Not a giant fan of windows behind the range, but it is what it is...so...most exhaust fan manufacturers and range manufacturers have determined the required air flow (cubic feet per minute - CFM) as well as the optimum distance from top of cooking surface to bottom of hood. Start by checking the specifications for CFM and distance from cooktop with the range manufacturer. Not sure of your location, but here in the States the IRC requires exhaust fans for kitchen, bath and laundry. Some areas, although they have adopted the Code, do not enforce it. But if broiling pork chops ever happens at your place...you sort of want it.

Hi there nicndrew -- wondering if you ever solved your venting issues if you went ahead and put your range into the fireplace. We have a similar issue - 140 year old victorian and the only realistic plan we can come up with for a new kitchen design is to put our range into an existing fireplace. Our floorplan is constrained by a stairwell as well as a couple of weight bearing walls so we need to work with what we have...I am hoping we can vent up and out the side of the house -- four flues in this chimney but the kitchen flue is closest to the exterior wall. The contractor is coming to take a look on Saturday but would love to gather some suggestions before then.

The minimum is 1219mm. By the way in your new design do you have a landing space to the left or right of your oven? If you opt for less distance maybe your designer should do some research on ovens that have doors that open side ways instead of top down.

I think your layout is generally good. With a one bedroom it's nice for guests to have access to the ensuite without having to walk through the bedroom. One thing I do notice though is that there is a lot of hallway/storage/circulation space in the center of the building (in the two bedroom portion) that might be better used as living space. You could pretty easily make the ensuite in the one bedroom larger for example. The wash house space seems unnecessarily large to me as well. You could push the wall dividing kitchen from wash house almost all the way back to where the toilet door is in this plan (you'd then have the toilet door open into the wash room to the right from this viewpoint rather than straight ahead). This would leave much more kitchen to porch access, which would be nice.