The House from Top to Bottom

It's been an interesting month, house-wise. We've had both the top (roof) and bottom (basement) worked on. The roof needed cleaning and the basement was leaning!

Although the roof is only 7½ years old, the aerial environment at our place is much shadier than it was when we moved in 23 years ago. Already, it was staining, but I thought that was just cosmetic.

Then I saw that moss was growing in the most shaded areas. Look at where the upper gutter meets the roof, above (click to expand). Below, see some green locust leaves but also moss at the shingle edges. I freaked. Something had to be done ...

We had the roof cleaning done by a local outfit with excellent references and reports on Angie's List. The cleaning required part of a morning and all afternoon; partly because of our steep pitches and partly because of the techniques and thoroughness of the job. (About 70% of our roof surface needed treatment.)

First, a commercial cleaning product that is basically a sodium hydroxide solution is applied. After working on the algae and moss for twenty minutes, a moderate pressure wash (100 psi) takes all the stuff away. The gutters get cleaned (yay!) and our aluminum gutter guards came out shining. (As a high school geek who inflated dry cleaning bags with hydrogen generated from sodium hyroxide, water, and aluminum, I wasn't surprised.) A fringe benefit was that ¾ of our deck got cleaned by this process as well.

The final step is installation of zinc strips to prevent the return of the algae, which in turn prevents the moss from taking root. Left alone, these organisms will consume the mineral (limestone) components of the shingles. Keeping it clean, we were told, instead of letting the moss have its way, should add 10+ years to the life of the roof.

Here are the "after" photographs. The lighting is, of course, different from the "before" pictures.

The basement was a stellar example of familiarity breeding invisibility and hence delay. There had been small cracks in a couple of spots in the basement for years. Had they been growing larger? Well, maybe. We didn't know how serious it might or might not be. Earlier this spring Joan asked me about one corner of the basement. Yes, I had seen the cracks there. I looked more closely, and saw that things had progressed. The upper courses of blocks had separated and, at the very top, had moved in an inch.

The top course had a newer crack along much of its length, and along the crack the blocks were developing a tilt.

Another wall joins this wall at a 90-degree angle, and behind shelves of slides we knew there was a crack. Hmm ... it had gotten wider over the last few years.

It was time to get a professional opinion. Angie's List turned up lots of basement waterproofers, but only a couple of basement repair firms. We contacted the one at the top of the list, and learned about 'curb creep.'

The affected walls were around two faces of the garage. Concrete, it turns out, is very stiff and transmits force. (Note that asphalt surfaces can develop slumps and ridges but concrete surfaces just crack.) Our driveway and garage floor were, of course, concrete. For 23 years the parking of cars had been transmitting shocks to the top course of blocks, where the garage pad meets the foundation.

We were told that this was not a serious structural issue, in a safety sense -- our walls would not come tumbling down -- but that the walls of the house supported by these blocks would warp and could cause drywall cracking, sticky doors, and such. We hope to stay in this house for another 20 years, so we decided to have it fixed.

The remedy was to install four "Power Braces", 4" steel I-beams, to prevent any further shifting. They are five feet apart and 2½ feet from the corner.

One of the braces had interference from a cold-air return duct. Its position was shifted to a point where only a minor cut-out of the end of the duct was needed, as seen above.

Here's a closer view of the corner.

The cracks were all sealed.

No bracing was needed on the other wall, above, because it was felt that it was cracking solely to accommodate the shifting of the first wall. If the crack reopens, that theory will have to be revisited.

Here's a closeup of the top of the Power Brace. It's connected to the floor joist, which can disperse and rebound from the stresses applied to the wall. Proper torque on that compressing bolt is 40 ft-lbs and no more. If the blocks retreat a bit, one can retighten to 40 ft-lbs.

We're hoping this will satisfy the domicile deities for a while. As it was, this gave me an "opportunity" to reorganize those portions of the basement that had to be cleared out for the work.