I’ve been following this site ever since our very uninformed decision to purchase a 1 1/2 story house
MN2008
| Posted in GBA Pro Help on
Good morning All!
First of all, many thanks for the invaluable information and advice….been following this site ever since our very uninformed decision to purchase a 1 1/2 story house in Twin Cities, MN. If only we knew…. Paying dearly for it but ig…
I have the impending siding job so adding the gables would be quite easy at this point
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MN,
First of all, can you tell us your name?
I think you tried to cram too many words into the title, and some of your words got cut off. You should post a comment with the missing information -- and any questions you may have.
Sorry, the first time poster mess up!
My name is Ilona.
Facing too many connandrums with our 11/2 story house. I will try to be concise but frustration does get to me.
After much research and consideration I figured out that I would not conquer the insulation/ventilation problem in our house. Most of the "ideal" solutions in the retrofit of Cape houses are prohibitively expensive and require a contractor that is familiar with such install, reconfiguration. I have been having hard time finding one who would be willing to even entertain the idea of installing the insulation on the outside of the roof instead solely focusing on the attics. Due to existing framing (2x6 rafters) and the finished ceiling and walls in the upstairs space our options to insulate were severely restricted.
As it is right now, I have completely sealed triangular attics behind knee walls, insulated with the dense packed (under floor boards and in slanted ceiling) cellulose. The floor supposed to be R-22 (6in). Back of the knee walls has horizontal r13 unfaced bats with covered in house wrap. Another 16in of blown in cellulose sits on top of the floor in the attic. No soffits or other way of venting. Went there inside after noticing very faint moisture stain above the only access panel door and found the roof decking severely stained and discoloured with what looks like mold. The nails protruding through the roof are rusty. The roof is new and was installed a few months after the insulation last fall.
Info on the web contradicts itself whether adding the side gables to the opposite walls of the attic will elevate or aggravate moisture/condensation issues? I dont want the roof deck to rot!
Thank you!
Ilona,
I'm not sure I understand, but I'll try to summarize.
Do I understand correctly that:
1. You insulated the sloped rafter bays with 5.5 inches or 6 inches of dense-packed cellulose, without any ventilation channels between the insulation and the roof sheathing. I'm guessing that you are talking about the sloped roof assembly between your kneewalls and the third-floor attic. Is that right?
2. Then you installed new roofing.
3. Then you noticed "a moisture stain above the access panel door" -- I'm guessing you mean a door in the kneewall, and I'm guessing that the stain was either on the kneewall or the ceiling above the kneewall.
4. Then you noticed that the roof sheathing (where? Maybe in the triangular attic behind the kneewall?) is "severely stained and discoloured with what looks like mold."
Did I get this right?
1.I had the insulation contractor do the job.
He insulated the sloped rafter bays with the blown-in densely packed cellulose. I don't have any way to know how many inches he was able to pack in there as well as in the very small triangular (3rd) attic on the very top, just under the roof peak. There is no access to any of it and the space below is finished with a drywall. Due to living arrangements and cost I could not remove the dray wall to fully expose the rafters thus blowing the stuff in.
Then he insulated the small attics behind the kneewall leaving just the one access door so we can service the radon pump if needed.
2. Yes, the new roof was installed after the insulation went in. Obviously, it made the house much tighter since the old roof was just it, very old, think shingles, no ice and shield.
3. Actually, the stain is a bit to the side of it where we had the old no structural chimney removed and the opening covered, sealed and re shingled as the new roof went on. The wall around the panel door in the kneewall was noticeably warmer than the rest of the area.
4. Yes, the staining is on the "underbelly" of the roof as seen inside the small attics behind the kneewall. Definitely, was not there when we access the area to install the insulation.
I was considering having a door test and infrared imaging done to see whether the insulation guys missed any spots or the access panel is leaking the interior air into the attic.
Since I have the siding replacement coming up I would be able to add the traditional side gables but I am very confused whether this would be helpful at all.
The house had no designated ventilation system in place all those years and I assume that, between the old roof and leaky attics, moisture problems were able to resolve naturally.
Regret buying the house very bitterly and just want to prevent any further damage at this point. I am willing to compromise comfort if it spares me more headaches down the road.
Ilona,
I'm sorry to hear about your problems.
If you paid a contractor for the insulation work, the first step is to call the contractor and insist on a remedy for your moisture problem. The insulation work you describe was performed contrary to building code requirements -- the correct approach requires a ventilation channel between the top of the insulation layer and the underside of the roof sheathing -- and contrary to the recommendations of building scientists.
In theory, if your contractor doesn't provide a satisfactory solution, your next remedies include small claims court or litigation with an attorney. Litigation often costs more than the value of the repairs, so you may be in a tough spot.
Ilona,
One other point: If the leak is near an area of roof repair -- the area where the chimney was removed and new sheathing was patched in -- it is conceivable the the stains you noticed are due to a roof leak.
