How do I repair this exterior wall?
+3
This is the exterior wall that needs repair. It’s some type of paneling. Behind the wall is a fireplace.
It looks like the wood is rotted. You will need remove and replace it.
Ann is right, it needs to be replaced. That particular paneling is called T111. It is readily available at any home improvement center.
I would find out why this has happened. Where has the water been getting in, for years?
How damaged is the rest of the framing around the fireplace?
Is the masonry water damaged too?
Just replacing the wood you can see is not a good idea without investigating the on-going decay inside there.
Start by fixing the water source that caused the decay. Looks like a product called Smartside. I like this product...holds up well when installed correctly. It probably needs more than just replacement...like up top where water drains and I would not install all the way to the ground/stone. Good news is the product is available. Quick fix is to divert water and replace. Better solution is to change design.
We see this issue a LOT in Texas where it's incredibly hot, incredibly cold, super dry and then it rains so much, there's flooding. Basically, what's happened is the trim is no longer doing it's job. Water is getting in and voila, rot and all that comes along with it. You're going to need to pick a span of time when you're expecting good weather for this repair. In addition to replacing the siding, you'll also need new trim and I would recommend also using one of the Great Stuff expanding foam products. Door and window comes to mind because it deflects and repels water as it seals all cracks.
If your budget allows for a change in the whole design, then I'd definitely replace the entire wall, check the insulation and perhaps replace it with something more efficient and then cover it with a horizontally surfaced siding that doesn't catch water and will expand/contract as the environment demands. Hope that helps.
Rot by water infiltration. Looks like someone tried to fix a leak and transition between the roof anf sidewall. The water just flowed down . You need to get behind there and replace any damage. The T111 siding can be pried off the wall. Add a gutter scoop and downspout along the roof and wall transition.