By: Otis Bradley
Project: Pacific Palisades, California – Finish Concrete Floors
Architecture: Elizabeth Stevenson
Builder: Otis Bradley Company, Inc.
Interior Design: Otis Bradley Company, Inc.
An extra $50,000 expense is not the way you want to start a job!
(See article on concrete caisons)
Many houses had been built in this neighborhood in the past 60 years – with no problems, but you just never know until you do the tests – drilling into the ground and finding out what you’ve got. Its amazing how soils conditions can be radically different over the distance of just a few feet. Geology is all about shifts, lifts, and millions of years of evolution. A hill, a ridge, a little valley can all be tell tale marks to the experienced eye – but often overlooked and sometimes can even fool the experts.
Because of the underground water that existed on this property, a massive foundation was called for by the structural engineer. In order to follow code, steel reinforced concrete caissons had to be sunk up to 40 feet into the ground.
Once the caissons were set, we had to place a grade beam on top of the caissons – this grade beam is essentially a 2 foot by 3 foot XXX steel reinforced concrete beam. This allows a structural concrete slab to rest on top of the grade beam – which will later be the foundation to a new home! The next time you drive into a multi story parking garage – look up at the posts and beams – typically they are built in this style. Although, on this project we were doing this in the ground – not in the air!
Typical parking garage below:
Because this massive slab of concrete was called for, why not make it the finish floors. Since all of this concrete was required by the engineering design, I decided to finish the concrete so the concrete could be the finish floors, saving cost from adding another floor like hardwood. At the time – this was an unusual idea.
I decided to form the concrete into large 5 x 5 squares to make the concrete look like giant tile. After “cutting” in the squares in the wet concrete – by hand troweling into a super smooth surface – the beautiful surface was later “stained” – colored with acid.
Finish concrete (see concrete floor video – click here) is an art. Scoring, coloring, and finishing can create either a beautiful material or an ugly mess. Like many processes in the building world, concrete installation is a science and an art.
Different scoring methods produce different results. Some installers (also typical in construction) insist that there is only “their way” to do it. Concrete coloring whether “stained,” integrally colored, or surface coated can produce drastically different results. Countless methods from “broom” to aggregate exposed to highly polished finishes will provide an endless number of options.
On this project we used acid staining, creating lovely color variations. However, you really don’t know exactly what you will get – so you better like the general idea and be willing to accept a lot of variation.
Tip – sometimes during a project you get hit with surprises – sometimes an opportunity to make it better!
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