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Block Foundations for Small Additions 1

Block Foundations for Small Additions 1

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    A jitterbug is used to give the footing an “alligator back,” which helps key the first course of block to the footing.

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    Before starting excavation, the author lays down sheets of plywood to protect the paver-stone patio.

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    He uses a plate compactor to prepare the soil underneath the footing.

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    While he rents excavating equipment for each job, he also owns a small dump truck.

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    An electric side-loading concrete mixer.

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    Footings are formed with 5/8-inch plywood.

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    They are held in place with 30-inch form pins driven in with a rotary hammer.

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    The concrete is reinforced with rebar held off the ground with chairs.

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    Short lengths of strapping screwed to the top of the plywood forms and backfill help strengthen the forms.

When I was starting out as a remodeler, some 25 years ago, I’d spend nights and weekends working on estimates for big projects I knew our company might not get — and many hours doing accounting and payroll when we did land one of those jobs. Over time, though, I realized I was happier with smaller projects, like kitchen and bath remodels and room additions, so I downsized the company. Running a smaller business means that I spend more time on site and less time in the office. At present, we’re a C corporation with three employees and an annual volume that ranges between $500,000 and $800,000.

Part of our strategy for remaining profitable has been to do as much of the work as we can in-house, including drywall, flooring, tile, and painting, as well as all rough and finish carpentry. This approach has not only helped us stay busy in the current slow market — it has also kept us on track when the market was hot and subs were more difficult to schedule for small jobs.

We even do our own masonry work — like the block foundation shown here. We added masonry to our skill set when Danny DoCouto joined the company 11 years ago. DoCouto trained as a union carpenter in all phases of commercial and residential construction, and had considerable masonry and excavating experience. He taught me to lay block, but mainly I act as tender, moving stone and block and mixing mortar. We don’t move as fast as full-time masons, but we make sure the quality of our work equals the quality we would get from any local masonry subcontractor.

Equipment and Tools

Four years ago, we grew tired of relying on local haulers and invested in a dump truck. At more than $40,000, a new diesel was out of our price range, but our local Hertz rental supply was selling a used Ford F-550 Super Duty 7.0-liter diesel truck with a 10-foot bed and 70,000 miles on it for less than half that price. After renting the truck for a week to try it out, we purchased it using a couple of business credit cards with zero percent financing.

We can now move gravel and fill whenever we need to, and can also tow whatever size machine we need to dig our holes. Sometimes we use the truck instead of a roll-off container, parking it in the driveway and hauling construction debris away to the transfer station when it fills up. For mixing mortar, we use a tow-behind-horsepower Stone electric mixer with a 5-cubic-foot capacity (800/888-9926, stone-equip.com). We were able to buy the mixer at a considerable discount online (about $1,100, including shipping) because it was a discontinued model with a bent wheel. It’s a medium-duty unit, well-suited for the volume of work we do, and portable enough that one man can pick up the end and wheel it around the site. We also bought a second-hand plate compactor from a local rental center, a jitterbug (used for pushing down coarse aggregate), a bull-float, various trowels, and a bunch of form pins.

In addition, we own a Bosch 11248EVS 1/16-inch rotary hammer, which is handy for setting form pins, and a Bosch Brute electric breaker hammer (877/267-2499, boschtools.com). For layout, we use both an optical transit and a CST/Berger LM800 series laser level (800/435-1859, cstberger.com). To store our equipment, we rent a 20-foot-by-20-foot locker and a portion of a storage yard that we share with a local landscaping company, at a combined cost of about $360 per month.

Excavating and Layout

It takes us about a week to block up the foundation for a small addition like the kitchen bump-out shown in this article. We start by taking steps to protect the landscaping as much as possible. On this job, we removed half of the paver patio that occupied our digging area, then covered the remaining half with plywood to protect it from damage. We work in an area with tight setbacks and not a lot of room to maneuver, so we often end up renting equipment that’s just big enough to get the job done. In this case, DoCouto dug the hole with a small Kubota tractor equipped with a backhoe, while I used the dump truck to dispose of the excess dirt at a nearby landscaping yard. For some jobs, we rent a 15-yard roll-off container and stockpile the dirt there (a $450 charge).

Footings

Unless the soil conditions are unusual, we usually form footings that are 12 inches deep and 24 inches wide. For form boards, we use 5/8-inch plywood ripped to width and secure the sides with form pins. We reinforce footings with parallel lengths of rebar, wired together every 20 inches with short lengths of rebar. To pass inspection, we use chairs to carry the rebar and always cap the form pins. It takes about a day to build the footing forms and set the rebar for a small addition and about an hour to place the concrete.

After screeding, we use a jitterbug to give the top of the footing what we call an “alligator back” — a little tooth for the first course of block to key into.