Our recessed 8'd x 20'w cement-floored rear north-facing patio is covered by our roof. This makes our living areas dark. We'd like to cut back the roof, replace it with polycarbonate panels, and close the wide side with 3' high walls with screens on top. Voila--a sunroom! What roof supports are needed, and what's a ballpark figure for materials and labor?
Braden R. ~ East Grand Forks, Minnesota
Hi Braden. This sounds like a pretty good plan for creating a sunroom on your East Grand Forks home and it shouldn't cost too much either. There's a rumor circulating down here in the southern states that Minnesota can get a little bit of snow during the winter and that would be my primary consideration when looking at your roof framing.
A short roof span of eight feet would normally only require 2" x 8" or possibly 2" x 10" rafters, but I'm not sure what type of snow load needs to be figured for the East Grand Forks area. The same thing is true for your polycarbonate panels. They are available in various thicknesses and in single, double, and triple wall construction and your snow load requirements can determine which you should use. There can be quite a cost variation between which type is used when building a sunroom.
I suggest you get with a local architect in your part of Minnesota and ask them to run you a few calculations for your roof load. Any project that has roof framing involved is going to need a building permit and you'll probably need drawings to show the building office, so you might as well get the architect involved even during the planning stage. I'm not sure how Minnesota law works, but in my area a draftsperson can draw plans for this type of project and they would also be capable of the roof load calculations. If Minnesota allows this, you might want to go that route as the costs can be a little less.
You also need to consult with the architect or draftsperson prior to cutting your roof back. I'm not sure what is supporting the outside of the roof you are considering cutting back or if it is just a cantilever that extends out above the patio. In any case, if the roof is a part of the roof framing over the main section of your home, the roof should be inspected to determine if cutting it back will affect the structural integrity of your main roof.
This may all sound a little complicated, but it really isn't and the architect or draftsperson should be able to determine all of this with one brief site visit. It would also be very worthwhile as it can relieve a lot of worry every time you have a heavy snowfall.
Trying to arrive at the costs for a job like this can only be an educated guess due to all the variables involved. If you want a budget figure, I would suggest using $8,000 for the project. It could be considerably less than that figure if the demolition of the roof is a simple job and framing the three foot walls doesn't take long. Labor costs in Minnesota may also be less than what they are around where I live. It's possible you could end up with only about $6,000 in costs, but I would use $8,000 as a safe budget.
It sounds like a very doable project and should be a very enjoyable sunroom.