Removal of mold

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Posted by: from Haliburton
8/28/2012 at 10:34:07 AM

Customer, seasonal cottage, block basement, half finished with cement floor, other half Canadian Shield rock. Walls NOT insulated, ceiling IS with fiberboard covering. Firberboard has mold surface, insulation under it does not seem to be wet or discolored with mold. No heat source in basement, electric heat on main floor. Rocks have been cleaned, dehumidifier removed most of the smell. Only one small window int the basement.

What do you suggest? Washing the surface of the firberboard does not seem to work and everything I read suggests mold is very dangerous and the spores can travel when dissturbed.

Should the fiberboard and/or insulsulation be removed? Should they be replaced? It seems the fiberboard stopped the mold from reaching the upstairs.

Is there any point to haveing the insulation under the main floor on a block basement? I realize it would be cost prohibitive to run electric heat in a basement all winter, but a heat source should exist. How about a infrared heater?

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Spencer from All Home Repair in St Thomas
Date/Time8/28/2012 at 11:42:21 AM

I would carefully get rid of the molded materials,masks,full face,plastic coveralls,plastic garbage bags secured with tape.

You are only using this building seasonally so maybe letting it breath (if you don't require insulation) would be the best thing.Otherwise you would have to treat it the same as a full time home and insulate with vapor barrier the whole thing.All areas of the envelope would have to be totally sealed to be effective at all using proper taping methods on the plastic. The basement should have a dehumidifier running but the runoff would freeze in winter so not during freezing season.

Yes,when you consider your use of the building maybe just removing all materials that are molded and letting the building freshen its own air without barriers would be the cleanest cost effective way.

Good luck


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Date/Time8/28/2012 at 12:10:11 PM

Good Morning Ted:

You are very lucky that the mould has not spread to the upper section. As Spencer has stated, removal of all mould infested products is the only way to rid yourself of the issue. However, if it is on the framing behind the fibreboard, then this must be treated.

As for what to do, you either have to insulate properly and heat, or allow good ventillation to keep the area dry. Strip the foundation back to studs and concrete and leave it open. You can purchase grates that are designed for basement/crawlspace ventillation. The code is one vent for every 300 sq ft of floorspace. I would suggest a minimum of 4 at various locations around the perimeter.

That should keep your foundation mould free. If you do encounter a bit in corners or on floor beams, you can spray it with a product such as 30 Seconds.


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Date/Time8/28/2012 at 8:13:49 PM

Because your basement floor is not completely covered with concrete. You need to treat it as a crawl space and ventilate it with a number of openeing, preferable half faceing the prevailing winds and the other half on the opposite side, to get max air flow.

The rock is most likely carrying in water when it rains, that's the source of the moisture and mold. I'd keep the insulation on the floor as it really helps with the cold mornings you get in the spring and fall. Just make sure you have a vapour barrier on the warm side ( underneath the floor and on top of the insulation).

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Ted in Haliburton
Date/Time8/29/2012 at 7:17:06 AM

Thank you very much for your replies.

From what I gather, none of you feel a heat source is necessary it the basement is has a proper air flow and a dehumidifier in the non winter months. I am thinking with air vents open in the basement, it would be a good idea to keep insulation under the main floor with vapor barrier on the wood between the insulation and floor, as suggested, because of the cold air coming into the basement from the outside.

This customer used the cottage a couple of times in the winter and althought heat rises, the floor would be cold without the insulation.


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