Crumbling Concrete Foundation | This poured concrete foundation is looking shabby. Believe it or not, you can make it look gorgeous again with minimal effort and tools. Copyright 2020 Tim Carter

Crumbling Concrete Foundation - Easy DIY Repair

QUESTION: Hey Tim. I watched your three-part video series on patching a concrete foundation on your website. It’s exactly what I needed to help me repair the cosmetic crumbling of my concrete. I’ve got questions. Will that method work to also patch defects in steps and flat concrete sidewalks and driveways? I have a 4-inch-diameter hole in the foundation that needs to be filled. What’s the best way to do this, just pack in some of that cement stucco you show how to mix up? Do you have any other secret tips to share? Casey S., Antigo, WI

Wouldn’t you love to have a nickel for every person that needs to patch concrete? Oh my, that would be so many nickels! There’s a better-than-average chance that you might have some concrete at your home that needs some attention. Great news! I’m about to share how you can achieve pro results with very little work and cost.

How do You Repair a Crumbling Foundation?

I recorded the three videos that Casey mentioned about six years ago. It was pouring rain but we had to shoot that day. Fortunately, I was under a covered porch and could demonstrate exactly what to do. The first video in the series is below. Links to the other videos are shown.

Here are links to all of the videos in this series:
How to Repair a Crumbling Foundation Part 1 of 3
How to Repair a Crumbling Foundation Part 2 of 3
How to Repair a Crumbling Foundation Part 3 of 3

What Tools are needed?

The first step in a concrete repair is to remove any loose concrete and get rid of all dust. You can use a chisel and a hammer or if you have lots to do, consider renting a rotary-hammer tool that has a chisel tip. These power tools can do a remarkable amount of work in a short time. I like to use a garden hose and scrub brush to clean away all dust and loose particles of sand.

Why do Concrete Patches fail?

The next step I would have never known about had it not been for a generous old concrete craftsman that shared a few of his trade secrets with me forty-five years ago. This mason saw me trying to do a small repair job and stopped to talk to me. He could tell I was about to make a mistake, one that perhaps you’ve made and a great many others.

He explained why most concrete patches fail. There are so many reasons, but the biggest one is a lack of bonding between the old concrete and the new material. This gentleman shared tales about him being a young apprentice. It was fascinating.

He was born and raised in Cincinnati, Ohio as was I. Back when he was in his 20s, just about every new house that was built had concrete steps with a stunning sandy texture. The steps were actually stuccoed. You rarely see this technique today because it’s an extra step in the process.

This expert craftsman said they’d never pour a set of steps on a Friday because they wanted to apply the stucco no later than18 hours after pouring the steps. In hot weather, they’d often pour the steps in the morning and apply the stucco in the afternoon for optimal results.

What is the Proper Stucco Mix?

The stucco mix was just a blend of hydrated lime, Portland cement, and medium sand. He said they used 1.5 parts of Portland cement, 0.5 parts of hydrated lime, and 4 parts sand. Blend all this together dry and then add enough clean water to make a mix that resembles applesauce.

But the true secret to getting the stucco, or in your case the patching material, to bond to the old concrete is to apply cement paint just before you apply the patching material. Cement paint is just a mixture of Portland cement and clean water. You blend enough cement with the water to make it the consistency of latex paint.

Just before brushing on the cement paint to the old concrete, this master craftsman said to get the old concrete damp. You can use a sponge, a brush, or an old spray bottle. Remember, you want it damp, not soaking wet.

You then brush on the cement paint and immediately cover it with your stucco mix. Never allow the cement paint to dry. It must be covered immediately. You’ll discover you’ll not have to rush if you work in the shade or on an overcast day. Working in the direct sun on a hot day is too hard on the materials and you.

How do You Patch Larger Holes?

Patching larger holes is easy. You use the same process but find some rubble or small pieces of stone, brick or concrete to help pack the hole. Don’t try to fill large holes with just the stucco mixture. You want the rubble to be covered with the stucco mix so use rubber gloves if you want to do this by hand. Do what’s necessary so the hole has no voids in it. It needs to be completely filled with the rubble and the stucco patching material.

The old mason left me with one other very important tip. He said the patching material or stucco must be covered with burlap and kept wet for 48 hours. Back in his day, that’s all they had to slow down evaporation. You can use 4 or 6-mil plastic sheets, but be sure you weigh it down so it doesn’t blow away and so the wind can’t get under the plastic.

The plastic allows the patching material to get much harder and create a bond with the old concrete that will last for many decades. I’ve driven by concrete I patched in the mid-1970s using this method in the past year and it still looks perfect.

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Replace a Foundation | This house is being restored and a new foundation is on the to-do list. Copyright 2020 Tim Carter

Replace A Foundation - Just Lift Up the House

QUESTION: I’m thinking of buying a house that has a crawlspace. The foundation is in very bad shape. While the house looks quite bad, it’s got good bones. Is it possible to completely remove a bad foundation and install a new taller one? What’s involved? Who does this type of work? What would you make sure gets done if you’re going to all this work? Hanna S., Hartford, CT

Hanna needs to negotiate a really good deal on this dilapidated house. The good news is the old foundation can be removed and replaced with a new cast-concrete foundation creating a full basement. The task is not much different than eating an elephant. You just take one bite at a time.

Moving an Entire Neighborhood of Houses

Hanna’s question reminded me of a fascinating time early in my building career. Fresh out of college, I had just rehabbed my first house in Cincinnati, Ohio. It didn’t need a new foundation, but it was otherwise in pretty bad shape. Four months of work transformed the house back into its former glory.

About a half-mile away, a developer wanted to put in a small shopping mall, but there were about ten houses and an apartment building in the way. Not only did he buy all these properties, but he proceeded to move them about a mile away on some wooded land he purchased at the end of a street. I remember watching these houses, and parts of houses that were cut in half, creeping down the road to their new foundations.

Hanna needs to contact different foundation contractors to see which ones have done exactly what she wants to do. Not all foundation contractors have the expertise to work underneath a house that’s suspended above the work site sitting on cribbing made with timbers the size of railroad ties.

These foundation contractors will also know the names of the different house-moving companies in the area. The first step in the process of tearing out the old foundation and installing the new one is to prepare the house as if it’s going to be moved to a new location. House-moving companies do this like you might brush your teeth. It’s just another job for them.

Lift the House High Enough

I’d consider several things if this were my job. For starters, I’d want to make sure the house was lifted high enough so there was positive drainage away from all sides of the house. The building code’s minimum standard is 6 inches of fall in the ground in the first 10 feet of horizontal distance away from the foundation. I feel 12 inches of fall is much better.

Create a True Full-Height Basement

If the budget allows, I’d also try to pour the new foundation walls as high as possible so a true 8-foot ceiling height might be achieved in the basement. Hanna needs to make sure a great high-performance vapor barrier is installed under the new basement concrete floor.

To lift an entire floor, you'll have to jack up floor joists. Pros do this by sliding large I-beams under the joists so all the joists go up at the same time and same rate.

Install a Radon-Capture System

I’d also install interconnected perforated 4-inch pipes beneath the new basement slab to capture radon gas that might be seeping up from the local bedrock. A riser pipe that connects to the below-slab pipes should then be extended up to the roof to vent the radon.

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