Cracks in the newly built mortar joints on the walls

have someone independent standing over the mixer making sure that every load of it was the correct ratio of material and correct final consistency?

Replying to Ponzutwo,
The company has a construction manager to supervise and manage the building work, but he didn't come to supervise it at all and insisted it was a 'normal process'. I was told that the private certifier from the company will only come when the waterproof for the bathroom is done and at that time will investigate the cracks. I guess that the problem was caused by a wrong ratio mixture of water+sand+cement? Or the poor quality of cement? My question is how we can assess the extent of the problem. Is there any other way to fix it apart from repointing? Rendering the whole walls for example?

my comment related bimguys suggestion that someone should have been there on day one to inspect the mortar. This is not only impractical, its also not possible to monitor for the duration of the bricklaying. I was trying to highlight the ridiculousness of the comment, which he appears to make a lot of to make people such as you, a layperson, feel small and inferior.

Mortar is a basic recipe. Brickies mix up tens of thousands of batches throughout their career. There is a standard mix recipe, and there are a small number of altered recipes that some builders use under an alternate solution to save money across their whole portfolio of builds, which requires documented approval to use.

The suggestion that someone inspecting the mortar on the first day would somehow alleviate dyour problems is farcical, regardless of what the standard says. There is zero guarantee that all subsequent batches of mortar mixed throughout the course of the project were the same UNLESS someone independent was standing over the mixer watching every shovelful go in and checking every couple of courses before it hardened/set. As you can see, impractical and never going to happen. In general, its trusted that the mortar will be mixed as required by the people who do it day in and day out for a living. Its not a common occurrence for someone to deviate so significantly from the recipes that the mortar will fail catastrophically or in any material way. There are of course horror stories and examples of exactly that happening, but this is usually an occurrence when someone unskilled is doing the job or the builder cuts corners too far etc, but these are exceptions. If this was the case in your case, your walls would look significantly worse and it would be obvious.

The builders supervisor is just managing the timeline of trades. They may (should) occasionally go and inspect the work. The final product is generally commensurate of the quality of the supervisor. But you will never see them going and inspecting mortar being mixed. Most of them have never laid a brick in their life and wouldn't know what they are looking for.

The cracks you can see could be from a number of reasons, but as long as they don't get any bigger, the bonding performance shouldn't be materially impacted in a real-world practical sense. If the mortar starts falling out in chunks or bricks become loose, you may need to have someone take a look. Mortar can be tested in a lab and results to its composition can give a definitive view of whether there is truly a defect in the composition of the mortar or not. This however is generally not something you or the builder would do unless there was a reason to do so. The builder would likely have a much more lax view of when this should be done, as its not in their interest to be proving a defect exists. Your current outcome doesn't look like it would be warranted but You could do so privately for peace of mind. It will cost you money. and then some if the results are that of inferior mortar and you wish to fight it.

Repointing or rendering is only a cosmetic fix. If it bothers you how it looks so much, that is an option, but it creates a barrier to inspection of something that could end up being a bigger issue. I wouldn't be looking to do anything to it until you are certain there is nothing wrong with it.

Your cheapest and mort practical option is to monitor. if it doesn't get worse, you can be more comfortable about future cosmetic fixes.

Your more expensive option is to get the mortar independently tested in a lab (a google will help you find one that does this). Even if you go down this route, what's your next step? The mortar would have to be significantly inferior before you would be able to claim the whole lot needs to be redone, and my gut feel is that the results will be within acceptable ratios.

In general, IMO, your bricks are fine, your mortar could be better. But unless theres something actually going wrong like mortar falling out and bricks becoming lose within the first couple of years, then there really isn't a problem here. Hairline cracks in mortar is common and no cause for alarm. If you start seeing stepped cracking, get someone to look at it. In the meantime, take notes of your conversations and dates. Take pictures so you have a timeline if you need it. best case you have a bunch of pictures of bricks and worst case you have evidence of degradation over a period that shouldn't have occurred which will give you the evidence you need to take the issue further.

nothing conveniently missed. I'm just not a narcissist.

Perhaps you could explain to the OP how the inspection before the mortar sets is done.

Thanh you very much for all of your comments and advice. I really appreciate those. I am still waiting for the response from the company and will let the forum know about it.
Regards

Dear forum members,

I just want to update our members on my situation. Recently, the company sent the photos of the cracks in the mortar joints to their structural engineer and here is his response,

“The cracks are not structural and only shrinkage cracks, and hence will not affect the structural integrity of the brickwork, walls or building in anyway. These would have occurred due to a combination of normal drying shrinkage and environmental factors such as drying out too quick due to the windy and hot conditions we have experienced in late January / early February. .... These shrinkage cracks, being much less than 1 mm in width, at worst, classifies them as damage category “0”to “1” under Appendix C of the residential slabs and footings code AS 28702 (classes 0 to 4, with 4 being the worst). This labels them as "Very Slight" cracks, which are "Fine, but Noticeable". The majority of the cracks would even be considered to be hairline and hence under Category “0”.”…

“As such, these cracks do not require repair and are expected to stabilise following the initial curing period following the setting of the mortar and would not be expected to open up any further. The brickwork was erected during a hot and windy week, and the cracking is the result of the cement drying out too quickly. The cracks are surface cracks only and do not affect the structural performance, or water tightness of the building in any way.”

We were also told that the cracks are mostly under 1.5mm (according to the document "Guide to Standards and Tolerances 2007_Table 3.02" from Office of Fair Trading-NSW), the brickwork is not considered to be defective. I feel that I am heading to a dead end.

If it is a non-structural issue, is there any way to enhance the look of the walls as they look really bad with all those cracks?

Best Regards,
Petin