Air flow problem or leaky Roof??

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Posted by: from Delta
2/28/2011 at 4:36:16 PM


We have a major moisture problem in our home. We have been advised different things from different contractors. Have had roof checked several times and have been advised that a) roof is ok for another 5 years b) roof is in terrible condition and our home would be the perfect candidate for Holmes on Homes!!?? c) e have an air flow problem??

So what do we do... Who can we call to solve this mystery once and for all?!?!

Attic is soaking wet and we don't know if it's coming from the roof or from excess moisture in the home? Soffits at the front of the house are dripping both a dark coffee coloured liquid and a clear liquid. Old/ non replaced windows in the home are always soaked. New/replaced windows have small amounts of moisture collecting on cil. House DOES have a musty smell (coming from Crawl)

Any advice would be GREATLY appreciated !

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Date/Time3/1/2011 at 7:40:32 AM

Hi there. The first thing I would check is if there are double vapour barriers any where. This would cause moisture on it's own, and maybe worsten other problems such as ventilation if the hot air not being circulated properly has a large percentage of moisture in it. You should only have a vapour barrier on the outside of the walls, but some oldtimers stuck plastic on the inside walls too creating a sandwich for moisture to get busy. You might be able to see what's been done by removing some of the insulation in the attic over the exterior walls (which should already be spaced away from the roof) and looking at the installed layers. Other wise another place would be arround the windows or plugs, best would be to remove a piece of casing from around one of your windows to check it out. If by chance there is not two vapour barriers, your going to want to focus on the attic ventilation, and keep in mind when you go up there that it should be much more near the temperature outside than inside. Other wise, check where your dryer vent is venting. If it's venting into the crawl space, humidity would build and definetely cause condensation on the windows, depending how much laundry is getting done. So if you think it's venting outside, check the ducting for cracks and gaps and make sure that with all this snow this year the vent outside hasn't been blocked, then the air would almost be comming right out of the dryer if that were the case. Good luck. Let me know what you find.

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Ron from Jaykob Isaak Inc in London
Date/Time3/1/2011 at 9:01:53 AM

We have had a great deal of snow this year and drastically changing temperatures, as a result there were many homes that had great big ice dams that stopped the run off water from getting to the eves.

This water can back up and over flow valleys or get under shingles and find its way into the house. if your roof looks OK (you want to get someone to inspect it and the attic inside $250 just to be sure) Dont go for a free inspection ever. These guys come out to for free to try to sell you something if you are paying them for their time you will find you will get honest answers and someone that really looks, dont just offer to pay someone that does it for free find an inspector or contractor that does inspections.

As an "Older" home I don't see any vent issues most homes that are "older" were not sealed like the homes today unless you have just done some major work your attic airflow will be fine.

Crawl space are musty smelling , the black drips are most likely old leaves that have rotted and being washed away you should have your eves cleaned at least once a year..

The high level of humidity in your home that causes the condensation on your windows should be tracked down it may be that the water from your attic has worked its way into the walls, or your doing alot of showers, laundry, soup making or boiling a lot of water maybe lots of hot showers but you need to find this source.

Unfortunately what ever you find will be expensive as the water has already entered the house, Luckily in most cases your insurance will take care of the damages inside .

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Date/Time3/1/2011 at 3:37:37 PM

First you must check to see whether or not you have a humidity problem inside your house.

A small, inexpensive and easy-to-use instrument called a hygrometer (sometimes referred to as a humidity sensor or relative humidity indicator) can measure the humidity level in your house and confirm whether the house has too much or too little humidity. It will need to be calibrated first.

A general rule of thumb to prevent window condensation during the heating season, the recommended indoor RH is 30 per cent to 50 per cent. When it is below -10 C (14 F) outdoors.

It appears from your description that you have too much moisture and now you must investigate the sources. First if you have a forced air furance with a humidifier, check to see if it is turned up too high. You may also have standalone humidifiers that could be adding too much moisture.

Next item is the crawl space. It could very well be a major contribution to your problem depending upon how it is finished. There are ways to control moisture in crawl spaces and ventilation there is key.

Next is to ensure all venting of bathrooms, kitchens etc are vented directly to the outside.

The high amount moisture in the attic is a sure sign that there is insufficient air movement and venting to allow the moisture to escape.

Hope this helps.

Kingsway Constructiion Inc.

Glenn Rosborough

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Dania in Delta
Date/Time3/3/2011 at 11:42:14 PM

Thank you everyone,

I will look at some of these options and keep you all posted!


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Dave in Oshawa
Date/Time4/6/2011 at 2:51:10 PM

Hi Dania,

This issue can be confusing at the best of times and advice from various sources can make your head spin. There are some conflicting messages even within the posts here!

First thing: is the roof ok? Simple question, when there is a heavy rain, do you have any leaking inside the home? Also, are your shingles showing any signs of curling or do they appear worn? If no to either/both of these, your roof is probably fine...for now.

With all due respect to Christien, a double vapour barrier is a bad thing. A VERY bad thing. Without doing a building science 101, the vapour barrier ALWAYS goes on the inside and unless you start pulling off large sections of drywall or plaster, you can't determine the integrity (or absence) of it.

From what you have said, it appears you have an issue with high humidity within the home. Glenn is right on the money with getting yourself a hygrometer. You can pick up a little battery-powered one from the Source for about $35 that will show you indoor temperature versus humidity. Stick it by your thermostat and check it from time to time or whenever you see moisture building up/condensing on your windows. Older crawl spaces will tend to smell musty anyway. It's just a fact of life, but like Glenn said, it is important to make sure there is adequate ventilation. That can mean mechanical with fans (bathroom and kitchen rangehood if it exhausts outside) or opening a window when you can.

If you have potlights into the ceiling below the attic, they can be a HUGE contributor to moisture in the attic. If you don't have much insulation, heat rising through the ceiling will condense and soak your attic. If your bathroom exhaust fan doesn't terminate outside (or it terminates in the soffit) again you are pumping lots of moisture into the attic.

Ice damming may be a contributing factor as well. If you notice icicles hanging from your eaves, you may have water backing up under the shingles into your attic. Not always the cause, but too little insulation in the attic may be contributing to ice damming.

Hope this helps your 'sleuthing' a bit more!

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Eric in Shawinigan
Date/Time4/22/2011 at 1:55:38 PM

There's the most easiest solution for the any roof leak. Look up Maxiflovent

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