Cost of adding a room over the garage in LA? (prebuilt, houses)

[Panks]

I would have put this in the House forum but my question is really about LA because my realtor said that because of special earthquake laws, you need to sink special posts on each corner that go down into the ground many feet...
OK, I may have the terminology wrong but thats generally what he said.

He said he thought it would cost $250/sft which seems super expensive for a basic room with a bath

Does that sound really expensive to you guys or am I stuck in 1980's pricing and my realtor is right?

BTW I have a slab foundation if that makes any difference

[EscapeCalifornia]

So $100k for a 400 sq ft addition over a 20x20 2 gar garage? Yeah that sounds like a lot, especially with all the starving contractors out there right now. I don't know about adding any deeply buried posts but I've heard that in my suburb in OC, adding a second story will require you to beef up the existing framing by pulling the drywall and installing plywood over the studs to add stiffness. Since its just a garage, they might just demo it and reframe the whole thing. Garages do have long unsupported spans so that probably makes it harder to go up than if you're adding above a couple of 10x10 bedrooms. The building inspectors would know all the rules but who knows how hard it is to get to talk to one in the city of LA.

[JTGJR]

Sounds about right. I remodeled my kitchen a few years ago and had hoped to extend the back of my home out about 6-feet. It would have cost me about $60K just for the framing and finishing work . . . before I actually started doing anything to the kitchen. And my work would not have required any significant earthquake prep.

I believe there are also specific requirements for fire suppression when adding on above a garage.

[SOON2BNSURPRISE]

It depends upon your specific lot and the condition of the current garage. Does your realtor have an engineering degree or is the realtor a building contractor? That is who you want to speak to, someone that has done this kind of job in your area. You could also go to your cities building department for advice and find out what the average cost to build your specific project would be in your city. Every project is different but they would be able to give you some guidelines about former and current projects.

[greggd]

Originally Posted by Panks

I would have put this in the House forum but my question is really about LA because my realtor said that because of special earthquake laws, you need to sink special posts on each corner that go down into the ground many feet...
OK, I may have the terminology wrong but thats generally what he said.

He said he thought it would cost $250/sft which seems super expensive for a basic room with a bath

Does that sound really expensive to you guys or am I stuck in 1980's pricing and my realtor is right?

BTW I have a slab foundation if that makes any difference

You will most likely have to core well below the existing foundation to accomodate the extra load of the 2nd floor. A contractor experienced in this type of work will not charge ridiculous amounts, but for someone not familiar with the processs.. they will generally overbid.

You core holes, drop steel or rebar and pour concrete. There are contractors that specialize in doing this and do it very quickly. Especially on flat accessible land. A general contractor will usually subcontract this type of work out to save $ & time.

[streetscenes]

There are some specific engineering requirements do to the large, open space of the garage door. It is partially a foundation problem but more of a framing problem. The building has to be made strong enough to resist the lateral forces in an earthquake. You see some houses with built in garages using steel framing. The company Simpson Strong Tie makes a specific prebuilt product used for framing garage door openings. Check out Simpson Strong-Tie - Helping to Build Stronger, Safer Structures

The figure of $250/SF is overstated, you could build the whole thing from scratch for less than that. I would think around $150/SF for a basic room over a garage, just a rough guestimate from where I sit.

[Beth56]

My contractor husband says that's about right because you must build up the existing foundation and create earthquake restraints. Possibly needing to sheer the garage structure and that price includes a bathroom and a set of stairs. So $250 SF seems very reasonable to add a second story to an existing garage.

[twillit]

Originally Posted by EscapeCalifornia

So $100k for a 400 sq ft addition over a 20x20 2 gar garage? Yeah that sounds like a lot, especially with all the starving contractors out there right now. I don't know about adding any deeply buried posts but I've heard that in my suburb in OC, adding a second story will require you to beef up the existing framing by pulling the drywall and installing plywood over the studs to add stiffness. Since its just a garage, they might just demo it and reframe the whole thing. Garages do have long unsupported spans so that probably makes it harder to go up than if you're adding above a couple of 10x10 bedrooms. The building inspectors would know all the rules but who knows how hard it is to get to talk to one in the city of LA.

Lucky the contractor quoted you the real cost to build the garage. Many so contractor's are so afraid of telling the truth because they know homeowner's will find someone else. Homeowner's lean towards the lowest bid and in the end, they pay just as much or more. Go to the contractor's board and read the hundreds of contractors that lost their licenses due to underbidding. People don't understand the stringent code requirement for retrofitting, etc. the expenses involved (if the company is legit). If you don't have $100,000.00 readily available, spend your money on something you know you will receive a return...

[twillit]

If you want to really know what your job will cost, first get the plans approved then take your plans to a lumber yard and pay the fee they require to estimate your projects materials. If you are not shocked by the numbers, add about 25% for extra and unforseen issues. If you are still willing to proceed, get a contractor to estimate the building cost. Once you have several estimates, pick the Contractor that can show you a building that he/she actually built which is similar to yours. You can check his credentials at the permit office if he actually was the contractor.

[ferretkona]

I built a small house over the garage back in 1980. It cost me $15,000 then, but I am a carpenter and most of the material came from job sites.
The fireplace was legal to install but a kitchen and bathroom were not. I had to permit this as a office/rumpus room. Added the bathroom and kitchen after the permit was signed off.

The city wanted this to be drawn by a engineer, I asked the city to accept the plans I drawn and make their own demands to conform. The cost then was in my advantage as they maxed out their demands and the addition cost was less than a engineer. Added sheer walls. I had to dig a 4 foot by 4 foot by 6 foot hole on both corners of the front of the garage and fill them with concrete to create a beam/truss.

The permit was not expensive back in 1980, only $1000 or so. I figure now the permit would cost $30,000.
The law generally allows what is commonly called a mother-in-law cottage in most cities. It is not always or even normal to get approval quickly, the city offices will give you hundreds of papers to fill out, and shuffle you desk to desk. The city actually had a town meeting to allow neighbors a chance to complain, if only a single neighbor did not approve the city was not going to permit the addition.

All in all I would suggest removing the existing garage and start new from the ground up.