Foam the duct system.
Originally posted by beachwalker
Don't you just love it when the subs begin blaming each other? Especially the pieceworkers, who just want to get in and get out.
On the matter of the foam, I have it on good authority that foaming the roof was tried on a number of the homes in the Las Vegas area and resulted in roof sheathing delamination. Don't have the details, but we have decided to install a new trunk line with new insulation. I just want to solve this problem and go on with my retirement. Not going to risk it.
"Football Season again finally"
That's exactly the same thing I've been wondering about the solar radiant barriers. It would seem to me that they'd be reflecting the i/r right back into the roof. Some of the manufacturers who make the composition roofing materials have fine print their warranties about overheating.
Originally posted by stevio
I have used Iceynene in our walls and am tempted to use it in our attic. However, they have not concluded the long term effects of the insulation to the roof shingles. It will make the shingles hotter and will possibly decrease the lifespan but again, there have been no long term studies available.
New development: HVAC contractor will not guarantee that new ducts with new fiberglass wrap will stop condensation... very disappointing.
Am now pursuing closed cell foam bids as these contractors guarantee results with 2" of foam on the ducts, which is about R-14, but it totally seals everything. I am strongly considering foaming the air handler as well, with provision to remove access and service panels.
Regarding the delamination story source, since he is a friend, I would prefer not to go down that road and suggest no one rely on that info and do their own investigations.
Beachwalker--I think you need to talk to your friend and try to find any substantial facts concerning this allegation. I don't think he has any.
Paul42--what does the article you presented have anything to do with roof delamination due to hot roof construction?
As I said, he's a friend who is still working and I don't want to "wear out my welcome" for free advice, so it comes down to a "who do you trust". Admittedly, there are always many sides to a story and I do not wish to besmirch the reputation of any product without significant facts, so again I recommend to everyone they do independent research and arrive at their own conclusions.
As far as the ducts condensing, seems to me by foaming just the ducts and the air handler it should solve the problem. They are talking 2" of closed cell polyethylene at R-14.
One curiosity: we have found precious little on the web regarding foaming ducts. Is this a new idea or are there other problems down the road?
Fairly new and some foams are not rated for Class 1 duct materials,mainly "flame and smoke developed ratings".
Is the inside of the duct insulated? What thickness? Or is the outside insulated with duct wrap, what thinckness? Is the wrap done right?
I was on a job where the contractor used duct wrap and it was hanging off the duct, they did a lously job, and there was a lot of condensation on the duct in the attic. I ripped off all the duct wrap, and installed duct board on the outside of the duct. I used stick pins and tie wraps to hold the duct board tight on the duct. I used the "V" tool to notch a "V" where the duct folds on the corners of the duct. That was five years ago and have not had a problem since. Make sure the duct board is tight against the duct.
Remember this duct board is installed outside the air stream so there should be no health problem associated with the insulation. Besides almost (95%) every air filter sold is made of the same material,(Fiberglass). I believe you can get 1 1/2 ductboard. If done right, it should do the job. Just a suggestion.
One of the two prospective foam contractors begged off doing the ducts and wants to foam the roof with Icynene and seal the soffits and vents. They claim supply duct leakage will be enough to help attic stay at temp and humidity that will prevent condensation.
Also spoke to local builder of high end beach houses and he is foaming his roofs with closed cell foam. Said with SC heat and humidity, fiberglass batts just don't work.
So now I am going back to get quotes on sealing the roof. The closed cell seals moisture, but may not move with the house in high winds, possibly opening cracks for air movement. The Icynene would be thicker,is permeable to moisture and more flexible. Any thoughts?
To answer another question: supply ducts are 16" and 14" diameter round galvanized with fiberglass batts (tight) of about 1 1/2", although compressed in many areas with 1/2" hanging straps and where they passed too closely to framing... they just pushed them up tightly compressing the batts.
Have you had your ducts pressure tested for leakage? If not you need to do this before spending any more money.
Am I correct in concluding they seal off all supplies and returns, then pump some air into the system to see how fast the pressure drops using a manometer?
Or do they do the supplies and returns separately?
Does the leakage number come in the form of a percentage of total cfm's or is it broken down for the returns and supply?
A duct blaster (small high powered fan) forces air into the ducts and tell you the amount of leakage. Also by using theatrical smoke they can pinpoint where.
For what it's worth there is some material on unvented/conditioned attic space published by the Florida Home Builder's Association as they were researching problems with wind driven water. Last year and this year too we have been pounded by hurricanes so there have been some studies done because these extraordinary conditions were creating problems with moisture penetrating walls and attic areas. Since I have been hit by several of these hurricanes (most recently Dennis) I have been following updated info concerning possible improvements to my home. Following Hurricane Ivan Last year I had the wet attic insulation removed and Icynene sprayed on the attic/roof inside deck boards. The ridge vents were removed and soffits sealed. I had a new roof installed with higher wind rated shingles.
While the report compiled by Dr. Joseph Lstiburek spends more time discussing wind driven water through wall cracks it has several pages on sealed unvented attic space. The link for the article which includes the link to the whole report is found here: