Parts of a Roof, Explained for Baltimore Homeowners
What each part of your roof does, what usually goes wrong with it, and what to call it when you call us about a problem.
Call 443-900-4815Roof diagram
A typical Baltimore-area house with the main parts labeled. The box on the right is a close-up of the roof edge. Leaks often start at the flashing, the valleys, a pipe boot or the chimney, not out in the middle of the shingles.
What each part does and what goes wrong
Here's each part from the diagram in plain English, starting at the top of the roof and working down.
Ridge and ridge vent
The ridge is the peak where two slopes meet. It's covered with ridge cap shingles, and a lot of roofs have a ridge vent under them that lets hot, damp air out of the attic. Wind lifts and cracks ridge caps, and a vent that wasn't put in right can let rain blow in. Ridge and shingle repair
Shingles
Shingles are the part you see. They shed water down the roof and protect everything under them. Wind tears them off, the granules wear away with age, and tree limbs crack them. A few missing shingles is usually a repair, not a new roof. Shingle replacement
Underlayment
Underlayment is the layer between the shingles and the wood. It's the backup that catches water that gets past the shingles. Once the shingles over it are gone, sun and rain break it down. Roof leak repair
Roof deck (sheathing)
The deck is the plywood or boards nailed to the rafters, and everything else is fastened to it. A leak that goes on for a while rots it, and you'll feel soft or spongy spots when you walk on it. We replace the bad sections when we find them during a repair. Roof repair
Flashing at chimneys and walls
Flashing is bent metal that seals the spots where the roof meets something else, like a chimney, a dormer or a wall. A lot of the leaks we find start here. Old caulk dries out, nails back out, and the metal rusts or gets pulled loose. Roof flashing repair
Step flashing
Step flashing is a row of small L-shaped metal pieces woven in with each row of shingles where a sloped roof runs along a wall. When it's missing, or someone used one long strip and caulk instead, water gets behind the siding and shows up on a wall or ceiling inside. Roof flashing repair
Valley
A valley is where two roof slopes meet and form a channel. It carries more water than any other spot on the roof, so worn shingles, leaves and bad nailing there turn into leaks. Roof leak repair
Drip edge
Drip edge is the metal strip along the edges of the roof. It sends water into the gutter instead of letting it curl back onto the wood. When it's missing, you usually find rotted fascia and deck edges. Roof repair
Rake edge
The rake is the sloped edge of the roof on the gable end. It takes a lot of wind, so the shingles and trim along it get lifted or blown off. Loose rake trim lets water and critters in. Trim, soffit and fascia repair
Pipe boot (plumbing vent)
A pipe boot is the rubber collar that seals around the plumbing vent pipe sticking out of your roof. The rubber cracks in the sun over the years, and water runs right down the pipe into the house. It's one of the most common small leaks we fix. Roof leak repair
Gutters
Gutters catch the water coming off the roof and carry it to the downspouts. When they clog, sag or pull away, water spills over and soaks the fascia, the siding and the foundation. Gutter repair and cleaning
Downspouts
Downspouts carry gutter water down and away from the house. A clogged or disconnected downspout dumps water right at the foundation, which is how a lot of basements end up wet. Gutter repair and cleaning
Fascia
Fascia is the board along the bottom edge of the roof that the gutters hang on. When water gets behind the gutter or the drip edge, the wood rots and the gutters start to sag. Soffit and fascia repair
Soffit and soffit vents
The soffit is the underside of the roof overhang. Its vents let fresh air into the attic, and that air leaves through the ridge vent, which helps keep the attic dry. Rotted or broken soffits let in water, squirrels and birds. Soffit and fascia repair
Chimney cap
The chimney cap is the metal cover on top of the flue. It keeps rain, leaves and animals out of the chimney. A missing or rusted cap lets water run straight down inside. Chimney cap installation
Chimney crown
The crown is the concrete slab across the top of the chimney around the flue. It should slope so water runs off. Cracks let water into the brick, and Baltimore's freeze and thaw winters make them bigger. Chimney crown repair
Chimney flashing
Chimney flashing is the metal that seals where the chimney comes through the roof. It's a common spot for leaks, especially when it's been patched with tar or caulk instead of being set into the brick. Chimney flashing repair
Parts of a flat rowhouse roof
A lot of Baltimore rowhouses have flat roofs, which really have a slight pitch toward the back or toward a drain. The parts are different from a shingle roof, and so are the problems.
Membrane
The membrane is the waterproof layer, usually rubber (EPDM), torch-down (modified bitumen) or a coated roof. Sun, standing water, and people walking on it wear it out, and it gets punctured by things left up there. Flat roof repair
Seams
Seams are where the sheets of membrane overlap and get glued or heat-welded together. They're usually the first place a flat roof leaks, when the edge lifts or the seam opens up. Roof leak repair
Parapet walls and coping
The parapet is the short brick wall along the edge of the roof and between rowhouses. The coping is the metal or stone cap on top of it. Gaps in the coping and cracked brick let water into the wall, and it shows up inside along the party wall.
Scupper
A scupper is the opening in the parapet that lets water drain off the roof into a gutter box or downspout. When it clogs with leaves, water backs up on the roof and finds a way in. Gutter and drain cleaning
Roof drain
Some flat roofs drain through an inside drain in the roof. If the drain clogs or the seal around it fails, you get standing water and a leak right below it. Roof leak repair
Not sure which part is the problem?
Call or text 443-900-4815. You can also just text your address and a few pictures and we'll give you an honest read on what we see.
Call 443-900-4815
