Attic
Frost on the attic boards and a stain that grows on cold mornings
You see frost on the roof boards, or a ceiling stain that grew after a cold night with no rain. Tell us what you see. We book an independent roofer to trace the warm air from your rooms into the attic, and the order of work, sealing first and vents second, 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
Inside the attic, part by part
- 1
Room air
- 2
Ceiling gaps
- 3
Bath fan
- 4
Cold roof boards
- 5
Frost and drip
- 6
Soffit vent
- 7
Baffle gap
- 8
Upper vents
- Hatch Needs gasketing and insulation to the ceiling's level.
- Fan duct Should run outdoors by the shortest path it can.
- Baffle Keeps a clear channel from the soffit vent up under the roof boards.
- Upper vents Take 40 to 50 percent of the vent area when the 1/300 ratio is used.
Questions
Settle these before the attic is opened
Why does my attic have frost in it?
Warm, humid air from the rooms reached the cold roof boards and froze there. The frost turns to water when the attic warms. The fix starts with the air leaks, not only the vents.
Do more vents stop the stain?
Not on their own if warm air keeps reaching the attic from the ceiling. The Department of Energy guide says to seal air leaks before insulating, and it treats more ventilation as a priority in cold climates. Our advice: ask the roofer to put air sealing first on the proposal and to show the vent sum, so you can see both.
What is the 40 to 50 percent rule?
Code allows a vent ratio of 1/300 instead of 1/150 only when 40 to 50 percent of the vent area is in the upper vents. Ask the roofer how your attic splits.
Is my bath fan part of this?
It can be. A fan that ends in the attic adds steam to it. The fan should vent outdoors by the shortest path.
Can I use gable vents with a ridge vent?
The Department of Energy guide advises against it, because the gable openings can short-circuit the air that soffit vents bring in.
Does insulation block the vents?
It can. The code requires a clear space between insulation and the roof boards at the vent, and baffles keep that space open.
Will sealing make the house too humid?
It can raise indoor humidity, which is why the guide pairs sealing with balanced ventilation. Ask the roofer how they plan to handle that.
What can I do in the attic before the visit?
Keep the hatch clear and closed against drafts, and run the bath fan during showers and for a while after, and make sure it vents outdoors. Aim for indoor humidity in the 30 to 50 percent range. Do not add insulation over the vents or start sealing yet. Look only from the hatch opening and keep off the insulation. Photograph the roof boards from there, and send the pictures with your request, with the date you saw the frost.
By timing
What each stain timing changes in the attic
- 1
After a cold, clear night
This is the timing the attic job exists for. The roofer looks for frost and dark patches on the roof boards, then follows the warm air back down to the gaps that feed it.
- 2
When snow melts
A stain in a thaw can come from heat escaping into the attic and melting what sits above it. The roofer looks at the insulation at the eave, which can be thin or squashed.
- 3
Only in or after rain
A stain that follows rain does not point at the attic first. The roofer sets ventilation aside and looks at the joints and the slope.
- 4
Same spot after every repair
The same spot every cold morning often sits under a bath fan, a hatch or a light box. The roofer starts there.
Signs
Signs the attic is where the stain starts
Frost on the roof boards
White crust on the underside of the boards on a cold morning is water that froze out of the air. Photograph it from the hatch opening before it melts, and keep off the insulation.
A stain after a clear, cold night
If the roof was dry, rain probably did not cause it. The attic's warm air is the first suspect.
A bath fan that ends in the attic
Ask the roofer to follow the duct from the fan. If it stops inside the attic, the steam goes up there.
Insulation over the soffit vents
Insulation that covers the low vents cuts off the air that should enter there. Look at the edges of the attic floor.
A drafty hatch
A hatch that does not seal lets room air straight up. Hold a hand near the edge on a windy day.
What it covers
What an attic job covers
Seal the ceiling
The roofer or another trade seals light boxes, wire holes, pipe chases and the hatch before anything else.
Send the fan outdoors
A bath fan duct that ends in the attic is rerouted to vent outside.
Open the soffit path
Baffles are placed so insulation cannot block the vents at the low edge.
Balance the vents
The roofer works out how much vent area the attic needs and how it is split between low and high.
