# Underlayment covering ridge vent creating condensation



## JasonBraun (Jan 5, 2016)

New steel roof installed 7 weeks ago. 
Condensation build up on roof deck creating bad mold growth on new plywood. Steel installed directly on plywood. 

Ridge vent covered with roof underlay and I am being told by roof contractor it only requires a couple cuts every few feet and that it's installed correctly. I believe it should be free of obstruction. He actually told me the synthetic was breathable!!! 
Also I have no fresh air intake (soffit vents) and being told that our home was not designed for soffit venting. How does a ridge vent work with out soffit venting?

Previous roof had 8 roof vents and we were told a ridge vent is plenty. 

Any help here would be great. I know it's not really a DIY issue in this case. I am being lied to and believe this is an installation mistake. Being told I should re-insulate my attic. 

Any assistance in how this venting properly done?

Thanks!


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## craig11152 (Jun 20, 2015)

Proper venting means _no more than_ 50% of your venting should be exhaust, in this case your ridge vent and _at least_ 50% should be intake from a system designed to be intake. 
without intake your ridge vent's functionality is very open to question. If it can't pull make up air from somewhere it isn't working at all. If there isn't intake venting designed to feed it, it might pull air from your living space if that is possible. 
Synthetic underlayment may be "breathable" I don't know but its certainly not vent worthy breathable. 

Pictures.....anyone willing to help needs pictures of your roof and your eve/soffit area.


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## craig11152 (Jun 20, 2015)

If you have attic access you can certainly cut back the underlayment from the inside with a straight blade. It would be a bit of a headache or maybe a huge headache depending on how many linear feet, how much head room and how much framing is in your way. Easier in a stick built than trusses. 
But that only addresses half your venting problem.


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## Bud9051 (Nov 11, 2015)

Hopefully they cut back the plywood so removing some of the underlayment will provide your needed opening. Yes they lied and they should be coming back to do that cutting.

But, as Craig said, that's only half of the problem.

They said "He actually told me the synthetic was breathable!!! 
Also I have no fresh air intake (soffit vents) and being told that our home was not designed for soffit venting." They sure can shovel it when they want duck the blame.

Breathable is "vapor permeable" it's not a screen door.
Attic ventilation can be designed without soffit vents, but it needs some form of low venting. We will need some pictures to advise on alternate methods if indeed soffit venting is not possible.

The stand-by calculation for attic venting is 1 ft² of NFA vent area (net free area) for every 150 ft² of attic floor. Half of that if the ceiling is well air sealed and has a vapor barrier. The resulting total NFA is then divided approximately half high and half low, thus that ridge has a target number for open area, not just a cut every few feet, and they know that.

Bud


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## JasonBraun (Jan 5, 2016)

I will upload marked up image.


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## JasonBraun (Jan 5, 2016)




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## JasonBraun (Jan 5, 2016)

The roofer told me that the wood under the west side was bad but it had a new deck installed over it years ago that was in good condition and he didn't want to tear it all off and replace it because it was structurally sound and was going to be very expensive. 

Still my argument it that there is no opening in the ridge. I have no other vents in the house. 

This is in a second home - It is not my primary residence so I am not there all the time. That's why it took so long to notice the problem.

I had to cut the ceiling on the second floor to find this. 
He is still telling me the ridge is installed correctly and the underlayment is ... I beg to differ and believe the condensation is because there is no venting in the roof.

Thanks for the input. I will be meeting with them this weekend.


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## Bud9051 (Nov 11, 2015)

That is really ugly and unfortunately will reflect on future home value.

For future reference, you can have the bottom of that roof deck treated so it looks better. It may be possible to hang that and other clean up on the roofer, very bad work and then lying about it. He should have insurance for this type of nonsense.

Google "ridge vents" and look at all of the examples of installs, non of then look like the description of yours. Then ask him for a copy of the mfg's suggested installation method.

Bud


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## craig11152 (Jun 20, 2015)

As mentioned before that underlayment can be cut back. I would do that ASAP in the slim hope it will help stabilize a bad situation. 

That bad wood almost looks charred like there was a fire. 

How come you had to cut a hole in the drywall? No attic access or no room to crawl around?
How about some outside pictures?


