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Starting To Build -
Basement Or Crawl Space?

Part 7 Of Our Real Life Remodeling Journey

Publisher's Comments

The following story is part of a series of articles about my family's experience with our home's remodel. Links to the other stories are found at the bottom of the page.

With the remnants of the old family room cleared away it was time to start excavating for the new, larger family room. Once again the back yard became a heavy-equipment zone as a backhoe and skid steer dug a large hole adjacent to the rest of the house.

Ultimately we decided to go with a crawl space in lieu of a full basement so the excavation was only about 4 feet deep. Two of the three foundation walls from the old family room were used which saved a little on the cinder block work required.

A Crawl Space Or A Basement?

One of the questions we debated as part of this remodel plan was whether to go with a full basement under the expanded family room or a crawl space. There were pros and cons with each.

Building a full basement wasn't going to increase the overall project cost significantly from the standpoint of going a bit deeper with the hole. Estimates were about $5000 more than a crawl space to dig to the necessary depth and include the necessary block work for the higher (deeper) foundation.

However, those costs started to increase when you considered what it would take to actually complete the space. There would be requirements for an egress point so a door or egress window would be necessary. Then there was the issue of how to integrate the space with the existing basement that sat under the rest of the house. Accessing the area would require changes to the existing basement for a workable traffic pattern and usability standpoint.

Finally, there was the question of whether to finish the space and the additional cost for that. Sure, we could have left the space unfinished for some time and finished it up on our own some years down the road but in truth, the likelihood of that becoming a reality was slim. If we took the finish-it-later route, the space would have turned out to be just a big expensive storage area.

Ultimately we decided on a conditioned crawl space with a concrete floor. "Conditioned" means its insulated and benefits from some of the heat given off by the ducts that distribute the air to the room above it. In other words, it doesn't get real cold or real hot and stays within a small temperature band. It'll provide ample storage space and there's enough room to move around on hands and knees comfortably.

If you're faced with a similar decision, think hard about what it will really take to make the full basement a good living space. If the funds are available, go for it. Otherwise you might consider saving the money or applying it to the spaces above the basement level, spaces you might make more use of.

Seeing Tangible Results

The excavation of the crawl space didn't take long and it was time for the new block foundation to go in. The amazing part about that effort was that it only took 2 days to lay several courses of cinder block for the new family room and mudroom foundations, primarily by one talented mason. He flung the mortar onto each block and had it squarely in place faster than I could butter a piece of toast.

foundation for additionThe New Foundation Wall

The concrete floor of the crawl space came next. Since this wasn't a full basement the thickness of the concrete was paired down to about 2 to 3 inches thick which also helped trim some cost. It'll provide a nice surface for the new storage area. The old family room had a dirt crawl space and if you've ever had to crawl into one of those, you know that it isn't pleasant.

pouring concretePouring The Crawl Space Floor

Once the foundation was finished the crawl space "pit" had to be protected from the elements, lest it become our backyard swimming pool should the rains come (and they did). The area was tented off using the largest tarps I've ever seen (well-worn I might add). The resultant effect was a predominant blue hue in the rooms with a window adjoining the tented space.

house under tarpI'm Sure The Neighbors Liked This Look

house under tarpThe White House Has Nothing On Our 'Blue Room'

Spanning the new crawl space are some nifty engineered wood I-beams, designed to bridge the 18 foot gap between the original house foundation and the new family room foundation. I can imagine days of old when spans like this would probably require the use of solid old-growth Douglas Fir beams or something of that sort.

engineered I-beamsEngineered I-Beams


remodel additionThe I-Beams Going Into Place


remodel additionThe Finished Floor Structure

Sealing The Foundation

Before backfilling the crawl space a special sealant was used to waterproof the foundation. We used a Poly-Wall product which goes on like a heavy paint. I was glad to have it because the older basement foundation walls would occasionally seep after extremely heavy rains.

waterproofing foundationSealing The Foundation


crawl space vapor barrierPlastic Crawl Space Vapor Barrier Under The Concrete

Part of the plan also included a crawl space vapor barrier. This was a heavy plastic that was laid on top of the dirt upon which the concrete floor was poured. Ultimately the combination of the sealed foundation and vapor barrier should give us a relatively dry crawl space.

Next Up In This Series . . . Closing The Addition

The addition finally gets closed up with wall and a roof. But is it built per the plans?? An "oops" occurs and weather throws us a curve ball. Read part 8 here.



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