Hello,
I have read a lot of stuff online and in forums that came close to my question, but they all danced right around the subject and never got to the exact problem I am having.
My house was built right after World War 2. Looking at a cross section, it is a brick exterior, about a 1 1/2″ airspace, a cinder block, a 1′ lathe, and then plaster that is painted for the room color. There is no 2×4’s in the walls. So, I am looking at a Slow Rise spray foam product. I have made inquiries with local companies about filling the airspace between the brick and the block, but they tell me that I will be sorry if I do this because it will seal up the house and cause moisture/mold problems. They tell me that I would have to, essentially tear down the brick, wrap the house in a Tyvek type wrap and then apply the foam and re-brick. Whew! With the rising price of fuel oil and absolutely no insulation in the walls, I need to do something.
So, my questions are;
1) Does any of what I’ve written above sound correct?
2) Would it make a difference if the product was waterproof or permeable?
3) To use this type of product, would I drill a hole in the mortar between brick at the top of the outside wall and let the foam “fall” down the inside of the wall?
4) If I did this, how would I know if the foam reached the bottom and didn’t stop halfway down the wall?
And finally,
5) Would I even notice a difference, in Ohio, with only an R-7 (the 1 1/2 in space) in the wall?
Thanks for any assistance,
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Replies
Id look into a different way to heat before you considered any of that, I wouldnt think you would want to do what your thinking, but Im not really expert on masonary. Whats your heating system now?
Well maybe r-7 would help but I dont think it would be too noticable. I would think sealing up the air leaks would help a lot more than adding R-7
Edited 7/10/2008 10:09 pm ET by danno7x
Can you take the lathe and plaster off then put 2x4's in? Or would that sacrifice too much space in the house?
To clarify, take down existing plaster and whatever, frame up 2x4 or 2x6, rewire and replumb while at it, spray the foam in, and then sheetrock and paint. It seems this method would be a little easier than rebricking. Maybe even use metal studs instead of wood 2x4's.
Handyman, painter, wood floor refinisher, property maintenance in Tulsa, OK
'Can you take the lathe and plaster off then put 2x4's in? Or would that sacrifice too much space in the house?
To clarify, take down existing plaster and whatever, frame up 2x4 or 2x6, rewire and replumb while at it, spray the foam in, and then sheetrock and paint. It seems this method would be a little easier than rebricking. Maybe even use metal studs instead of wood 2x4's.'You might as well tear the house down for what that would cost! It would take generations to pay that back.If you could get access to the block core(assuming it's hollow) from the top plate, then you could foam from there or blow in cellulose, but it would be very hard to have it be consistent. I would focus on easier ways to make your house more efficient, by air-sealing the attic and crawl, and maybe upgrading your HVAC eqpmt. If you can access the attic fairly easily, you could spray foam on the roof deck. That would make a big difference, and be minimally invasive.See if you can find an energy auditor in your area. They will have the info you need to make a smart decision.
Hello,
Thank you all for your replies.
I have a NEW fuel oil system. I went with fuel oil again when I replaced the system 4 years ago because we liked the warm heat. I deeply regret that decision now, of course.
The attic has about 12" of insulation. The bricks have been sludged, or filled, when they were laid. The cinder block was not completely sludged...It seems more hit and miss.
I have thought about putting up new 2x4's and drywall, but that would decrease my room size too much. The rooms are already 1940's small.
I have thought about trying to convert the fuel oil to NG for the furnace, but have had little success finding information.
On a commercial project we did about 1 3/4" of tripolymer foam http://www.tripolymer.com/ between solid exterior brick and sheathing and it worked out just fine.
Jeff
I agree ... behind the lath/plaster is a lot of work for the return ... better to install rigid and drywall over.
Behind the brick ... oohh ... I think that is a fundamental problem from a masonry standpoint. I'm not a mason, either, but if my architectural training memory is working at all (which it may not be), I'm thinking that the airspace should not be filled. It has a function and I think you better talk w/ a well versed mason or the CMI (Concrete Masonry Institute). It's a masonry issue, I think ... check it out thoroughly before you go that route.
That aside ... you'd still have issues of consistency that you couldn't guarantee (and expanding foam could pop the brick off) ... ditto inside the block cores ... CMU (concrete block) by nature has a very high percentage of thermal bridging. Even with filled cores, the net R-value is small. Plus if it has horizontal bond beams w/ solid grout, it's difficult to fill or be consistent. Even if you don't have any vertical or horizontal structural elements, consistency will be a problem.
Insulating the inside would be a big job, but you could get R-10 to R-21 as you choose ... trouble is you lose floor space and you've got a lot of detail work to do.
