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Ventilating an Attic

Who is the best person/type of company to call to install an attic fan?....roofer, electrician, etc? My attic happens to be on the second floor of my home and is entered via door from a bedroom. No ventilation. I'm comfortable downstairs in my first floor bedroom but guest upstairs are burning up in summer unless a/c thermostat is set very low. I would prefer not to tamper with the roof if possible, but instead have ventilation put at the top side of house. Would appreciate suggestions/advice, especially from anyone who has had this problem.

Re: Ventilating an Attic

The best contractor might be found in the Yellow Pages under "Roofing Contractors"----there are many ways to cool down an attic----an attic fan, especially an electric fan may not be the best option to consider; elec fans burn lots of electricity, & as they age can be a possible source of an attic fire----any installed attic fan should have a fusible switch (firomatic, thermal cutoff switch) inside the motor (many of the knock off models in home improvement stores do not) that will open if the fan motor overheats & starts to cause a fire---there are solar powered fans now that are a lot safer & burn no hi voltage/hi amp elec.

Could you provide more info---your general location, the total sq. footage of the attic, the color of the shingles, any insulation now in the floor joists (R40 recommended), or rafters???; any soffit vents, eave vents, ridge vent, gable vents (vertical side walls); have you yet installed a permanent large thermometer in the attic to check the summer temps, that can often reach well over 100 degrees---attic should remain vented in the colder months to prevent ice dams on the lower part of the roof.

Consult the video below for ventilation ideas & calculation formulas, also Google "how to ventilate a residential attic" for numerous info sites on this topic; you may have to download the free Adobe Flash player if you have trouble accessing the video.


Re: Ventilating an Attic

The attic fans I'm familiar with, are positioned in the back of the gable end vents (no cutting of the roof needed). They require electrical connections, a switch or an automatic thermostat activation.

Therefore, an electrician will be the best sub contractor to install it. Other choices will be a contractor who specializes in attic fans (who might be difficult to find) or a HVAC contractor.

Re: Ventilating an Attic

Natural convection current venting is far better than an electric fan. If the house is air-conditioned, electric fans can create a negative pressure in the attic. When this happens, every small gap in the house envelope will allow the cooled house air to be sucked into the attic and out of the house!

Have a roofer create ridge venting on top and inlet venting at the eaves. Natural air currents will enter below and work their way to the ridge, cooling the underside of the roof decking in the process. You can't have too much air moving through the attic. Ideally, the attic temperature should not be greatly hotter than the outside temperature.
Natural venting is free , once installed, and does not cause a negative pressure to suck your expensive air-conditioned air out of the house.

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