Bathroom Addition - V2 | Page 19 | Construction and DIY projects | Forums

Very good question. I'll try to be concise:

Foundation - We used way too much concrete. What should have been 7 yards was 11. I would have poured with foam in place. I would have also asked the civil engineer to give me a design that wasn't built for a 4 story building (cheapest bid, again).

Walls - I went 2x4 16" OC on all walls except where I had plumbing - 2x6 16" OC. What I should have done: 2x6 24" OC everywhere. I had no logic but started building without thinking. This gives more room for insulation, is more stable, and makes for easier routing (electrical, plumbing, etc).

Finishing - I would have liked to have done polished concrete but was worried about slipping in the bathroom so I'm glad I did tiles. The shower could have been inset (instead I built up the floor for the drainage). This normally isn't an issue but I think that it would have looked cleaner and I would've had more headroom (low ceiling due to roof line).

Ceiling - Drywall, oh god how I spent too much. I wish I had done this myself but I ran out of time. I think that your T&G ceiling is the best by far because of ease of installation.

Windows - I used the cheapest and regretted it. Bad build quality. 

Exterior - Let in bracing and exterior foam board is awesome for a thermal break but means that your siding can get wavy (it doesn't have a hard surface to back against). I think that this is the right approach vs plywood sheathing but I need to review the details, I didn't do something right.

Roof - I had to lay the panels backwards because of the way the snap-lock was. Nothing to be done here, just think ahead.

Things I did right! Short list: Light, lots of light. I installed all LEDs so that the bathroom is well lit at night but during the day no lights are needed. This was key for me as I wanted light and privacy as well. 

I still have to go back to town to wrap up the permit because of the city arborist but otherwise it's all rented out and I got an extra $250/mo for the work. Bad investment but good learning experience.