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Jonlei
Old uninsulated cinderblock home with moisture issues
Jonlei

Hi! We recently purchased a 1950s house in rural Colorado. The house is cinder block construction with no insulation. It is plastered on the inside and stuccoed on the outside. This is our first winter in the home and it's real cold. On the north facing interior corners of the home, there is a moisture problem that forms when it's really cold. See attached picture.

There are no exterior cracks and no leaks that I have found. I have to imagine it's just cold and moisture coming in from outside.

My wife and I are considering insulating the outside with insofast or a similar product and re-stuccoing the exterior. Do you think this will solve the moiature issues (on top of just keeping the place warm)?

Edit: I can't get the image to upload...

Clarence
Re: Old uninsulated cinderblock home with moisture issues
Clarence

You could use one of the many Exterior Insulation and Finish Systems ( EIFS )

Mastercarpentry
Re: Old uninsulated cinderblock home with moisture issues
Mastercarpentry

Do a foam-based synthetic stucco on the outside. It is waterproof and it will allow you to make the best use of the thermal mass of the block walls. With the color built in, it will never need painting and sans physical damage it will last at least 50+ years, probably a lot more. It will greatly help with dissimilar heat condensation issues but if enough moisture is being generated inside it will also retain that more as well. Be sure no water is leaking or coming in elsewhere. And I'd do a band of waterproofing under the foam where the first course of block meets the slab before covering with the foam. Since there's nothing to rot, you can extend the foam and stucco below ground level if that won't look bad. Now the slab and block walls can be used to your advantage as thermal mass.

On that end of things, you will neither heat or cool the place rapidly. Don't think hours or days, think weeks. And since you're adding time it will take less energy to reach the same point as if it were done quickly such as in a frame home. The walls will take care of themselves for heating after you've isolated them so direct your heating efforts at the slab. Yes there's a lot of initial heat loss there- especially if the soil is moist. But in time it will warm decently and stay warm and that will help keep the soil dry under it. Since the block is in direct contact with the slab it will follow suit. I live is a similarly-built house, but mine has exposed block with sheetrock over battens inside. My walls do less for me but my slab remains the focus of my heating. My electric box heaters warm the slab as much as the air and they get a month head start on the heating season. 3KWh of heat makes my tiny 600SqFt house warmish 2/3 of the SC winters which are mild, with another 30% needed for the coldest 1/3 of the heating season. 1/3 of my space is workshop/storage which by keeping the door closed allows me to reduce the heat needed by 1/3 and closing off the 1/3 which is my bedroom in the daytime takes away 1/6 more (since it's about half a day). Given that the slab and walls are holding a lot of my heat, it doesn't take much energy to re-warm those unused rooms once the doors are open but it does take time. And since I have to heat the slab constantly because of the low energy heating, those doors are my thermostat when it gets too warm inside on nicer days. My heating costs me about $750 a year and while it's rarely toasty inside it's always comfy averaging 73 degrees. It never goes past 8 degrees lower or higher because the slab and walls soak up the excess or release some heat back inside. When summer comes just one fan cools the whole place and 2/3 of summer the temps and comfort are similar; that slab at work for me once again saving the night coolness for daytime use. The other 1/3 of summer is a bugger, but that's how southern summers are and I'm OK with that. 7-10 days each summer it's sweltering in here, even for someone used to it like me. The fan may take $50 worth of power annually so for about $800 a year I'm quite comfy almost always year round. That's with no attic insulation- none. That's well in the cost range of the average older uninsulated frame home here. I'd insulate above me and do at lerast 50% better but 1: that would be a headache of epic proportions the way this place was built and 2: this is a dirt-cheap rental which is why I stay here at all.

It's because I live with and work with what I've got instead of trying to make it do what I want it to instead that makes this tenable. If you can stand the quirks you can do much better than me after that foam and stucco goes on. We will never get what a well-insulated frame home gives, but we will never have rotted wood or termites in the walls, or floors caving in, or siding to maintain and repair, or hear the neighbor kid's stereo no matter how loud it is. That's worth something too.

Phil

Clarence
Re: Old uninsulated cinderblock home with moisture issues
Clarence

Better check with your termite bonding company before extending the EPS board below grade.
EIFS is not recommended below grade.

keith3267
Re: Old uninsulated cinderblock home with moisture issues
keith3267

You may have an opportunity to try something a little radical here. But first, your climate in Denver is much different than SC, however Mastercarpentry did have a lot of good points. My first concern is that the concrete block is very conductive of heat, so even with the outside of the blocks insulated, they will tend to suck heat from the house and send it into the ground. The ground is about 50-60 degrees warmer than the outside air though.

