# Attic moisture and carpenter ants



## Duderino (Jan 7, 2019)

Hi, here is some history: 

We have a 1944 house in Canada. The upstairs contains some living space (bedrooms) under the roof and some small attic areas: one large attic area on the south side and two smaller corner attic areas on the north.

The attic areas have little ventilation. The roof was re-shingled about 8 years ago. There are only a few passive vents. I tried to improve the ventilation on the large south attic area by cutting some venting at either end of the house and installing a screened cover at each end. The two small corner attic areas only have one vent each

About 10 years ago we installed fiberglass insulation in the attic. There is insulation against the inside walls and on the floor of the attic. No insulation on the outside roof surface 

Last spring when the weather started to warm up, we started to see some carpenter ants Inside one corner of the house (one floor beneath one of the small attics). I tried to figure out how they were getting into the house and thought they were eliminated, but this winter we are seeing a few ants again

I inspected the small attic near the ants and there is lots of moisture condensation on the inside of the roof surface. It appears that warm moist air from inside the house is condensing against the inside of the roof. I saw very little evidence of mould or decay (and no ants) but didn’t do a very thorough inspection 

Any suggestions appreciated! Do I need to improve the ventilation of the attic areas? (More vents?). Any suggestions on the ant problem?

thanks


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## Nealtw (Jun 22, 2017)

Duderino said:


> Hi, here is some history:
> 
> We have a 1944 house in Canada. The upstairs contains some living space (bedrooms) under the roof and some small attic areas: one large attic area on the south side and two smaller corner attic areas on the north.
> 
> ...


 Not sure you are ready for this.
Heat comes from the wall below and warms the roof section above it so venting in the soffit is need in every bay. Every hole in the ceiling or walls that are exposed to the attic space should be sealed air tight to keep moist warm air out of the system. There should be solid blocking under the nee walls between the joists so there is no air movement between the floor and the attic. The air coming in the soffit area needs to be allowed to continue above the insulation on the sloped ceiling to the vents at the peak. And again the room upstairs can't have any air leaks into the attic space. 
That is the perfect world, how close to that can you get.


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## Dave Sal (Dec 20, 2012)

You want your attic temperature to be as close as possible to the outside air. That means adequate insulation for your region, air sealing, and enough venting, both soffit vents and roof vents.
In my 1500 sq ft tri-level home, I have about 25 soffit vents on the upper level and 20 on the lower level.


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## Mystriss (Dec 26, 2018)

No comment on the moisture situation, but we have carpenter ants. The queens come poking around our house every year.

Are you allowed to spray in Canada? We spray around the foundation and the eaves to keep them out, been working great for almost 20 years.


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## White Cloud (Dec 29, 2018)

Duderino said:


> ...Any suggestions appreciated! Do I need to improve the ventilation of the attic areas? (More vents?). Any suggestions on the ant problem? thanks


Yes you need to vent your attic better from the information you have provided. 

You are going to need to treat for ants. This can be done professionally (please be careful...not all companies are the same!!!) or you can treat for them yourself just as effectively. First learn about them and then treat accordingly. They are unsightly more than damaging to a home, and only can (and typically do) cause damage where its already going on already do to moisture issues...

Good Luck,

j


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## 195795 (May 24, 2013)

Install continuous soffit venting and full ridge venting


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## DoomsDave (Dec 6, 2018)

@Duderino, welcome!

Are you sure the ants are carpenter ants? They are a bigger problem where the wood gets moist, but your ants may be from the ground, too.

Carpenter ants are big black ones, some are really big, up to an inch 2.5 cm long.


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