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Dovetail Greene
Dovetail Greene, General Contractor
Category: Home Improvement
Satisfied Customers: 377
Experience:  Licensed Building Contractor & Certified Building Designer
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We purchased our home last year, it was build late 50s I believe

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We purchased our home last year, it was build late 50's I believe and is a bungalow with a dirt crawl space and California roof/ceiling throughout. roof was done 5 years ago with 40 year singles and a ridge vent installed at same time (already has vents around bottom of roof line as well) this summer we had rivets of water coming down the walls in the kitchen which is the highest point of the roof line. We tore the ceiling down and pulled all the insulation out went through the summer and lots of rain without any leaks in the kitchen at all (left cavity open so we could see any leaks), brought in a roofing specialist who filled in a small area of the roof ridge vent that was short who told us roof and singles were in good shape. Thought we were fine to fill cavity back in put in baffles and roxul insulation (baffles give about 1" space to outside roof) dry walled all but one strip over range as we are going to change existing extractor fan which vents only to ridge vent and not outside. It was up for 6 days and on the sixth day the walls had condensation, my wife had used range for a couple of hours that day. Any help with this would be very gratefully appreciated as we are at a loss other than to tear every ceiling down at this point.


My name's Kel.


Have you installed the new extractor fan?

Is it vented to the exterior?

Was a fan running or were windows open during the couple of hours of range use?


Do you have fans in the bathrooms?

Are they vented to the exterior?

Do you use them when you shower?


Where are you located in Canada?

Customer: replied 3 years ago.

hi Kel

its still the old fan and windows were open. extractor in bathroom vents to outside but doesnt work very well, we are in ontario.

Are the walls with condensation finished or did you remove the finish hand insulation?

Are these exterior walls?


If they're still intact do you have any idea how well they're insulated?

Was the condensation in one particular place or all over?

Customer: replied 3 years ago.

walls are finished, not sure on insulation but if its like the ceiling then would be to code. three interior, one exterior wall condensation was on all walls (rivets of water) when original insulation was removed it was the taken out it was most on one of the interior walls were range, dishwasher and sink are

Did you discover the condensation early in the morning or after all the cooking?
Customer: replied 3 years ago.

after the cooking, but to be honest didnt look before. original problem the condensation happened around 3-5pm after sun had been on roof most of the day, this was at 4pm this time, i've wiped the walls down andam not using range for next few days to see what happens

The real puzzle is the condensation occurring after the sun was shining.

I'd expect it to occur early in the morning.

A wood frame building doesn't have much mass.

It radiates its heat to the surrounding environment at night and cools.

In the morning with showers and cooking there's warm moist air that hits the cooler inter walls and condenses.


From what you've told me I can't put my finger on a precise cause and cure.


Need to practice good moisture management. A home in Ontario wants to have a relative indoor humidity of 20 - 30%. Any more and you'll be plagued with condensation.


Upgrade the bath and kitchen fans. Make sure they're vented to the exterior. Make sure the outside vent hood has a flapper on it to prevent back drafting.

Go to the Home Ventilation Institute website to learn about how to size fans for the space and how to manage the moisture levels. Run fans during showers and cooking.


Purchase a battery powered hygrometer to measure relative humidity.


Reduce all bypass and infiltration.

Bypass are small passageways from conditioned space into ceiling assembly. warm moist air flows through these. Caulk around windows and any penetrations in the wall or ceiling assemblies.


In short you want to increase the thermal properties of walls and ceilings so heat doesn't move as quickly. You want to reduce moisture levels to 20 - 30% RH.


Does this make sense?



Dovetail Greene and other Home Improvement Specialists are ready to help you
Hello again Steve. This's Kel checking in to see how the condensation problem's unfolding. . .

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