Now if you house is made of cinderblock instead of concrete block, it will be a little less conductive so it will be more effective. If you have access to the top of the block walls and can see down into the cavities, you can fill them up with vermiculite. Wear breathing protection when pouring this stuff as it shares some characteristics of asbestos. You might find a slow expanding foam that can fill the cavities.

Insofast looks like a good product if you are going to attach siding, but it might be cheaper to just use regular 4x8 foam boards. Use an adhesive to attach them to the block walls. If you go more than 1.5" thick, then you will need a system to mechanically attach the metal lath to the concrete blocks through the foam. Maybe drill the holes for the anchors and put 16p headless nails barely into them, head first, point out. Then glue the up to 3" thick foam panels to the wall, pushing the nails through the foam. After the adhesive sets, pull the nails out through the foam and screws holding the lath can go in their place.

Now for the something different. You are going to need some heavy equipment. The earth is always radiating heat outward from its core to its surface. The theory is that if you can insulate a cone outward from your foundation, you can funnel some of this heat into your house. This is one of those Mother Earth News type theories from the 70's. Considering that the earth is about 58 degrees 8 to 10 feet below the ground in most places, you not going to heat your house with this.

But if you dug out from your foundation, down at about a 45 degree angle to about 5.5 feet, you could lay down 4x8 sheets of foam board and backfill so that you have a continuous insulation down the outside of your house and 45 degrees outward from the ground level. This in theory should help keep the floors warmer. I would at least run the foam down below grade to the bottom of your foundation though as Mastercarpentry said.

This will go a long way to cutting your bills, but to be comfortable, you may find that an additional 1/2 foam boards on the inside of the blocks will be needed. Concrete or cinderblocks will always feel cold as you get close to them if there isn't a barrier between you and them, even if the air temperature is warm. 2 or 3" on the outside and 1/2" on the inside should work well for you.

Jonlei
Re: Old uninsulated cinderblock home with moisture issues
Jonlei

Thank you so much for all of the ideas. It sounds like moisture issues are quite common with these types of houses and I'm happy to hear there seems to be solutions to the problem.

Mastercarpentry
Re: Old uninsulated cinderblock home with moisture issues
Mastercarpentry

Because of the thermal transfer of block, I don't think vermiculite adds much insulating really. One thing it does add is one heck of a mess if there's any penetration of the block wall. Somebody ran a forklift blade into the second block of a 12' warehouse wall. Normally an easy patch but not with vermiculite flowing like a river for the next week till the cavity was empty. We'd shovel the pile out and as soon as the hole was exposed here comes more vermiculite. And more. And more. It blew everywhere, you've never seen such a mess. Since the roof had been installed at that point there was no way to put it back nor was anybody volunteering to do the job. The store owned decided it was acceptable to just patch the pierced block and leave that cell stack empty. What nobody told him was that as thin as vermiculite is and with no mortar on the ends of those blocks except at the outer bonds, there was a loss of vermiculite in a "V" shape above that hole; it wasn't just one cell stack. I've had similar problems with vermiculite-insulated stud walls when repairing rot.

Not for me, no thank you. I wouldn't even have it for free. I hate the stuff passionately, and that's before you enter the asbestos factor of old vermiculite from the Libby mine. YMMV now but the first time you've got to go into that vermiculite filled block wall you will agree with me, I promise.

I'm not sure what the properties of they styro we used with the synthetic stucco were, but it was rated for below-grade use provided it was covered by the mesh, base coat, and stucco finish completely; it could not be left exposed. It was all sourced as part of the system, you could not use anything else or it voided the warranty. That's been nigh on 20 years ago now, I haven't done any since then.

Phil

keith3267
Re: Old uninsulated cinderblock home with moisture issues
keith3267

The conduction of heat through a cinderblock is less than a concrete block so vermiculite does help. But if he is in the habit of driving a forklift around his house, then maybe it would be a bad idea. However that was only one suggestion. I think using foam boards is the best idea, 3" on the outside, 1/2" on the inside. The 1/2" on the inside would be more crucial if the blocks are concrete instead of cinder.

Mastercarpentry
Re: Old uninsulated cinderblock home with moisture issues
Mastercarpentry

The vermiculite problem doesn't need a forklift, only an opening such as drilling a hole for a wall anchor or replacing an outlet box. It's like sand in an hourglass but takes longer than an hour to scream at as you're cleaning up. Agreed on the foam- better insulation, better as a base for covering with anything, and better to deal with in the future. BTW, I've almost never seen cinder-block used down here in SC, just a few old structures from the 00's to the 20's. That's why I presume concrete block when someone says cinder-block as not many people know the difference and just call it all cinder-block.

Cinder-block is the stuff you use to make chimleys with next to winders on houses and such. Ever-body knows thayat! :rolleyes:

Phil

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