We have had a floor installed in our bathroom - dolomite crushed stone, followed by a reinforcement mesh, and finally Maxit 318. In the concrete floor slab, some holes appeared after we removed the old floor and the drain pipes. Beneath the slab, the panel ceiling of the recreation room is visible.
The craftsman (or rather the clumsy one) did not fill in the holes in the slab before he poured on the dolomite. Therefore, I see a risk that the dolomite crushed stone will flow out and voids will form under the concrete slab in the bathroom.
I would prefer not to break up the floor and have it relaid, but instead, repair the holes from underneath after removing parts of the panel ceiling. The repair is mainly to prevent further dolomite crushed stone from running out. The floor's load-bearing capacity at present seems unchanged as long as the dolomite hasn't run out in larger quantities.
Here is the solution I am considering:
1. Inject foam sealant into the holes from underneath, as much as will fit.
2. Attach plywood panels (at least 12 mm) over the holes with either nail anchors or screws with plugs.
Now to my questions:
- Is this a good solution?
- If something happens, what will the insurance company say about it?
- What alternative solutions are available? For example, is injecting from above something that would be appropriate, or is it "overkill"?
I would be incredibly grateful for answers. It would be really nice to have a proper bathroom... Thanks in advance, everyone.
The craftsman (or rather the clumsy one) did not fill in the holes in the slab before he poured on the dolomite. Therefore, I see a risk that the dolomite crushed stone will flow out and voids will form under the concrete slab in the bathroom.
I would prefer not to break up the floor and have it relaid, but instead, repair the holes from underneath after removing parts of the panel ceiling. The repair is mainly to prevent further dolomite crushed stone from running out. The floor's load-bearing capacity at present seems unchanged as long as the dolomite hasn't run out in larger quantities.
Here is the solution I am considering:
1. Inject foam sealant into the holes from underneath, as much as will fit.
2. Attach plywood panels (at least 12 mm) over the holes with either nail anchors or screws with plugs.
Now to my questions:
- Is this a good solution?
- If something happens, what will the insurance company say about it?
- What alternative solutions are available? For example, is injecting from above something that would be appropriate, or is it "overkill"?
I would be incredibly grateful for answers. It would be really nice to have a proper bathroom... Thanks in advance, everyone.
Depending on how thick the floor joists are, a splash of plastic padding or something similar might be useful. It's a bit harder than foam sealant. However, I think it might be smart to use a little foam sealant at the top to seal during the work, but take it little by little. Foam sealant expands a lot and cures upon air contact, so if you use too much, it cures at the bottom first, and when the rest expands, there's a risk of tension against the floor...
Thank you for the warning about spray foam. I knew it expanded, but not quite that much...
Do you - or anyone else - have other tips that are useful for someone who has never repaired concrete in their life? I'm mainly thinking about which tools are good to have on hand, good brands and product names for the padding, and so on.
Does anyone know if the building codes or equivalent say anything about this?
Do you - or anyone else - have other tips that are useful for someone who has never repaired concrete in their life? I'm mainly thinking about which tools are good to have on hand, good brands and product names for the padding, and so on.
Does anyone know if the building codes or equivalent say anything about this?
Difficult to say exactly, as I only have photos to rely on right now. Roughly, the largest holes are 15 cm long and 4-6 cm wide. They go through the floor joists; the surrounding material is a couple of centimeters thick or more.
I've discussed my idea with a skillful (part-time working with it) friend, who thinks it should hold even without plywood but with filler instead. I've bought filler and foam sealant at Bauhaus, so this weekend I'll be removing the ceiling panels.
Many thanks for your responses. More tips are welcome.
I've discussed my idea with a skillful (part-time working with it) friend, who thinks it should hold even without plywood but with filler instead. I've bought filler and foam sealant at Bauhaus, so this weekend I'll be removing the ceiling panels.
Many thanks for your responses. More tips are welcome.
Putty?
Maybe...
I would probably recommend trying to insert some form of pin (spikes) or screw at an angle from the side into the fracture edges.
If it's going to hold that dolomite in place.
IF I were to do it, I think I would use undercasting mortar (I think that's the name), a mortar that expands slightly when it cures. Regular mortar, and even putty, shrinks!! That is, there's a risk it'll detach from the edges of the holes.
Putty is for cosmetic repairs, it has very little strength.
Maybe...
I would probably recommend trying to insert some form of pin (spikes) or screw at an angle from the side into the fracture edges.
If it's going to hold that dolomite in place.
IF I were to do it, I think I would use undercasting mortar (I think that's the name), a mortar that expands slightly when it cures. Regular mortar, and even putty, shrinks!! That is, there's a risk it'll detach from the edges of the holes.
Putty is for cosmetic repairs, it has very little strength.
I imagine a solution where the expanding foam provides most of the filling and strength. I plan to apply the filler last, so the surface will be smooth if I ever want to remove the ceiling panel. The dolomite layer is no more than 6-7 cm, and the edges of the holes slope in the right direction. Do you still think there's a risk that the expanding foam alone might not hold?
Now I have injected a whole lot of foam. When I opened the ceiling panel, dolomite gravel absolutely poured down. It filled up half a paper bag before it subsided!
A little foam at a time, wait an hour for surface dryness, then add the next. A big advantage was that the dolomite gravel flowed quite easily, so no cavities appeared where the foam didn't reach.
Now I'm waiting overnight to let it cure, then I'll put the panel back. Unfortunately, it turned out that it wasn't possible to remove it without damaging two panel lengths, so next week I have to stock up on 2 x 3 meters of panel... Oh well, you can't have everything.
A little foam at a time, wait an hour for surface dryness, then add the next. A big advantage was that the dolomite gravel flowed quite easily, so no cavities appeared where the foam didn't reach.
Now I'm waiting overnight to let it cure, then I'll put the panel back. Unfortunately, it turned out that it wasn't possible to remove it without damaging two panel lengths, so next week I have to stock up on 2 x 3 meters of panel... Oh well, you can't have everything.