We are having a condensation problem at the apex of the high ceiling in a Great Room. There is only hydronic radiant floor heating and no A/C in the room. The windows are operable but seldom open. The structure is a restoration of a Historical craftsman style, all wood construction totaly insulated & remodeled free standing building. There is no attic space but a roof / ceiling sanwitch with a vapor barrier. There is no way to provide vents at the eaves due to the configuration of the roof overhang and literally no space at either gable end to provide vents. Trying to use any roof fans would not be acceptable to the Architect or Owner. The only solution that I see is to add a contiuous copper ridge ventl. There is no mechanical ventilation internally.Please advise.
Just verification that there are no leaks in the roofing membrane or elsewhere.
Good afternoon. My name's Kel. When you say there's a condensation problem at the eave -- do you mean there is pronounced moisture on the finish surface at the apex? Do you have any idea how much insulation is in the roof / ceiling sandwich? Are there any extreme sources of moisture like a hot tub? Do the baths and kitchen have exhaust fans? Do the owners use them? How many people reside in the home? Have you used a hygrometer to measure humidity levels? I need the answers to these questions. My response will be in two parts. One, managing mositure levels to reduce condensation potential. Two, venting.
the problem is not at the eave it's within the room running along the apex of the ceiling. The roof insulation is probably an R30 . Currently the room is not occupied by the family only workers finishing and staining. There are no spas, or tubs I don't believe that the sinks are in use yet. The room will be used like a family and entertainment room. There are 8 people in the family but travel a lot.
No I haven't yet taken anhumidity reading.
What kind of insulation is in the roof assembly? Is the indication of a problem condensation on the windows? What kind of finishes are being installed? Drywall with acrylic paint?
Since the project is in Los Angeles we need to comply with the State energy code therefore R-30
for the roof probably batts.there are no painted surfaces ,the walls however appear to be some type of pre-formed panels, as I said this is a Historic restoration.
Is the condensation occurring on all surfaces or just windows? How long have you observed the problem? Is there an unusual amount of glass in this space?
The condensation is only on the ceiling. The Contractor has been dealing w/ this problem for a while, it does not seem to be continuous. There is probably less that 24 % glass ratio to floor area.
I'm wondering about the R30 ceiling. Something has to be chilling the surface to get the condensation to form. Do you only see condenation in the morning? Is the heat turned way down at night when the workers have left? Are there still a lot of wet processes going on? Things like plastering, painting and tiling?
No plastering or paintinno tile but probably some brickwork.
I just called the Contractor and he said that the condensation occures a couple of days after the rain. The roof insul. is rigid poly....3" thick , which would be approx. an R22 plus the roofing membrane, vapor barrier, sheathing, and wood ceiling, no air space.
The more we discuss this the stronger I feel about the ridge vent as the solution.
The brickwork is releasing A LOT of moisture. I'm guessing most of the condensation will disappear when it's cured. Get a hygrometer after the brickwork has cured. It should be 20 and 40%. Any more and when it's cold outside you're likely to have condensation. The interior moisture levels have to managed. If for architectural reasons no ducted fans are acceptable then windows will have to be opened. Cooking and bathing with eight people is a huge moisture load. The moisture load HAS to be reduced. Venting the ridge is treating the symptom not the cause. If you don't manage the moisture there's a good chance even with a vented ridge the insulation performance will be degraded and there will be a good chance for mold. That kind of roof assembly is going to cool down at night. Venting is the last line of defense not the first. Do you see my point about managing the cause?
Do you have any other questions?
I understand. Thank you.
Licensed Building Contractor & Certified Building Designer
Hello again. If you'd like to continue the discussion to find an architecturally appropriate solution to managing moisture please feel free to get in touch. Yours, Kel