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smccull493 07-09-2008 07:07 PM

Help fixing a concrete step
I am trying to fix a single concrete step to my front porch. Over the winter it basically disintegrated all around the edges & was unsafe, so I took a sledgehammer to it & broke away all the concrete I could. I don't want to use a jackhammer to break it all away because our asphalt driveway was poured around it & I'm afraid of doing more damage than I can repair myself & am on a limited budget.

I am a complete novice with anything like this so I am looking for some place that might give step by step instructions.

From surfing the internet I've learned that I can probably poor new concrete over the old stub, but have to use a bonding agent of some kind - is there a brand name I can look for that's best?

I can build a form from 2 x 4s, but are there any tricks to this, other than just getting them the right size and shape? Do you put anything between the form and the concrete before you pour it so that it will come off when dry?

Will the concrete in the bags at the home improvement store work for this? Is there anything specific to look for when buying?

How do you make it level and smooth on top?

Thanks in advance for any help.


Termite 07-09-2008 09:13 PM

That's a big project to tackle if you haven't ever worked with concrete. I'll try to help...

You can pour concrete over the parts you removed, but consider it a band-aid fix that won't last for a number of years. The best course of action would be to totally remove the bad stairs and pour new ones in their place. You'd be doing some more demolition, but essentially new stairs would entail the same processes as capping the damaged stairs.

Ok, capping...

First, prep the old concrete. You need to plan to pour no less than 1-1/2 or 2" of new concrete on all surfaces, so break out enough of the old stuff to accomodate that. If you pour the new layer very thin, it won't be as strong. Getting the new concrete to bond to the old is a challenge. You can use bonding agent to help, but be sure to start with very clean old concrete.

You can use bag mix from the hardware store. There are also topping mixes that are made for this sort of application. They cost more, but might be more effective.

Mix the concrete to a consistency somewhere between peanut butter and honey. You want it wet enough to be workable, but too much water will yield very weak concrete.

Build SOLID formwork around your stairs in the shape of each step. You'll have to form the sides and the risers, but the tops must remain open. Remember that wet concrete weights about 130-140 pounds per cubic foot, so you must make the forms solid enough to resist the outward forces that the concrete will excert. Be sure to use some sort of oil to facilitate release of the forms when you're done....The sell form release agent, but you could get by with vegetable oil or Pam sprayed on if you aren't doing too much.

When you place the concrete in the forms, rap on the side of the forms and use a rod of some sort in a plunging motion to help consolidate the concrete at the edges so you don't have air pockets (especially visible ones).

Use a float (like a trowel but thicker with softer edges) to get the top of the concrete very close to the finished level. Add more where you need it and take some off where you need it. A piece of wood sitting on the tops of the forms can act as a screed if you go over the surface in a sawing motion with short strokes. Use your float to get the finish pretty close to where you want it. At this stage you really should let the concrete sit for a while, but you're not experienced, so I'd say just finish it right away. You can use a push broom dragged gently over the surface backwards to create a non-skid surface. Last, use a concrete edge tool to form a rounded edge on the treads and landings as necessary.

Do your homework at a bookstore (at least) before tackling this. Also, have help present. You'll need someone mixing and at least one person placing and consolidating the concrete.

Termite 07-09-2008 09:16 PM

Also, remember that your stairs must be dimensionally consistent in rise and run. Code requires no more than 7-3/4" rise, and no less than 10" run. No tread can differ in any measurement from any other tread more than 3/8".

smccull493 07-09-2008 09:46 PM

Wow, I had no idea this was so complex. Before I attempt it myself I think I will call around for estimates. Thanks so much for the answers to my questions!

4just1don 07-09-2008 10:03 PM

ONE way would be precast steps from the local redimix plant. Easy to handle for a couple people,they are pretty,consistant rise and run etc. ALL you have to do is measure and put them on level to 'slightly' tilted from house surface!!

And about as cheap as buying forms and crete IF your carrying it home in barrels in a pickup(thats how its done here),,,small projects, they have barrels at redimix plant and you buy as many as you need. plus its messy,and did I say heavy??

Sometimes you can get a blem or second for a real good price,,,used to anyway!!

Other way,which I didnt like too well was stacking blocks for a 'one step' back door deal,and surewalling them together,slushing the centers,,,they look ugly after a few years,,,but they work well!!

Termite 07-10-2008 08:01 AM


Originally Posted by smccull493 (Post 137680)
Wow, I had no idea this was so complex. Before I attempt it myself I think I will call around for estimates. Thanks so much for the answers to my questions!

I wasn't trying to scare you off!!! :no: You probably wouldn't regret having a pro look at it though. Precast could be a good option too.

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