The first question would be, does the local regulating authority require special certification for such work? Some plumbing jobs must be done by pipefitters, etc.
OTOH, there may be vendors (online) who specialize in selling integrated systems to DIY-ers.
This seems like an onerous and punitive code. Would it be better to first seek legal advice to fight it. Can you get a waiver?
Casey

Thanks for your thoughts Casey -- I asked the same thing (about a waiver), but DH seems adament that it won't be a possibility, and it's too sore a subject right now to press. Our village is NOT very gererous with waivers, and we need to save our 'begging room' with the city for a hoped-for zoning variance on our garage frontage.

FWIW, DH actually IS certified as a master pipefitter/welder, so IMO, he's technically qualified to do everything but the design work. But in a nutshell, 'specialized certification' is my concern. Our village's new inspection team seems very rigorous, and is definitely 'anti-DIY'. So far, all of the city inspectors we've called have gasped and/or groaned pre-visit upon hearing that DH DIY'd, until they actually see his work, at which point they begin to drool over the beautiful workmanship and quickly change their tune...

This is my area. I am not a designer but am involved with fire suppression systems.
The system would have to conform to NFPA 13d or 13r. I would highly recommend having an engineer/designer design the system. Typically these systems are fairly simple requiring a limited number of heads. Additional good news is there is plethora of heads available that can match almost any decor scheme. Find out your what exactly your municipality requires and go from there. A designer will be able to quickly and easily be able to make sense of it all and draw up the proper specifications.
follow the link or talk to a local fire contractor who understands nfpa 13d/r and have them do the design.

The link I am posting tells what you get, and what you need to supply.

Here is a link that might be useful: Fire sprinkler design service.

You Rock Jason! -- That looks like exactly what we need. Our village's code is pretty vague, but it refers to the 2003 International Fire Code -- which I'm assuming would point to the NFPA 13-D design standard for a single-family home.?

Our other question is that we're planning a significant add-on in a year or two, and we're wondering if we can install the 'main' system now and add on to it as well. Do you happen to know that?

Alot of variables there. Personally I would try and wait until the addition was going on. Do you have any drawings yet for the addition (an idea of the SF and what kind of rooms it will include)? The biggest problem with just 'adding on' is it can screw up the hydraulics. Also in the long run the design costs will likely be lower if you do the whole project at once.

We do have drawings for the addition, but they're not really final since we've got issues with front setbacks... And, I'm not sure the city will sign off on the renovations until we install the sprinkler system. We might need two systems?

And a good reason to install most of the system now is that two of the four bedrooms and both bedroom hallways currently don't have finished ceilings. Better yet, they don't have finished floors (plywood only), which makes access to the first floor areas below much easier now than later.

Current house is 2-story, about 4,000 sf, 4 bedrooms. The addition will add a 2-story living room, 3-car garage, small office and large master suite above, totalling about 2,000 SF of new AC space.

well if you have a rough idea on the addition you can talk with the designer about the best approach.

Go ahead and get this system designed and installed. Note: you can save costs by using CPVC pipe such as Blazemaster).
Just be sure to talk to the designer about the proposed addition and let him/her see what drawings you have for the additions. Two systems might be the easiest/ best approach. Also be sure to get a waterflow alarm (this will alert you when the system is operating or if somehow a pipe/ head gets broken or leaks)
The designer should be able to provide a lot more info than I can, as A) I am not a designer B)my area of focus has been more toward special hazards.

PS: here is info on a multipurpose system so you could possibly save money on the addition (it taps your cold water lines vs running a separate pipe from the meter) Ask the designer if this might be an option (it will depend on your water pressure and volume).

http://www.firesafehome.org/sprinklers/multipurposeSystems.asp

here is an idea of what the varieties of heads are like:
http://www.firebusters.com/sprforhome/sprpictures.phtml
http://www.firebusters.com/sprforhome/moresprpictures.phtml
info on blazemaster pipe: http://www.blazemaster.com/featuresBenefits/overview.asp
they can be made minimally intrusive on your decor scheme

Also Email me: JASON1083 AT COMCAST DOT NET
let me know where you are in Tx and I may be able to provide you some additional designers to contact.

Thanks so much Jason --
We're in Houston, TX, and would very much appreciate any contacts. I'd hate to have to fly in a guy from NY if there's someone local, and in a city this size, there should be.

Try:
Western States Fire protection
Houston office:
4456 Campbell RD
Houston, TX 77041
Tel: (713) 896-9941
Fax: (713) 896-9945

If not talk to some of the local contractors and your AHJ. If they are requiring them I am sure there are couple NICET certified designers around.

As for the man in new york, if you can give him the documents/drawings he asks for he will do it remotely in a few days. He's a freelancer so there is no pressure to give them the installation contract and his price is hard to beat. (Check with your AHJ to be sure they will allow this to be a DIY project, personally I see no reason why they shouldn't)

Good Luck