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How to fix block mortar before garage makeover - caulking or mortar?

Interior - Cracked mortar in cornerHi All,

I'm planning a garage makeover inside with a fresh lick of paints (before a floor epoxy coating and new storage) but before I do that I've noticed these cracks (highlighted in red) in the mortar between the blocks (no cracks in concrete masonry blocks which is a good sign I feel).

I want to fix the mortar before painting so is sealed, especially since I can see daylight through one of the areas and don't want water coming through.

Reading other similar posts, do I caulk with some mortar repair or use some cement mortar mix? Inside and/or outside? I'd appreciate any product suggestions.

It is mainly in one corner of the garage so I am concerned there is water pooling from rain making the clay soil move more moving the slab but the floor has no cracks so I don't think it's a massive issue currently.

I want to give it a go myself so I ideally want to keep it on cheaper side so any reassurances to avoid any full structural repairs is appreciated.

Interior - daylight between blocks

Interior - Cracked mortarExterior - visible mortar crackingInterior - beside columnExterior - base

Photo - showing daylight from inside.

Close up of mortar.

Do I seal this up with something?

External wall faces neighbours garage wall so doesn't have to be aesthetically pleasing as can't see it.

Interior with cracked mortar near column.

Do I scrape these rocks away and grade with something so rain drains away from slab?

Location is Victoria, Australia.

Appreciate any advice.

Cheers.

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Jason

@sav006,

Thanks for your question. I'm certain that @MitchellMc will be more than happy to assist when he is back on the site tomorrow.

In the meantime, let me tag some helpful and knowledgable members in @ProjectPete, @Brad and @TedBear to see if they might like to kick off the discussion with how they would go about tackling this problem.

I'd also like to point you towards our most popular project on the Bunnings Workshop community - Epoxy garage floor project by @maknilsin.

Thanks,

Jason

TedBear

To start the conversation, my suggestion is, as with all problems, to firstly ensure that you are fixing the problem and not just fixing a symptom. If it were my home, I would dig out those stones outside where the crack is, to inspect the footings. If there is a problem there that is no longer supporting the wall, then you will need to attend to that, otherwise you will be fixing new cracks until the wall collapses or finally resettles. If it is caused by something that is now stabilised and won't get worse, (e.g has there been any major building nearby in the past year where vibrations from compactors could have caused the cracks?) then you can patch the cracks with a caulking filler such as Selleys Mortar Works:-

https://www.bunnings.com.au/selleys-gap-filler-440g-grey-no-more-gaps-mortar-works_p1231979

The larger gaps might be better filed with a dry mix mortar product... best consult with a Bunnings' store member to get latest advice on the right product (I haven't needed to do any mortar repairs for a few years, so my product suggestions will be out of date).

If you need to keep the rain water away from footings, place some slotted drainage pipe, below ground along the wall, connect it to a small soakwell (placed away from the wall) and place the stones back around and over the top of the pipe. https://www.bunnings.com.au/vinidex-50mm-x-10m-black-slotted-draincoil_p4770250

https://www.bunnings.com.au/impala-600-x-600mm-2-piece-plastic-soakwell_p4772514

MitchellMc

Hi @sav006,

It's great to see you've already received some helpful advice from @TedBear, and he has underlined some issues that need to be addressed around whether this is a continuing issue or something that has resolved itself.

There is a big difference between resolving the issue and patching so you can give it a lick of paint. Fixing the issue of why the wall has cracked starts as per @TedBears advice. Once you establish that the wall isn't currently moving or settling, you can cut out the remaining mortar where the cracks are with an angle grinder and refill the joints. There is currently not enough room to pack in a mortar into those hairline cracks to complete a structural repair of the area unless you remove more of the joint first. The mortar needs to be packed right into the middle of the joint, and I would recommend Timbermate Concremate Expanding Cement - 1kg for this.

If you believe the wall has settled or do not wish to cut out more mortar, then you can cover the cracks both inside and out and then paint. I would suggest filling all the gaps with Sika 300ml Grey Sikaflex 11FC Plus Polyurethane Adhesive Sealant as it is a flexible and paintable sealant. I'd suggest this over mortar, as any patching you do will be a very thin aesthetical layer on the joint's facade which serves no structural purpose. The Sika 11FC will flex with the wall if it is still moving, whereas the mortar will crack again.

Please let us know if you need further assistance or have questions.

Mitchell

sav006

Thanks for the replies so far @TedBear and @MitchellMc

The garage is 20 years old (not new build) so my feel is it has settled and won't move any more.

There are no cracks in the garage floor itself which makes me think it's not a major structure issue but I do want to look at the digging out the stones to inspect and install a basic drainage solution as TedBear suggests as the building inspection when we bought 12 months ago flagged it as a potential issue and think water is just pooling at the base foundation causing some small movement.

I think it has settled so preference would be to use the caulking so might look into that Sika product.

If I consider grinding out some of the existing mortar to get a better hold. What time of cutting disc do you suggest? I want to make sure I don't chip the block too so steady hand will be needed.

Thanks again.

TedBear

Since these are small gaps and you will be working near a pillar (confined space) I would recommend using a Multi tool, if you have one, and and a diamond blade (eg https://www.bunnings.com.au/powerfit-63mm-diamond-blade_p6320556 ).

That will give you more control to avoid damaging the blocks as they are less aggressive than an angle grinder.

You wont need to go too deep if this is a cosmetic repair.

If you think you need some structural stabilisation you could screw some metal straps (or use small right angle brackets at the pillar) across the crack at a few points, but it sounds like you have determined that the wall is now settled in position.

A multi tool is an excellent tool for getting into many tight spots I find and can do fine work (as well as be destructive if out of control of course).

MitchellMc

@sav006,

As @TedBear has suggested, if you are doing a cosmetic repair with the Sika 11FC, you shouldn't need to remove much mortar at all. You will be caulking the product, so you should be able to force it into the finer gaps, and it will also bond well to the surface.

Mitchell

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