Most of the Highlands went up between 1960 and the mid-eighties, and the siding tells you the decade — rough-sawn cedar and T1-11 on the seventies split-levels, painted lap and brick wainscot on the older ranches off Curling Drive. Each one fails differently, and each one stains from a different direction.
Walk the north and northeast elevations up here and you will find the same thing: a gray-green film in the grooves of the T1-11, dark streaking under the eave, a fuzzier bloom where a juniper crowds the wall. That is algae and mildew, not dirt. It gets a foothold here because the hill and the mature junipers shade those walls most of the day, and because the nightly downslope air off the Boise Front holds cold and damp against the siding hours longer than a flat Bench lot ever does. You can blast it with pressure and it will look clean for a season, because you removed the visible top layer and left the root structure in the wood grain. Soft washing uses a cleaning solution that kills the organism first, then rinses it off. That is why it stays gone longer.
Almost every Highlands house has it — a horizontal band across the lower two or three feet of siding where the heads throw onto the wall instead of the lawn. Two things are in that band. One is mineral: Veolia water up here commonly runs 10 to 13 grains per gallon, and at 100 degrees the droplet flashes dry and leaves the calcium behind as a chalky crust. The other is dirt. Beds up here are decomposed granite and bark rather than sod, so every cycle kicks pale grit onto the wall and it packs into the grooves. On painted lap it reads as a white haze. On cedar it goes gray, sometimes with an orange cast where iron in the line has met the tannin in the wood. Honest note: that orange is a rust stain, and it is a separate chemical treatment, not something soft washing lifts.
South and west elevations are the opposite problem. At roughly 2,900 feet with no shade, forty years of UV breaks the binder in old latex and leaves loose pigment powder sitting on the surface. Rub the wall with a dark rag — if the rag comes back the color of your house, that paint is chalking. Here is the part nobody tells you: washing chalked paint is not a cosmetic fix. Removing the chalk exposes whatever is underneath, and if the coating has failed unevenly you get a blotchy wall and vertical clean streaks where the rinse water sheeted. We test a low patch first. If the south side is far enough gone that washing will only make the fade obvious, we say so, wash the elevations that will actually respond, and leave that wall for the painter.
T1-11 is plywood with a face veneer. Put a pressure tip on it and you fur the grain, chew out the grooves, and drive water behind the shiplap joints where nothing dries. Cedar does the same, only faster, and once the surface is raised it holds dirt worse than it did before. So on siding we run soft wash: pre-wet the foundation plantings, apply the solution at low pressure, let it dwell so it does the work chemically, then rinse at a pressure closer to a strong garden hose than a pressure washer. That is $0.18 per square foot and it is safe on cedar, T1-11, hardie, stucco, vinyl and painted lap alike. Pressure still has a place here — driveways, patios, the concrete stairs down the slope — just not on the walls of your house.
Best window is late May through September, after the irrigation system has pushed its dirty first water through every head and while the walls will dry the same afternoon. We work off the ground here, so the slope matters more than the height — on a daylight basement the downhill elevation is three stories from the low grade, and we reach it with poles rather than standing a ladder on loose granite. House washing is $0.18 per square foot. Memberships run monthly or quarterly with no contract, and every job carries a 7-Day Rain Guarantee, which is worth something on a hill where one squall can put the whole slope back on your siding. Locally owned, fully insured, 4.9 stars across 115+ Google reviews. Same-day and next-day slots are often open. Call (208) 453-6760.
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Not the way we do it. The damage people picture comes from a pressure tip held on wood, which raises the grain on cedar and chews the grooves out of T1-11 plywood. Soft washing does the work with cleaning solution and dwell time, then rinses at roughly strong-garden-hose pressure. Nothing on your walls sees the kind of force that splinters siding or pushes water behind the joints.
Because whatever cleaned it last time probably removed the surface layer and not the organism. Algae roots into cedar grain and into T1-11 grooves, so a pressure rinse takes the color off and leaves the colony. It regrows from there. Shade is the other half — north walls up here sit in juniper shade and hold the cold, damp downslope air overnight, which is exactly what it needs.
No, and we would rather tell you before than after. Chalking is the paint binder breaking down under foothills UV, leaving loose pigment on the surface. Washing removes that powder, which can actually make the fade more visible and can streak if the coating failed unevenly. We test a hidden patch first. If your south wall is at that stage, it needs paint, not washing.
Leave the system alone — just skip the cycle the morning of, so we are not working a soaked wall. Plants get pre-wet before we apply anything and rinsed again after, which is what actually protects them. Foundation beds up here are usually juniper, barberry and decomposed granite rather than delicate perennials, but tell us about anything you have babied and we will tarp it.
It prices at $0.18 per square foot of wall surface, not floor plan. A typical Highlands split-level with a walkout lower level lands higher than the number people expect from the street view, because the downhill elevation is a full extra story of wall. Send a photo of the front and the downhill side and we can quote it over the phone at (208) 453-6760.
Yes, and that is the right order — siding first, glass second, because a soft wash rinse will spot windows that were already done. Window work uses 100% pure deionized water with no soap, so the panes dry clean with nothing left on them. Bundling saves a trip on these narrow streets off Bogus Basin Road, where parking twice is its own project.
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