Moisture Problem..Attic

Recently got such a great response from all you folks thought I would try again… :smiley:

New construction. I have a 5/12 pitch steel roof. Under it is tar paper, and 5/8(I think) ply. Right now at the stage we are in…framed interior…we have a problem with moisture that accumulates on every metal screw that has been put in the steel roofing thru the ply. Ice crystals form and it eventually melts and falls on the slab concrete floor. My guess is that the exterior exposed heads of the screws are probably surrounded by ice that forms on the roof after snow/melt/freeze cycle and get so cold that moisture forms on the inside of the structure. My concern is this normal and will it go away once the drywall and insulation go in the ceiling or will it continue to drip on the inslulation in the attic and eventually cause it to compact? Any and all suggestions/help appreciated…thanks…:slight_smile:

New Home High Humidity.
I expect you should not have this problem when the Attic is sealed from the rest of the home .
Make sure all baths and Kitchen do not vent to attic and that there is adequate ventilation in the attic both air in and out .
Make sure attic entrance Hatch has a gasket and insulated.
Roy Cooke…

That is another of my concerns…adequate ventilation. The roof has a ridge cap venting system that runs the entire length of the house. They installed a cheescloth like material across the venting area to keep out bugs and critters. My concern is that this cheesecloth has become so soaked that it freezes and does not allow any air flow. Maybe after the first summer and it dries out real well and the attic is closed in…this will nowt happen next winter? I hope…

When you get the home closed the first sunny day that will melt and dry if there is a place for air to get in .
What part of the country do you live in .
Roy Cooke

North Eastern Washington State. 45 miles from the Canadian border.

Tim, I understand your concern, this is something that can be found on a home that does not have the proper ventilation however as your home is not yet finished there is not yet a proper ventilation system in effect.

I suggest you continue to educate yourself about attic ventilation, see and look for the ‘Principles of Attic Ventilation’ piece, this should be very informative.

As others have posted the moisture collecting on the thru fasteners should not be a concern at this point. What does concern me is the use of ‘cheese cloth’ at the ridge. I have seen lots but this is a new one…while at AirVent’s site take a look at the peak ventilation products they offer, you will notice that they stress a few things, NFAV (Net Free Air Value), external baffles on the ventilation product and a filter fabric built into the ventilation product.

My question is…how difficult is it to get the proper and adequate ventilation product that meets these basic requirements? Often it is simply a problem of the supplier(s) in the area not chosing to offer AirVent brand or another brand that meets similar requirements simply because they can offer another brand for less money. AirVent is a national company, however I have to make extra efforts and special orders to get it here in Central PA.

Several other factors are likely in place at this time too that will add to the concern you have, remember that moisture goes up as it evaporates. Heat systems often used in new construction such as propane heaters can create moisture. When finished the home will have drywall as a barrier, a vapor barrier will likely be inplace on the ceiling and a closed attic system will be in effect with the proper NFAV at the eaves (NO GABLES END VENTS!!!) and the ridge vent. The advice about no terminations of plumbing, bath or other moisture carrying vents to the attic is spot on.

Please think hard about the cheese cloth, if it is cheese cloth it will likely embrittle over time and if a bug wants to chew through it it will. I would remind you that your are the buyer of the home and you had a choice in the color of the carpet and siding and… so why shouldn’t you have a choice in the attic ventilation products used?

FYI, I formerly was a roofing contractor that had a reputation for cutting no corners and being able to solve ventilation problems, I consulted for insurance claims and homeowners alike. Currently I am a general contractor and I still see ventilation issues and get to fix them after someone else did it wrong (yes even new constuction). Attic Ventilation is a difficult thing to understand as it is not completely tangible and this does make it hard for alot of tradesman and builders to pick up on, however mathematically it is not hard to formulate the proper NFAV that is needed for a home.

I wish you the best.

Thanks for the help and reference information…REALLY appreciate you all taking the time to share knowledge…take care…:smiley:

I was wondering how the metal roof was installed and how far do the screws penetrate the sheathing. Were the screws attached in the valley or on top of the rib? if this is the type of metal roof you have, if so the screws in the valley are more likely to leak over time due to the rubber gromet wearing out from erosion.

New construction…so everything done recently. Screws penetrate the sheathing about 1/4 inch. and they are in the valleys…LOTS of em. Hope I am in heaven before the grommets wear out…:smiley:

I would read the MFG. installation manual.

These roofs in my area are professionally installed using 30LB felt paper with strapping running horizontally, fastened thru the sheathing into the roof rafters, then the metal roof is screwed thru the high point of the rib, thru the strapping and then thru the sheathing.

If this roof is just attached thru the valley into the sheathing(you said it was 5/8) where is the strength. The reasoning for attachment on top of the rib is to lessen the erosion to the rubber grommet.
Hope this helps

A carry on question if you please. I just remembered the contractor has put my HVAC in the attic area of the house. Assume there will be a certain amount of heat escape into the attic area. This should be dry air and can I assume will not cause any moisture buildup problems?

Should be no air loss to the attic only heat could be convection from the unit and they are well insulated .
Hope he does not put a water trap in the attic as it could freeze,
Roy Cooke

Thanks Roy…there is a water trap under the unit that drains down to the utility room and will drain out on the floor and down a floor drain there. I assume since it is right under the unit it probably will not freeze. I was sort of surprised that the HVAC contractor has it draining onto the floor instead of routing it into the washer drain pipe which is only about 18" away…wouldn’t that make sense to do that?

Is the drain for condensate?
If it is, it has to go to an indirect waste. That might be why it was done that way.
Just my opinion.

Marcel :slight_smile: