Not the usual insulation question

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Old 06-01-10, 03:46 PM
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Not the usual insulation question

I'm new to this forum and tried to do my duty of searching the archives for this question before posting but after multiple searches I can't find a similar posting. My problem is a two story seasonal cottage in central Wisconsin, built in approx. 1919. It has a single story enclosed wrap around porch. We only use it in the summer but it quickly becomes very hot and uncomfortable. We have no central air and try to get by with fans w/out much relief. It has no insulation, including none in the attic and none in the ceiling above the wrap around porch. There are two gable vents but no roof vents, ridge vents, or soffit vents. No venting at all for the wrap around porch roof. We will need to replace the shingles in the next year or two and thought we should put in a ridge vent at that time but have heard different opinions about whether putting insulation in the attic would be all that much help beyond trying to solve the poor ventilation problem. Also, without soffit vents will the ridge venting really be all that effective? Would it be better to put in a gable fan? What about the wrap around porch roof? Put in several standard roof vents.....but where would the flow originate from if no type of soffit vents? Any advice would be greatly appreciated.
 
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Old 06-01-10, 03:58 PM
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ridge venting will provide little relief with out some place for the air to come from. Insullation will provide a lot of relief with some ventilation. but the insullation must be done to cover all avenues for the hot air to enter your dwelling. I personally would insullate the heck out of the cottage and add something like an attic fan with ridge vent or vents high on the gables.

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Old 06-01-10, 05:06 PM
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Thanks for your thoughts. Would a gable fan end up pulling air in from the ridge vent? Do you think a gable fan on one side with a gable vent alone on the opposite side would work as well as the above plus the ridge vent?
 
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Old 06-01-10, 06:34 PM
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I don't think a gable fan and ridge vents is a good idea. I would consider roof fans up high and gable vents for the fans to pull air in with.
 
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Old 06-01-10, 11:58 PM
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When you get ready to replace those shingles, they make a vented drip edge that will give you some venting down low where it will do some good. Same for that wrap around porch. If heat gain is the issue, go with a lighter color shingle. There are some products that reflect more heat than others. Roof vents on that porch would work for the high vent, but my innovative mind is wondering if something couldn't be fabricated for a vent right where the roof line is flashed to the siding. The slope may be too low, but I'm picturing something like half of a ridge vent. If the slope is too low, then some type of thin metal duct all the way around constructed to blend in with the siding. Like I said, inventive, but when you replace the shingles, a lot of options become possible.

For the upper attic, a ridge vent and 4 low gable vents will help, but edge or soffit venting with ridge or high gable is best. I have used attic fans and even gable to gable, they work. They just move so much air, that they get the job done one way or another.

Bud
 
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Old 06-02-10, 06:20 AM
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Thanks Bud, I didn't know about the vented drip edge and I'll look into that. Do others agree that adding insulation is a 'duh!, of course' type of situation or will it be marginal benefit beyond a good ventilation solution. The reason I ask is that there is difficult access to the porch ceiling and the attic has old knob/tube wiring that angles down to ceiling light fixtures and it won't be that easy to keep it uncovered with insulation.
 
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Old 06-02-10, 04:51 PM
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Stay away from that knob and tube. Since this is just a summer house and doesn't even have A/C, I would see what happens with the increased venting first. The insulation may not be worth it since there is no artificial heating and cooling.
 
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Old 06-07-10, 09:17 AM
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Thanks everyone for your input.... the different ideas and suggestions were helpful. I think we'll go with light colored shingles and get the ventilation issues fixed first and then see if we want to figure out an insulation solution if the improvement was minimal.
 
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Old 06-11-10, 07:51 AM
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"It has no insulation, including none in the attic and none in the ceiling above the wrap around porch."

What you can do with is some large trees to create a bit of shade.

The problem is radiant, conducted and convected heat.

The heat from the sun is coming through the roof and walls. (And the windows?)

No amount of fans will do much about this.

What you need is effective insulation.

You intend to replace the shingles in a year or two, so that is the time to deal with the roof - the largest source of heat.

There is a system called SIPS that was in effect designed for your holiday home.

SIPS is a system of polystyrene sheets 8x4' with waterproof plywood on both sides.

You take the roof off and replace it with a layer of SIPS waterproof plywood and polystyrene, then fit the shingles on top. This system is designed to be air tight, as one big problem for housing is the amount of air that leaks in and out, warm air being replaced by cold in winter and cool by hot in the summer.

You should go for white or some other light coloured shingles that will help to reflect the radiation of the sun away from your home.

When you have done the roof, then turn to the walls and that porch. Again chosing white or another light colour to reflect away the suns radiation.

It is better to stop the conduction of heat from the roof and walls with a complete insulation break, than to add holes that will allow hot air to enter your home.

In really hot or cold places 14 inches of polystyrene is recommended to ensure no additional heating or cooling is required.

Five inches is fairly normal, the thickness you go for is down to you depending on how much power you want to save and how much you value comfort.

Adding external shutters to any windows that face the sun will make a noticable difference.
 
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