Low-slope
Same porch, same drip, and a third repair on the way
If the porch, back kitchen or addition roof drips after every repair, ask about its slope before anyone touches another shingle. Tell us which roof it is. We book an independent roofer to measure the pitch and say what that roof can carry, and the answer goes into a written proposal.
Asking where the water gets in commits you to nothing.
What we do
We help you find where the water really gets in and book a diagnostic visit with an independent roofer, who puts the fix in a written proposal.
Our word before the ladder goes up
- You owe nothing for asking, and you can walk away.
- The visit looks for the way in before any roof talk.
- You see the repair proposal in writing before work starts.
- The $100 credit follows the rules on our Terms page.
The roofer you hire answers for their own work and contract.
Signed Roofing Pros Syracuse, (315) 640-3590
What this word covers
The drawing
Where your porch roof sits on the ladder
- 1
Under 2:12
- 2
2:12 to 4:12
- 3
4:12 and steeper
- 4
Your porch roof
- 2:12 mark Below this rise, the code does not allow asphalt shingles.
- 4:12 mark Between 2:12 and 4:12, shingles need a double underlayment.
- Shingle bracket Shingled roofs belong at 2:12 or steeper.
- Membrane bracket Membrane products cover the flatter roofs the shingles cannot.
Questions
Settle these before the work is priced
Can shingles go on a porch roof at all?
Yes, if the roof is 2:12 or steeper, with a double underlayment between 2:12 and 4:12. Below 2:12 the code does not allow asphalt shingles, so the roofer should propose a product made for low slopes.
What is a 2:12 pitch in plain terms?
The roof rises 2 inches for every 12 inches it runs sideways. Do not climb up to measure it; ask the roofer to write the pitch down.
Is a membrane roof the same as a flat roof coating?
No. A membrane is a sheet product laid and sealed across the roof. A coating is a liquid applied over an existing surface. Ask the roofer to name exactly what is proposed.
Why did the last roofer not mention slope?
A repair can be done at the visible drip without anyone measuring the roof. Ask any roofer for the pitch as your first question, and expect a number.
Does a flat roof still need to drain?
Yes. The code asks for a slope to the edges or a drain at each low point. Ask where the water goes on the finished roof.
Can my porch roof be repaired without a new product?
If the roof is steep enough for shingles, a repair at the true cause may hold. The measured pitch is what decides, so get that number first. It answers the porch only, so ask for it as its own line.
What does the proposal need to show?
The pitch of each section, the named product, how the wall joint and low edge are handled, and where the water leaves. Ask for each of them as its own line.
How do I look after the porch roof until the visit?
Put a bucket or towel under any drip, and take a dated photo of each stain with the weather noted. Keep clear of light fittings and switches near the wet spot. A sagging ceiling means keeping people out of that room and calling the roofer. Stay off the roof. Hold off on more sealant or tar, because every new layer makes the old covering harder for the roofer to read.
By timing
What each stain timing changes on a low roof
- 1
Only in or after rain
A drip in rain on a flat roof sits at the low edge or at the wall where the roof meets the house. The roofer checks both, after measuring your roof's pitch.
- 2
After a cold, clear night
A porch ceiling can stain after a clear cold night because room air reaches a shallow roof deck. The roofer tells that apart from a leak before proposing a new product.
- 3
When snow melts
In a thaw a flat roof holds meltwater longer than a steep one. The roofer looks at whether the water has a way to the edge or a drain.
- 4
Same spot after every repair
The same spot after every repair is the classic sign of a slope problem. Shingles belong on 2:12 or steeper, so the pitch is measured first and the product follows from it.
Signs
Signs a roof is too flat for its covering
A repair on top of a repair
Patches, tar and extra shingles on one small roof show that earlier fixes did not hold. Tell the roofer the order they went on.
Shingles on a roof that looks level
If you can hardly see the pitch from the yard, ask what it measures. Flatter than 2:12 is outside what the code allows for shingles.
Water that stays after rain
Puddles or dark stains that linger on the roof surface mean the water is not leaving. That is a slope and drainage question.
A stain where the porch meets the house
A drip at the wall line of a lower roof is common on additions. The wall joint and the slope both need a look.
A porch ceiling that stains often
If your stain returns every season, write down which weather brought it. That pattern helps decide between slope and condensation.
