Short answer: An accessory dwelling unit is a small, dense building where a lot of systems live close together, so problems that would take years to surface in a big house can show up in months. A little seasonal attention keeps the roof, the envelope, and the mechanical gear working, protects your rental income, and stops small issues from turning into the kind of water and mold repairs that cost real money. Here is a practical, ADU-specific rhythm you can follow across the year.
An accessory dwelling unit is a small, dense building where a lot of systems live close together, so problems that would take years to surface in a big house can show up in months. A little seasonal attention keeps the roof, the envelope, and the mechanical gear working, protects your rental income, and stops small issues from turning into the kind of water and mold repairs that cost real money. Here is a practical, ADU-specific rhythm you can follow across the year.
Spring and Summer: Water, Air, and the Envelope
Warm months are the time to deal with anything water-related while it is dry enough to actually inspect. Walk the roof or scan it with binoculars for lifted shingles, cracked sealant around vent penetrations, and debris trapped behind the ridge; on a flat or low-slope ADU roof, clear standing-water spots and check that scuppers and drains run clear. Clean the gutters and, just as importantly, confirm the downspouts carry water at least a few feet away from the foundation rather than dumping it against the slab, since a compact building has very little soil buffer around it. Spring is also the moment to service cooling. Many ADUs run on ductless mini-splits, and their filters and outdoor condenser coils clog faster than people expect, quietly cutting efficiency and shortening compressor life. Rinse the reusable filters monthly during heavy use, keep the outdoor unit clear of leaves and mulch, and make sure the little condensate line is draining freely so it does not back up inside the wall. Finally, look at the exterior finish: touch up any bare or peeling paint and re-caulk gaps around windows and doors before the sun bakes the joints open.
Fall and Winter: Sealing Up Before the Cold
Before the first cold snap, the goal is to keep heat in and moisture out. Replace worn weatherstripping and door sweeps first, because in a small unit a single leaky door is a meaningful share of the whole building's heat loss and it shows up directly on the tenant's utility bill. If your ADU has a tankless water heater, run the manufacturer's descaling or flush cycle annually; hard-water scale is the number one reason these units lose output and throw error codes, and a flush is far cheaper than a callout. Test every smoke and carbon monoxide alarm and swap batteries on a fixed date so you never guess, and if there is any gas appliance, confirm it vents properly. Where winters bring hard freezes, insulate or heat-tape any exposed supply lines, know where the ADU's own shutoff valve is, and consider leaving a cabinet door open under a north-wall sink on the coldest nights. Reverse the heating side of the mini-split maintenance too: clean filters again and clear snow or debris from around the outdoor unit so it can defrost.
The Small Habits That Prevent Big Repairs
Most expensive ADU repairs trace back to something small that nobody caught in time, so build a couple of five-minute habits into the year. Once a season, look under sinks and around the water heater and washer connections for the faint mineral crust or dark spots that mean a slow drip; catching a supply-line weep early is the difference between a wrench-tighten and a floor replacement. Keep a simple log of when you last flushed the water heater, changed filters, and cleaned the gutters, because a compact unit that gets sold or refinanced later is far easier to document when you can show consistent upkeep. If the ADU is tenant-occupied, give whoever lives there a short one-page cheat sheet with the location of the shutoff valve and electrical panel and a request to report any drip, musty smell, or alarm chirp immediately; the person living in the space is your best early-warning sensor, and a quick text from them beats discovering a problem at move-out. None of this requires a contractor, and it is exactly the maintenance that lets the more expensive systems reach their full lifespan.
Frequently Asked Questions
Spring and Summer: Water, Air, and the Envelope?
Warm months are the time to deal with anything water-related while it is dry enough to actually inspect. Walk the roof or scan it with binoculars for lifted shingles, cracked sealant around vent penetrations, and debris trapped behind the ridge; on a flat or low-slope ADU roof, clear standing-water spots and check that scuppers and drains run clear. Clean the gutters and, just as importantly, confirm the downspouts carry water at least a few feet away from the foundation rather than dumping it against the slab, since a compact building has very little soil buffer around it. Spring is also the moment to service cooling. Many ADUs run on ductless mini-splits, and their filters and outdoor condenser coils clog faster than people expect, quietly cutting efficiency and shortening compressor life. Rinse the reusable filters monthly during heavy use, keep the outdoor unit clear of leaves and mulch, and make sure the little condensate line is draining freely so it does not back up inside the wall. Finally, look at the exterior finish: touch up any bare or peeling paint and re-caulk gaps around windows and doors before the sun bakes the joints open.
Fall and Winter: Sealing Up Before the Cold?
Before the first cold snap, the goal is to keep heat in and moisture out. Replace worn weatherstripping and door sweeps first, because in a small unit a single leaky door is a meaningful share of the whole building's heat loss and it shows up directly on the tenant's utility bill. If your ADU has a tankless water heater, run the manufacturer's descaling or flush cycle annually; hard-water scale is the number one reason these units lose output and throw error codes, and a flush is far cheaper than a callout. Test every smoke and carbon monoxide alarm and swap batteries on a fixed date so you never guess, and if there is any gas appliance, confirm it vents properly. Where winters bring hard freezes, insulate or heat-tape any exposed supply lines, know where the ADU's own shutoff valve is, and consider leaving a cabinet door open under a north-wall sink on the coldest nights. Reverse the heating side of the mini-split maintenance too: clean filters again and clear snow or debris from around the outdoor unit so it can defrost.
The Small Habits That Prevent Big Repairs?
Most expensive ADU repairs trace back to something small that nobody caught in time, so build a couple of five-minute habits into the year. Once a season, look under sinks and around the water heater and washer connections for the faint mineral crust or dark spots that mean a slow drip; catching a supply-line weep early is the difference between a wrench-tighten and a floor replacement. Keep a simple log of when you last flushed the water heater, changed filters, and cleaned the gutters, because a compact unit that gets sold or refinanced later is far easier to document when you can show consistent upkeep. If the ADU is tenant-occupied, give whoever lives there a short one-page cheat sheet with the location of the shutoff valve and electrical panel and a request to report any drip, musty smell, or alarm chirp immediately; the person living in the space is your best early-warning sensor, and a quick text from them beats discovering a problem at move-out. None of this requires a contractor, and it is exactly the maintenance that lets the more expensive systems reach their full lifespan.
How do I get help with this?
Call (877) 300-2747 and describe the situation, your exact location, and what you need. Timing is confirmed on that call rather than promised in advance.
Call for help: (877) 300-2747 — a straight answer and an honest estimate before any work begins.