Check the other vents
Gable vents sitting beside a ridge vent are checked for how they affect the airflow.
The sequence
What happens, in order, in the attic
Tell us what the attic does
You send what you saw on a cold morning, and whether a stain followed.
The roofer traces the air
An independent roofer follows warm air from the rooms up into the attic.
You hear the order of work
The roofer says what to seal, what to vent and in what order.
You read the proposal
Each step is written down, with the vent split stated, before work starts.
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
The 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
This pageAir sealing, venting or drainage comes after. Then the stain is less likely to return next winter.
Seal the ceiling, then count the vents
Vents move air, but the ceiling decides how much warm air gets up there to begin with. The energy code asks for a continuous sealed air barrier, and says insulation that lets air through cannot count as the seal. Gaps at the hatch, light boxes and pipe chases come first.
The hatch deserves its own line. It should close on gasketing and carry insulation to match the ceiling. Ask the roofer to put every gap in the proposal as a separate item.
You can find some of the gaps yourself on a windy day. Hold a hand near the hatch edge and where pipes go up through the ceiling, and feel for moving air. Do not touch any wiring. Mark each spot with a note or a piece of tape on the ceiling side, and tell the roofer where they are. Your list shortens the search and keeps the proposal specific to your house. Send it with the form and we book the visit.
How the vent area should split between low and high
Proposals quote one of two ratios, so you should know which. Code sets vent area at 1/150 of the attic floor. It allows 1/300 only if 40 to 50 percent of that area sits in the upper vents. Onondaga County is in Climate Zone 5, so the split is the number to check on your proposal.
The Department of Energy guide favors 1/150 where condensation is likely, with the area split evenly between exhaust and intake. Ask the roofer which ratio they propose and how the numbers come out for your attic.
Gable vents and ridge vents work against each other
If your house has gable end vents and a ridge vent, tell the roofer. The guide says gable vents and ridge vents do not belong on the same roof, because the gable openings can short-circuit the airflow and defeat the soffit vents.
It is an easy thing to miss from the ground, and it is worth a look when the stain keeps coming back despite new vents. Photograph each vent from the ground and send the pictures with the form.
Humidity, sealing and the bath fan
Most sources recommend indoor humidity between 30 and 50 percent in the heating season. Sealing a house can leave the air more humid, so the guide pairs sealing with balanced ventilation to keep it in range.
Start with the fan. A bath fan should vent outdoors, not into the attic, and the duct should run as directly outside as it can. If you have two fans, ask about both, and tell us on the form where each one ends, or that you do not know.
Questions to settle before any vent is cut
Cutting a new vent into your roof is hard to undo, so ask the questions first. Start with the simplest: is warm air getting up through your ceiling, and where? If the roofer cannot say, the vents may be solving the wrong problem for you.
Then ask for the sum. The roofer should be able to tell you how much vent area your attic needs, how much you already have, and how the new area splits between the low and the high vents. Ask for the numbers in writing, and ask which ratio they used and why.
Ask what will happen to the bath fans, because a fan that ends in the attic can undo good venting. And ask what comes first. A plan that starts with sealing the ceiling and ends with vents is the order we advise, and sealing is the step the Department of Energy guide stresses.
If a proposal skips any of these, send it back with your questions. If you have no proposal yet, tell us what the attic does and we book the visit.
Paperwork
What the proposal should say about air and venting
The air leaks found
A list of the gaps in the ceiling and where they are.
The order of work
Sealing first, then venting, with the reason.
The vent plan
The vent area needed and how it is split between low and high vents.
The fan duct
Where each bath fan will vent, outdoors and not into the attic.
Price
What moves an attic proposal
- How many gaps and chases need sealing
- Whether the hatch needs gasketing and insulation
- How much insulation has to be moved to place baffles
- How many bath fan ducts need rerouting
- How many vents are needed and where
- Whether the roof allows a ridge vent
Where
Attic Ventilation pages by place
Reading
More on attic air and venting
Roof Leak or Attic Moisture: A Five-Minute Check
One question about the weather sorts most stains.
How Much Attic Ventilation a Syracuse House Needs
Seal first, then size the vents.
Tell us what the attic does and book the visit.