"outdoor" room construction

[BigguyZ]

My brother is doing some major remodeling of his house, prompted by a tornado that ripped through Minneapolis a year ago.

On the back of his house, there was a one-story attached garage. It was damaged, and my brother didn't like the driveway that took up a lot of the back yard going from the alleyway to the back of the house. So he opted to have a detached garage built right off of the alley. Then, he's turning the old garage into an outdoor living room. The roof was restructured and will be a flat roof with a deck on top. Then two of the 3 exterior walls were knocked out, leaving one wall that's completely exterior, and another that's shared with the house. The one shared with the house will be cut open to allow for a double patiow door, while the remaining wall will stay.

Currently, the walls are gurtted from the inside, with the original stucco exterior intact.

What I'm wondering is, what materials would we use for the "interrior" of the remianing wall space? Drywall, even greenboard, would rot pretty quickly left to the elements. Real Stucco would be an option, but it's incredibley extensive. The other idea my brother had was to use the foam stucco siding, that's used for skirts. You could sheath the wall with 1/2" ply or some other water proof material, and then glue the foamboard to that. The insulative property of the material isn't needed, but the weather resistance should be good.

What do you guys think? What other options are there that we haven't thought of? Cost is a factor, as there's an entire house to finish fixing up. I'm familiar with working on houses, but exterior work like this is a new matter to me.

Thanks!

[pelligrini]

For the inside, especially near the ends where there will be direct weather exposure you will want exterior rated products. I'd install everything just like if it was an exterior facing wall.

You might take a look at some of the cementuous siding products. James Hardie is a big manufacturer. They come in a variety of types and finish textures. You can work the panels much like gypsum drywall. http://www.jameshardie.com/homeowner...panelSiding.py

There's also T1-11 siding. It's a wood product, but it's been used outdoors for years.

The stucco panels would work, but remember EFIS will damage fairly easily.

[jking]

My thoughts were pretty similar to the above. ^^^^

Consider the "interior" of the room to be exterior walls. Even thought they may not get directly wet, they're now an exterior wall. Using exterior rated products.

I'm not sure if it would look out of place, but, another option to consider might be SmartLap. It's a wood product, but, comes in similar sizes as masonite & Hardiboard.

[Russianwolf]

cement board used in bathrooms.

[cabinetman]

There's also T1-11 siding. It's a wood product, but it's been used outdoors for years.

I used T1-11 (5/8") for the exterior sides of my shed. I primed and painted the panels before installation (several applications). That was 7 years ago, and there's rot at the bottom edges that I'm going to have to fix. It is SYP, and I thought I had sealed the siding completely. The bottom edges were not near ground level.

For the cost difference, I am thinking of using a vinyl siding, as a replacement (if I do a tear off), or as an add on.

.

[Stytooner]

I have the same issue with the same siding I installed about 12 years ago.
It is the Sun that gets it. We have painted again once since then and it still shows the bottom 6 to 8 inches as failing.
I will be recovering with the 4 by 8 sheets of the look alike cement based stuff. I have one wall completed about two years back and that is the way to go. I have the same stuff on my new shop, but it looks more like stucco finish. It doesn't have the lines like the T1-11 look alike does. Seams show a little more, but looks great when done tightly and caulked and painted.

[cabinetman]

I have the same issue with the same siding I installed about 12 years ago.
It is the Sun that gets it. We have painted again once since then and it still shows the bottom 6 to 8 inches as failing.
I will be recovering with the 4 by 8 sheets of the look alike cement based stuff. I have one wall completed about two years back and that is the way to go. I have the same stuff on my new shop, but it looks more like stucco finish. It doesn't have the lines like the T1-11 look alike does. Seams show a little more, but looks great when done tightly and caulked and painted.

Are you saying that there is a cement type board that has the same details as the T1-11 plywood?

.

[pelligrini]

Hardi's Sierra 8 has a very similar woodgrain texture and vertical lines to T1-11. I don't think it has the lapped panel joints like the T1-11 I've worked with. The biggest drawback I've seen with the cementuous panels is dealing with the butt joints.