Insulating & Sealing and Old House

Mike T., Swampeast MO

After 11 years, I'm finally getting my ground floor truly finished.

Was injecting foam into the big floor-to-ceiling (with it's own roof) bay yesterday. (12 cans of Great Stuff--LOTS of BIG voids in the old framing at the angles.)

It happened to be raining off-and-on. Sometimes downpours with the wind coming from various directions--mainly at two "facets" of the bay. Found a leak into one of the weight pockets. Maybe 2-3 oz. of water entered.

The bay is utterly original and the 10 year-old paint job on the outside is merely weathering properly. The exterior is solid 1¼" cypress. Extremely wide boards with an odd flashing detail above the windows. Odd, but in perfect shape. Weather has been exceptionally dry here for months. I have almost zero doubt that this leak has been occurring for decades--if not forever--in certain conditions.

Everything perfectly dry this morning, but of course there are no casings. In all the rest of the windows I've installed 1" of rigid foam against the casings inside the weight pockets and sealed with caulking.

Something tells me that I shouldn't insulate these weight pockets. Perhaps insulate but not caulk around the edges?

---------------------------------------------------------

In a broader question: Is some water penetration inevitable in <I>any</I> structure in certain conditions?

This is not my only leak. This project is so long-standing and I have such intimate knowledge that I know every design flaw and concession ever made (including my own) in this house. Despite mine and two professional roofing companies efforts I still get an occasional minor leak in a dormer. The far ends of the bay and the front porch roof are only non-leaking because of caulking and one of my favorite sayings is that "caulking is NEVER a permanent fix".

Steam Bunny

Is it possible by having the weight pocket open you reduced the resistance permitting the wind to blow in an increase in air accompanied by rain? You need to resolve this whether or not you continue to insulate because dry rot follows leaks & leaks don’t just go away. If outside air can enter, you might want to caulk or (preferably) nail (if cypress isn’t bowed) any open joints in the face board before applying the foam board.

I did the same, some 30+ years ago & it’s helped to prevent air infiltration. An additional ‘easy’ is to cut approx 3 x 5 pieces of color appropriate terry cloth & when the cold arrives, “lock” them into the sash cord at both roller & lower window (4 to each double hung window). If someone forgets & attempts to open the window they’re less likely to get ‘lost’ in the works than other materials and you still have the ability to fully open the window if needed.

Folk are likely contemplating condensation problems, a reasonable concern. I didn’t notice any problems when we replaced south side siding & face boards a few years back.