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How to repair the hole by/under the front concrete stairs?

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  • Apr 22nd, 2020 10:57 am
[OP]
Deal Fanatic
Feb 15, 2006
8836 posts
3307 upvotes
Toronto

How to repair the hole by/under the front concrete stairs?

We have an old semi-detached house. At the front stairs, there is a big hole underneath. At first there was some cracks at the side, which got bigger. At first we thought it might be a sinkhole that we should fill with some soil, or gravel or cement. But as the crack got bigger, we removed a cracked concrete piece. My daughter then put her cellphone in and took pics of the big empty space there.

I'm concerned about the strength of the stairs the way it is. Should we fill it with soil, gravel, or cement/concrete? It may take many bags. Or should we just put some cement/concrete at the side to fill the hole.
Images
  • stairs with hold.jpg
  • big hole looking from outside.jpg
  • Inside the hole big space.jpg
23 replies
[OP]
Deal Fanatic
Feb 15, 2006
8836 posts
3307 upvotes
Toronto
Anyone?
Member
Dec 30, 2013
294 posts
139 upvotes
Mississauga
You can tell it been patched before, looks like poor job on the cinder blocks from the inside pic, I wouldn't try to fill the space, just mix some concrete, put a piece of metal mesh and patch the hole for quick fix and to prevent animals, it will need to be redone properly eventually
[OP]
Deal Fanatic
Feb 15, 2006
8836 posts
3307 upvotes
Toronto
What would need to be redone properly, and when might that be? I didn't know there'd be so much space underneath the concrete stairs, so I'm concerned of the strength of the stairs, if only the side is patched to prevent animals going in.

If wanting to fill in the space/hole, what should be used?
Deal Addict
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Jan 2, 2012
3688 posts
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KINGSTON,ON
You definitely want to cover that up as quickly as possible. Raccoons will be nesting in there before you can blink, especially in Toronto.
The stairs aren't likely to collapse unless there are a whole section of blocks missing.
You don't need to fill the entire cavity, just the hole using a hydraulic mix. The tricky part is keeping the cement from falling into the cavity. Mix up small amounts of the cement and build it up slowly.
Deal Fanatic
Mar 21, 2002
6413 posts
1078 upvotes
Concrete stairs are typically hollow inside. Solid concrete stairs would be too expensive and too heavy. Buy a sack of high quality cement and then confine your efforts to patching that hole on the side.
[OP]
Deal Fanatic
Feb 15, 2006
8836 posts
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Toronto
Thanks. I did block the whole to prevent animals going in. We'll patch it up soon, with a mesh, and concrete mix. Yap, it'll be challenging to make sure the concrete patching doesn't fall into the hole.

Without this hole, we didn't know there'd be this empty space underneath the stairs. Don't know why the builders (house was built in 1958) didn't just fill it up.
Deal Fanatic
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Oct 16, 2008
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Maple
Arrgh wrote: Thanks. I did block the whole to prevent animals going in. We'll patch it up soon, with a mesh, and concrete mix. Yap, it'll be challenging to make sure the concrete patching doesn't fall into the hole.

Without this hole, we didn't know there'd be this empty space underneath the stairs. Don't know why the builders (house was built in 1958) didn't just fill it up.
Finer mesh may help to hold cement.
Temp. Banned
Dec 18, 2009
1710 posts
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Toronto
Arrgh wrote: At first we thought it might be a sinkhole that we should fill with some soil, or gravel or cement.
Hi OP, take a lesson from somebody who made a similar mistake when I was younger and stupider. I once thought I had a sinkhole in my from yard and filled it back up with soil. Turned out my sewer line had collapsed and one of the worst weeks of my life ensued.

This isn't Florida, if you have a "sinkhole" consider its location and if it is near water or any sort, you might have a bigger problem.
Jr. Member
Sep 21, 2004
125 posts
79 upvotes
North Vancouver, BC
hoponpop wrote: Hi OP, take a lesson from somebody who made a similar mistake when I was younger and stupider. I once thought I had a sinkhole in my from yard and filled it back up with soil. Turned out my sewer line had collapsed and one of the worst weeks of my life ensued.

This isn't Florida, if you have a "sinkhole" consider its location and if it is near water or any sort, you might have a bigger problem.
This is not a sinkhole. It's a crack in the side of stairs that got worse over time as water got in, probably froze and expanded and then eventually wore down. Patch it up as others have stated...

Stairs are not built as a solid piece - it would be terribly expensive and stupidly heavy! They are also not filled in with dirt underneath - it would get in the way of framing up form work for the stairs and again is not needed so would be a waste of money and effort.
I tried to find a picture of a pre-cast set of stairs (framed stairs on sites is the same thing) but oddly hard to find a picture of the backside!
Stairs.png
[OP]
Deal Fanatic
Feb 15, 2006
8836 posts
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Toronto
BouncyBall wrote: This is not a sinkhole. It's a crack in the side of stairs that got worse over time as water got in, probably froze and expanded and then eventually wore down. Patch it up as others have stated...

