Basement Insulation After Flooding

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Posted by: from Toronto
8/16/2013 at 12:53:11 AM


I recently got my finished basement flooded and am in the process of rebuilting it. The walls have a tar paper (stll there), something that looks like Roxul, a vapour barrier and drywall.

I removed the walls, vapour barrier and insulation 4 feet from the floor (drywall sheets are placed horizontally).

So here are my questions:

1. Given that the tar paper is there, it's dry and goes all the way to the top (partially covered by walls in good condition), should I remove it anyway?

2. Given that from 4 feet and above I still have the (Roxul) insulation, should I install the same for the rebuild or should I spray foam - I know the foam is recommended but I'm not sure it's the way to go when you have some Roxul insulation already installed.

3. If yes to the foam, how should it be "attached" to the Roxul insulation?

4. I was thinking of extending the poly vapour barrier a couple of inches to go under the subfloor. Any thoughts on that?

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Date/Time8/16/2013 at 10:14:47 AM


If all is dry above the four foot level, I wouldn't change it unless you really want to. Of course the cost may be a factor. I would replace the damaged bottom area with similar Roxul or another batt type insulation. The foam is good but being that it's a basement the foam may be overkill. The major benefit of foam is that it can expand into small cracks and crevices the regular batt insulation can't reach. As to the vapour barrier, use new 6 ml plastic ad tuck tape it to the existing vapout barrier. The main poupose of vapour barrier is to control moisture from the varience in temperature between the inside and outside temperatures and related condensation.

Short answer is, if you have the cash and want new, do it all. If you just want to fix the damaged area, don't go overboard as it would be money ill spent.

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Date/Time8/16/2013 at 12:47:39 PM

If you have spray foam a vapour barrier is not required, I would spray foam and tape the poly to the roxul, a couple of inches down but make sure you have a good seal. The tar paper I would change just from a moisture standpoint as some pockets may retain water.

Our services would advise you to tear the rest of the drywall out, tar paper and spray foam the entire area to maintain a continuous seal.

Jason @ Shine Dustless Refinishing

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Colin from Drage Contracting in Alliston
Date/Time8/27/2013 at 11:51:27 AM

Hello Al,

If you have dry / moisture free above the 4 ft level, I would highly recommend removing the OLD tar paper and replace with new. As well, If you currently have Roxul insulation installed, you are a step ahead. Roxul is mold and moisture resistant as well as if you submerge it in water you will see it is water resistant as well.

I would highly recommend you continue with the Roxul insulation and use 6mm poly over top as you vapour barrier. Make sure to tape all seams and leave a 4-6 inch under the sub floor. Use acoustic sealant around the perimeter of the room (damaged area) and affix the 6mm poly vapour barrier to the floor with the acoustic sealant.


Colin Drage

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Al in Toronto
Date/Time9/2/2013 at 9:47:58 AM

Mark, John and Colin - thank you so much for taking the time to respond and for so valuable insights.

I've got the insulation, poly and drywall, and will be starting installation this coming week. I'll be back with some questions about flooring.



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