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TOPIC: Condensation Issues

Condensation water damage? Big job to fix?

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I was recently house hunting and came across a great property which fits my bill for all but the roofing issue. A previous prospective buyer had the place inspected and it needed work to fix a condensation problem with the roof. This is a 24 year old post and beam saltbox sitting on ledge with a crawlspace (no basement). Upon entering the house I noticed heavy water marks on the horizontal beams along the outside perimeter of the kitchen, and in the upstairs bedrooms. Regardless on who buys the house the seller has taken responsibilty to fix the issue supposedly with blown in foam insulation. That's all I know. I did notice small round vents at the soffits but don't see any ridge vents or any other vents. If I had to guess, in the bedrooms, the slopping ceilings have T&G then foam insulation then the metal roof because the realtor said there was "foam againt the metal causing the issue". If this issue is resolved is there a way to get rid of the water marks? If it wasn't fixed by the seller and I took on the responsibilty, would this be a huge financial mistake? Please take a look at the attached photos and let me know what you think.
John Ketchum

3/21/2011
If the roof deck is direct to the foam insulation and does not have any venting, it is likely that you will continue to get condensation and sweating issues. How moist is the soil in that area? Is there any sort of vapor retarder on the crawl space floor? I am not sure what blown in foam insulation is. The water marks may be cleaned up or blended out with re-finishing. It depends what was in the water that was washing back down over the beams.
Eric Novotny
An informed customer is the Best Customer!

3/22/2011
Hello and thanks, The ground around the house is pretty much ledge on the sides and front and in the back it looks more moist but hard to tell because there's still snow on the ground but directly under the house I believe is ledge with crushed stone layering a crawl space but that's just by description. I haven't seen it yet for myself. I've also attached a picture of the roof that looks in somewhat rough shape. The soffits have small round vents every 3 feet or so and there are no gabel vents. As far as ridge vents, I really don't know what it would look like in a metal roof but maybe you could tell from the photo. Hopefully this weekend I'll be able to get my head up into the attic to see what that looks like but I'm concerned about the sloping T&G ceiling because it almost sounds to me like that would have to come down to add venting to that portion of the ceiling and also add sheetrock instead to use as a vapor barrier(?) All in all I'mnot afraid to put a little elbow grease into the place but when it comes to condensation I might be pushing it a bit. Thanks for replying and I'll take more photos of the attic and maybe I'll have a better picture of what I'm up against. Thanks, John
John Ketchum

3/22/2011
I also don't recall seeing any bathroom venting either so that may be an issue but I did however see the vent for the dryer. I've learned a lot from reading this forum which is great and just guessing, without actually seeing the attic it sounds like lack of ventilation and also lack of a proper vapor barrier and insulation to keep the warm moist air out of the attic.
John Ketchum

3/22/2011
Get into the attic and post up your findings. Venting the bathrooms to outside will help with the indoor humidity. Applying a vapour retarder on the floor of the crawl space will help with moisture migration into the home as well. With that type of roof system, you need to keep the humidity down in the home in the winter months or you are going to have issues. Additional ventilation of the roof may be required and if they have soffit venting now, I would check the ridge venting for proper exhausting.
Eric Novotny
An informed customer is the Best Customer!

3/23/2011
OK. Today I went and took a close look at the attic of this house. As you can see from the photo it has 2x8 24 OC down the length of the house. There used to be insulation up against the metal roof but has since been removed. By looking at the timbers it looked stained on the rafters and the purlins had mold. There were no gabel (closed windoes instead) and no venting from below. To be honest I would love to ditch the metal roof, add sheathing and asphalt shingles and be done with it but I'm open to suggestions. I also checked out venting from within the house. The upstairs bathroom vented into the attic. Big no no. The downstairs bathroom vented into a crevis beside the chimney which ended up dumping the waste air all the way up into the bedroom. Another big no no. I'm really curious on what my options are but like I said the metal roof has a couple of patched holes and looks a bit tatered at the seams. Any comments on this would be greatly appreciated. I can attach more photos with the next reply. Thank you! John
John Ketchum

3/27/2011
Another photo of the attic. BTW the crap hanging down form the edge of the rafetrs is not rotted wood but leftover insulation paper.
John Ketchum

3/27/2011
One other concern I had was venting from the soffits up into the attic. By looking at this photo the passage is blocked. I'm not sure what that id there for considering that is the ceiling of the bedroom but nothing is going to get by that if I lat down sheathing. John
John Ketchum

3/27/2011
The roof is not the issue in this home. Yes, an exposed metal roof will sweat more than a plywood backed asphalt roof, not because of the material but because of the temperature. The metal roof will have a lower surface temperature when compared to the plywood decking of an asphalt roof and therefore "sweat"/condensate more. The issue here is venting. That will still be the issue with the new roof if you do not fix it. Humidity leaves the living spaces below as a result of diffusion and bulk air movement. That humidity must have a way to leave the home. This can be handled by any number of ventilation approaches (active ventilation via fans or passive ventilation venting in the roof). I would also encourage you to seal up the attic floor to mitigate the amount of humidity and air that is going into the attic.
Eric Novotny
An informed customer is the Best Customer!

3/28/2011
Thank you very much for advise and information. It's been very helpful but the dream of owning this home has come to an end. The seller decided and went ahead adding spray foam to the underside of the metal roof. All 5.5 inches of it between the rafters. Knowing that the roof has come to the end of it's affective service life I have no idea how the new owner will ever replace the roof now but that's no longer my concern. Thank you again for your help.
John Ketchum

4/12/2011
OK, Being an Engineer my instilled determination won't let this go just yet. If the attic area was spray between the rafters this makes it impossible to remove the old metal roof. OK, well, how about this? on the attic floor lay 2x8 on end attached to the existing 2x8 24 on center rafters. That's a false floor with insulation in between. Run 2x6s up from the 2x8s to the rafters about halfway down the slope to stiffen the roof then add collar ties on the existing rafters. That stiffens up the entire attic portion of the roof. Outside add 2x4 purlins vertically mounted directly to the metal roof nailed into the horizontal purlins under the metal roof. Add sheathing on top of the new verticale purlins and finish off the new roof as usual. The new roof would be vented between new soffits, up between the metal roof and new sheathing and out a ridge vent. The only issue it does not address is if condensation developes anyway through gaps in the foam. Otherwise you have a new vented roof on top of an old metal roof sealed with the foam. Any comments? thank you!! John
John Ketchum

4/13/2011
That is a pretty involved solution but about what I would expect from an engineer. As long as the venting is there, you will be fine. Are you going to buy the home or not?
Eric Novotny
An informed customer is the Best Customer!

4/13/2011
I'd love to but I'm still on the fence. The venting would work fo rthe new roof but I've heard from many sources, especially the roofers that submitted quotes, that spraying foam on the underside of the metal does not solve the condensation issue. Putting a new vented roof over the metal solves the potential water leakage caused by a deteriorating metal roof and improves the looks of the roof but I think that's about it. Please feel free to comment. I need all the professional help I can get. Thank you. I promise I'll get off the fense soon.
John Ketchum

4/13/2011
There are plenty of roofers that also say that shingle roofs without ventilation will not last. They too would be wrong. Spraying foam on the underside of the roof, when done properly, will solve the condensation issue if it is applied to proper depths and is continuous. That being said, you better know that the roof is a lifetime application because getting it off in the future is going to be a real treat. Turning the attic into conditioned space (moving the insulation layer to the roof deck) is a fine solution if you provide for return and supply air to the attic to prevent the air from stagnating.
Eric Novotny
An informed customer is the Best Customer!

4/13/2011