Two buildings stitched together
A pop-top raises a one-story house by adding a full or partial second floor on top of the original walls. A rear addition extends the footprint into the backyard. Both are common around Washington Park because lots are narrow and owners want space without moving. Both also create places where an old roof plane, old siding or old brick meets new framing, new flashing and new roofing, sometimes decades apart.
Those transitions are where leaks start. A valley where a new roof meets an old one can back up with ice. Step flashing along a new wall that rises above an older lower roof can be missing, short or covered over. The line where new siding meets original brick may rely on sealant that has dried out in Denver's sun. Water that gets in at these points rarely shows up right where it entered. It runs along framing, follows a top plate, and appears as a stain on a plaster ceiling in the original part of the house, sometimes a room or two away.
Roof leak or plumbing leak?
A stain in a ceiling below a pop-top could be either. These patterns help narrow it down before you call anyone.
| Points toward the roof or addition seam | Points toward plumbing |
|---|---|
| The stain grows after rain, snowmelt or wind-driven storms | The stain grows after showers, baths or laundry upstairs |
| It sits near an outside wall or under a roof valley | It sits under a bathroom, laundry or kitchen on the new floor |
| It stays dry for weeks in dry weather | It appears or spreads in dry weather |
| There are icicles or ice ridges at the same spot in winter | The water meter moves when every fixture is off |
What to check from inside and out
- From the ground or with binoculars, look at the valleys and the line where the new walls meet the old roof.
- Look for missing or rusted flashing where a chimney passes the new roof line.
- Check attic spaces or knee walls of the original house for water marks on rafters or sheathing.
- Press gently on stained plaster: soft or bulging spots mean water is still present above.
- Note which rooms were original and which were added; it helps any roofer or contractor trace the path.
Questions for a roofer or contractor
Ask before any repair is closed up, and photograph what they find.
- Is the flashing at the old-to-new transitions continuous, or was it pieced in?
- Do the original and new roofs drain into each other, and is the gutter sized for that?
- Is there a path for ice dams to form above the original eaves?
- Has water reached the framing or insulation of the addition, and does it need to be opened?
- Was the addition permitted, and do you have the plans? They can show how the seam was designed.
General information for Washington Park, not a quote or professional advice. In an emergency, call 911.