ᐅ Filling joints in a precast concrete slab – which material to use?

Hello,

I am currently facing the frustrating question in my new build: "How do I properly fill the joints in the concrete ceiling?" At the moment, I am still a beginner in this area but not completely inexperienced.

I could use some professional advice.

1. How and with what should I do the first layer of filling? — Meaning, how deep and with what kind of material?

2. How and with what should I do the second layer of filling?

3. How and when should reinforcement tape be embedded?

When, how, and where should I place it so that it isn’t sanded off? I assume this happens at least if I place it flush on top of the joint. After step 1 or step 2...?

4. What grit size should be used for sanding the joints?

5. With what should the pores in the concrete ceiling be filled, and does the ceiling need to be primed beforehand?

Many thanks in advance for the helpful tips.

Best regards and enjoy the holiday

Michael

Hello!

Another post lost again – so here’s the short version:
1st, 2nd, and 5th: Gypsum with plastic content.
3rd and 4th: Not at all; burrs are scraped off.

I always apply a primer. It doesn’t hurt and costs nothing.

Best regards,
Tom.

Michael1976 schrieb:
Hello,

I am currently facing the frustrating question in my new build: "How do I properly fill the joints in the concrete ceiling?" At the moment, I am still a beginner in this area but not completely unskilled.

I would need some professional advice.

1. How and with what should I apply the initial filler? – That is, how deep and which kind of material?

2. How and with what should I apply the finishing filler?

3. How and when should reinforcement tape be embedded?

When, how, and where should I place it so it does not get sanded off? I assume this might happen if I lay it flush on top of the joint. Should this be done after step 1 or step 2...?

4. What grit size should be used for sanding the joints?

5. What should be used to fill the pores in the concrete ceiling, and does the ceiling need to be primed beforehand?

Many thanks in advance for the helpful tips.

Best regards and have a nice holiday

Michael

From your description, you have a hollow-core slab ceiling that is prestressed on the top side and not concreted in. I recommend consulting a specialist for this, as these elements tend to retain condensation inside the hollow cores for a long time and exhibit extended shrinkage behavior. I have already encountered problems after 2 years with Dennert ceilings.