No way. Is plumbing already there? Is he a licensed electrician AND plumber? In my state, you cannot do electrical or plumbing without being licensed (unless you are the homeowner).

Will this be inspected?

Sounds low to me for what you describe (esp with a bath involved).

The average bathroom renovation without moving any plumbing is 12K, and the average attic conversion is more like 75K. While you can do a very low budget project for half of that, you aren't going to be able to do this nearly as cheaply as the "handyman" has quoted you. That quote is waaay too cheap. I'd bet this guy isn't licensed and insured. And I'd bet he isn't including all of the actual stuff that needs to be done to make that a legal habitable area, if that's even possible. You will need to add better insulation and HVAC to the list. Attics are really hard to temperature control well without adequate insulation. And you'll boil to death in the summer if you don't have AC.

{{gwi:2065545}}

In addition, was the structure originally designed with a live load in mind or only storage? You may need to beef up the joists structurally before it can be living space. If you don't know the answer to that, you need to get an engineer's report as the first step or it may sway more than a treehouse when you're add people to the space.

To judge using the treadmill as scale, it also may not have enough legal habitable room to comply with codes. You have to have at least a 7'x10' foot floor space with 6 1/2 feet of headroom for a bedroom, and I don't think you even have that clearance at the peak. With the code required amount of R value for the insulation for your area, you might have to fur it out even further to get that in and reduce the headroom even further. Is there also a window that can serve as an emergency egress? That too is required for fire safety reasons. Your bath will need a 5'x7' space at 6 1/2" for a working bath. You cannot count or use the floor space that is below that 6 1/2 feet.

You need to get further estimates from licensed and insured contractors who will guide you through the process and make sure that the project is even possible, and if so, will pull the proper permits and have it inspected. Adding an illegal bedroom conversion only makes it a safety hazard and devalues the home.

Always get at least 3 estimates before taking on a major project. The lowest is usually cutting corners or working with unlicensed trades (especially true if the estimate is much lower than the others).

This is over a garage, so you will want to be sure the floor is really well insulated (since the garage is unheated) and will need to be finished well to prevent toxic exhaust fumes from invading the living space.

I think your estimate sounds low since it includes a bathroom. I would expect to pay about 2-3x for that much work.

Almost a fifth of the price involves allowances. Allowances are not prices they are estimates. You will be expected to pay the actual cost of hiring an electrician and plumber which could be a far greater amount than estimated. Make sure the allowances are only for materials and subs; his labor should be in the base bid price. Ask if he will mark up materials and subs covered by allowances.

You will need an exhaust fan with a duct to the outside. You didn't say where the project is located but you will probably have to provide heat for the space. It seems pretty obvious that this room will be used as a sleeping room so one or two hard wired smoke detectors will be needed. A carbon monoxide detector MUST be installed.

I would guess the project will cost well over $20,000 not including what you buy unless the contractor is uninsured, and ignores licensing and permitting requirements.

As for minimum space and height requirements, if the local code is based on the 2009 IRC, the 70 s.f. minimum floor space for a habitable space (bathrooms are not considered habitable spaces) includes the space where a sloped ceiling is 5 ft or higher and a level ceiling is 7 ft. or higher for a minimum of 50% of the required room floor area.

The minimum height of a habitable room level ceiling is 7 ft and 5 ft at a sloped ceiling. A bathroom must have a ceiling height of 6-8 in front of each fixture.

The required "means of egress" from all spaces in the house must be 3-0 wide for corridors and stairs and lead to an outside door without passing through a garage.

Habitable attics and every sleeping room, in addition to a means of egress, must have an "emergency escape and rescue opening" of 5.7 s.f. (min. 24" high and 20" wide) with a max. sill height of 44" above the floor.

You need to decide if the habitable space will be used as a sleeping space because the building inspector will either ask you or just assume it is one.

As for insulation, some jurisdictions have different requirements for an existing structure which may be contained in the International Existing Building Code or state amendments to the IRC. Where I live the wall, floor and roof cavities must be filled with insulation equivalent to fiberglass batts however you might want more depending on your climate and cost of heating fuel.

