How to repair alfresco concrete slab gap?

[Sam12]

How can i align the bricks and concrete floor on this alfresco and whats the best idea to close the vertical gap as well

 

 

[JacobZ]

Hi @Sam12,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

I suspect that this misalignment in the bricks and the gap opening up is due to the lower slab subsiding.

I suggest you enlist the services of a professional specialising in slab stabilisation and underpinning as the underlying issue must be resolved before any cosmetic repairs can be done.

You might like to use a service such as Hipages or True Local to find someone local to you who specialises in this field of work.

Let me know if there's anything else I can clarify or assist with.

Jacob

[Sam12]

@JacobZ Thanks, i think its just poor quality of work because it is same from the time of built, what cosmetic changes can i do to avoid rain water going inside

[JacobZ]

Hi @Sam12,

If you're confident that there is not an underlying issue, then it's fine to go ahead with a cosmetic repair.

You could pack between the brick and concrete slab with Lanko 701 Duragrout. Clean the void thoroughly with a stiff bristled brush to remove all loose material. Once clean, you will need to mix it to a fairly thick consistency to ensure it it doesn't fall out. Apply the Duragrout with a Brick Trowel and compact it into the hole to ensure the whole void is filled. 

Realigning the front face of the concrete with the brick could be achieved with a render such as Dunlop 20kg Multipurpose Acrylic Render. You might like to check out How To Render for some guidance on this process.

Please remember to wear all relevant personal protective equipment when working with cement-based products. Specifically, a mask, gloves and eye protection.

I'll tag some of our helpful members to see if they have any other ideas, @Dave-1, @Noyade, @Nailbag.

Let me know if you have any other questions.

Jacob

[Dave-1]

Afternoon @Sam12 

Now that is an interesting problem, The thin layer of bricks makes me think that the brickwork was done after the slab was poured and supported underneath somehow. Do you know if the slab is supported behind the bricks? 

Are you intending to install a handrail of some kind? You could potentially "hide" it by extending a handrail/slats over the top of the slab to the bricks.

I have used Concretemate to repair a few sections on my patio and it worked well. Concrete patio repair is the project.

With your patio and edge extension you could do the same if you can seal the inside underside of the slab otherwise a different product would be needed such as the one @JacobZ has recomended. I would still be tempted to add some concrete screws on the edge of the slab to help give something for the concrete to bond to and make it at least 25mm in width (new section)

Dave

[Sam12]

@Dave-1 This photo may give some better idea. Tried to check whats supporting the slab.

All I can see there is some hollow section after bricks  and then big square box - not sure what to call that.

I see some thermopole under the upper slab also. Also just noticed that bricks are not aligned with both lower and upper slabs and hence the misalignment. Bricks were done after the slabs.

 

Does the moss on slab indicate drainage issue as well? Or is this normal for slab

 

[Dave-1 · Accepted solution]

Evening @Sam12 

Thank you for the pics Sam, Id hazzard a guess that the slab has been made with corrorgated iron underneath it (same as my patio, common practice at least a few years ago) With that gap and the hollow bricks you could follow a mixture of @JacobZ's suggestion with the mortar and also add in some steel that pokes out from the mortar a little from the edge of the slab. This is to give the new part of the patio something to bond to. If you are unfamiliar with concreting and formwork you could do it in two stages (one of the other members may know more for this part) so mortar the gap with steel poking out of the mortar, let it cure and then build up some formwork the same depth and width that you want to extend the patio (I am only talking about 40mm ish) anything more and then other issues raise their head. I have only used concrete mate and it was easy but stressfull at the same time. There are other cement products that would be cheaper I would say.

As for the moss at the bottom of the slab id say water hangs around that area a fair bit. Anything that sits in and around wet areas will degrade faster. You could put in drainage or level the ground up. Depends on what your yard does. The green actually reminds me of water that has stained concrete.

Dave

[Nailbag]

I would be following @Dave-1 recommendations in filling in all gaps between the concrete and brickwork as the first priority to stabilise and support both upper and lower sections. You could then potentially render the face of the walls with a DIY rendering solution. Alternatively a simple DIY solution would be to build a garden bed say 500mm off the wall and plant it out with medium shrubs or hedging plants. Westringia Wynyabbie Gems are a very robust fast growing shrub available in various affordable pot sizes that are fast growing. 

Regards, Nailbag

 

[Sam12]

@JacobZ Thanks! Should i make a form or structure first so Duragrout will set in place and not fall out.

[Dave-1]

Evening @Sam12 

Id make the mixture so its fairy firm and not slump, for the first stage. At the same time I would wait for @JacobZ's knowledge

Dave