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A homeowner renovating a mid-1980s addition in Rochester, New York, is seeking an insulation plan for a vented cathedral ceiling with shallow, irregular truss cavities. The account describes removed cellulose, sagging ceiling material and missing ventilation baffles, but provides no final repair plan or expert response.
A homeowner renovating a mid-1980s addition in Rochester, New York, is looking for a way to insulate its vented cathedral ceiling after removing cellulose that had contributed to severe drywall sagging. The account describes shallow and irregular truss cavities, absent ventilation baffles and roof sheathing the owner expects to replace later; it does not report a chosen design or completed work.
The homeowner says the existing ceiling drywall sagged between framing bays, with one especially wide sag. After removing the drywall, the owner found cavities packed tightly with cellulose and a stretched polyethylene layer beneath it. The insulation has since been removed, and the owner is preparing to start over. The report does not establish whether the weight of the cellulose alone caused the damage or whether other factors contributed.
The roof is described as a vented assembly with a ridge vent and several soffit vents on each side. The homeowner found no baffles in the cavities and suspects the ventilation may not have worked well, but says this is an inference rather than a confirmed assessment. The roof sheathing looks inconsistent from below, with old and new sections and gaps; the owner reports no active leaks and anticipates replacing the sheathing during a future roof project.
Insulation depth is another constraint. The owner describes 2-by-4-inch bottom chords in the trusses and roughly five inches of framing depth where the trusses meet the exterior wall. The owner says the framing bays vary in width, and only two are spaced 24 inches on center. Adding depth below the existing framing could reduce an already-low area, which the homeowner says is about seven feet high at its lowest point.
Why Shallow Roof Cavities Matter
The account illustrates why adding insulation to a cathedral ceiling can involve more than selecting a product. A retrofit must work within the available framing depth and roof geometry, while also addressing how the roof assembly manages ventilation and moisture. In this case, the owner wants to retain a vented roof and avoid spraying foam against sheathing that may later be replaced.
Those choices may affect the practical options, but the source does not provide an engineered assembly, code review or building-science diagnosis. The homeowner is considering a combination of mineral wool and cut-and-cobble insulation while acknowledging that a dropped ceiling might be needed. These are possibilities raised in the question, not recommendations confirmed by a professional.
For readers facing a similar project, the practical takeaway is that existing conditions matter: uneven cavities, gaps, limited depth and the condition of roof materials can all affect the design. A solution that fits one bay or one climate may not suit another. Before closing the ceiling, the roof assembly and proposed insulation strategy need to be evaluated together rather than treating the insulation as a standalone upgrade.
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The Existing Roof Assembly
The homeowner identifies the house as being in climate zone 5A and says the addition dates to the mid-1980s. The roof already has ridge and soffit vents, but the discovered lack of baffles led the owner to question whether air could move through the intended ventilation path. The source records that concern; it does not confirm the performance of the vents or document an inspection.
The account also describes a roughly 42-inch area without framing, left from old skylights, and a mix of roof sheathing that looks poor from inside. The owner reports no active leaks, while expecting to replace the sheathing later as part of a roof redo. That planned future work is relevant because the owner does not want to apply spray foam to the underside of the existing deck.
The source is a homeowner’s question posted to GreenBuildingAdvisor, not a published inspection report or a record of a completed renovation. The owner says they have experience as a paint contractor and have previously insulated rim joists and wall cavities, but considers this ceiling project more advanced. The supplied material contains no answer from a building professional.
“There were no baffles before so I suspect it wasn’t functioning well for the past 40 years.”
— The homeowner, in the question posted to GreenBuildingAdvisor
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No Retrofit Design Is Confirmed
The source does not state how the ceiling will ultimately be rebuilt, what insulation materials or thicknesses will be used, or whether the ceiling will be lowered. It also contains no professional reply, calculations, permit information or assessment of the existing roof structure. The homeowner’s references to suitable R-values and ventilation performance are concerns, not documented design conclusions.
It remains unclear whether the missing baffles reflect a blocked or absent ventilation channel throughout the roof, what the condition of the sheathing is across the full assembly, and how the unframed 42-inch area will be addressed. The account reports no active leaks, but does not include a moisture survey or a full roof inspection. No cause for the drywall sagging is confirmed.
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Inspection Before the Ceiling Closes
The immediate next step described by the homeowner is to begin again after removing the cellulose and ceiling drywall. The source does not say whether the owner has since consulted a building professional or received a response to the question. Before installing insulation or replacing the ceiling finish, the project would need a plan for the irregular framing, ventilation path, roof-deck condition and limited depth.
Any final design should be checked against applicable local building requirements and the specific roof assembly, ideally by a qualified building professional familiar with cold-climate cathedral ceilings. If the roof sheathing is replaced later, the sequencing and compatibility of the ceiling work with that project also remain to be determined. The source gives no schedule for the future reroof or for completion of the insulation work.
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Key Questions
What did the homeowner find above the sagging ceiling?
The homeowner says the cavities were tightly packed with cellulose above stretched polyethylene. The account does not establish that the insulation was the sole cause of the sagging.
Does the source confirm that the roof ventilation failed?
No. The roof has ridge and soffit vents, but the homeowner found no baffles and suspects ventilation may have been poor. The source includes no inspection confirming how well the assembly ventilated.
Has a specific insulation method been selected?
No. The homeowner asks about combining mineral wool and cut-and-cobble insulation, while also considering whether ceiling height would have to be reduced. No method is confirmed as the final plan.
Why is the future roof replacement part of the question?
The homeowner expects to replace the roof sheathing during a future reroof and says that is one reason spraying foam against the current roof deck does not seem suitable. The timing and scope of that work are not given.
Source: rss
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