>>>. I have made inquiries with local companies about filling the airspace between the brick and the block, but they tell me that I will be sorry if I do this because it will seal up the house and cause moisture/mold problems.
This doesn't make sense to me, because if the foam is done correctly then there will be no cold surface for condensation to form on. The material on the interior side of the foam will rise to approximately room temperature, and the cinder block on the exterior side of the foam will be at outside ambient temperature. No?
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.â€
That space is a rain channel. If you look at the bottom of the brick you will find spaces for the water to drain. Do not fill this with foam!
If you have a good foam contractor with a thermal imageing gun, hire them to find the cold spaces in the blocks and spray foam into the block. This is done in the northeast now with walkout basements, it works very well!
There is no "correct" way to do this. That space is, at most, an inch wide. That means about R-7. It's also a moisture barrier (assuming that the installer can even get to all the space through all the mortar slag in the space. This means, in cold climates, you WILL have condensation in the wall cavities, since the vapor barrier is on the outside and there is not enough insulation in the foam to keep the cavities warm enough to prevent it. You will also lose your drainage plane for moisture wicking in through the masonry, so your bricks may well deteriorate prematurely from freeze/thaw cycling.
If it wuz me (and it ain't), I'd sooner put 3" of foam on the inside and deal with the interior trim issues.
Mike HennessyPittsburgh, PA
Thanks guys. That's good info that I hadn't understood.Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.â€
Scott,
If you put the foam between the brick/block ... the inside surface of the foam is the outside surface of the block ... they share the same plane and roughly the same temp. It's the brick on the exterior side of the foam ... and yes, it will be CLOSER to ambient than the exterior of the cinder block.
The theoretical problem is getting consistency in that air space.
I've always understood that if there is no surface for condensation to occur, it won't. That is ... foam touching another surface, regardless of conditions or temperature, will not support condensation ... uh ... you have to have an airspace adjoining the surface for condensation to actually happen. I'm no expert in the nuances of moisture migration through materials and how/when it can/will condense (I understand about dew point, though).
Hello,
Again, thanks for all your replies.
There doesn't seem to be an easy way to do this. Whatever I do, I'm going to have to do a lot of research on it because it probably will not be cheap!
I looked at the tripolyer site and they claim to be able to do exactly what we are discussing. I will follow through with them and learn more. It looks promising. Thanks for the lead on them. Has anyone else used their product in this type of application?
I probably need to do an energy audit to find out where the biggest bang for my buck will be, but once again, I'm unsure who to trust/contact. Any ideas for that topic....in the Dayton Ohio area?
Thanks again.
Good luck. In my experience not many people actually do residential audits. And then it might be iffy, so be aware. If you get a 'free' audit from someone ... e.g. the utility or a HVAC guy ... be VERY aware ... you often get what you pay for. The HVAC or insulation guys are just looking for a place to sell their product ... they have a bias. The utility may only look at stuff that applies to their energy product (e.g. elect or gas).
Seal it up ... start w/ that ... but link that w/ a good ventilation (e.g. exhaust) system. An old house you risk sealing it up and then creating moisture issues. Yes, sealing weel and then 'punching a hole in the house' w/ an exhaust fan is still more energy efficient than ventilating at the whim of the wind.
Windows are a big energy item, so if you are inclined to replace windows, think about it a llittle bit now. Think if you might be able to do them a little later ... or maybe now. If you do windows, choose your glass and your frames carefully. You have one chance to do it ... do it well and get the biggest bang for your buck.
Hey, I'll look around for an energy auditor too. I'm in Kettering.
This is a great discussion board. I appreciate all of your input.
I do have new windows. They are the latest and greatest vinyl with multiple air chambers and argon gas and low e glass. The windows are actually warmer than the walls! I'm going to put in a fireplace insert, with doors, to minimize the flue draft when not in-use.
I've tried contacting the tripolymer people, several times, but they must be making too much money already.
I have too much time and money invested to bump the walls out into the room and re-plaster. Crown moulding, window gingerbread, updated electrical, etc., etc.
I'm going to continue looking and monitoring this thread. I'll let you know if I find an "ah-ha" solution.
Thanks again.
I have a house built similar to yours. I have a 5" thick brick, then 3/4" nailers, then a 1/2" black fiber board ( insulation), then drywall.
I was thinking of putting up foil faced foam on the inside with drywall on top of that.
I'm not sure of the thickness of the foam.
I think pulling the drywall off of interior walls in a room wouldn't be that hard and I could add some wall plugs while I'm at it.
I know it isn't perfect but it will help. I like the fact that the foam panels will be continuos from wall to wall. No bridging 2x4s.
Edited 7/14/2008 4:42 pm ET by popawheelie
Edited 7/14/2008 4:43 pm ET by popawheelie