LESLIE: Ron in California is on the line with some questions about a cathedral ceiling. What can we do for you?
RON: I’ve got a house that has a very high cathedral ceiling. It’s about 35 feet tall. And I’m getting a new roof put on my house. And the ventilation in my attic is pretty bad and the fellow that gave me a quote, he told me that they recommend a ridge-vent shingle system?
RON: My question is: how efficient is this ridge vent in high winds and rain?
TOM: So, first of all, generally speaking, aside from the fact that you have a cathedral ceiling, a ridge vent is a very effective part of an attic-ventilation system. It’s not effective by itself. You have to have soffit vents at the overhang of the roof so you have an intake point where air can get under and into the same cavity, run up underneath the roof sheathing and exit at the ridge. It’s kind of a system, so you can’t just do one without the other.
The problem with a cathedral ceiling is that, generally, you have almost no room to ventilate. If your roof rafter, for example, is a 2×10 and you have 8 inches of insulation in there, you only have, if it’s done perfectly, a 2-inch space between the top of the insulation and the bottom of the roof sheathing.
RON: I don’t think there’s any insulation at all in the living room. There’s only about maybe 8 inches of room.
TOM: Yeah. Well, they may have put something in there but I don’t know that a ridge vent is going to make much of a difference. The best way to insulate a cathedral ceiling is with spray-foam insulation. But in an existing house, you’d have to take off the – either the sheathing from the outside or you’d have to take off the drywall from the inside.
Now, you mentioned that you had a ventilation problem. Is the sheathing on the outside of the roof decayed? Is it sagging? Do you think you’re going to have some structural damage there when you take the shingles off?
RON: No. I just – it gets awfully hot in my attic. In the rest of my house, I’ve got full-blown attics – I mean regular-sized attics – but in my living room, I have this cathedral ceiling.
TOM: How big of a space is that? How big is that particular section of the house?
RON: Well, the living room, it’s about 30×30.
TOM: So, let me make a suggestion to you. This would solve it. And since you’re doing the roof, it’s not terribly more to do it this way, for the roof part of it. It’s going to cost you some money from the insulation. But if it’s 30×30 – you obviously don’t want to touch the ceiling underneath, because that’s a real mess. But what you could do is you could take off the roof sheathing from that 30×30 second – section – pull out the fiberglass insulation and then have a spray-foam company spray-insulate the whole thing.
If you spray it, you will not have to do any ventilation, because spray foam is a non-ventilated type of a product. So you’d have to worry about moisture or heat and 8 inches of foam is – it equates to about twice as much of fiberglass insulation. So you’ll have a well-insulated surface there – a well-insulated ceiling – and you won’t have to worry about the ventilation issue. And since it’s only a 30×30 section, you know, that’s not a lot of extra work when it comes to the roofing side. And whatever the insulation costs I think would be well worth it.
I did it to my house in much that same way. I actually – I had a two-story house with a regular attic, so in the upstairs, where I can get in the attic, we sprayed up under the sheathing. But we had another area that had a very, very shallow attic – only a foot-and-a-half in some places – so we pulled the sheathing out from the outside and sprayed down on top of the sheetrock. It worked great. The room is so much more comfortable after we did that. So I think that’s something you might want to consider, because I don’t think you’re going to accomplish it. Ventilation or not, it’s always going to be an uncomfortable room for those reasons.
RON: Sort of a measured cost per square foot on foam, as far as the spray-in foam?
TOM: Yeah, I can’t give you an estimate but I would say – I would suggest that you look up Icynene – I-c-y-n-e-n-e. They’re the leading spray-foam manufacturer in the country. And that’s the product I used and it worked really, really well. This one particular room I’m talking about, in all the years we’ve lived in this house, it was always a little hotter in the summer and a lot colder in the winter. And right after we did this, literally, the next day, it was for the first time ever the same temperature as the rest of the house. So, I’m pretty impressed with the product.
RON: OK. Well, I really appreciate the information, because I was – now, I can get just a standard roof vent on the rest of the house that has the big attic, so – right?
TOM: Yeah. Ridge vents – like I said, ridge and soffit vents are a great combination for everywhere else. But for that cathedral, I would take the sheathing off and spray-foam it. And I think you’re going to like what happens.
RON: OK. Thank you very much. That’s very helpful. And that was I-c-y-n-e-n-e?
TOM: That’s it. Icynene. Icynene Spray-Foam Insulation. Look it up.
Thanks, Ron. Good luck with that project.