That said, a roof leak would not explain the mold on the underside of the roof sheathing.
Ilona,
I'm assuming that you have been visiting GBA long enough to find the articles that are relevant to your problem, but in case you haven't, here are some links:
Two Ways to Insulate Attic Kneewalls
Insulating a Cape Cod House
How to Build an Insulated Cathedral Ceiling.
Thank you, Martin. Obviously, this the least desired possibility. My understanding was that there simply was no way to create a continuous air channel between the attics and the peak of the roof. House has no soffits, no gable vents and I declined the ridge vent installation ( no soffits to feed it) since I worried about it pulling the air from everywhere else in the house. The 3rd attic at the peak had no acces or venting. This the attemp at creating " hot roof" a là MN
I know it is a dead horse issue around here but judging from the number of Capes in my area alone you would think that someone would come up with a workable/affordable solution to the problem.
I really don't know how the moisture issue can be mitigated short of removing all of the ventilation between the finished ceiling and the rafters. And then what do I do? I don't have any room for soffits and I don't have the ridge vent on the brand new roof.
Would you advise to have the side gable vents installed if the insulation is removed? would this worsen my problem? I wish I did not need the space upstairs and could let it be what it truly is...a glorified attic!
Ilona,
As many of my articles point out, insulating an old Cape is challenging. By far the best approach is to install an adequately thick layer of rigid foam above the roof sheathing -- obviously, a remedy that is best performed when you need a new roof.
We recently published an article on this kind of retrofit: Solving an Ice Dam Problem With Exterior Rigid Foam.
Just because the right approach is expensive, doesn't mean that cutting corners is a good idea.
In your case, installing sidewall vents in the triangular attic behind your kneewalls may help. From an energy use perspective, it's not a great idea, because it will probably increase your energy bills. The effectiveness of this remedy depends in part on whether or not the triangular attic has a good air barrier at the attic's thermal boundaries. Most don't.
Installing these sidewall vents won't address the fact that your sloped roof assembly is insulated incorrectly.
Yes, I will be looking at the roof to make sure that it is not the "patched" part creating problems.
Yes, indeed, I have read the suggested articles multiple times as well as quite a bit of Canadian literature on the subject. The issue with all the proposals is that they either assume there are existing ventilation system in place or that one can install such system prior to insulating. In many cases ( such as ours) it cannot be done without a major demolishing job.
I am from Europe so this is a very steep and rapid learning curve since the buildings are constructed so differently there. The multitude of opinions left me utterly confused and desperate. I have considered demolishing the interior ceiling and installing the closed cell spray foam....well, with the current depth of the rafters I was told it would still not prevent thermal bridging and would not give me the required R value but it would definitely cost me an arm and a leg.
Ditto for creating double roof deck with the sandwich insulation...enormous cost and lack of interested contractors, was told by the house inspector " not many people would appreciate the value of such roof systemin MN" and, we my family not planning to be here for the rest of our lives, I could not justify the cost either. and So the cellulose was supposed to be middle if the road solution...
The insulation guy came endorsed by MN Energy Resource, not really sure how good of a credential that is.
His take was that in MN climate it is not so much about "ventilation" but rather about "insulation" and here I am grasping at the straws.
Will be calling the insulator up but in the meantime, what can I DO as a homeowner to stop the issue from getting worse?
Any advice would be greatly appreciated
Ilona,
To lower the humidity level in the attic behind your kneewall, you can either (a) install sidewall vents as I suggested in Comment #9, or (b) install a portable dehumidifer in the attic. This last suggestion is obviously only a temporary way to reduce damage to your house. It's not a long-term solution.
If I were you, I would insist that the insulation contractor made the necessary repairs, at the contractor's expense. Installing insulation contrary to building codes violates best practices, and does not represent adequate work.
Thank you, Martin, just saw your response regarding gable vents. I realize the drawback but desperate times call for desperate measures.
Absolutely agree about not cutting corners and felt I was being very conscientious and diligent in my research. Met up with multiple insulation contractors and each had a different theory and proposal how to deal with the house.
Unfortunately, the proper way of insulating 11/2 story homes is prohibitively expensive for many homeowners.
Again, thank you for your time and advice, Martin. Very much appreciated.
Ilona,
Your story is one more example (if one is even needed) of why halfway measures -- even measures that "usually work" -- are so risky for both the contractor and the homeowner. It just takes one disaster to eat up the annual profit of a contractor, or to ruin a homeowner's renovation plans.
The damp spot that is causing staining on your ceiling or kneewall is almost undoubtely caused by an air leak. I'm betting that interior air has found a channel leading to the cold sheathing, and that the roof assembly includes an exit point through which the air escapes. If you can find and seal this air leakage path, you may solve one of your problems.
That said, sealing the air leak won't solve the mold problem on the underside of your roof sheathing, nor will it eliminate the risk associated with the use of cellulose in unvented rafter bays.