As for the structure, the framing seems fairly new so if it was really labeled as a "bonus" room on the original permit drawings it would have been designed for a habitable space load instead of a storage load. All of this should be covered by the tables in the building code so an engineer should not be needed unless the knee walls are intended to transfer rafter load to the floor joists. The worst case is you would need to open the garage ceiling to add some joists but it might be wise to open the ceiling anyway because the best way to seal the floor is to spray an inch or two of foam insulation from below, in fact I don't know of another way that works. Putting a sleeping room over a garage requires great care. I would have two CO detectors in the new space, one hard wired and one battery operated. CO is a dangerous killer. I would have lost a client if newly cut flowers had not wilted soon after delivery.

Thanks for your inputs. The contractor is licensed and insured. The bonus room will be finished as a guest room with a bath. The bath plumbing to the outside and the AC have already been there. The insulation has also been on the wall and ceiling. His estimate is

Hang and finish sheetrock in bonus room
Install insulation and baffles as needed
Install sub-floor in closet areas
Rough in for shower and bathroom
Install six outlets and one circuit in panel
Install all plumbing and electrical fixtures ($800 allowance) (customer to supply all electrical fixtures)
Install all trim, hardware and doors
Paint all affected areas
Install vinyl in bathroom floor ($450 allowance)
Install carpet in stairwell and entire bonus room ($1450 allowance)
$14,839.00
Install window in gable inn $1280.00

I also asked the Home Depot Affordable Contracting to quote finish the bonus room as the following

Purchase required permits
Install rest of missing insulation on walls and ceilings
Add exhaust fan to bath room to vent to outside
Add GFI outlet in bath with home run wire
Add rough plumbing for bath
Install 30x60 acrylic bath RH and shower walls
Install shower valve
Install electrical per code and add smoke detector
Install sheetrock on walls and ceiling to slick finish
Add 4 cut down flush doors for access to crawl spaces
Install 2- 6 panel Masonite door units
Install 3 �" base molding throughout
Trim out windows with casing
Add locks to doors and hardware
Install toilet, 30" vanity, marble top, faucet, flat mirror, shower rod and bath accessories
Install handrail on stairs
Add HVAC vents in ceiling
Install ceiling fan in main area, light in closet and wall light in bath
Lighting allowance $160
Add 24� wire shelving in closet
Paint walls, ceilings, trim and doors

Proposal Price is $13,675.00. Carpet and vinyl to be install through Home Depot Carpet Services (additionally). To add window to front gable $850. There already have had two windows on the left. I prefer to add a third one in front (Is it a good choice?). See the picture {{gwi:2065546}}.

How do your expert think about the estimates, reasonable? Can your experts help me to see which estimate looks better and is there anything missing or I should pay attention to? Thank you for your answer.

Personally having HD install anything is a bad choice and a complete crap shoot in my opinion so I would be inclined to eliminate them right from the beginning (I probably would not even let them know where I lived let alone inside my house).

Well their prices are comparable, but HD's has more legal stuff specified. If you like your first guy, go back, and get in writing--permits, venting, GFI, access panels, etc.

I think you have more work to do, including not asking a handyman and talking to a contractor.

Talk to some actual licensed contractors, not handymen or box store umbrella weasels. You need at least 4-5 more estimates from legitimate sources. That may mean you have to call 10 guys to get those quotes, but that's just part of the process. It will take time, and you can use that time to become better educated about all of the processes here. Learn about proper insulating techniques for your location would be the first thing for you to research, and the second would be to learn about how to properly waterproof your wet zones in your bathroom. DO NOT rely on a contractor to know or do those things correctly. Know yourself. Otherwise you could end up with frozen pipes and water damage behind your walls.

And yes, even with the plumbing already roughed out, the quotes are too low. A plumbing rough in probably has saved you 5-6K, and that's not insubstantial, but that's maybe 10% of the minimum total that the job will end up costing you.

Hi Coody,

I know this thread might be quite old, but I thought I wanted to add my answer anyway.

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Regards,

Thomas - http://www.splitlevel.net/