I have decided to remove all the Tapcon screws (yes all 2,000 of them) and plug the holes. I am not risking moisture or water creeping up through the concrete. The screws are easy enough to remove, but how do you suggest I fill the holes and with what? The pre-drilled holes are quite narrow and anything too thick will just sit at the top. Thanks
Subfloor
- Thread starter wcheaib
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I'd step back and think about that for a bit. Are there then going to be 2000 additional, but shorter holes drilled in the floor .....and the membrane. How can you be certain that you will be successful sealing the membrane holes so moisture is kept under it instead of leaking past it and into the plywood.
I mentioned additional holes because it probably does require as many holes as before being that you have 5/8 plywood. One screw in each corner and one in the middle isn't going to be enough.
Have you contacted the manufacturer about the issue yet?
I mentioned additional holes because it probably does require as many holes as before being that you have 5/8 plywood. One screw in each corner and one in the middle isn't going to be enough.
Have you contacted the manufacturer about the issue yet?
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Here's what I am seeing. The brown is the moisture level in the soil below the slab. The moisture or humidity level inside the over drilled hole cavity might be similar to that of the soil.
The dark blue is the highest moisture level in the slab and it gets less and less as you go upwards. This is just my own vision of what might be happening around the screw area.
The screw itself probably does a fairly decent job of sealing the hole.
If you are thinking about removing all of the screws, how about this idea. Remove the screws, re-drill the holes for the next larger size (diameter) Tapcon screw, but only drill the depth needed for the correct length screws. Seal the screws this time when they are installed.
Maybe even find a sealer that can be squirted down into the hole before driving the new screws.
What size and gauge are the current screws?
The dark blue is the highest moisture level in the slab and it gets less and less as you go upwards. This is just my own vision of what might be happening around the screw area.
The screw itself probably does a fairly decent job of sealing the hole.
If you are thinking about removing all of the screws, how about this idea. Remove the screws, re-drill the holes for the next larger size (diameter) Tapcon screw, but only drill the depth needed for the correct length screws. Seal the screws this time when they are installed.
Maybe even find a sealer that can be squirted down into the hole before driving the new screws.
What size and gauge are the current screws?
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T think it would be very hard to find where each old screw hole would be to be able to put the new screw in
I would still looking at going over the concrete slab with something like this instead of trying to fill each hole
which will go down into each of the holes if applied with a trowel as the trowel forces the product into the holes where as a paint roller just goes over the holes
This product will waterproof the slab as well
I would still looking at going over the concrete slab with something like this instead of trying to fill each hole
which will go down into each of the holes if applied with a trowel as the trowel forces the product into the holes where as a paint roller just goes over the holes
This product will waterproof the slab as well
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I don't think he was planning on removing the plywood Jon so the holes would remain in the same location.
In the past, I have filled a grease gun with adhesive and attached a few lengths of narrow stainless steel tubing to inject carpet adhesive under carpet to get rid of bubbles. I've done it on 3 different occasions. Same thing could be done if a polyurethane sealant could be put into the gun. A grease gun has 100+ times the power of a caulking gun so the sealant could easily flow through an 8th inch nozzle if he could make one up.
Not everyone has McGuyver's ingenuity. Filling the gun with polyurethane sealant would be messy and not sure how many times you'd have to reload the gun for 2000 holes.
In the past, I have filled a grease gun with adhesive and attached a few lengths of narrow stainless steel tubing to inject carpet adhesive under carpet to get rid of bubbles. I've done it on 3 different occasions. Same thing could be done if a polyurethane sealant could be put into the gun. A grease gun has 100+ times the power of a caulking gun so the sealant could easily flow through an 8th inch nozzle if he could make one up.
Not everyone has McGuyver's ingenuity. Filling the gun with polyurethane sealant would be messy and not sure how many times you'd have to reload the gun for 2000 holes.
How many of the screws will break when you try to remove them. More than one out of two thousand for sure.
I wasn't thinking of re-drilling anymore holes. If I decide to go with a fixed system, then I can glue the plywood directly onto the concrete and nail down the engineered hardwood on top of that without penetrating the concrete slab. The alternative (which is less preferable) is to lay down a floating click system. So all I was going to do was refill the holes with some type of concrete to get my slab to the way it was. I don't think troweling will necessarily make its way all the way down the 4" hole. I was at Home Depot yesterday and they recommended I use Quikcrete Concrete Crack Seal. I just need to figure out how to get it all the way down the hole.
Highup - You were asking about the screws. They are called ITW Tapcon 24165 - 3/16" x 2-3/4".
Jon - In Canada, the concrete in the basement is really cold so in the absence of in-floor heating, we will laydown a moisture barrier like the Delta FL along with plywood before installing the engineered hardwood. This creates a bit of an insulator.
Jon - In Canada, the concrete in the basement is really cold so in the absence of in-floor heating, we will laydown a moisture barrier like the Delta FL along with plywood before installing the engineered hardwood. This creates a bit of an insulator.
The hole is barely larger than 1/8" so no way is any cement product going to get forced all the way down to the bottom of the hole. With that small of a hole (5/32") spaced 16" apart, I don't see any real structural integrity issues with the slab either. If they were 2 inches apart, and in a straight line, maybe.
Lets assume there is some rebar in the slab............ the slab isn't going to crack and separate or move apart. The building inspector is correct about the intentional cuts that are sometimes put in slabs as 'control' joints. They make concrete crack at those points instead of randomly. Concrete does crack. If the concrete forms a hairline crack because of those small drilled holes, it's because the concrete was stressed and wanted to crack at that location anyway.
The concrete isn't going to crack and turn into gravel, so personally, and if it was my place, I wouldn't worry about that issue at all.
You see the drawing I sketched earlier? That was how it would actually look before the plastic dimple board and plywood was installed.
The concrete is drier at the top, because of the constant evaporation of moisture into the room.
Shown here, the plastic and plywood is installed. The moisture can't evaporate anymore, so the moisture content in entire thickness slab builds up and becomes more or less equal. The only real issue I see, is the lack of sealant which would stop the moisture vapor from slowly coming up above the top of the membrane.
Remove the screws, vacuum the hole, apply sealant to the screw and unto the hole, then install a 3" screws?
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Thanks. I actually just received an email from Tapcon and they too have never seen this done before. They did say that if I remove the screws I cannot put them back in as the grip becomes lost by removing them. I am fine with this as I will just glue down the floor. In terms of filling the hole is there a liquid cement or sealant you would recommend I use? And how would you advise to get into that narrow hole?
Email from Tapcon:
Short quick answers. If you have more questions please send them to me:
1. Target depth for Tapcon should be 1” to 1-1/4” and NO more. Hole should be ¼” deeper than the embedment of the Tapcon.
2. Do not remove Tapcon for you cannot reuse that hole with another Tapcon.
3. As long as the Tapcon is in full contact with the slab you are OK. If hole is too deep it will not affect the strength of the Tapcon.
4. Never seen or heard of it being done that way.
Email from Tapcon:
Short quick answers. If you have more questions please send them to me:
1. Target depth for Tapcon should be 1” to 1-1/4” and NO more. Hole should be ¼” deeper than the embedment of the Tapcon.
2. Do not remove Tapcon for you cannot reuse that hole with another Tapcon.
3. As long as the Tapcon is in full contact with the slab you are OK. If hole is too deep it will not affect the strength of the Tapcon.
4. Never seen or heard of it being done that way.
Their recommendation says 1/4 inch deeper than hole. That probably allows for some residual dust settlement.
Have you tried removing any screws to see how easy they come out?
I'd just buy a few polyurethane sealants and see which one is the thinnest or runniest. Cram the nozzle into the hole and see what will go in, then put some on the screw threads and screw it in. No reason to try and fill the hole. I think all you are doing is sealing the screw area so no moisture vapor gets above the top surface of the membrane and into to the plywood.
It's not like you are plugging the hole to stop water from squirting out. The moisture is already in the concrete anyway and that's normal since there's no plastic vapor barrier. Look at the second drawing. You just don't want moisture getting into the plywood. The screw probably seals ever so slightly around the plastic membrane so it would take quite a while to affect the plywood or the flooring. ......still, it would probably be worth pulling a screw or 5 to see how easy they come out, then weigh the options of a larger diameter but shorter screw like Tapcon said.
Sometimes, applying a little bit of force as if to drive the screw in, then immediately reverse the drill and pull it out. Being long screws, they might break, I just don't know.
Maybe a smack with a hammer and wide punch directly on the screw, then immediately drive it out. The smack, might break the tension in the screw/concrete contact so it doesn't snap off when driving it out.
Try it over in a corner and see what happens if you still plan on removing them all.
I mentioned driving the screw inward first because I found that pulling some newly installed deck screws out would snap them off. If however, if I drove them inward first to loosen them, then immediately reverse the drill, they came out every time without breaking.
Rusty automotive bolts work the same way. Tighten first, then loosen. That method often breaks the tension holding the fastener in.
When I say "tighten" first, as for your application, I don't actually mean making the screw turn. I just mean applying force in that direction, then reversing the drill and removing the fastener.
This tool might just be the safest ticket for initially "driving" the screw inwards.https://www.craftsman.com/products/craftsman-impact-driver
One medium smack with this, then remove the screw with a drill or battery powered impact driver.
This might not even be necessary, so it's an option if the screws don't want to come out easy.https://craftsman-brand-production.s3.amazonaws.com/spree/images/2049515/original/spin_prod_887079112.?1492492677
Rusty automotive bolts work the same way. Tighten first, then loosen. That method often breaks the tension holding the fastener in.
When I say "tighten" first, as for your application, I don't actually mean making the screw turn. I just mean applying force in that direction, then reversing the drill and removing the fastener.
This tool might just be the safest ticket for initially "driving" the screw inwards.https://www.craftsman.com/products/craftsman-impact-driver
One medium smack with this, then remove the screw with a drill or battery powered impact driver.
This might not even be necessary, so it's an option if the screws don't want to come out easy.https://craftsman-brand-production.s3.amazonaws.com/spree/images/2049515/original/spin_prod_887079112.?1492492677
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The next larger Tapcon is 1/4" I think. If that would work better than a longer screw of the same diameter, you might want to countersink the plywood slightly to accommodate the head of the larger screw.
Ask Tapcon about using a slightly longer screw since removing the current one will damage the existing 'threaded' concrete surface.
You might want to blow the hole with a turkey baster or something similar so aid the sealant application.
What kind of drill do they recommend for driving in the fasteners? Regular drill or impact driver?
Still not understanding this setup
How larger an area you you talking about?
Seeing you are removing the screws what would happen if you lifted the ply then coated the concrete with that sealer, it will go down the holes as you are forcing it with a trowel. Maybe an hour to cover the slab instead of filling each individual hole?
If you are going to glue the floor what are you actually going to glue to?
Jon - the area is 3,000 sf give or take. I was going to remove all the tapson screws, remove the plywood subfloor and Delta FL dimple board. Basically remove everything off the concrete. Then I was going to refill all the pre-drilled holes. In terms of the new floor, I would glue the plywood straight onto the concrete. The engineered hardwood would then be both nailed and glued onto the plywood.
But now here's the new wrinkle. My GC is telling me its perfectly ok to do what he did. He said he would scope all my pipes to make sure nothing was punctured while pre-drilling and would bring in an engineer to set my mind at ease that there will be no issues with the puncturing of the bottom slab. He is refusing to remove the screws and plug the holes. As I see it I have 2 options (1) Have him check the pipes and have a 3rd party engineer sign off that all is good. Also have my GC sign a guarantee that should anything go wrong, I have recourse against his company (the company has been around for a number of years), or (2) Fire them and holdback the amount owed for the subfloor. What are your thoughts on this?
But now here's the new wrinkle. My GC is telling me its perfectly ok to do what he did. He said he would scope all my pipes to make sure nothing was punctured while pre-drilling and would bring in an engineer to set my mind at ease that there will be no issues with the puncturing of the bottom slab. He is refusing to remove the screws and plug the holes. As I see it I have 2 options (1) Have him check the pipes and have a 3rd party engineer sign off that all is good. Also have my GC sign a guarantee that should anything go wrong, I have recourse against his company (the company has been around for a number of years), or (2) Fire them and holdback the amount owed for the subfloor. What are your thoughts on this?
Well, you know from what Tapcon told you that they didn't do it right. Do you really trust them to do anything else?
I'll go through these one at a time.
If nothing was punctured, he's probably right about that from what you describe. I'm guessing now, but like I mentioned earlier he probably didn't puncture anything unless he used 5 to 10 inch long drill bits and ran them to their full depth.
The Tapcon people said he didn't do it right even if there were no punctures in the pipes. So his method may be perfectly OK even tho that his method wasn't what is recommended. What was the real damage by using his method? I don't know. Most probably none.
The water/moisture presence in the slab will become the same from the top to the bottom of the slab one the membrane is layed down. Before that, it was drier on the top (lived in space)
OK, so now there are holes that go all the way through. The water/moisture presence in the slab can't be any different with 2" holes than 4" holes that go all the way through to dirt.
Now if there is so much water under the slab it's like poking holes in a boat you might be more concerned. I don't think you have that or you would have had water on the slab surface before this project began.
The contractor needs to know what fastener length and diameter is required for this particular use. I think he went overboard on length because he wanted a little overkill. I suppose he should have called Tapcon and asked about the ideal screw shank diameter and screw length for this sort of situation. Most contractors shoot from the hip I think.
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