Why flat additions on Castle Hills ranch homes leak first
A lot of family rooms, dens and enclosed patios here were added decades after the house was built, often with a nearly flat roof tied into the main shingle slope. If the addition was framed without enough pitch, water sits in low spots after a storm. Over time, the old rolled roofing or built-up tar cracks under that ponding and the summer heat.
The tie-in is the weak link. Shingles from the main roof should lap over the flat membrane with metal flashing between, but older additions sometimes rely on tar and patches. We cut back to sound material, add tapered insulation or crickets where the slope is too flat, and install a new membrane with a proper transition. Our low-slope repair work starts with a water test to confirm where it's actually getting in.
Picking a membrane for a small low-slope roof
For residential additions and carports, we mostly install two systems. Modified bitumen is a thick, layered roll roofing that handles foot traffic and patches easily. TPO is a white single-ply sheet with heat-welded seams that reflects summer sun and keeps the room below cooler.
Either is a big step up from the old rolled roofing that many 1960s carports still have. If the flat section is small and the deck is solid, a silicone coating can extend its life for a while, but coating over wet insulation or soft decking just traps the problem. We'll tell you which situation you have after looking.
Keeping the shingle roof above in step with the new flat section
When the flat roof is replaced, it's a good time to check the shingle roof that drains onto it. Mature trees in Castle Hills shade those slopes, leaves collect in the valleys, and wind pushes that debris down onto the flat section, where it clogs scuppers and drains. Clearing those paths matters as much as the membrane.
If the main roof is near the end of its life, replacing both at once usually costs less than two separate projects and gives you one clean transition. Read our article on flat roof options for older homes if you're still weighing materials.
