A Mini-Split Line Through Your Wall Belongs in the Roof Plan

A mini-split heat pump has two halves. The indoor head mounts on a wall, and the outdoor condenser sits on a pad or bracket. Between them runs a bundle of insulated refrigerant lines with a condensate drain alongside, passed through a hole in the exterior wall. In many Chesterfield houses that hole is in a finished lower level, a bonus room over the garage, or a rear addition, and it is often placed high on the wall because that is where the indoor head mounts. High on the wall means close to the eave, and that is the detail a roof replacement can run into.

This page is for the homeowner who already has a mini-split, or who is weighing one while the roof is still on the house. A roof crew does not install or service a mini-split. Keys Roofing is a roofing contractor, and a line set is mechanical work. What the roof job does is move ladders, staging, gutters and drip edge right past that line set, and it can change the water path that the condensate drain depends on.

Town roofing

Many Chesterfield houses built over the last few decades sit on lots large enough for a finished lower level and a rear addition. Those additions are common places for a mini-split, because a ductless unit runs off a small line set and avoids a full duct run. A roofer walking a Chesterfield roof will often find a line set on a back wall near the gutter, and sometimes on a side wall where an addition's roof meets the main house.

The hole through the wall is usually sealed with caulk, foam backer or a wall sleeve. That seal is part of the exterior wall, and on many of these houses it sits just under the soffit or fascia. When the roof comes off, the roofer will work the drip edge and starter course along the eave, and the gutter will be unhooked and rehung. Each of those steps passes within a few inches of the line set.

The freeze and thaw cycle makes this worse. A St. Louis winter brings days below freezing followed by days above it, and the condensate drain on a heat pump often runs outdoors. Water that stops in a low spot of a drain line can freeze and back up toward the unit. For the roof job, the question is whether the drain outlet sits where the new eave detail or new gutter discharge will send water onto it, or where ice from the eave can land on it.

Where the line set exits and why the eave matters

Check three points before the roof date is set: where the line set leaves the house, how far it sits below the soffit, and where the condensate drain exits. A line set that comes through the wall a foot or more below the soffit and clear of the gutter usually sits out of the roof work. A line set that comes through the fascia board, or sits within a hand's width of the drip edge, needs a plan.

A fascia-mounted line set deserves a closer look. The fascia is part of the eave detail, and the roofer may need to lift the drip edge and, in some cases, the fascia board itself. If the line set is caught in that work, the crew should stop and call you before cutting or pulling anything. A line set that is pulled, kinked or split at the wall can take the unit down, and that repair is a refrigerant job, not a roofing job.

The condensate drain is the other item to check. Many installs run the drain down the wall below the line set and let it drop onto a splash block or into gravel. If the new gutter discharge or drip edge sends water over that spot, the drain can end up under a stream of roof runoff. Ask whether the drain outlet will sit below the new discharge point, and whether the drain line stays in place through the tear-off.

What the roof crew needs from you

The crew needs to know the line set is there before the first ladder goes up. Walk the wall with the roofer on the first visit and point out the line set, the condensate outlet and the wall sleeve. Photograph them from the yard, and ask that those photographs go into the job file with the shingle and gutter photos, so the line set is recorded in the same place as the rest of the work.

Plan for the ladder. Crews set ladders against the eave, and a ladder rail can land on a line set cover if the wall is the only surface available. Ask where the ladder will sit on that wall, and whether the crew will use a stand-off or ladder jack that does not lean on the line set or its cover. A cover that cracks under a ladder rail is a visible failure you will see on the first day.

Plan for the dropped bundle. At many Chesterfield houses, shingle bundles come up on a hoist and land on a ground tarp or staging spot. A bundle that swings into a line set cover can crush the cover or push it off the wall. Ask where the hoist line will swing, and whether the crew will keep bundles on the far side of the house from the mini-split.

Ask the City of Chesterfield whether the mini-split was permitted, and ask the installer whether a mechanical permit was pulled for the work. A roofing permit usually covers the roof work and does not cover the line set. Ask your roofer whether the roofing permit will be pulled before the tear-off and whether the roofer has seen the mechanical permit on the house. A roofer can tell you what the roof permit covers. The mini-split installer answers for the mechanical side.

What it costs

The roof bid should show the line set as a known item with a line of its own. A typical bid carries a line for detaching and reinstalling gutter, a line for drip edge, and a line for flashing at the wall. Work on the line set, such as lifting it or resealing the sleeve, should appear as a separate line that says who does the work. If the roofer will only touch the wall sleeve seal, say so in the bid. If the roofer will not touch the line set at all, say that too, and ask who will be on the wall if the line set has to move.

Do not expect the roof bid to include refrigerant service. A roofing contractor does not disconnect, drain or reconnect a mini-split. If the line set must be disconnected for the tear-off, the HVAC installer does that work, and the homeowner pays that installer separately. Get that cost in writing before the roof date is set, because the HVAC visit has its own schedule.

What to ask

Ask the roofer in writing where the line set and condensate drain will be after the work is done. A scope that says the line set stays in place, the sleeve is resealed and the drain is re-pointed to daylight is a scope you can check on the day. A scope that says the crew will work around the mini-split is not specific enough to check.

Ask the mini-split installer, if you have one, whether the line set can be left in place for the rehang work, whether the sleeve seal will be replaced after the roof is finished, and whether the condensate outlet will be moved. Ask for the answers by email.

Ask whether the crew will keep staging boards and foot traffic off the wall below the line set. Roofers often rest a staging board on the eave. If the board bears on the wall and the line set sits behind it, the board can push the line set. Ask where the staging board will go before the first day.

Call the Keys office at (314) 220-2333 to set a walk of the wall before the roof date is fixed. Ask for the crew to photograph the line set, the sleeve and the condensate outlet on that walk, and ask for the list of what they plan to leave alone in writing.