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How to Seal a Chicago Crawl Space: Concrete Floor or Encapsulation Liner

Apr 6, 2014 • By Matthew Stock.

Crawl Space

Homeowners are called upon to make lots of decisions about their homes:  What color to paint the bathroom?  Put in new windows this year or next?  Carpet or hardwood on the living room floor?

Naturally, some of these decisions are easier to make than others and some require making up one’s mind about a sequence of things.  For example, many homeowners with crawl spaces below their homes often must decide whether to leave the crawl space as is, a damp, dark and unusable cave, or to seal their Chicago crawl space and turn it into dry, bright (and much-needed) storage space.

That’s usually not a tough decision because most people don’t want the humidity and potential for mold and insects that a raw crawl space promises and who can’t use more storage space around the house?

Once that decision is made, however, the tough decision arises:  Put in a concrete floor or encapsulate the crawl space?

Either is a great approach but are there advantages to one over the other?

Seal a Chicago Crawl Space – Concrete Floor or Encapsulation

Both encapsulating a crawl space and installing a concrete floor will have the desirable result of a dry, stable crawl space that can be used for storage but there are significant differences:

Concrete Floor – To install a concrete crawl space floor, the crawl space must be cleaned and leveled as much as possible. Then, a heavy plastic vapor barrier is laid down and concrete is pumped in through a window or other opening to a thickness of 2 -3 inches.  The floor is leveled to a “rough float” finish and allowed to cure.

The main advantage of a concrete floor is that it is a hard, solid surface that is immune to punctures and most other damage that might occur in a constricted crawl space.  Concrete also forms a seamless covering over the floor with no formed openings for water leakage.

Concrete has its disadvantages, too.  Although a poured concrete floor may be seamless, the concrete itself is porous and can allow seepage in the crawl space if the plastic underlayment is breached.  Also, pouring a big slab of concrete in the crawl space and allowing it to cure properly will induce a significant amount of humidity into the home.  Finally, pouring concrete is expensive and can be messy.

Crawl Space Encapsulation – Encapsulating a crawl space is begun by leveling the surface of the crawl space and laying down a pad of insulating material.  A 12 -20 millimeter polyethylene liner is then laid over the insulating material to cover the floor.

Sheets of semi-rigid insulation are then applied to the walls of the crawl space and sealed to the floor liner and to the building walls at the top.

When complete, crawl space encapsulation creates a bright white space that is dry and stable and can be used for storage.  Unlike a concrete floor, it also covers and seals the walls and, although all seams must be sealed the material itself is completely impervious to water.

Of course, before either approach is taken, basement waterproofing applications such as interior drain tile can be installed to control ground water and hydrostatic pressure.

So, if your crawl space is dark and dingy and occasionally used belongings are piling up because of lack of storage, it is probably time to seal your crawl space either by installing a concrete floor or by encapsulation.  All you need is three feet of height to give an installer room to work.

Oh, and you’ll need an expert basement waterproofing contractor to recommend and install the best solution.  At U.S. Waterproofing, we’ve helped thousands of Chicagoland homeowners make their crawl spaces dry and usable and we can do the same for you.  Why not ask for our free advice?

Tags: seal chicago crawl space, seal crawl spce

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