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## joecaption (Nov 30, 2011)

What's up with those huge gaps where the rafters meet, and the OSB patch job?
Attic ever been air sealed?
Balloon wall constrution?


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## 1985gt (Jan 8, 2011)

Steel directly to the plywood? If this is correct that is a bigger issue IMO. You will have condensation running up and down the whole roof deck.


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## Windows on Wash (Aug 30, 2011)

Steel down to the deck is okay with the underlayment in place.


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## 1985gt (Jan 8, 2011)

Windows on Wash said:


> Steel down to the deck is okay with the underlayment in place.


Yes I agree, but the OP's post stated steel directly on to the plywood, and the ridge vent covered with underlay. I take is as they put the steel down to the plywood and only put underlayment under the ridge vent. If this is the case I'd be real concerned with the rest of the job with the reasoning behind that. If I'm mistaken well it would be the first time, just ask my wife! :whistling2:


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## ZTMAN (Feb 19, 2015)

Is the area in your pics over a porch or entry way? Looks like a very low area between insulation and the ridge


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## craig11152 (Jun 20, 2015)

some pictures of the outside would be nice. 
What kind of steel roof is it?


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## JasonBraun (Jan 5, 2016)

The roof has underlayment on the entire deck. Steel product says that it can be applied without strapping. I was wondering about airflow between... but I don't think that is the problem... I am being told that the ridge didn't need the underlayment be cut open and a couple slits every couple feet is enough. Roofer telling me that's not the reason I suddenly have a condensation problem. I think he's full of crap...
I think they wrapped the roof one day and sliced the ridge so rain wouldn't get in, but some air could escape (it rained between install days) and when they finished the roof put the ridge cap on at the end they forgot to cut the underlayment away. 

I had no access to the small crawl space at the peak where I took the photo. I had to cut open the ceiling to get there. There are nee walls on either side, front and back with slopes baffles and insulation. Never had an issue with moisture before. I had things stored in a couple cardboard boxes in the crawl spaces for 6 years and were dry till a couple weeks ago. 

He also tells me soffit venting wasn't an option here. There is no air intake. Any thoughts how to vent this structure now? Thinking of removing drywall on 2nd floor and using foam insulation on underside of roof... 
Thoughts?


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## craig11152 (Jun 20, 2015)

If you have baffles that is a good sign. Can we get a picture close up of the soffit area?


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## JasonBraun (Jan 5, 2016)

Best I can do right now for soffit area from outside.


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## JasonBraun (Jan 5, 2016)

Thanks Guys! I appreciate all the feed back. 

I will be meeting with the roofer this weekend at the cottage. He still is ducking the fact that the ridge was installed incorrectly and that is a main source if the problem, not 100% but I am sure it would not have been this bad. 
I will post some pictures of the resolution. I have learned a lot from this!

Still considering removing drywall and insulating the roof with foam. It would hide the ugliness and provide a barrier to the cold roof and I would not have to worry about it anymore. Which was the reason for a steel roof in the first place.

Any reason not to do that other than the expense? 
Think it should vent and dry out first?
What should I do about the mold leave it or clean it with something?

Cutting the ceiling I noticed they used 3/8 drywall... Go figure.

Again, Thanks A Bunch!


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## Whack a mole (11 mo ago)

Old post but can still be relevant to people searching. Roofing manufacturers have installation requirements for each of their products. If it’s not installed according to their requirements it will void any warranty so it’s critical that you understand what brand of each component of the roof is being installed. Don’t assume the roofer is going to get it right. For example, with asphalt shingles and a ridge vent, if the roofer doesn’t cut the vent properly, and if the roof isn’t getting adequate air intake, then the roof will get too hot and will cause premature shingle degradation and your warranty will be void. A ridge vent requires the gap be cut a certain amount that is dependent on the way the vent material is made (which determines how much air can get through it). Point is, there no one single method roofers can use regardless of name brand of materials - the method is dependent on the materials being used. So as a homeowner, take your time and figure it out by going to the manufacturers website - don’t just trust that the roofer will get it right. Or you can hire a home inspector prior to the roof installation to help you work out the requirements. I mean no offense to roofers, most are awesome at what they do, but it’s critical to have a plan so you can have confidence it was done right and that the roof will last for 20+ years.


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