Martin, assuming the worst and the contractors unwillingness to remedy the problem, would you say that I should have the cellulose removed from the slanted rafters bays? It would leave me without any insulation there, ~5in gap or so. Most likely possibility for winter condensation and frost since the interior air would inevitablepy leak through the drywall! Etc.
I could probably have the siding guys to install a gable vent on each end of the 3rd attic at the peak. Would this be a semi-good replica of the more favorable soffit-ridge vent set up which I cannot have?
Ilona,
There are lots of uncertainties here. You never explained why you (or your contractor) decided that it was impossible to install vent openings at the bottom of the roof slopes (either at the soffit or at the side walls of the triangular attic). Nor do I understand the reason why you decided not to install a ridge vent.
Some contractors are able to install ventilation baffles in sloped roof assemblies from above (from the third-floor attic). This approach was recently described in a GBA thread: Insulating kneewall slopes from above.
In theory, one possible solution is to remove the existing cellulose and to retrofit ventilation baffles in the rafter bays from above.
Martin,
Our house does not have any roof overhang, the roof ends at the outside walls. Was told by multiple contractors that I would need to cut into existing roof to add rafters and create overhang where the soffits could be installed. They all have said it was a major and costly undertaking and not worth pursuing in our situation. Due to our climate and amount of snowfall, any type of "in roof, under shingle" venting at the lower part of the roof was dismissed. Without having the air intakes at the eaves I thought the ridge vent would be useless and could in fact, create more problems.
Again, I am self educated in building science, trying my best to research and come up with the workable solution. I do try my best to find knowledgable contractors and I have obviously failed in this instance. It is very hard for an average homeowner without the relevant educational background to figure out the fault-proof solution. So one trusts that the long existing and licensed company has enough experience to advise wisely.
Retrofitting from above might be impossible. The 3rd attic has no acces from inside of the house, it is also extremely small. My roof pitch is not high enough to create much room in that attic.
The side gable vents were omitted due to the insulation contractor proposal to seal and insulate rather than ventilate.
Considering that mistake have been done and it is a spilled milk at this point my question would still stand:
Would adding the gable vents on the side walls of the triangular attics, removing the cellulose from the slanted ceiling and adding another two gable vents on the opposite sides of the 3rd attic help in mitigating the moisture/condensation issue?
Obviously, the insulation in the slanted roof rafters would not meet required R value but than again, no insulation could achieve that value in the current set up.
I do realize the inadequacy of the gable vents but that might be all I have at this point. I am sure I am not the only homeowner who cannot afford thousands of dollars to bring the 1949 house to today's standards.
The roofer will coming by to look at the issue , he is mentioning installing a bunch of square venting boxes somewhere near the halfway up the roof. This is what they do in MN, I am told but I have my doubts whether this would make sense.
Still no word from the insulation guy. Talked to my city inspector and it sound like installing the insulation in the rafters without any venting was not against the code. They do recommend one or the other solutions to homeowners but ultimately, when it comes to insulation, it is between the homeowner and the contractor to come up with the plan. So there, back to the square and I still don't really know what to do next...
Ilona,
Even if your local code authority allows the type of installation you have, doesn't mean that your insulation contractor didn't screw up the job. If you have enough condensation on your roof sheathing to cause rust and mold, you've got a problem, and your insulation contractor must return to the job and fix it.
If your insulation contractor refuses, the usual remedy is a lawsuit -- although, as I pointed out earlier, hiring a lawyer can be expensive.
You wrote, "I am sure I am not the only homeowner who cannot afford thousands of dollars to bring the 1949 house to today's standards." That's true. Unfortunately, GBA can provide remodeling advice, but we can't provide financial advice or financial assistance.
When a homeowner has an urgent problem with a house that is mortgaged, the usual way to get the money to fix the problem is a bank loan. It is in the interest of the bank that lent you the money to buy the house to come up with a way to preserve the value of the house.
Ilona,
One more point: If the roof sheathing above the triangular attic behind the kneewall is moldy, that's evidence that there is a significant air leak from your interior space into the attic. The air leak is introducing warm, humid air into the attic, and the moisture in the air is condensing on the roof sheathing.
If you can find the air leak and seal it, you should be able to solve the mold problem.
Thank you, Martin. I am plan on having another insulation contractor to come out and assess the current situation. I did not crawl throughout the entire attic to check for moisture/mold evidence in other areas. It does look like the worst staining is directly above and in front of the access panel so your suggestion of the air leak ( in this case, through the access panel or the framing around it) might be spot on ( no pun intended!).
As Martin says, get better air sealing and some outside air ventilation (in Winter). The former should be done by someone with a blower door. If you can't accomplish the latter with passive ventilation, you can use pressure balanced mechanical ventilation (small fans).
Install a humidity meter to monitor the results.
Thank you, Jon! I am scheduled with a local contractor to do the whole house assessment with the door blower and infrared imagining. Will posts the results once it's done.