DIY Home Improvement Forum banner
1 - 20 of 23 Posts

·
Registered
Joined
·
5,159 Posts

·
Registered
Joined
·
960 Posts
Discussion Starter · #3 ·

·
Registered
Joined
·
5,159 Posts
It looks like the slab has settled in that corner by as much as 1.5". Water getting under the slab may accelerate the process of settling. water may enter there and find a path to your basement. It does look like the foundation was sealed but cracks may develop.


If it continues to settle eventually water will collect there.



If it was mine and I was not planning on replacement I would dig all that crap out, pipe in some mortar to fill the bulk of the void and then caulk what is left.
 

·
Registered
Joined
·
960 Posts
Discussion Starter · #5 · (Edited)
It looks like the slab has settled in that corner by as much as 1.5". Water getting under the slab may accelerate the process of settling. water may enter there and find a path to your basement. It does look like the foundation was sealed but cracks may develop.


If it continues to settle eventually water will collect there.



If it was mine and I was not planning on replacement I would dig all that crap out, pipe in some mortar to fill the bulk of the void and then caulk what is left.
I just added a few photos. Not really, it has around 2 feet roof over it, and it has a little slope going outward.

It seems the slab goes down a lot, but from the other side, the slab does not appear to go down a lot, maybe it is just like this?

It is big gap, and it requires a lot of sealant. Can I use "Pre-Caulking Filler Rope Backer Rod Roll" instead of filling in mortor?

Thanks.
 

·
Registered
Joined
·
3,205 Posts
I would just interject that there are probably better sealants than the Dap product.

Cleaning out the old is always advisable. An oscillating multitool with a scraper blade works really well and is much more fun than a hammer and cold chisel.

The joint must be clean and free of dirt. If there is a gap below (bottomless crack) and you have the room, you should fill the joint with a foam backer rod. This helps ensure the joint can flex and is only adhered to 2 surfaces.

I would recommend Loctite SL10 or SL20 depending on whether or not the surface is level (where you can use self levelling sealant) or not. Sikaflex also makes good concrete sealants as does Sonneborn / BASF. (NP1).
 

·
Registered
Joined
·
960 Posts
Discussion Starter · #9 · (Edited)
I would just interject that there are probably better sealants than the Dap product.

Cleaning out the old is always advisable. An oscillating multitool with a scraper blade works really well and is much more fun than a hammer and cold chisel.

The joint must be clean and free of dirt. If there is a gap below (bottomless crack) and you have the room, you should fill the joint with a foam backer rod. This helps ensure the joint can flex and is only adhered to 2 surfaces.

I would recommend Loctite SL10 or SL20 depending on whether or not the surface is level (where you can use self levelling sealant) or not. Sikaflex also makes good concrete sealants as does Sonneborn / BASF. (NP1).
From the photo, you can see it is not level, the sealant should go to the side (as attached photo). A big gap, not sure if sealant can hold.

What does self-leveling mean? Does it only work for horizontal gap?

https://www.amazon.com/SIKA-CORPORATION-91065-Sealant-10-Ounce/dp/B000RUKZSA/
 

Attachments

·
Registered
Joined
·
3,205 Posts
Yes, it only works with horizontal gaps. If the crack is on a slope, like where the sidewalk meets the house you can still use it, but you need to be very careful not to overfill the horizontal gap or it will run out and ooze down the slope.

The same could be said for cracks on a driveway for example. If it has too much slope, it will all run downhill just like water would. That makes a mess, so if you use self leveling you need to know its limitations.
 

·
Registered
Joined
·
960 Posts
Discussion Starter · #11 · (Edited)
Yes, it only works with horizontal gaps. If the crack is on a slope, like where the sidewalk meets the house you can still use it, but you need to be very careful not to overfill the horizontal gap or it will run out and ooze down the slope.

The same could be said for cracks on a driveway for example. If it has too much slope, it will all run downhill just like water would. That makes a mess, so if you use self leveling you need to know its limitations.
How fast can it run down? Can I use plastic scraper to push it back against wall? Or I use some news paper if it runs down. There are also so many different choices, which one is better: https://www.homedepot.com/s/Sikaflex?NCNI-5

How about this one: https://www.homedepot.com/p/Sikaflex-10-1-oz-Crack-Flex-Concrete-Sealant-7116110/300934565

Or another other good brand recommendation?

Thanks.
 

·
Registered
Joined
·
3,205 Posts
One thing I will add is that for large, lengthy cracks you might want to buy the bigger quart tubes, and the bigger quart caulking gun to go with it.

You will spend a fortune if you buy the little 10 oz. tubes.
 

·
Registered
Joined
·
960 Posts
Discussion Starter · #14 ·
It slowly oozes, like molasses. Best thing to use is clean silica sand, if you need to make a dam for it, you just sprinkle sand along the edges to contain it.

Sikaflex is a good trusted brand.
I don't know why you mention "sand", it is vertical gap, about 1" gap, we talk about using Pre-Caulking Filler Rope Backer Rod Roll and sealant only, what is the purpose of "sand" used here?

Thanks.
 

·
Registered
Joined
·
960 Posts
Discussion Starter · #15 ·
One thing I will add is that for large, lengthy cracks you might want to buy the bigger quart tubes, and the bigger quart caulking gun to go with it.

You will spend a fortune if you buy the little 10 oz. tubes.
Not really, only 4-5 feet with big gap, then using Rope Backer Rod Roll can save a lot of caulk, most part (along the wall) is small gap.
 

·
Registered
Joined
·
3,205 Posts
Post 10. Self leveling ONLY WORKS IN HORIZONTAL GAPS. That is what we were talking about, and that is where you would use sand... around the edges of a crack, anywhere you dont want self leveling to run... you use the sand to contain the sealant to the crack only.
 

·
Registered
Joined
·
960 Posts
Discussion Starter · #17 ·
Post 10. Self leveling ONLY WORKS IN HORIZONTAL GAPS. That is what we were talking about, and that is where you would use sand... around the edges of a crack, anywhere you dont want self leveling to run... you use the sand to contain the sealant to the crack only.
How about this one? When it dries, the surface is soft or hard? I prefer something soft (such as bathtub sealant). The current gray one in the photo is also soft.

Thanks.

https://www.homedepot.com/p/Sikaflex-10-1-oz-Crack-Flex-Concrete-Sealant-7116110/300934565
 

·
Registered
Joined
·
5,159 Posts
Simply said. Sand, foam or mortar are used to fill the bulk of the void and then you seal it with whatever caulk you buy.
 
1 - 20 of 23 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top