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Old 10-28-2009, 02:32 PM   #1
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Cement Block Basement Walls

The Background

I want to eventually sell my very small house. That will require me doing something to add bedrooms in the basement because upstairs renovations have left me with only one.

I've re-graded the lot, installed extra long down spouts, trenched the basement interior perimeter. laid down washed rock and weeping tile to a sump, installed heavy poly, had a new cement floor put in, parged interior walls.......and a partridge in a pear tree.

I'm very close - but juuuuuust shy of perfect for a completely moisture free basement. The weak link in the chain..........are the block walls.

No water is present, but there is a vaguely dampish mineral deposit showing up on the floor along the one interior side and a half perimeter.

It does not appear to be dependent on how MUCH it rains......just that it rains. It does not appear to be dependent on the DIRECTION the rain is coming from..........just that it rains.

In this instance - exterior weeping tile is not an option for a variety of reasons that are immaterial to my query.

My Understanding

From everything I've read, rain and ground water will permeate blocks from the outside literally filling up their interior like a bucket and then leaching with time thru the cement/cindercrete.

One Option I Saw

I ALMOST bought material from this place: http://www.diybasementwaterproofing....baseboard.html

But delayed the purchase because my place was briefly up for sale this past year.

Then after thinking about it for a while, I got concerned that perhaps the small "drain pipes" in the installation might become clogged in short order with (high content) alkali/minerals from the soil making all the work and expense for naught.

In addition, I have already framed, insulated, wired and poly'ed the walls making a pile of work to disassemble and re-do.......I mean I WOULD do the work if this was the right application for the product......then there's the 2" clearance from wall required for the product......hmmmm.......??

My Question

If the block voids are the problem....what about drilling a hole X 2 in each and every block and filling them up with something (remember - this is a tiny house) Putting something like that expandable foam stuff in. Obviously the fear.....no......terror....... would be putting too much of the stuff in and having a block blow.

I'm actually prepared to buy some blocks and experiment in this regard.

When blocks are cemented, are they not open to each other? If so, that would give some leeway for expansion wouldn't you think?

* * * * * * *

I'm fresh out of ideas. Any suggestions or comments would be greatly appreciated.....thanks !


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Old 10-29-2009, 10:57 AM   #2
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Was really hoping I could pick some brains here.

<<<<.......and no paddle either.......


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Old 10-29-2009, 11:37 AM   #3
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Basement de-watering has a long and deserved reputation of being filled with scam artists and empty promises.
That said, there are probably a few companies and products who are providing what they promise. I am not familiar with them though.
Again I have no direct experience with it, but I do not think the expandable foam idea would function like you hope.

The other thing I wanted to mention is a room in the basement can not be considered a bedroom unless proper egress is provided. Such as a window or door to the exterior. You may want to look into this before spending money to create a bedroom that a Realtor can not advertise as such.
Sorry, I'm more opinionated than helpful.....lol
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Old 10-29-2009, 12:05 PM   #4
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Don't you worry about being too opinionated - I'm all over whatever you might want to share.

* * * *

I think I might just ask the Realtor about the window (fire) exit thing. I know in Canada it for SURE is a requirement for a basement (suite) being advertised for rent.

I'm just not sure about the legalities when selling......good point !

* * * *

Ya - that foam - hmm......it's one of those things that makes sense on paper - and only IFof course - the rest of the information about the blocks "filling up" is in fact accurate.
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Old 10-29-2009, 01:11 PM   #5
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It is not just code item.

Without an egress window(s), the bedrooms will not be considered habitable area when it comes to an appraisal to determine the amount of money that can be borrowed. - Less qualifying area, leass valuation and a lower amount that can be financed. The lower limit on the amount financeable can limit the people that can qualify to buy. If th you looking for people that can cash you out without a big loan (very rare), then it is not a factor.

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Old 10-29-2009, 02:12 PM   #6
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Here is the older Building Code for Canada booklet, since you mentioned that: http://rapidlibrary.com/index.php?q=...code+of+canada It's free, and has all the correct combinations for minimum egress in bedrooms.

Bedroom and Basement Egress Windows
Sill height 44in. max. above finished floor . .F-b13 [310.1] {310.4}
5.7sq.ft. min. clear opening . . . . . . . . . . . .T-b9 [310.1.1] {310.4}
Min. 20in. width and min. 24in. height . .. . .T-b9, F-b13 [310.1.2,3] {310.4}
No windows <3ft. to property line . . . . . . . . . . . . .[302.2] {T-5-A}
Security bars must have approved release hardware [310.4] {2320.13}
Window wells min. 9sq.ft. and 36in. min. dimension .[310.2] {310.4}
Window wells >44in.below grade must have permanent ladder
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..[310.2.1] {310.4

Your local area may be different, check with your building department.
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Old 10-29-2009, 03:42 PM   #7
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Cool ! Thanks guys..........appreciate it.

I'm definitely going to look into that stuff.

* * * * * *

Did any of you care to comment further on the block wall issue?

After reading some of the info at the bottom of the page regarding water seal (epoxy ?) paint products - I've been mulling things over and wondering about just painting the perimeter FLOOR with the stuff to seal it up.

The standard floor paint/stain I used is just flaking off and as I mentioned....accumulating the leached out mineral deposits.

Oh hey.............there's a picture option here.........might have to do that tonight.
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Old 10-30-2009, 03:31 PM   #8
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I'd forget the foam idea. If you wall was done correctly, the blocks' cavities were probably slugged full of mortar as the wall went up. That's how the reinforcement is secured and how you get a solid wall.

Water will always find the easiest way in. If the foam idea would actually work, the water would just come in through the mortar joints or the concrete in the blocks themselves.

Although it is a bit of a band-aid for a greater water problem in many cases, a lot of people have good success with cleaning the walls, removing all paint and applying a couple coats of DryLock or a similar waterproofing paint intended for the application.

Sealing at the floor level won't hurt but it isn't going to keep the water at bay. The only 100% reliable way to fix this is to excavate the outside and install an appropriate dampproofing membrane around the foundation and a perimeter drain at the footing level (to a sump pump or daylight drain).
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Old 11-02-2009, 11:51 AM   #9
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Thanks for the input Kansas.........appreciated. You're absolutely right about the external weeping tile being best case scenerio - but - as I mentioned - that isn't an option in this particular case.

* * * * *

After reading the comments and links about how application of an appropriate paintable product might in fact be the best idea........I did some checking around and found THIS stuff:


AND - it's alkali resistant it says.

So that's what I've bought.

$150 for a five gallon pail is CHEAP.............if it works.

Time will tell.


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