roof vent, ridge vent or what?

[floatee]

a roofer just walked through my finished attic, trying to give me ideas about ventilation. at the moment, the roof has none at all. (it's a

1930 bungalow, about 1800 sq ft, attic and main floor together). and boy does it get hot up there.

at first he talked about adding 4-5 roof vents onto the roof on the non-visible side (north facing), along with a ridge vent. cost would be about 150 per vent installed, with $300 for the ridge vent.

but the more he thought about it, the more he thought a powered roof vent would be the ticket. he said the one unit could solve all my ventilation needs, that with one of them i'd no longer really need any additional roof vents or a ridge vent. he said the vent itself would cost about $400, with $200 to install it.

so, does all this sound about right and accurate? i live in RI and, believe it or not, during the summer it does get hot here. or at least in my attic it sure does, to the tune of around 130 degrees.

thanks for any help you can offer.

[No]

Does the "finished" attic have a small unfinished 'attic' above it? In other words, is there a continuous area behind or above the finished area? Or, is he talking about venting the finished space?

Roof venting should allow air movement under the entire roof deck. Soffit vents to allow air in and ridge/roof vents to allow it out. If your attic is finished it may be impossible to achieve this type of venting. A whole house fan in the finished space may help keep that area cool but is not, IMO, considered roof venting.

If your attic is finished like I envision. (Drywall or paneling against roof rafters, knee walls and no space above). I would do the following:

If insulated behind finish surface. From inside of knee wall, unfinished area, add those Styrofoam air channels between the insulation and the roof deck, add soffit vents and a ridge vent.

In no insulation Just add the ridge vent and soffit vents.

If you also have a space above the finished ceiling then I would add a powered vent to help with the draw.

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[Goedjn]

If you're trying to use the attic space, then you want the ventilation between the roof deck and the attic insulation, which usually means soffit and ridge-vents. In your case, since the attic is already finished, with the rafter-bays already sealed off and stuffed with insulation, you probably don't want to do that.

Since you can't do anything about the heat-gain without being fairly destructive, your alternative solution is to move as much air through the solar oven as possible, to carry said heat away again. That means either many square feet of ventilating area, powered air-changes, or something that makes enough of a chimney that it will suck large amounts of air through smaller openings.

The power vent will probably work, and it's cheap enough that you can do that now, and then when it's time to re-shingle your roof, you can spend an extra few thousand dollars, and put another deck on sleepers, so you can ventilate above the existing roof.

[trader4]

A powered roof vent for an attic this side should not cost anywhere near $400 for the unit. I'd go with the ridge vent, as it's simple, effective and doesn't need power. You also need to make sure there is enough air intake through soffit vents or similar.

As for the poster who has the power attic ventilator set at 80 degrees, that is way too low and a waste of energy. If it's 75 inside, that's only a temp delta of 5 dgrees, which any decent insulation should handle very easily. At that temp, the fan will be running way too much. IMO, the fan should kick on somewhere around 105 or so.

[Joseph Meehan]

You estimates seem high, but it is difficult to tell from here. I suggest you get a second opinion locally.

I am not a fan of power vents (pun not intended). They tend to fail and they tend to vibrate. Good old natural draft works wonders.

[Robert Gammon]

Powered vent price quote is WAY too high. Home Depot sells several models, NONE cost more than $90 $200 to cut a hole in the plywood, run power to the motor, mount the thermostat, install the vent, brace it adequately, and seal the opening sounds about right.

Adding soffit vents is easy, just cut a hole of the right size and screw in the grill. Grills are under $10 for a 6x9 size and adding 5 or more on BOTH sides of the roof is a WISE thing to do. You can install the soffits, it takes one with a bit more skill to properly install a ridge vent. Nope not impossible, but the risk of creating a leak says that I want this job performed by a pro.

However agree that ridge vent plus adequate soffits is the LONG term, LOWEST cost solution. Powered vents can be troublesome and the motor DOES need to be replaced from time to time, (maybe twice in 25 years)

[C & E]

I've had a power vent for 15 yrs now and I can't say that it performs any better than a ridge vent and eve vents. Also, an unexpected and sad surprise to me, those fan motors give you about 5 to 7 years before they have to be replaced. A real pain to be sure. When the roof needs to be replace in the near future I'm closing off that fan. The comment about vibration is also true. I find the thing to be irritating.

[mm]

VERRRY good question.

I would have an answer depending on what Floatee's answer is.

[floatee]

VERRRY good question. I would have an answer depending on what Floatee's answer is.

Yes -- the finished attic *does* have a small unfinished attic above it, so that there's a continuous area on three sides of the "room". that being the case, the roofer is talking about venting the unfinished attic and not the finished space, though he suggested i put small circular vents in the ceiling of the finished area so that the fan can suck air out of that space as well.

i must say i'm boggled by the variety of opinions. one problem with where i live is that there's a lack of knowledgeable tradesmen, so it's hard for me to really put my faith in any of them.

Let me add this, though: the insulation in the unfinished attic space is spotty and very hard to get at: it's under nailed-down plywood sheathing. also: the place has no vents at all: no soffit vents, for instance, and the guys that've looked at it say soffit vents would be a pain in the ass to install.

I'm nearly at a loss here, so if anyone here has more questions that'll help clarify the situation to enable more complete suggestions, fire away. and thanks for the help so far. my ignorance in these matters knows no limits but it's getting better, somewhat.

[mm]

Well, I'm sure this helped other people, but a lot of it is too much for me.

I'll just say that I am a big fan of power vents. I have a regular unfinished attic.

I'm in Baltimroe and when I bought my townhouse it had front and back full width soffitt vents and a full width ridge vent. It wasn't nearly enough. it used to be 140 or more in the attic on sunny summer days.

I left the fan set at 85 degrees I think and I think it took 30 degrees off the attic, and I know it took 10 degrees off the second floor. I rarely use AC and the first half of the summer, it was too hot even to go upstairs after I got home around 5:30 or 6. I would eat in the kitchen and sleep in the basement, and go upstairs the next morning to wash and change.

After the fan I could go upstairs whenever I got home, watch tv, and sleep there.

I haven't noticed any vibration in 22 years, but there is an attic between me and the fan. When everything else is quiet, I can hear the fan a little bit.

The motor has had to be replaced three times or four, but I buy them at the local electric motor repair place, and it takes about 20 minutes now (not counting turning off and on the breaker). Again, I have direct access, standing on the attic floor, remove one nut and bolt and loosen two of them, take off the electric cover plate and undo two wire nuts, then pull out the motor and remove the fan blade. Reverse to install. Took 40 or 60 minutes the first time, and 20 since then.