# Tiling against Exterior Wall of Previous Addition



## Keeyter (Sep 18, 2010)

We ripped apart a horrid shower installation and found that one of the walls was an exterior wall and the bathroom is part of an addition. The old exterior portion still has the board sheathing and the previous installation had Hardie Backer Screwed right to the Board Sheathing. Between me, my guys, the plumber, and homeless guy on the corner none of us agree on the new installation and have seven different opinions. 

What would you guys do? Remove the board sheathing or go right over it?


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## GO Remodeling (Apr 5, 2005)

So the old exterior wall is now an interior wall? Any membrane system with a low perm rating. 

If any portion is still an exterior wall then I would open the wall and insulate. Wedi would then be my choice for the wall system.


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## Keeyter (Sep 18, 2010)

Correct - the picture shows what use to be the exterior wall, there is a bedroom on the other side of it. My thoughts was to remove the board sheathing and go over the original studs with CBU and then Noble TS. Plumber is worried about structure removing the board sheathing (I found it ironic that a plumber was worried about that, but hey). Another opinion was to frame a wall front, that's just wasting real estate. No part of this original wall is exterior anymore at any point.


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## tjbnwi (Feb 24, 2009)

I'd remove the board sheeting for no other reason than to pick up the 3/4" of room space. Sometimes evey fraction matters. 

Other than that, as long as you don't tile directly over the boards flip a coin. 

Tom


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## Keeyter (Sep 18, 2010)

Thanks Tom

I was leaning that way, every inch counts in these older homes.

Always nice to get a few opinions as well tho.


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## hdavis (Feb 14, 2012)

Be prepared and pay attention. I worked on a house that pulling the board sheathing would have dropped a roof on you. They may not have been structural when they were put on, but over the years and through modifications, they can be supporting vertical loads.

I hate surprises - I'd leave it if there was a decent way. A lot of potential downside for 3/4" gain, but maybe worth it if you may need the room.


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## hdavis (Feb 14, 2012)

I'll elaborate. When people put on additions like that, they may have put a nice piece of lumber up to act as a ledger to support a shed roof, and nailed it into the studs. Or they may just have nailed into the siding boards. If they did that, the siding boards become the structural support for the shed roof. That's one real life example. It's worth a peek at the general structure above that area to see if the boards are now critical structural elements and if that's a structural wall system you're dealing with. You could also have cut studs for one reason or another that weaken the wall, but the boards make it stand.

Most of the time, it isn't going to be a structural problem to take the boards off.


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## Keeyter (Sep 18, 2010)

All makes sense to a point, they did tack a 1x up against the Sheathing Boards to pick up the Sub-Floor. The addition wall that joins the original house is a gable wall. 

Here is a pic - doubt it helps but it's pretty and you can hang it on the fridge. Red is addition, Blue is Bathroom

I'll crawl up in the attic, I haven't been in one in too long anyway.


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## CO762 (Feb 22, 2010)

Looks like an old balloon framed house that has been hacked into over time. Unless you can see more of the framing, I'd just frame a new wall. If they want those few inches, then tell them it'll probably entail cutting into walls to reframe that load bearing wall.


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## hdavis (Feb 14, 2012)

Looks unlikely to be a problem from here...

By now you've taken a peek and hopefully it's a go.:thumbsup:


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## Keeyter (Sep 18, 2010)

We decided to leave the worms in the can on this one. We plumbed the wall out and called it.


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## CO762 (Feb 22, 2010)

You had half a slip sheet already there--you could have floated a plumb wall


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## hdavis (Feb 14, 2012)

Keeyter said:


> We decided to leave the worms in the can on this one. We plumbed the wall out and called it.


Safest call you could make.:thumbsup:


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