What it covers
What a low-slope repair covers
Get the pitch measured
The roofer measures the rise over 12 inches of run and records the result for each roof section.
Identify the covering
They note what is on your roof now, how many layers there are, and how it was fastened.
Check the wall joint and edge
Where the low roof meets the house wall, and where it ends at the gutter, are looked at closely.
Match product to slope
The proposal names a product made for the measured pitch, such as a single-ply membrane.
Plan where water leaves
The roofer shows how water will reach the edge or a drain on the finished roof.
The sequence
What happens, in order, on a low roof
Tell us which roof it is
You describe the porch or addition and how many repairs it has had.
The pitch gets measured
An independent roofer measures each section of your roof and looks at the wall joint.
You hear what fits
The roofer tells you whether shingles can stay or a different product is needed.
You read the proposal
The work, the product and the water path are written down before anything begins.
Where you are
Find out first, then repair, then fix the cause
The order is the point. Each step stops the next one from being a guess.
- 01
Find out where it gets in
An independent roofer visits to find the way in. You get the answer before anyone talks about a covering.
- 02
Repair that one thing
This pageThe roofer sets out the specific repair. The written proposal covers the work they would do. You read it before work starts.
- 03
Deal with the cause
Air sealing, venting or drainage comes after. Then the stain is less likely to return next winter.
How to tell whether your porch roof is too flat
You do not need to climb up to start. The roofer should measure the pitch and write the number into the proposal. Two inches of rise over 12 inches of run is a 2:12 pitch, and four inches is 4:12.
The number matters because it decides what product belongs on the roof. Do not accept an answer of "it looks fine" when the question is slope.
A house with a porch, a back kitchen and a dormer may have three different pitches. Ask for one number per section, and send us which sections leak. They tell the roofer where to start, and you can check the proposal against them.
Why patching shingles on a flat roof keeps failing
A shingle works because water runs downhill off it. When the roof is nearly level, water can creep sideways under the laps and find a nail, so another patch changes very little. That is why the code sets a minimum slope for shingles in the first place.
If your roof has been repaired more than once in the same place, ask the roofer one question: what is the pitch, and is that steep enough for what is on it? The honest answer may mean a different product, not a third repair.
What a membrane roof is, and what to ask
Single-ply membranes such as EPDM, TPO and PVC are made for low slopes. The code sets a design slope of at least a quarter unit in 12 for them, so even a nearly flat roof must still be shaped to drain. Mineral roll roofing is not allowed below 1 in 12.
Ask the roofer which product they propose and what slope it is made for. Ask too how the edges and your house wall are finished, because those are the places a flat roof is most likely to let water by.
If the roof has nowhere to send its water
A roof that does not slope to its edges needs a drain at each low point, and a clogged or missing one lets water stand. Look from the ground or an upstairs window after the next rain. Water still sitting there a day later is a finding the roofer needs to hear about.
Send us what you see and the roofer will have it before the visit.
Before you agree to a different product
A change of product is a bigger step than a patch, so slow down and ask for the reasons. Ask the roofer to show you the measured pitch, name the product and explain why it suits that slope. Ask what the old covering is and whether anything under it needs attention.
Then ask how the finished work meets the house wall, and where it ends at the gutter. Those two places decide whether the roof keeps water out, because a good membrane on a poor joint still leaks.
It is worth asking what the roofer will do if something unexpected turns up once the old covering is off. A good proposal says how you will be told before work continues.
Paperwork
What the proposal should say about the slope
The measured pitch
A number for each section of your roof, not a description like "fairly flat".
The product and why it fits
The covering named, with the slope it is made for.
The edges and the wall joint
How the roof is finished at the house wall and at the low edge.
Where the water leaves
The way to the gutter or a drain on the finished roof.
Price
What moves a low-slope proposal
- The area of each flat section
- How many separate low roofs the house has
- The product chosen for the pitch
- How the roof meets the house wall
- What the boards under the old covering look like
- Whether water needs a new route to leave
Where
Low-Slope Roofing pages by place
Reading
More on porch and addition roofs
Porch Roof Leaks After Repairs: What the Slope Tells You
Get the pitch measured before the next repair.
Tell us which roof keeps leaking and book the visit.