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Posted by: from Montreal
5/29/2012 at 7:12:44 AM


Mold professionals in my area - I am buying a home and the home inspector is not sure if the attic space has mold. He noticed some blacked areas on the plywood on the roof. I need to know for sure and if I choose to buy the house, I need an estimate on if it's possible to remove it and how much would it cost ?

Thank you

Luisa Saracino

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Date/Time5/29/2012 at 8:16:41 AM

Mold is very bad, especialy if you have children, you can buy test kits and do it yourself, if you are not sure of this, it's best to hire a professional and have this done.

The 1st thing you must do is find out the cause of the mold and mildew, probably from NO air movement in the attic, check if you proper ventilation coming in at the eaves, if you just clean it up, it more than likely will come back if you don't find the cause. In any case the area will have to be cleaned and sprayed with a sealer.

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Date/Time5/29/2012 at 9:00:11 AM

I agree with the previous post. The first thing is to find the source of the mold. It can either be roof leak or some sort of infiltration (if it is more localized) or, more likely, it's an issue with your ventilation in the attic. You are likely harboring moisture, and frost on the underside of the roof sheathing, in the winter, and it's not evaporating cleanly.

The next step is to test the mold. In most cases, it's not as bad as people would have you think, but it can be an environmental hazard. You should get an air quality expert to test the air quality in the attic, and in the home below.

Thirdly, there are several processes for removal of the mold, but the most likely to use, is soda blasting. Its a process, similar to sand blasting, but with soda, that doesn't leave a gritty residue. There is also a dry ice blasting that can be done, that leaves no residue at all.

You may want to remove the insulation and replace it, if the mold turns out to be hazardous.

Hope this helps.

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Date/Time5/29/2012 at 9:05:57 AM


The best advice that I can give is to follow the industry consensus standards. IICRC, EPA, AIHA, and ACGIH all require three components for effective mold remediation: (1) correct the underlying cause of unplanned moisture, (2) remove the mold or the moldy building materials, (our team utilizes dry ice blasting - it is an expensive method; however, one of the quickest and most effective) and (3) address spores that are released from areas of active growth. Therefore, before any testing is ever done (and it does not have to be done), all remediation projects should pass visual criteria to include (1) absence of visible mold (2) absence of mold type odors, (3) absence of settled dust in an around the remediation areas, and (4) verification that appropriate engineering controls were used during remediation.

The most economical way to determine how to proceed would be to invite a qualified professional to the home to review the attic space. Their review should strictly be based on a visual assessment. If they can not confidently confirm the growth of suspect mould growth than I would recommend that non-viable samples be collected as required.


Adam Altobelli, B.A. (law), ACAC: Council-certified Microbial Investigator

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Date/Time5/29/2012 at 9:46:30 AM


Why buy a house with mold when there are so many available for sale that don't?

Run, do not walk, away!


Andrew Parker

Par-Tek Construction Services

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Gaby from Amg Renovation in Hearst
Date/Time5/29/2012 at 10:38:48 AM

Hi, my name is Gabriel certified carpenter and inspector, here what you can look for and ask:

1, in your attic, look for rusted nails coming trough your roof if there is you know there's not enough ventilation that might cause this problem (Easy fix)

2. ask questions about the roof, How long was it done and if they had any problems before, by law they have to tell you any problems,

3. look for stains on the level below around that area (mold area) again ask if they had any leaking problems in the past.

They are all easy to fix but of course at a price, other problems that can be there because of that is in the wall if it was leaking bad? I dont know the real situation but sometimes its better to walk away like somebody said here and find a better house (Specialy with kids) but dont be afraid to ask allot of questions if they are afraid to answer never mind that house.

hope I helped you with those answers.

Good luck to you.

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Justin from Legendary Exteriors in London
Date/Time5/29/2012 at 11:01:17 AM

In most cases if the inspectors can't tell if it is mold or not then more then likely it would be the beginning stages of mold. It can be removed (scrapped or sand blasted) and the cost is minimal. Ensure bathroom vent is sealed properly and that the soffit vents are not blocked.

Justin Menard Legendary Exteriors

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Date/Time5/29/2012 at 11:02:55 AM

Hi this is Stephen.

I'm not a mold expert but You can buy mold test kits from home depot for about $10.00. So don't spend a fortune. If it's black or grey specs then it probably is. If it's a small area it's treatable but make sure you have found the cause such as a small leek where moisture is present.

Hope this helps

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Mark from Arbutus Sundecks in Richmond
Date/Time5/29/2012 at 12:18:41 PM

All above answers are correct, you can see by the picture that the insulation has been pushed to far into the soffit area and it is blocking the airflow of the attic, causing condensation. Its an easy fix they sell waffle boards for this at any lumber store

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JENOMA High Quality Renovations in Dollard des Ormeaux
Date/Time5/29/2012 at 1:57:35 PM

Hi Luisa,

There are several important factors to consider:

First is it mold? a simple mold test from Home Depot will answer that.

2nd. If it is mold, how much of it is there (it may be easy to clean with a disinfectant like Microban), or it could be quite far along, and the insulation and possibly even some wood in the attic or roof may (or may not) have to be replaced and the area disinfected.

3rd factor is: what is the cause of the mold in the attic? that too may be a simple fix, or could require elaborate repairs.

My advise would be to assume the worst, and try to get the seller to accept the responsibility to have it repaired. Don't trust him to do it, just have him pay or agree to pay, or take it off the price of the home, and you should make sure that it is repaired properly. It may turn out to be a simple fix, and maybe a blessing in disguise. You can get an estimate from a reliable contractor (like JENOMA High Quality Renovations) before you buy. Make your offer conditional to the outcome of the moold tests.

Good luck Norm

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Date/Time5/29/2012 at 11:17:07 PM

Hi Louisa,

It probably isn't mould. It is most likely dead dry rot. Dry rot is an organism that needs food and water in order to live. What happens is ; in the winter the plywood deck of your roof is cold (because it's cold outside). The warm air created by your heating ssytem rises (like heated air always does) and finds a way into your attic where it contacts the cold surface of the plywood. Because the air is carrying a lot of moisture, the cold surface cools the air releasing the moisture contained in the warm air, and condensation forms on the surface of the plywood. This supplies the moisture, the wood is the food, and the organism floats in with the air movement. If your ventilation system works properly the condensed moisture is evaporated as quickly as it forms, therefore not allowing the organism to take root. From the sounds of it, your ventilation of the attic is working OK in the non-cold seasons, but not well enough in the cold weather (evidenced by the black stuff [dead dry rot] on the plywood). All you have to do is simply add more vents to your attic.

I wouldn't waste money on the mould carpetbaggers.

Dan Brown, RHI

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Date/Time5/30/2012 at 4:34:34 AM

wow Dan from HightecH Installations

Are you saying she shouldn't even check if it's mold or mildew??, not good advice at all.

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Dellos Construction in Ottawa
Date/Time5/30/2012 at 10:56:49 PM

It would definitely mean a water damage area and depending on the size of the area it may be a mold concern. What it does mean is that the roof has leaked in the past and my still be leaking.

The cost of the repair would be $250 per sheet plus the cost for the shingle repair. The cost for that would completely depend on the size of the area.

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Date/Time6/2/2012 at 8:04:21 AM

Mold is a big problem. If you are buying a house with mold, expect to spend thousands to tens of thousands repairing it.

Just by getting rid of the mold, doesn't solve the problem of what is causing to mold to form.

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Date/Time11/13/2012 at 7:55:29 PM

Hey Gary,

The picture beside your posting shows dry rot, not mould.

Dan Brown, RHI

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Terry in Toronto
Date/Time4/9/2013 at 1:16:47 AM

Hi Luisa,

I hope your problem is solved by now.

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