Stairs are not built as a solid piece - it would be terribly expensive and stupidly heavy! They are also not filled in with dirt underneath - it would get in the way of framing up form work for the stairs and again is not needed so would be a waste of money and effort.
I tried to find a picture of a pre-cast set of stairs (framed stairs on sites is the same thing) but oddly hard to find a picture of the backside!
Stairs.png
Thanks hoponpop and BouncyBall. That really helps.

It looks like the wall thickness at the side of the stairs isn't very thick. That's what lead to my worry that the hold might need to be filled. But your explanation makes a lot of sense.

I bought the cement mix. Will try to patch it up soon.
Deal Addict
May 18, 2015
1623 posts
617 upvotes
Ottawa,Ont
Arrgh wrote: We have an old semi-detached house. At the front stairs, there is a big hole underneath. At first there was some cracks at the side, which got bigger. At first we thought it might be a sinkhole that we should fill with some soil, or gravel or cement. But as the crack got bigger, we removed a cracked concrete piece. My daughter then put her cellphone in and took pics of the big empty space there.

I'm concerned about the strength of the stairs the way it is. Should we fill it with soil, gravel, or cement/concrete? It may take many bags. Or should we just put some cement/concrete at the side to fill the hole.
If you dont mind the side of the stairs being 2" wider or so in that spot, I could explain a way for you to repair it better
[OP]
Deal Fanatic
Feb 15, 2006
8836 posts
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Toronto
nikels21 wrote: If you dont mind the side of the stairs being 2" wider or so in that spot, I could explain a way for you to repair it better
Thanks, please.
Deal Fanatic
Dec 5, 2009
5681 posts
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What am I looking at in that 3rd photo? Does the hole go into your cold cellar?
[OP]
Deal Fanatic
Feb 15, 2006
8836 posts
3307 upvotes
Toronto
fdl wrote: What am I looking at in that 3rd photo? Does the hole go into your cold cellar?
It's all on the outside. It's the hole or empty space under the concrete stairs. My daughter stuck her cellphone inside that hold to take that picture.

The stairs go up to a porch enclosure just before the front door.
Deal Addict
May 18, 2015
1623 posts
617 upvotes
Ottawa,Ont
Arrgh wrote: Thanks, please.
Take a piece of plywood large enough to cover the hole from the inside, looks like maybe 12” x 24”. Drill two holes in it and put a long bolt or threaded rod in each hole. Now rotate it so you can slide it underneath the stairs through the hole. Then pull it tight, so now the hole is blocked from the inside. Now you need to build another form that is the same size for the outside. Also with two holes for the bolts to go through. Now tighten the bolts so you have just 2” of opening between the piece of wood and the old concrete. Now cut two pieces that are just 2” wide to close that gap. Attach them and then tighten the bolts/threaded rod. Now just pour non-shrink grout in the 2” gap until the forms are full. Wait 4 days and remove your forms and then cut the bolts flush. The attached picture is a top view of it.
Images
  • DEE58316-7381-4E70-A4C2-ECAF8183D808.jpeg
[OP]
Deal Fanatic
Feb 15, 2006
8836 posts
3307 upvotes
Toronto
nikels21 wrote: Take a piece of plywood large enough to cover the hole from the inside, looks like maybe 12” x 24”. Drill two holes in it and put a long bolt or threaded rod in each hole. Now rotate it so you can slide it underneath the stairs through the hole. Then pull it tight, so now the hole is blocked from the inside. Now you need to build another form that is the same size for the outside. Also with two holes for the bolts to go through. Now tighten the bolts so you have just 2” of opening between the piece of wood and the old concrete. Now cut two pieces that are just 2” wide to close that gap. Attach them and then tighten the bolts/threaded rod. Now just pour non-shrink grout in the 2” gap until the forms are full. Wait 4 days and remove your forms and then cut the bolts flush. The attached picture is a top view of it.
The hole is not quite that big (12"x24"), but I see what you mean. A piece of plywood wide enough to go in, but can be longer, and have the plywood tight against the hole to prevent concrete from falling in.
Newbie
Jan 2, 2014
24 posts
5 upvotes
Toronto
Looks like water damage slowly degraded the block or original poured cement .

You can use tile mesh and some cement to fix . If you have a grinder you can clean it up a little better and cement it flush .
Deal Addict
May 18, 2015
1623 posts
617 upvotes
Ottawa,Ont
Arrgh wrote: The hole is not quite that big (12"x24"), but I see what you mean. A piece of plywood wide enough to go in, but can be longer, and have the plywood tight against the hole to prevent concrete from falling in.
Yup! Exactly
Deal Guru
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Mar 13, 2004
11299 posts
3037 upvotes
Toronto, Ontario
Another option would be to cut a concrete block to size and cement it in there good. let it fully dry over a few days & then put a water proofing rubber sealant on maybe the bottom half of that wall to help protect it from water damage. Or do fully concrete as mention above & still put the rubber coating on the outside to help protect it from water/water
0_o
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