White fluff and damp on the underside of the balcony

[betongexperten]

Hello Cotton!

I think you understood what I meant. If the stratification goes all the way around as you say, it's probably a top layer of concrete (overlay) on the structural concrete, a 2-layer balcony. The structural concrete is reinforced with a load-bearing function. There might be a waterproofing membrane/insulation layer between the layers. The overlay is probably unreinforced or there might be some kind of crack reinforcement, see http://www.bf.nu/bf/uploaded_files/balkongbesiktning.pdf (some information there also includes what I previously mentioned). The overlay might be constructed with a slight slope away from the facade.

I think I understand what you mean. The balcony has deflection along its length. Some deflection can be acceptable, hard to judge from the picture.

Do you also have reinforcement drawings of the balcony or other construction drawings? If I understand you correctly, the pillars were there from the beginning? Another question is whether the walls really had a load-bearing function.

Where in the country do you live?

As you may notice, it seems necessary for you to get a proper condition assessment of your balcony in the future. There are many question marks to clear up. You could try to find out more about the upper layers from the tiles + overlay down to the structural concrete and how it's constructed. Is the overlay unreinforced, etc.?

Regards

 

[Bomull]

Hello Bomull!

Yes, you probably understood what I meant. If the layering goes all the way around as you say, it's likely a topping concrete layer (overlay) on the structural concrete, a 2-layer balcony. The structural concrete is reinforced with a load-bearing function. There might be a waterproofing membrane/insulation between the layers. Probably the topping concrete is unreinforced, perhaps with some type of crack reinforcement, see [link] (some information including parts that I mentioned earlier). The topping concrete might be executed with a bit of slope away from the facade?

I think I understand what you mean. The balcony has sagging in the longitudinal direction. A little sagging can be acceptable, hard to judge from the picture.

Do you also have reinforcement drawings of the balcony or other structural drawings? If I understand you correctly, the columns were there from the beginning? Another question is if the walls really had a load-bearing function?

Where in the country do you live?

Thanks for the link! I actually contacted bf today and got the phone number for a company I hope can check the balcony. I live in Småland and the company seemed to be based nearby. It has a slight slope; water doesn't flow towards the facade, but the slope could probably be better.

Unfortunately, no reinforcement drawings, and I don't know whether the intended fuel store walls were supposed to be load-bearing. I can't imagine it being anything other than the columns from the start.

/Sam

 

[eviljava]

Do you have any overlay/coating/tile that prevents you from inspecting the top side?

We actually had tiles (thicker model) there previously. The grout and substrate had deteriorated over the years. In some places, it was just pure sand. It was so porous that a small tree plant even started growing in the grout.

This resulted in moisture being retained under the tiles, which in turn caused the facade (lightweight concrete) to be thoroughly damp near the slab. Moisture had also been drawn into the subfloor inside via capillary action. We chiseled away all the tiles, but I seem to recall that the slab looked okay. I.e., no cracks or exposed reinforcement. Now we have sheet metal over it as a seal.

I interpret your response as suggesting that it might not be particularly urgent since the top side looks OK?

Another question:

What can be done about minor frost damage on the front edge of the balcony? I've noticed that it's starting to crack there. Presumably due to meltwater being absorbed in early spring (daytime), which then freezes at night and causes the frost damage?

Is it common to impregnate the concrete with hydrophobic liquid or similar? Would regular concrete oil work?

 

[betongexperten]

Cotton:
Glad you were able to reach someone via BF. Good luck moving forward and feel free to post in the thread when you know more.

eviljava:

For your balcony type, the top reinforcement prevents the balcony slab from bending. Therefore, the condition of the top reinforcement (uppermost reinforcement layer) and its anchorage in the concrete is of utmost importance for a safe balcony. This is because your balcony type is subjected to tensile stresses on the top and compressive stresses on the bottom. Concrete has high compressive strength and only about 1/10 of tensile strength in relation. Therefore, concrete structures are reinforced for static reasons in construction zones that are subjected to tensile forces. In your case, the tensile forces are at the top, with the greatest stress closest to the clamping against the facade.

Concrete structures are also reinforced for other reasons to avoid cracking from concrete shrinkage, known as crack reinforcement. This reinforcement is also placed in the concrete's compressive zones. The minor damage you described on the underside should be seen as a warning sign and it might therefore be a good idea to have someone knowledgeable inspect your balcony.

It is possible to chisel away the front edge of the balcony and then cast a new front edge with frost-resistant concrete. For this measure, one must be sure that the balcony is not damaged elsewhere, or will not be damaged in the near future. Again, this is a reason to have the balcony examined.

Yes, there is the possibility of protection with hydrophobic agents (gel or liquid); it can be effective if there is no ongoing damage mechanism. This could be an option after a repair is made or in undamaged areas. It is important to achieve the desired effect and to avoid negative side effects from these types of treatments.

Further reading tips where you can learn more: http://www.bobattre.se/TemaBalkongInspektera.asp?Page=P03

Hope I could explain a little more.

 

[eviljava]

Thanks for the answer!

I'll try to find someone who knows about balconies at least to do an inspection. I don't think it's urgent, but I now realize that the balcony should be included in the maintenance plan.