How to remove musty smell in garage?

Garages are typically not constructed to the same stringent standards as habitable rooms, particularly when it comes to moisture management. The musty smell you’re experiencing is likely due to dampness in the bricks, which can be a common issue in garages. This dampness could be coming from the ground, with the slab or lower course of bricks wicking water up, especially if there's insufficient waterproofing or drainage in place. If the smell is most noticeable near the lower sections of the walls or bricks, this is a strong indicator that the issue is confined to the area below the dampcourse line (the barrier that prevents moisture rising from the ground into the walls).

Before you proceed with insulation and plasterboard, I’d strongly recommend sealing both the inside and outside lower courses of the bricks. You can use a good quality brick sealer or waterproofing paint to help prevent moisture from entering. Additionally, sealing the concrete slab is essential to stop moisture from rising through the floor. This can be done with a concrete sealer. You might also want to inspect the garage for any potential drainage issues, such as poor ground slope or blocked gutters, which could be contributing to the moisture problem.

Once the sealing is done, the insulation and plasterboard should help control the temperature and humidity inside, but it’s important to address the source of the moisture first. If the problem is left untreated, the musty smell might persist or even worsen over time.

Please let me know iff you have any questions.

Mitchell

Thanks Michelle, this is *extremely* helpful. I'm so thankful for this recourse, really.

I will of back and once again inspect if the smell is more prominent towards the ground.
Also, there does seem to be some slight ground slope issues.
Before putting the sealers on, would you suggest that i hire some heaters of some kind to try and evaporate any dampness in the bricks?

You might like to pick up one of these Crommelin Moisture Meters @fadetoblack. They could help point towards an area where moisture is entering. I'd seal the outside of the wall first and then check to see if the moisture levels inside drop. You can then consider heaters or just aerating the area to help dry out the wall. I'd make sure the inside is sufficiently dry before sealing as you don't want to trap moisture in the wall.

Mitchell

Thanks Mitchel,
I'll look to seal the outside first and then give it a week or so and see how it goes.
To be on the safe side, would you recommend sealing the entirety of the outer brick wall?
I guess it might also be worth sealing the inside the neighbour's garage wall that directly boarders mine as well.

Also, there are some sizeable cracks between the concrete and brick wall that appear to lead to raw earth. Do you have any tips on sealing these as well?

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I would seal the lower three of four courses of bricks on the outside and pull back any soil that might be touching them @fadetoblack.

That looks like a very suspicious gap, which also looks quite moist. A highly suspect area, as you can see where moisture has penetrated and stained the concrete. Does water enter here in heavy rains? If so, I suspect you might need to add a drainage pipe between the two walls or check that it was installed when building. If rain is falling between your wall and the neighbours, it most likely has nowhere to go and sits there before being absorbed into the slab and walls.

I'd fill the depth with a filler rod and then Sikaflex over the gap to bridge between the slab and wall.

Mitchell

Thanks Michelle,

I’m not sure if water meters when it rains as we only just got the place. But there were considerable rains this here in Melbourne this morning and no water appeared in the garage.

would u suggest digging all the gravel and dirt around the garage until I get to the concrete slab?

Yes, I would @fadetoblack. Soil should never be up against the bricks like that. It's a great way for water to enter the brickwork. It is then wicked up through the mortar joints into the whole wall and even the roof.

Mitchell

Thanks Mitchell, I’ll be sure to dig away all the soil around until I get to the concrete slab.

one last question, I’ve just finished cleaning the garage floor with chemicals and a pressure hose and was now going to let it dry then apply concrete sealer.

would this be ok to do at this stage?

EricL

Hello @fadetoblack

I suggest giving it another 24 hours to make sure that all the trapped moisture has evaporated away from your concrete slab. Keep your doors and windows open to promote air circulation. If it looks like rain will be occurring, I suggest postponing your sealing project. I recommend checking the weather in your area and making sure that you'll be having a few sunny days in a row before you start sealing your driveway.

If you need further assistance, please let us know.

Eric

Thanks Eric,
I'm actually sealing an indoor garage, which I've spent two days cleaning with concrete cleaner and a pressure cleaner that I got at Bunnings.
I will give it a few days though. My biggest concern is the issues with rising damp in my garage. Mitchell suggested I get to the root cause before sealing all the inner and out bricks – which will involve digging all the gravel and soil from the perimeter.

I'm just not sure if I need to solve the rising damp through the brick before I look at sealing the concrete slab or not?

