Make Your Home Healthier & Energy Efficient

Frequently Asked Questions


Does my crawl space have mold?

Yes! Mold is found on absolutely every surface.

However, the question should be: “Does my crawl space have higher mold levels than what is found in the outside air?”

When checking for mold, 10 minute air samples need to be compared to the same outside, which is considered to be the baseline. A visual inspection is also possible, but not as conclusive.

My sewer backed up in the crawl space. Will concrete help?


Consider that if a sewer backs up in a dirt or gravel crawl space it is impossible to effectively clean it. Even removal of the gravel or dirt will still leave residual contaminants. Sealing the crawl space with a vapor barrier and laying a 4″ concrete slab floor will result in no more sewage!

Won’t I have water seepage and water standing on the crawl space?


To ensure a dry floor, the following must be done. . . preliminary waterproofing, (such as perimeter drain site, sump pump or foundation crack injection), and installation of a plastic vapor barrier between the ground and concrete.

Is it messy?

Your home will be left as clean as when we started. Runners and plastic are laid down to protect your floors. Concrete is delivered to the crawl space via “small line” (4″ flexible rubber hose). A concrete ready mix truck delivers the concrete to us on the street and we pump from the street through a variety of opening into the crawl space and without any damage to your driveway, landscaping or home interior.

We don’t have an outside vent. How do you access the crawl space with the concrete hose?

There are many possibilities, some of which include windows, doors, heat registers directly above the crawl space, and even dryer vent openings. Crawlspaces adjacent to the garage can be accessed by cutting a clean hole at step height through the sill and directly into the crawl space. 

I have foundation cracks. What should I do?

Most foundation cracks are a result of concrete shrinkage while the foundation is drying during construction.

Sometimes cracks occur from settling, and usually happen within the first three years of the home. Horizontal cracks may need structural repair, but most cracks are vertical and do not affect the compressive strength of the foundation. However, cracks on outside walls are subject to water seepage and should be repaired. Urethane grout injections are the best type of repair in a crawl space because crawl space cracks tend to be larger and also move. Urethane is an expanding flexible repair suitable for these characteristics. 

How does concrete solve radon?

The concrete itself does not seal off radon as it can still penetrate though this porous material. Visquene (plastic sheeting) does stop radon and is used on every job as a vapor barrier and a radon system, stopping nearly 98% of the radon from entering into this area. 

Some of my friends have concrete crawl spaces with water seepage problems. How do you offer such a great warranty?

There are many examples of poor concrete work in crawl spaces. There are no set guidelines to follow and builders have often just poured concrete over dirt to help with the sale of a home but over time outside draintile systems fail and water begins to show up on the concrete. Our drainage system is installed next to the footings in advance and will intercept the water and provide a passage way directly to the sump pit to be pumped outside. Foundations cracks are also injected to stop water seepage.

Does concrete stop mice and rats from entering the home?

These rodents are burrowing animals and they often enter the home under footings and into the crawl space. A concrete floor is an impenetrable barricade.

If I have mold, what do I do?

Mold requires a food source, such as wood or cellulose, and water to grow. You can’t remove the wood from your house but you can control the humidity levels. Most mold cases in crawl spaces are because the exposed dirt is moist and humidity levels are high. Before trying to clean up existing mold, you must remove the humidity. Our concrete solution effectively dries the area concerned and will allow cleaning of the mold to begin. Small amounts of mold can be wiped clean with a damp cloth, whereas large contaminations require professional help.

Does a vent to the outside contribute to mold growth?

An outside air vent will allow high humidity levels in the summer months to enter the crawl space. This humidity can condense on cold water supply lines and the ductwork of your air conditioning system. Once this occurs, the basic ingredients for mold exists, water and wood, and mold spores can grow and reproduce.

Can I use my concrete crawl space for storage?

We consider an ABC concrete floor system a mini basement. Use your crawl spaces for storage as you would a basement. 

How soon can I use my concrete crawl space for storage?

We recommend three weeks, as there will be some residual water content emitted as the concrete cures.

We have plastic down and still experience bad smells emanating from that area. Will concrete help?

This is a very common complaint from our homeowner clientele. Some people try many products to control bad smells, including lime, charcoal, and even bleach. Plastic covers, due to their inherent leaking, sometimes aggravate the situation by keeping the ground humid and intensifying the smell. Our concrete floor system will totally encapsulate the ground and permanently eliminate the foul air from that area.

My crawl space has vents to the outside; doesn’t that let in cold air in the winter and hot/humid air in the summer?

Venting crawl spaces is an old idea that has become the standard for the entire country.

Unfortunately, venting can actually cause more damage than good. Humidity levels in the summer are extreme and when they enter the crawl space, water will condensate on air conditioning ductwork and cold water lines. This condensation will cause corrosion on the air ducts and expose the wood floors and joists to water. Mold has a much better chance to grow when these conditions exist.

Winter months are much drier, but open vents will cause the living areas, particularly tile and wooden floors, to become especially cold.

Our recommendation, once a concrete floor has been installed, is to seal off outside venting and open the forced air system of your HVAC heating system. This will provide air flow and drier conditioned air in the summer, and warm air in the winter which will subsequently rise through the floors to provide a warmer living environment. You will save money in the long run from having to battle the temperature extremes in the crawl space caused from the venting.

Why do I have an exposed crawl?

The house was built like this because building codes allow exposed crawls. It would have been a substantial savings for the builder at the time. The building codes are from the 40s and very little thought or effort has been put into the crawl space dilemma. Our firm is working with researchers and other professionals to rectify the oversight.

I’m thinking of turning my crawl into a basement; is that possible?


There are problems associated with this procedure, however. One is the expense. Reputable companies doing this type of work quote prices anywhere from $60 to $100 per square foot. That doesn’t include finishing the basement. The second problem is that a serious waterproofing situation could be created from the improper join of the original footing and the new foundation. Even knee footers can create unstoppable water problems. Our recommendation is to build a nice living space as a vertical addition or build out. Create a space you can enjoy. 

If I ever need structural supports, can I place them on the concrete floor?

We can add depth to the areas needing support and add rebar to strengthen the concrete for the additional load. Metal screw jacks are often used for support posts.

My crawl space is gravel and dry; why should I be concerned?

A. Even a gravel crawl space will increase the humidity of the air. Remember that a crawl space is just a hole in the ground and water will be attracted to that area. Gravel works well as a cover-up and to hide this condition. Gravel will also add a tremendous amount of dust in your house, especially if you have a forced air heating system. 

What is causing the corrosion on my HVAC system in my crawl space?

A. Water condensing on A/C ductwork during the humid summer months will cause corrosion.

What is the best time of year to do this type of work?

A. Because a crawl space is indoors and more or less a conditioned air space, our crews can effectively work year round. The concrete has an ideal curing situation in a crawl space. Winter weather presents challenges with outside cleanup because of freezing water, but we can pour concrete and apply sprayfoam in any weather conditions.

This review is long overdue. After looking at other companies, Nu-Crawl was who we chose. If you do your research, you'll understand why. What was once a disaster of a place is now somewhere you don't mind going into to for extra storage. What I find unbelievable is with the recent negative 24 degrees we experienced in the Chicago area, the crawlspace feels warmer than the 69 degrees I have my furnace thermostat set at. Sooooo glad we went with Greg and his crew and product.

- Karen Munthe

Great company, Great system, Great people. If you want the best these guys are it. Do some homework and you'll see. Thanks for great job on the crawl space.

- Kevin Wilson

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Phone: 630-561-5200 
Address: 502 Stratford Ave
Elmhurst IL 60126