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Maxfieldo
Skylight condensation and ceiling shadows

I live in a townhouse in upstate NY and since I bought my home, almost 20 years ago, during the winter months I get condensation on my skylight window. Sometime, when cooking or if I have the humidifier too high, condensation will form on the glass and drip down the inside of the skylight wall-Img1. Img2 is how it is located...above the front door-well sealed. There is a small like door on the top part of the skylight, Img4, but I believe it is not suppose to be airtight but circulates air in the skylight space, maybe-don't believe it is blocked as long as I can see through the skylight? Any suggestion on how to keep the moisture from building up and dripping down the wall? Part 2 is on that same ceiling the skylight is on, and only in that area of the house I get shadows of the studs-Img4...this year it has been the most prominent. I have been away from home for the better part of the winter with the thermostat down to about 55 degrees. Any suggestion on why that is happening? Thanks to all who have any suggestions.

Timothy Miller
Re: Skylight condensation and ceiling shadows

Howdy consider having a inner opening window installed. Casing trim around the skylight opening and Plexiglas laid on it thus creating a dead air space. I have seen this stop the condensation on the skylight. The shadowing on the wall /ceiling is thisthe north exterior wall?

Maxfieldo
Re: Skylight condensation and ceiling shadows

Thank you for the reply Timothy. This is a North facing end, but the first year I have been away for a good part of the winter and first time I have ever got this shadowing. No one else in the townhouse complex has the problem with the skylight condensation. I'm thinking it has something to do with the little door at the top of the skylight and what it's purpose is. Thanks again for the help.

Timothy Miller
Re: Skylight condensation and ceiling shadows

Hi, the wall/ceiling is likely condensation. Is there a humidifier on the furnace? You might consider turning it off. Did you turn the heating way down while you were out of town? I would be sure to use bath exhaust fan when showers taken.

Maxfieldo
Re: Skylight condensation and ceiling shadows

Hi again Timothy. I decided to talk to the builder who built these townhouses. He said the humidity is best between 25% and 45%. Mine is about 40-42%. He said it's not too high but that is what is causing the humidity build up on the skylight. He said at another house he built he installed, like you suggested a outer somewhat airtight window and he never heard back from the owner. If I'm going to keep the humidity level where it is for winter time I will have to build the outer window.
He said the problem with the shadowing on the wall is because it is the North side the rafters and studs are transferring the cold to the sheetrock during the cold winter we had and my being away for most of the winter. Moisture is condensing and the shadow is DUST accumulating on it. Never would have thought that. Thanks very much again for your input Timothy.

Timothy Miller
Re: Skylight condensation and ceiling shadows

Howdy, i would turn down the furnaces humidifier in the winter to 30%. The "dust" sounds flakey, sorry for humor, did you ask the contractor to wipe the dust off?
The shadowing is moisture discoloration of the paint. This north area is a cold spot so condensation can occur easily. You might want the corner checked to see if a gap in insulation and correct it as if fiber glass if it is lifted from the ceiling this can occur. The studs do radiate heat- out of the home. It is colder outside then in in the winter.

bp21901
Re: Skylight condensation and ceiling shadows

Here is a pic of an interior storm window on our skylights which solved the condensation issue.

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Maxfieldo
Re: Skylight condensation and ceiling shadows

Hi again Timothy and BP21901. My townhouse was built in 1990. I think I will be turning down the humidifier to around 30%. I brushed the discoloration and it is not dust...it is discolored paint. I will have to check the insulation also. Thanks BP for the picture. I will have to come up with a design for an interior window before next winter.

bp21901
Re: Skylight condensation and ceiling shadows

The storm windows I made were pretty rudimentary. I'll describe my design so you and others can improve upon it. I used plexiglas and then Azek for the frames. I used lap joints instead of miters at the corners. I rabbeted the edge of the frame to accept the plexiglas and then glued up the corner lap joints. I did not glue the plexiglas to the frame, I used a thin bead of caulk. To fasten it to the skylight well, I installed a frame of brick molding on the inside perimeter of the well since I had that in the garage taking up space. I used simple foam weather seal between the frame and brickmold. I used 3 screws on the sides and 2 on the ends to tighten the storm window to the brickmold.

Timothy Miller
Re: Skylight condensation and ceiling shadows

Howdy, you're welcome. To paint over the wall staining on the call/ceiling i would suggest a spray can of White Kilz primer sealer. spray the staining let it dry an then a coat or two of paint. Oh did anyone check to make sure it is not a slight roof leak? Or possibly ice damning?

Maxfieldo
Re: Skylight condensation and ceiling shadows

Thanks again both...Your skylight looks good BP and thanks for the ideas. I checked for any ice damage and there is none that I can see Timothy. I do have some Kilz and will use it. Thanks again, I appreciate all your help.

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