EricL

Hi @fadetoblack

I suggest following Mitchell's recommendations before you seal your garage floor. The last thing you want to happen is to have your sealer peel and lift due to rising damp from underneath. It definitely has to be addressed before you move forward with sealing.

If you need further assistance, lease let us know.

Eric

Thanks Eric, I really appreciate al this!

The same goes for the concrete slab. I get the feeling that moisture is transferring through/under the bricks and into at least the edge of the slab. So, it's best to try to resolve the issue with the bricks first before sealing the slab.

Mitchell

I just realised that this gutter pipe goes straight into the ground. I’ll dig around it to see if it’s the culprits.

once I remove all gravel/soil from the outer brick, how long do u think I should wait until applying concrete sealer. Until the smell goes away or the damp spots turn to ‘normal’?

For the outside, I'd apply the sealer after you've had a couple of days of dry weather @fadetoblack. That will allow the wall to dry out.

Mitchell

Thanks Mitchell,
I was actually referring to the concrete slab inside the garage though.

I'd seal the outside and then wait a week before sealing the inside @fadetoblack. The staining won't go away on the concrete, but you might see it dry out a bit during the week.

Mitchell

Thanks Michell. This is all very helpful.

Hi Mitchell,
I finally got around to removing the soil and gravel from the outer edge.
There seemed to ve a mixture of dense clay, sand, gravel, plastic sheets and odd bits and pieces (our town house it sitting on the grounds of the old Kodak Factory)

I'm curious to know where you would suggest I go from here. It looks like there was a rim of brick on the bottom that has crumbled away over time. Does this need replacing? also, I wonder if its worth cleaning all the brick with a high pressure spray gun before drying it out and then applying the brick sealer?

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JacobZ

Thank you for the update.

I'd suggest you start by clearing out the drainage pit that you've uncovered and see if there is anything connected to it. Take the grate off and scoop out any of the material you find inside. If the drainage is blocked, this could have some connection to the smell.

The plastic is a vapour barrier that is placed under the concrete slab to prevent moisture from rising through the slab. You can see that it was rolled up the side of the concrete at one point in time. Having the edge of the slab exposed can allow water to travel sideways into your concrete slab which can in turn move up through the slab and inside the home. I'd suggest removing any soil that is sitting on the plastic, then rolling it up the side of the slab and backfilling to keep it in place.

Pressure cleaning the wall will remove any dirt and contaminants that can affect the adhesion of the sealer, so it is definitely a worthwhile step.

Let me know what you think.

Jacob

Thanks Jacob, should I look to seal the concrete on the outside wall as well. The plastic looks a bit tattered and I'm worried it will just be a matter of time before it degrades?
Also, would it be worthwhile backfilling with pebbles or something to keep the soil from reaching it?

#Edit. I just inspected the plastic a bit more closely and found that there are indeed a few holes in. I wonder if it's worth placing a new barrier up or if sealing it would be sufficient.

I also took the grating of. Whilst the grating was jammed pack with clay and gravel, the pipe was thankfully clear of any dirt.

JacobZ

Anything we can do to keep water away from the bricks and slab is worthwhile. Even if it is not the cause of the smell, keeping water away from direct contact with the slab and brick is going to help prolong their life.

Considering the condition of the plastic, painting the side of the slab with this Bastion Matte Concrete Sealer would certainly be worthwhile.

Backfilling with gravel is also a great idea as it will help stop the soil from coming into contact with the side of the slab. You could also add some garden edging to retain the soil and create an aesthetically pleasing division between soil and stone in your yard.

Check out How To Install Garden Edging for some guidance.

Let me know what you think.

Jacob

Thanks Jacob,
I actually bought a tin of Baston concrete sealer from Bunnings on the suggestion of another team-member.
I guess now I should clean the outer slab and brick with a pressure cleaner as much as I can, wait a week for it to dry and then apply the sealer?

My question is though, how deep should I dig to reveal the slab, clean it and seal it?

Also, for the sake of longevity, would it be work sealing the entirety of the outside and inside brick wall?

JacobZ

Yep, what you've said is correct. Clean the slab, wait for it to dry and then apply the sealer.

I'd suggest painting the sealer on the top 150-200mm of the slab. I would be surprised if it went down further than this, but if it does, then 150-200mm should be fine.

Sealing the bricks would also be worthwhile as it will prevent water from seeping into the bricks and degrading them over time. You can use this Crommelin Water Based Brick And Render Sealer if you'd like to retain the natural aesthetic of the brick, or you could paint the bricks with a suitable exterior paint.

Let me know what you think and if you have any further questions, please don't hesitate to ask.

Jacob