Basement Insulation!!!

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Posted by: from Toronto
2/7/2013 at 10:31:00 AM

We had originally bought Roxul Safe and Sound insultation for our exterior basement walls. But, was thinking of changing it to Roxul Comfort Batt for exterior walls.

I was reading an article from Mike Holmes website that said you need to create a" Thermal Break" and you should use either spray foam insulation or rigid foam insulation instead. He basically indicated this would prevent future mold issues.

So here is how our basement is done now...painted cinder block walls with waterproofing paint. Filled any cracks with polyurethane foam. We have framed it with 2 x 4's with Sill Gasket under the base. Elecrtical rough in is happening as I speak(for Contractors who saw my previous post...hired an ESA certified electrician to do the work!). So, next step is Insulation....

Was going to move the Save and Sound to the ceiling....(anything I should know about that?) and put Comfort Batt on the exterior walls and seal with 6ml poly vapour barrier.

SO..should we return the Roxul insulation and go with the a spray foam or rigid foam insulation instead.

Any advice is greatly appreciated!!!

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Date/Time2/7/2013 at 10:59:54 AM

Roxul insulation is perfectly fine for a basement wall insulation, as long as you use vapour barrier.

Mike Holmes likes to use the spray foam as it gets in every crack and crevice and goes nicely along the 2x4's.

If you are considering spray foaming the walls and taking the Roxul insulation back, I would get a price on cost to spray foam the basement as my starting point.

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Laurence from Realtime Renovations in Pickering
Date/Time2/7/2013 at 11:17:46 AM

I have always been very leery of vapor barrier in a leaking basement. Waterproofing from the interior of the foundation is the quick and easy fix. It is not preventing the foundation from leaking.

To be done properly this must be done from the exterior. I would have maximized my investment by starting here, with proper exterior foundation waterproofing.

Your foundation will leak eventually and regardless of what type of insulation you use. Mould will form if there is any water present. The vapor barrier adds another layer of issues as it traps the water in the wall.

My recommendations are to stop the interior project and get your foundation fixed properly.

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Date/Time2/7/2013 at 11:43:15 AM

First off, safe and sound is not rated for exterior walls, use it on interior walls and in ceilings between floors only.

It's too late to use ridgid insulation. It's put on the exterior wall before the framing, that is what gives you the thermal break.

Price out spray foam insulation beforehand, it's extremely expensive, and is only worth the extra cost in certain situations (like a garage with a room overhead).

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Date/Time2/7/2013 at 11:50:19 AM

I hope this will help you. We are a company that provides waterproofing to residential / commercial clients from the roof to the basement. If you have evidence of water entering at one time or another from the foundation wall it would be a good idea to make certain that exterior drainage is adequate and that the foundation walls are as water-tight as possible. This would be my main concern for one reason, simply by sealing the interior walls will not prevent infiltration at the floor line leaving the the wall plates vulnerable to mould and deterioration.

To answer your question regarding a Thermal Break it is necessary to have the continuity 100% or as close to that as possible, the best way to achieve this is to use spray foam insulation it will act as a vapour barrier and thermal break to best achieve continuity at electrical junction and any other obstruction along the wall. I hope that we've been able to help and good luck.

PS. Save your batt insulation to sound proof between the upper floor and adjoining rooms like the bathroom if there's one or sleeping areas (just a thought)!



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Date/Time2/7/2013 at 12:11:08 PM


You have a lot of good information.

My suggestion is simple, it's a matter of how much of a budget you have. New technology has improved the spray foam insulation so much and the benefit is that the foam can reach places that the batt or sheet insulation can't. The cost is higher but if you want the best performance, go with the foam.

Having said that, if the basement is "just a basement" and will only be used for storage and the odd activity, the foam may be overkill. The primary concern is moisture. If this isn't an issue, the insulation factor isn't a major concern. The R-value can be similay and at that point the budget is the determining factor. It is a mater of good better, best.

Good luck, and enjoy.


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Date/Time2/7/2013 at 12:23:25 PM

I will do:

1. Make sure your drain tiles are working well and have well installed damproofing and dimple membrane below the soil level. You can also use those waterproof membranes but must protect it from UV exposure as they are rubber.

