Does a garage need a damp proof course? (DPC)

In modern British homes, a DPC is a legal requirement, according to building regulations. For example, in a property with a standard cavity wall, this would be placed at least 150mm above ground level. They can usually be found in the 2nd or 3rd mortar joint, on a properties external wall.

A damp-proof course is not guaranteed in a garage. This is since a garage is not considered a habitable space. They are often single skin construction and offer very little in the way of damp proofing and insulation.

However, there are still some garages that will have a DPC installed. Also, some will have a DPM built into the concrete foundation they sit on.

How to tell if your garage has a DPC

does a garage need a damp proof course

To find out if your garage has a DPC, you will need to look at the mortar joints above external ground level. Usually if a damp course is installed, you will be able to see a black line in between the mortar joint.

If you don’t find any evidence of a DPC, it is quite likely there wasn’t one installed when the garage was built.

Identifying a DPM will be more difficult, as this is below ground level. If you do notice a large amount of damp rising through the floor, you either don’t have a DPM or it is defective. If damp is already rising, then this doesn’t really make a difference either way, the damp would still need fixing in the same way. The only way to tell would be to completely dig up the floor.

How to stop damp in your garage

Due to the way they are built garages are prone to damp. They are generally one skin of brick or concrete blocks, and they lack insulation. Also, as we have already mentioned, they may completely lack any damp proofing that you would find in your home.

There are several ways to stop damp in your garage. However, the type and extent of the work will depend on a couple of main factors:

  1. Where is the damp entering?
  2. What are your plans for the garage?

The first point should be quite easy to determine.

If water is coming through your walls, it is likely due to some form of penetrating damp. This could be due to external defects, such as damage to brickwork, pointing and render. As well as defective seals around windows and doors.

When water is coming up from the ground into the bottoms of your walls, this is more likely to be rising damp. If this is the case, it will usually mean you either don’t have a DPC, or if you do, it has failed. It could also point to issues with your DPM (or lack of).

If damp is rising straight through the floor, then this is rising damp again. It is due to either a faulty DPM, or no DPM was ever installed.

Finally, where water is penetrating through the roof, you likely have a leak that needs fixing, maybe the roof needs replacing.

How you deal with any of these issues, is dependent on how you plan to use your garage once repairs are carried out.

If you plan to keep the space as a garage, then the fixes are usually quite simple. You can see some ways to fix each type of damp below.

Repairing penetrating damp in your garage

This is quite common, as it includes any area of the building where water is penetrating from outside. To get to the bottom of this, you will need to locate the defect.

You should look for obvious damage to bricks, old worn and damaged pointing and faulty seals around windows and doors. Also, make sure you check any gutters and downpipes for damage and leaks.

Most of the fixes here are quite simple, for example, replacing damaged bricks, repointing, applying new sealant around windows and doors, repairing, or replacing existing render, and fixing damage to guttering.

Also, if you wanted to take external damp proofing one step further, you could opt for an external masonry paint. This should completely seal the garage.

Fixing issues with a garage DPC

There are several ways to add or repair a garage DPC. The two most popular options are:

  • Applying a tanking slurry internally – This is usually installed up to around 1m on internal walls. If you wanted to take this one step further, you could go floor to ceiling, and this would also stop penetrating damp. You can read more about our favourite tanking slurry by clicking here
  • Using a chemical DPC – This is a popular way of adding an entire DPC, and it is also very DIY friendly. Again, you can read more about our favourite chemical DPC kits by clicking here

Either one of these options should stop water from rising on internal walls.

Stop water coming up through the floor

If your issue is a wet floor, then there is a good chance you don’t have a DPM. If you do, it is likely damaged, and this problem will need fixing.

There are several ways you can damp proof a floor. The most complicated would be to dig everything out and start again. This would include adding a new DPM and laying a new concrete floor.

Alternatively, you can opt for a simpler option, such as a waterproof membrane or tanking slurry. Either of these could be applied to the floor and would offer a waterproof barrier to stop the water rising.

Repairing leaks in your garage roof

This will be highly dependent on the type of roof you have on your garage. This could be a corrugated roof made from a variety of materials, including:

  • Plastic
  • Metal
  • Fibre cement

You could also have a standard pitched roof, a lean too, or a flat roof. Each of these will require a different fix, therefore you will need to determine the type of roof and where the leak is coming from. Only at this point, will you be able to decide on how you rectify the issue.

If in doubt, you should speak with a professional to make sure you get this fixed properly.

The best way to do this is compare local quotes. You can save quite a bit of money by comparing this way and guarantee the job gets fixed properly.

Our favourite place for this is Bark. They are an online comparison site and offer a service that compares local trades. Its quite common to see discounts as high as 50% off.

Click here to get instant quotes and see how much you could save

Conclusion

Not all garages have a DPC. It is not a requirement with building regulations, so in many instances they will not be installed. However, if you are building a new garage from scratch, it would probably make sense to add one. After all it adds extra protection and will make your garage a more usable space.


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