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attic Insulation repair

I have had some water damage from a plumbing issue in the attic. I will be having some work done & want to educate myself before that happens.

1. A portion of my blown in attic insulation will be replaced. Previously r19, new r30: what impact will there be from having 2 different degrees of insulation in the attic? 'should ALL of it be upgraded?  What additional (percentage, perhaps) of cost if all of the attic is done, should I expect?

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Posted 2012-08-13T18:34:21+0000  by engineersdaught engineersdaught

Hello and thank you for joining our How to Community.


Sorry to hear about the damage you’ve had in your attic. I know how disturbing that can be.


To answer your question; there is no negative impact from having two different degrees of insulation. The R value indicates an insulations resistance to heat flow. The higher the R values of the insulation the greater the insulations ability to stop the heat loss.


The only impact from having two different degrees of would be a higher insulating ability of the replaced section in comparison to the existing one.

Should it all be upgraded? No not all of it necessarily needs to be upgraded.


Would it be beneficial? YES you would experience greater energy savings during cooling and heating months.


Cost of product and installation services greatly varies from location to location; rule of thumb is to get three written estimates from a three local contractors to get an idea of an approximate cost of the service.



 Hope this helps.




Posted 2012-08-13T20:01:30+0000  by George_HD_CHI




I often reccomend that howeowners contact their local utility companies. These companies often offer low or no cost energy audits of your home. They will punch the data into their computer and give you approximate payback times for each suggested improvement.


I can tell you that R-19 is absolutely minimal. Upgrading to R30 or higher would bring you immediate comfort improvement as well as lower heating/cooling bills. The less temperate your climate, the higher will be your savings and comfort.


Years ago, I had my 1970 house audited by the gas company. Increasing insulation from the existing R19 to R30, at the then gas prices, had a payback time of only 4 years, even as it increased the comfort in the house. One thing for sure, long term, the cost of natural gas, and energy in general,  will only go up!


Along with insulation, proper ventilation of the attic is very important. Ventilation will help lower the temperature in the attic in summer and help keep moisture from accumulating in winter. Excess heat increases your air-conditioning bill and can also shorten the life of your shingles on the roof. Moisture causes all kinds of problems from outright water damage to mold growth.


It is almost impossible to have too much natural ventilation. Power assisted ventilation can create problems, especially if you have air-conditioning. Creating a negative pressure in the attic can cause the house to leak conditioned air from the house interior into the attic. 


The general goal is to have the outside air enter the attic from the lowest point on the eaves and exit at the highest point on the roof, washing the underside of the roof with a constant flow of cool air. These are natural convection currents. Hot air rises and cooler air replaces it.


Hope this is of assistance.

Posted 2012-08-14T16:28:07+0000  by ordjen
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