Base overhang water infiltration, how to flash?
Hello,
I have this base overhang that houses the gas fireplace (Pic. 1). The builders (or some previous owners) had put 2×10 boards to cover the base, all the way to the brick patio so that I didn’t have access or view of what was going out under the overhang. I found black mold on the floor and a lot of bugs in the ceiling of the basement room just behind the overhang so I decide to investigate and removed all the 2×10 boards. As I was expecting, there was substantial water infiltration and I even found a hole in the board underneath that was big enough to let a raccoon go through. Upon removing those boards (2×10), I also notice that I could see daylight from the basement.
So, now, I want to fix it so that water, bugs and critters cannot enter the house anymore. My plan is to remove the rotten OSB board (Pic. 3), inspect what is there, fix it and recover everything with a plywood. I want to be somewhat prepared to close if efficiently once I open it because it leads directly in the house. One thing that I don’t know is how to flash it once I put back the bottom board? Should I slide something behind the existing (in poor shape) flashing and then bend it below the structure for a few inches? I am dealing with EIFS and it is super hard to find people fixing those in my area so if possible, I would prefer not to rip out the EIFS wall even though I know that the OSB board behind is just wood dust now.
Let me know what you think, I can send more pictures.
Thanks
Louis
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Hi Louis
You don't mention how the water got in. Fixing the problem of water ingress would come before and may be be part of deciding flashing details. Could water be coming down from above, from the roof or chimney flashing? FWIW, some of the flashing at the bottom does not look too terrible but where it directs the water is critical - away from the building with no option to dribble back on the bottom of the overhang.
The bottom of the cantilever, your overhang, may need a little thought depending on what critters you deal with. It may involve some sturdy sheet metal, steel or aluminum; or possibly only sturdy angle to protect the outside corner around the bottom from gnawing teeth - inside corners are much harder for critters to attack. You may want to consider bricking (sorry,, can't tell from pics if it was bricked under before) under the overhang to make it less comfy to critters. A root membrane of some sort under the bricks would help with long term neatness and maintenance. I think it would be better to not enclose the under area. A wire enclosure would keep the under area visible and ventilated for drying while excluding larger critters, but may or may not matter that much.
Best luck,
Rufus
Thank you Rufus, this is very helpful.
I took one more picture showing the above and I would not be surprised that the water infiltrates there, at the junction between the chimney and the fireplace cantilever (new picture).
If this is the case, this may be a bigger issue as it may also start from the gutter not doing a proper job (I see this by the dirty wall of the chimney), then overwhelming the flashing between the chimney and the little roof and them drenching the bottom of the cantilever at every big rain event. This would mean that the water does not come from under as I was thinking but rather from high above.
Cheese quite a project at hand, probably too much for a DYI.
P.S.: I installed a trail cam under the cantilever last week and found who I am dealing with: a rat!
Ah, rats... Sorry to hear that. Be aware it could well be plural and they may not just be on the first floor.
Well, do a little research on excluding them. It's harder than you could wish. I think you probably do need to armor the bottom of the cantilever, at least along the outside corners. Ending your work with a solid masonry surface below the overhang will help but not eliminate the problem - especially since they know there is a comfy condo up there... I have dealt with this a little and the most direct and quickest way seems to be snap traps; 2nd maybe live traps, but then you need to kill them. Do read up on using traps - it's not a "put in your coin and out pops your resolved problem". It takes some thought, care, time and effort, unless you're real lucky. The youtube innovations are probably limited to situations where the problem is huge and thus provides a few dozen kills quickly for the camera. Search terms like "snap traps rats forums" will get you real people discussing their real experiences (as opposed to hundreds of merchants).
It sounds like you have good ideas about the water from above. It may not be too hard to improve the situation there. It would be good to look at the top of the chimney, also.
In my opinion and experience, finding and paying the best tradesman in the neighborhood, for whatever trade is usually worth it. Sometimes that can be difficult but my point is the cost is more, by far, balanced by reliability and quality of work. Doesn't mean they know all the latest green stuff - it means they show up when they say and view your issues with a lot of experience and tested methods and likely earn enough to feel comfortable about being honest and straight. Your time wasted on seriously late or no-show by itself would pay for any premium in price. Just my $.02, but BTDT.
Rufus