We are about to start a project very much like this (as soon as the town gets back from vacation and we get our building permit). We are putting a shed dormer on the east side of the house to increase the usable space in the bedrooms, then doing sort of a half-shed dormer on the other side to get enough height to add a bathroom.

I can't share much about the experience yet, since we're just in the beginning stages of this, but here are the drawings.

This is the existing house (looking at the east and south sides).

This shows the new shed dormer from the south (front) and east views. This is all bedroom space.

This shows the north (back) side of the house and a cut out of the west side, which shows the small shed dormer where the bathroom will be located.

wi-sailorgirl - thanks for the pictures (your flower beds are beautiful). How much usable square footage will the small dormer add? Can I ask how much your estimates where?

In terms of the addition of usable square footage, it's difficult to say. What I can tell you is that we are gaining an 8x8 bathroom on one end of the upstairs "hall" and a walk-in closet on the other end, and neither of those was possible before. We are actually raising the entire roof on that side of the house in addition to the dormers so we are also eliminating the knee wall in the bedrooms. I anticipate we'll gain quite a bit of usable space there as well.

The scope of the project is pretty vast. In a nutshell we are taking the roof off the east side of the house and raising it, adding in the shed dormers, adding windows in the bedrooms in the shed dormer, adding the bathroom (which I would say is medium to upscale in terms of finishes as we're doing tile and a frameless glass shower), reshingling the entire roof, adding the deck and pergola and adding a sliding door to access the deck. The estimates we received ranged from $50,000 to $130,000. Once we got a little deeper into the inner workings of how our house is put together and what we need to do in terms of structure, it looks like we'll end up spending in the range of $85K. (Ick ... I've not typed that number before. That makes it a bit too real for my tastes).

We also live in an area that seems to be on the higher end in terms of building expenses and I have no idea why. The roof, for instance, is not going to be anything special (30-year asphalt shingles) and accounts for about $18,000 of the budget.

This is a project that started out of necessity. Existing dormers (you can see one peeking out in the existing house photo) were installed improperly and never insulated properly. After having insulation and roofing experts come out, we determined that the only way to really FIX the problem (which involves shoveling the roof when it snows, going up on a ladder to break up ice dams every time its done snowing and occasional leaking) was to remove the dormers all together. Of course we also needed to reshingle the roof. And as long as we're doing that .... and well, you know how it goes. Sort of takes on a life of its own.