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We are remodeling our kitchen. My DH has removed the drop ceiling and we like the idea of a high sloped ceiling. So he installed air baffles, and insulation, and new lights for the new spectacular looking kitchen.
Unfortunately, the other day, when it went from 54 degrees to 18 degrees (or less), I came into the kitchen and the ceiling was dripping. Inside the house. All along the lowest part of the roof, above our newly installed window. DH came home from work and pulled out the insulation he had just put in, and looked. There is no leak, just condensation. The heat from inside the higher ceilinged kitchen was causing it.
My question is... what do we do now? Has anyone else had this problem? How can we prevent this from happening again once the actual ceiling is installed? Do we have to give up the high ceiling? It would be a shame, since our kitchen is so small looking without it.
Hi Ivy,
I'm not sure if you have finished yet, but here is what I think you need. If that ceiling is actually the rafters then the R19 should be R30. Under it should be rafter vents open to your soffits to allow cold air under the insulation. The R19 may not be working well enough as a vapor barrier and might not be completely filling all the air spaces allowing warm moist air to contact the cold roof. This will cause the condensation. When you strap the ceiling and put up the drywall, it will act as more vapor barrier and separate the cold surface from the warm moist air. As long as moisture cannot condense on the cold roof then your condensation should go away. Another thing you can do if the rafters are not deep enough for R30 insulation is to add an additional layer of ridged foam insulation board over what you have now. That will add an extra R10 and the foam will also have a vapor barrier effect to help seal the ceiling in case there are gaps in the R19. You can still strap the ceiling for drywall by using 4" drywall screws. The foam board is ridged enough to support the strapping and the 4" screws easily penetrate the foam to the rafters. You also need to get insulation on the exposed wall. I'll attach a pic to show how I used the ridged foam insulation. I'll also link you more pics of what I did for insulation. Hope this helps, let me know if you need anymore info. Maybe some others might chime in with better ideas, this is the method I used.
DaveNH- Thank you so much for your knowledgeable answer. I am so glad there are people like you here!
We did install the vents, but obviously that was not enough. My husband insulated the outside wall, but over the sink could not do much at this time, since we are still using the sink area. He used some yellowish spray foam to seal any gaps.
I will get him to read this post, since he is really much more knowledgeable about the products he's used than I am. Thank you again for your help!
What Dave said is very true, but one other thing that will help with you problem. After adding insulation, cover the entire ceiling with a good quailty plastic sheating. Staple it to the underside of the rafters and seal it well around top of walls and at seams. This will prevent moisture from within the home from contacting the cold surfaces above the insulation and condensing. Keep the warm moist air in, and the cold dry air out ! As long as the two can not meet, there won't be any condensation. Good luck! Tim
Thanks Tim! Sorry I didn't respond sooner, had some surgery. We are starting to really get going on the rest of the kitchen. That info will help a lot!
i'm in a similar situation, where i'm insulating some upstairs rooms that have a knee wall, then a short section of sloped ceiling that is actually the underside of the rafters.
the rafters are only 2x6, so i installed some kraft-faced R-21 fiberglass insulation in the rafter bays from the soffit vents up past the collar ties. i planned on screwing 2" rigid board insulation to the underside of the rafters, then the strapping, then drywall.
DaveNH - in your pictures, did you use faced or un-faced fiberglass insulation under the board insulation? if you used un-faced, do i need to bother ripping all the kraft paper off mine, or just cut slits in it? what kind of fasteners/washers did you use to attach the boards?
I can see in the picture DaveNH used faced insulation. As a rule, the faced side faces the living space. I can't tell for sure, but it looks like nails or screws holding up the board insulation- whatever works!
Hi,
I temporarily tacked on the ridged foam board with nails just to hold it before screwing on the strapping. I used 4" drywall screws to go through the strapping, foam board and into the rafter. So foam is sandwiched between the strapping and rafters. The foam is so ridged the strapping holds on nice, tight and flat over the foam board. I used the pink stuff, but in hindsight the foil faced 2" foam would have a little higher R value. I didn't peel or cut the insulation facing under the foam board, it is right up against the foam and just adds to the vapor barrier. The faced side of the insulation goes toward the living space as claypa pointed out.
I would really recommend using rafter vents under the insulation on your knee wall. It is good to let cold air layer exist between the roof and your insulation. This will help keeping the room from warming your roof, which keeps the snow from melting and ice dams forming.
I hope this helps and good luck with your project. Let me know if you have any questions.
Dave
