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Old 07-16-2006, 09:45 PM  
quigleybmd
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Default Attic venting

I have a 1950 single story ranch in NYS. There is no basement and the heat/hot water pipes are in the attic. Most of the attic is insulated in the floor joists, and most of the hot water pipes are insulated with foam collars. I did that myself. But there is older fiberglass insulation in the rafters in the attic. I just had the roof redone, and my roofer said that I should really get rid of the insulation in the rafters. He said the roof wasn't getting any ventilation. There is (and was) a ridge vent, but with the insulation, presumably it isn't doing much. There are long eaves, but no soffit vents either (I could easily put those in). Should I remove the insulation from the rafters? My concern is that the water pipes would have to be 100% insulated (right now they aren't - eg. where there are T-connections, where the pipes are close to an outside wall and are difficult to access in the attic, etc..). I'm worried that the cold water pipes could freeze, and/or the hot water pipes could wind up causing more snow melt and more ice dams. etc..
I do have a 'whole house fan' in the attic which we use every day in the summer, and that does a good job of blowing out the hot air in the summer.
What's the right thing to do? Thanks very much for any input.



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Old 07-17-2006, 12:23 AM  
glennjanie
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Hi Quigley and Welcome to the forum:
The only reason you should need insulation in your rafters is if you are using the attic for living space. That insulation should be taken down and put between the ceiling joists; as much as 12" at the joist level is very beneficial. Take extra care to put that much on the pipes up there so that they will always be the same temperature as the living space below. Once the insulation is down on your ceiling I would sure be a big help for your shingles to have soffit vents to feed air to the ridge vent. It is best for the attic space to be near the outside temp and stop the rise of heat at the ceiling level. It will save you a lot on heat in the winter too.
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Old 07-17-2006, 06:46 AM  
manhattan42
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You would probably do better by removing the attic vents altogether and keeping the insulation in your rafters, then adding insulation to your gable end attic walls if any.

Otherwise you will be hard pressed to keep your pipes from freezing in the ventilated attic space in New York winters no matter how much insulation you place up there.

You would need to cover the pipes with at least and R-49 for New York winters.

Better to keep the attic a conditioned space in this case in my opinion.

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Old 07-17-2006, 04:10 PM  
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That is an interesting point Manhattan. Kentucky has higher temperatures for longer periods than in New York. Attic venting is highly regarded here because of the heat and humidity. My experience would have prompted me to insulate the ceiling and ventilate.

Many of the questions here have geological significance. Climate differences are just a part of what makes it hard to give a blanket response to a question like this.

I wonder if CraigFL, down there in Florida would have a different idea?

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Old 07-17-2006, 07:05 PM  
manhattan42
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It can actually be done either way: by insulating the rafters or by insulting the attic floor.

The original poster's setup is both wrong and counterproductive for New York state, since the rafters are insulated yet the space is ventilated. That's sort of like installing high efficiency replacement windows to save energy, then leaving them open all winter.

The idea of insulating the attic by insulating the rafters and gable end walls with no ventilation is that the attic then, becomes a conditioned space, just like the rest of the house. Warm air from below heats the area typically above freezing which would be the best option when plumbing supplies are installed in an attic.

If one were to ventilate the attic in New York, then there must be at least R-49 insulation in the attic floor and the pipes kept from freezing, and akin to running the water supplies in an outside wall.

By insulating the rafters, it is akin to running water supply pipes in an interior wall where the space is conditioned.

Plumbing codes in this regard are region specific and are based on the mean winter temperatures and degree heating days established by the state's building code.

Pipes run through attics in Florida can be done with only moderate concern for pipe insulation.

In New York State, with a mean January temperature of between -10F (Adirondacks)and +20 degrees F(Long Island), pipe freezing in an attic is a serious concern and it is rare to see plumbing run into unconditioned attic spaces.

Unvented attics and unvented underfloor spaces are also more energy efficient than conventional vented crawlspaces and attics. And although one actually ends up 'heating' these areas in winter, it actually ends up using less less energy to heat the house overall once the area has reached a maintenance temperature.

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Old 07-18-2006, 09:37 AM  
inspectorD
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Default Nice job..

Manhattan makes a really good point, When insulating an attic in our area the best thing to do is to condition the space. This goes for any time you have mechanicals in the attic also. An air handler with all that duct-work works much less if the area around it is acclimated to the season.
The insulation job has to be done correctly however, I have even seen the pro's put it in backwards. Consider who is installing the insulation and what part of the country do they come from.

Insulating the rafters is a good way to do this ,proper soffit and ridge vents with prop a vent work fine. The issue shows up when your rafters are 2x8 and you cannot fit r-49 in that space.

We would go to a foam insulation at that point with no venting, a whole different animal.

Hope this adds some thought.....

I'm scarce around these parts lately due to a brisk business.
I miss you guy's....



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