I plan on building a detached double garage next year. I'm trying to educate myself on the process and have a few questions.

A little info on what I'm planing. The garage will probablly be 28X30 with a storage loft. I have an existing garage (work shop) that's 16X26 and would like to build the new one attached to the front of this one. Existing shop has poored footings (on ground) with 2X8 planks for a floor.

Now for the questions: 1. Who do I seek out (professional) to first design this garage and to tell me if they can be attached or not. Would that be an architect or an engineer...who does what.

2. In my area, garages bigger than 525 sq.ft. need an engineered slab. What does this mean and who do I see about this?

3. Would I be abled to poor a floor in the existing shop?

I know I'll have to talk to the city for permits and could get info from them but I just want to be a little prepared so I'll know what to ask them.

Thanks for any info you might have.

Dean

A competent architect would be a good choice to design your garage. You're talking about some long spans, especially with storage above, and joists, gorders, columns, headers and foundation must all be carefully designed. If an "engineered slab" is required, I suspect you're in a region which has expansive soils, usually clays. Otherwise, a simple slab on ground would be sufficient. Your architect may be qualified to design such a floor, or he or she may choose to retain a consulting structural engineer for it.

So what does "engineered" slab mean....is it still a slab on grade but different thickness or amount of steel/re-enforcing or does it require footings below the frost line?

In your opinion, is it possible to span 28' with no center support and have storage above? I'm I talking a lot more money for this, would be better with a narrower span 24'? or doesn't make much difference.

It doesn't make much difference whether the span is 28 feet or 24 feet; either will involve some very careful design of all components, not just the joists. Unit loads on the foundations may be high, and loads on headers over the entrance doors will be large. There may be concentrated loads which require special foundation and footing arrangements. There are a few alternative designs which should be explored. Many codes require very heavy design floor loads for "storage" spaces, several times higher than for normal residential floors. The issue of fire separation needs to be addressed.

If the reason for the "engineered slab" is expansive soils, then the slab has to be engineered to resist uplift. or worse yet, uplift in one area but not another. If there are unstable soils, then the slab needs to be structural, probably with intermediate supports. Also, a large slab such as that may need to have control joints and/or expansion joints. Control of water on the slab may be another issue.

Architecture may look easy, but that's because someone has done their work. When that work isn't done correctly, or not at all, it won't look so easy.

Thanks Richard, I have a better idea now...will now what questions to ask when I look into this. I do plan on getting expert help (architect). I just wanted a little background when I start calling around.

Dean