You need to provide a sketch ( or blue prints) of this space with all walls and all doorways and all measuremtns. You keep mentioning a window? Where? We can't help you without a drawn out space with ALL the measyrements.

Have an electrician and plumber and HVAC Specialist come over to assess what needs to get code updates. To use as a safe bedroom, you need a window of proper size and location for fire exist and satisfying local codes. Then we can assess layouts.

The window would go where that dark-colored, screen-covered, square-shaped vent is now. Other side of the space behind the unfinished wall

again we need the info listed above and as Flo said none of that will even be needed if we don't know where the plumbing/bath can be located, where hvac will be located (you will need either to add on to your existing unit or get a split unit up there) too many unknows .

Patricia,

You've got the order of operations wrong, again. Any permit to remodel the OP's attic space would be based on a review and approval of plans and specifications submitted to the local municipality's building dept. Ditto for approval by any neighborhood architectural review board if there are restrictive architectural covenants.

The OP is crowdsourcing ideas for the layout. Eventually someone will need to put pencil to paper (or the electronic equivalent) and produce plans. The OP will be well served by consulting with one or more professional remodelers to identify the feasibility of the project and get an idea of costs before committing to designing a space that doesn't get built.

an actual measured floor plan with the stairway included in the floor plan, please.

I don't see the window in the photos, is it already existing?

What direction is the window? street side? morning light? Is it merely a statement or will it open?

An attic suite can be a great additional living space, but building out an unfinished space and carrying materials through a finished portion of the home can AND WILL be a bug mess. Are you able to bring materials through an opening from the outside?

Any window put in this attic has to meet strict codes. This is for emergency escape among other things and it has to be operable with a minumum of 24" tall x 20" wide after opening to exit out of. That just touches the code regulations. Height above floor, etc . Personally looking at this space unless a window is going on the large flat wall that is shown in the photo it doesnt appear there is another space large enought for a window to meet code requirements without structurally changing the space. This will mean a lot of engineering to meet code for the trusses and roof etc. She needs to hire a competent contractor who will bring in an engineer before she even brings this to us.

I agree with @Design Interior South. An engineer will determine whether the joists are adequate to carry the load of a living space-expecially a bathroom, and whether or not there is adequate space for an egress window that will meet code.

An architect should be your first consultation. The floor joists need verified (typically ceiling support is 10psf, storage is 20psf, vs Bedroom/Living of 30psf/40psf). The rafters of the main roof extend down to kneewall, so providing an opening to get to the back 'L' will require structural reworking. The window size needs to provide light for 8% of floor area as well as large enough for emergency escape and rescue. Ceiling height needs verified (must meet height and sloped ceilings have specifics). HVAC needs to be verified if requires a new unit. Insulating a rafter assembly (the sloped ceilings) can be complicated in a seasonal climate (to avoid condensation and mold). Tax assessments should update when adding bedrooms, and septic systems if used are based on number of bedrooms. Buildings are complicated, and usually when kids are involved people choose to do it right.

Patricia, you seem confused about what a permit is. It is not an engineer's report. It is a legal certificate of permission from a local governing body to do something; in this case, to execute building/renovation plans. No local governing body I know of in the US issues a permit until AFTER they have reviewed detailed plans and specs, submitted as per their requirements. Exactly as Charles Ross Homes stated.

First you plan, including specs. Then you apply for a permit, which you may or may not get. Sometimes you are told what you need to change in order to get the permit in the future. And sometimes, you are told—in legalese—to go jump in a lake.

Patricia, you seem confused about what a permit is. It is not an engineer's report or anything like it. It is a legal certificate of permission from a local governing body to do something; in this case, to execute building/renovation plans. No local governing body I know of in the US issues a permit until AFTER they have reviewed detailed plans and specs, submitted as per their requirements. Exactly as Charles Ross Homes stated. It's possible the governing body will also want you to submit an engineer's report before granting approval, but they are not the same thing.

First you plan, including specs. Then you apply for a permit, which you may or may not get. Sometimes you are told to go back to the drawing board; that is, you are told what else you need to do, or what you need to change in your plans, in order to get the permit in the future. And sometimes, you are told—in legalese—to go jump in a lake.

"Sorry but the permit comes first you can call it the engineers report or what ever but first you have to know IF you can do this." While I concur that a feasibility assessment should be performed before any design work, the first step is rarely to contract with an engineer unless the goal is to run up the cost (full disclosure: I'm a licensed P.E.) A competent remodeler can usually determine feasibility, albeit that other professionals' input may be required during design.

I'm correcting the misinformation you provided to someone who needs help. "Regular" words, including permit, report, plan, and spec(ific)s, all have distinct meanings. When you use them incorrectly, you mislead innocent readers.

When you have a "Pro" designation, more should be expected from your advice to non-pros.

All of that in additon to using spell check. Especially for a "pro" Makes the read very tough.

Thank you for English lesson

" Thank you for English lesson "

You're welcome.

It willl be a cool space as long as nobody gets trapped up there if a fire occurs, and the floor can support all the furniture and people, and it doesn't get too hot or cold, and nobody gets sick from stagnant air.

I don't see any window at all. In my neck of the woods, you need a window with adequate egress --- ie big enough for a person to escape through if you want to put in a bedroom. My SIL has an apartment she rents out which would be a two BR and rent for considerably more if there was a big enough window in the second room.

If you haven't done so already, I'd talk to your code enforcement officer. Another friend had her house labeled not fit for human habitation after a few minor corners cut on the regulations. It wouldn't have been a problem, but there was a fire and with the firemen came the code enforcement officer. The fire was minor and was caused by an idiot, rather than anything related to the corners cut in remodeling, which had been done a number of years before.

There's no need to hire a structural engineer nor to check with the building official at this point in the process (they'll get the opportunity to review the plans submitted with respect to current code requirements.) Checking with one or two experienced remodelers should be sufficient to determine what alterations are needed to meet code requirements for a bedroom and ensuite bath. They should also be able to provide some ballpark estimates of the associated cost. Then, if the OP wants to proceed, the selected contractor can recommend the right design resource to get the project to permit.

I for sure would want to know if possible before any step forward, I have done these conversions some easy some very expensive and all first needed to understand the issues and costs.

If you would have "done these conversions," in the U.S., Patricia, you'd be a qualified remodeler--not the interior designer/decorator your houzz.com page indicates you are. And you wouldn't be calling for an engineer's opinion regarding feasibility. You'd have sufficient knowledge to make that call vis a vis the applicable statewide building code.