I built mine myself, brick by brick, it took me 5 years. I had to dig the foundations out twice, as after the first dig, there was a heavy down pour of rain and they collapsed in! Within a year of finishing my '4 cars at a squeeze' block, complete with ceiling mounted engine hoist, I went and bought another four garages (already built!)! So, I'd say double is very true! My doors are 7'x7'...got to get it straight reversing in! In these new garages I'm in the process of installing a two post ramp. I was unable to raise my roof, the planning council wouldn't allow it. So I went down instead! To dig the huge pit, I had to cut up the concrete floor. Did this with my angle grinder, and covered all the neighbors cars parked outside their houses white, with the stone dust that blew away in the wind. Oops, I was not popular, and had to offer to wash a lot of 'boring' cars! Wouldn't you just love me as a neighbor!!