2. Fix all cracks above the soil level (also below soil level before the damproofing

3. Use waterproofing paint on the exterior

4. Use a waterproofing chemical on the interior side of the concrete wall.

5. Install 15lb felt paper on the interior side of the concrete wall (glue down)

6. Install a 1" rigid foam on the basement walls

7. Install your 2x4 right up to your rigid foam

8. Install your R12 roxul between the studs

9. Install the 6 mil poly vapour membrane

10. Install drywall

A lot of people will say #5 is not needed but the key here is redundancy.

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Date/Time2/7/2013 at 12:28:15 PM

Before you begin work in any basement, repair any water intrusion problem that might exist. Having said that. I always suggest to my clients the use of 2" ridged insulation boards. They come in 2'x8' sheets. And you use PL 300 adhesive to fix them to the concrete foundation. Cut peices to fit up between the floor joists on the outside walls as well. Then use Tuck Tape to seal every seam between every peice.

Then use spray foam to fill any larger gaps, such as the joints between the peices in the floor joists and those on the walls. Against the wood as well. This gives you an R-10 and a thermal break. Also run foam along the bottom of each board where it meets the concrete floor. Now leave about a 1/2" to 1" gap between the foam board and frame your walls over a foam gasket. At this point you can add some roxul or pink in the frame to up the R value.

Having said that, your frame is all up. It is a little pricey but having the basement spray foamed is your best bet at this time. This is the route I go with my clients with lots of money. Having said that, my own home has 2" foam and then some insulation in the framed walls. It gives me an R value of R22. A thermal break with the right product is important.

May I also suggest you use DRIcore 2'by2' flooring panels or a similar product. This will let the basement floor breath. And if you have water intrusion it will run below it and to your floor drain.

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Date/Time2/7/2013 at 3:06:33 PM

As usual, Holmes is full of it. Roxul safe and sound coupled with vapor barrier sealed with accousti-seal and tuck tape has been used for years. Whereas the rigid stuff with spray foam is a new method. Only under very specific circumstances do I use the rigid stuff. Other than that I stick with what's tried and true.

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Edward in Ottawa
Date/Time2/7/2013 at 3:08:17 PM


I'm not a contractor so my comments come from the other side. I'm currently on my 2nd basement renovations and thought I could help with the insulation part. First, the 2lb spray foam is absolutely outstanding and based on the framing is already done your ready to have it spray foamed. I would not use any type of bat insulation in the basement walls. The contractors comments about being more expensive is true and I'm not surprised they are negative about it. When I did the basement insulation 5 years ago I did the Walltite and what a difference. It cut our heating bill in half for the cottage (year around property). All the contractors at the time thought I was crazy to spend the extra money versus the pink bats, even a contractor friend of mine thought it was a waste. What you will find with contractors is unless they use it and understand it they will not be advocates of it. My friend has since converted on account how well it worked over the traditional method.

I'm redoing my house basement at this time and have already lined up the insulation company to do the spray foam. You will not regret using it. There is a tone of industry information now that compares the different Canadian spray foams that was not available 5 years ago. I had to rely on US research originally.

I would like to say the contractors above that pointed out that you need to fix the water problem from the outside and not the inside is bang on. The paint will not prevent water leakage and you need to fix it from the outside so it is not coming through the wall period. Make sure you scrape off any loss paint of cement before you do the spray foam.

Hope this helps.

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Audio Authority in Vaughan
Date/Time2/7/2013 at 5:07:37 PM

Your thought of moving the Safe n' Sound to the ceiling and using the thermal Comfort Batt for exterior walls plus the poly is fine. If done properly it works very well.

Just a note; be careful wich batts you order as both types of Roxul insulation come in varying sizes depending on wether you will be using them in wood or steel stud framing, (the steel stud is hollow and therefor needs a slightly wider batt).

As for the ceiling, install the batts midway inside the floor joices, (leaving a gap, both on top and between the drywall sheets or dropped ceiling tiles) This tends to be more effective in reducing sound transfer.

Hope this was of help.

Eli Anese

Audio Authority

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Date/Time2/10/2013 at 5:05:59 PM

Hi Melissa,

As you have read in all the previous postings, they all mention the same thing which is the most important: your budget. If installed properly, rigid, batt, spray foam will all perform to their specifications. Complete the research of pricing your different options and then decide what it's worth to you.

It is like asking someone which car is better to take from Point A to Point B. Any car will complete the task but a Ford Focus is a different product and a different price then a Lexus. It is up to the purchaser to decide if the increase in price of the product is worth paying for.

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