We are about to add on a few rooms (for our growing family) to our (very small) house and I was was wondering if anyone had some tips. Here are a few questions off the top of my head:
1. is it worth hiring an architect versus a designer? i'd love to save the money there as it should be relatively simple
2. should we go up or out or both? we need to add one or two bedrooms and a bathroom, at least. we are considering a screened in porch too.
3. while we are building, should we consider adding a rental apartment? i'm not crazy about having someone else share our property, but if you think it is the best thing ever, i'd like to know.
4.general tips from those who have been through it?
The fact that you are asking question 2 answers question 1. You need an architect.
My rule is that anything that F's with the structure of the house requires someone who is trained/licensed to manage those issues appropriately. Architects are; designers and builders are not. End of story.
Beyond that, architects are awesome at space planning. Builders tend to be good at certain things that they do over and over. A good architect, OTOH, is more likely to have the skill set and experience to look at your specific house, as it is currently built, and figure out how to get the most usable space and amenities from the most minimal, cost-effective* addition. They will also think of ridiculous numbers of things that would never occur to you until it was too late.
On 3, why consider it if you don't want/need to earn the money? Are you in a neighborhood where everyone else has Granny flats or basement apartments and there's a huge demand? Are they allowed under your existing zoning? If you would more than make your money back, either through rentals or through increased value in the home, then sure, go for it. But not sure why otherwise you'd devote limited budget to something you have no interest in. OTOH, if you are looking at a Granny flat as an aging-in-place option, that might make a ton of sense.
4. What NV Teacher said. Also: if you have laundry in the basement, this is a good time to move it to a more useful/accessible place. Think hard about what other future changes you may want -- i.e., don't do a second-floor remodel if you plan to do the kitchen in 5 years and will end up ripping out the wall with all that new plumbing in it [note that this is how our kitchen remodel morhped into doing the entire back half of the house]. Invest in the things you can't see, like quality windows and insulation; e.g., if you have to choose between good cabinets and granite counters, well, you can replace a Formica countertop easily and quickly in 5 years when you have the $, but you can't rip out and re-do the cabinets below it without losing the lovely granite slab on top. Realize that your budget is going to get you only about half of what you really want, and that there will come a time when everything feels like one huge expensive compromise (it will pass). Beware the curse of "while we're at it." If it is an older house, have the areas inspected/tested for lead paint and asbestos (there are health concerns and federal requirements you don't want to screw up by accident, and asbestos isn't just around pipes). Confirm your electric service and water supply are sufficient for the new space; having to drop another subpanel or run a new water line to the street jacks up the cost. If you are going up, take a hard look at the foundations and framing of the basement/first floor to make sure you don't need to shore that up. And always, always make sure your builder pulls all required permits, because you are still on the hook if they screw up. Etc.
*Some architects suck at paying attention to cost. Choose carefully.