types of damp. Then finally, we’ll go into treatments that can solve your damp problem.

Treating damp in an old home

The most important step in treating damp in an old home is diagnosis. Without finding the cause of your damp issues, treatment is basically useless. Sure, you can treat the signs of damp that you see. But unless you solve the issue causing these signs of damp, they will eventually return.

Thankfully, different types of damp have different signs and symptoms. We’ll take a look at signs of damp in just a moment. First, here are the most common damps found in older homes.

Common types of damp in old properties


This damp affects areas of rooms with very little air movement. This could be the corner of a room, near windows, behind wardrobes or on the ceiling.

You will often see black mould as a result of condensation. It can also make your clothes or soft furnishings in the room smell musty. Condensation is typical in older homes because there can be dramatic changes in humidity and airflow throughout the house.

When hot air collides with colder surfaces, this causes condensation. If certain parts of your home are warmer than others, this is a breeding ground for condensation and the mould that comes with it.

Rising damp

Rising damp only affects the lower floors of a home. This occurs when water is sucked up by the brickwork. With this damp, you may notice a ‘tide line’. This is from the minerals in the ground. It is a great indicator that you have rising damp.

You may also notice rotting timber (floorboards and floor joists). Plus, peeling paint or wallpaper. Rising damp is more common in older homes because they often don’t have a damp proof course. Or if they did have a DPC, it has now failed.

Penetrating damp

This type of damp typically flares up during heavy rain. When wind is pushing rain into the side of your home, it often penetrates through defects in the brickwork.

If you notice isolated patches of damp on your walls, this is likely penetrating damp. Penetrating damp is prevalent in older properties because cracks in brickwork and mortar will worsen over time. These cracks may have formed years ago and gradually got worse.

Damp from a leak

A small leak over time can cause big problems. Older homes can have leaks from several places. For example, old pipework pipe work or an old roof are both common causes.

If your ceiling is damp, a leaking pipe or roof is likely the cause. If your floorboards are wet and there is no evidence of rising damp, your damp issue could be a leak from a water pipe. With older pipework and roofing materials, old buildings are always at risk of developing leaks.

These are the most common forms of damp in an older house. Below we will look at methods you can use to solve each damp problem,

Treating condensation in an old home

Condensation is primarily found in rooms that have poor ventilation. For example, if you have a small room that isn’t used often, this will often have poor air circulation. It is also common in bathrooms and kitchens due to the high levels of moisture.

Condensation can be treated with ventilation; this can be as simple as opening a window. However, you can use a dehumidifier to speed up the drying process. You can also put a fan in the room to create a through-draft. This will allow the air to circulate.

Once you’ve treated the condensation, keep the room ventilated as much as possible. Opening a window in your bathroom after a shower, for example. You can also install an extractor fan which really helps.

Treating rising damp in an old house

Rising damp in an old property can be treated with a chemical damp proof cause. The reason that rising damp occurs, is due to a DPC that isn’t working correctly. Some older houses don’t have a DPC. Instead, they used lime mortar to counteract damp issues. If this is the case, a chemical DPC can still be used.

You can buy many brands of chemical DPC. And with good DIY knowledge, you can install it yourself. All you need is a drill and some decent masonry drill bits. Simply follow the instructions provided and drill holes at the correct intervals. After this, you can inject the chemical DPC. If you follow the instructions, injecting a chemical DPC in your home is a pain-free way of solving rising damp.

Treating penetrating damp in an old property

Treating penetrating damp can be a bit more difficult than treating other forms of damp. There are a variety of ways to treat this type of damp. One is to use a waterproof sealer for the brickwork. This is applied to the outside of your home. It seals the brickwork so that no moisture can enter. This is a viable solution. Unless you have large cracks in the brickwork or the mortar.

If you have large cracks in the mortar or in the brickwork, it is best to repair these. Just using a waterproof sealer will not solve the problem, as the defects will still exist, and the damp will still be able to penetrate. You can use something like a mortar epoxy to fill cracks in broken brickwork. Alternatively, if the damage is particularly bad you may need to replace individual bricks.

For the mortar, we recommend repointing. You may need to hire a builder to do this. But, if you are confident at DIY you could probably do small areas of pointing yourself. Once the repointing is complete, you can then use a waterproof sealer to protect the brickwork.

Once you’ve treated the outside of your property, you can deal with any damage that has been caused inside. Thoroughly dry out the rooms affected by the damp. You can do this by simply opening a window and turning on a fan. A dehumidifier could also speed up the process. From there, you can use mould-resistant paint to kill the mould and stop it returning.

Treating a leak in an old property

If you have a leak in your home, this will usually require the help of a professional. For example, if you have identified leaking pipes, you’ll need a plumber. On the other hand, if the roof is causing you problems you will need to call in a roofer. Both are quite specialist and unless you have some experience or are a very competent DIY’er you could make problems worse.

The important thing here. is fix the leak before you start trying to repair the damage it caused. Once the pipe or roof has been fixed, you can allow the affected area to dry out thoroughly. Again, you can use a dehumidifier to speed this process up.

Once dry, you can use mould-resistant paint to kill any mould and stop it growing. It is also worth exploring the areas of your home that you can’t see. For example, if you notice mould on the ceiling, check the floorboards above. Peek under the floorboards too. If the floor joists have been affected badly, you may need to repair these also.


As you can see, treating damp in an old house is not that dissimilar to how you would treat damp anywhere else. Finding the cause of your damp is the most important part of solving your problem.

Once you have figured out which damp is responsible, you can treat it accordingly. The treatments mentioned above can all work very well. Plus, the great thing about most damp treatments is they can be done DIY, and most are quite inexpensive.