Roger R
Basic Member
Posts:131
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| 22 Jul 2013 03:20 PM |
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Quad-Lock makes a foam panel system called Re-Etro to insulate old structures. The panels are from their ICF system, and they supply special plastic clips to hold the foam to your walls.
http://www.quadlock.com/retrofit_insulation/index.htm
On the outside of a CMU building I can see how the clips would be necessary, to hold the panels in place and to keep a small air space between the CMU and backside of the foam panel.
I question the necessity of the clips for the interior of the house. Do you think it is ok to glue the panels onto the walls (exterior only) inside the house - with no air space? Some of the walls are covered with 5/8" sheetrock (which was glued straight over the CMU), some of the walls are painted CMU.
I want the insulation of the foam, but don't want future problems. Sheetrockers glue directly onto CMU all the time. Is it ok to do this with ICF panels too?
...Or - Is there a better way to insulate the CMU walls than this Quad-Lock system? |
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Midsouth ICF
New Member
Posts:65
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| 22 Jul 2013 05:39 PM |
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Fur the wall out and spray foam it. |
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Ryan Gunn
Owner, Midsouth ICF Builders LLC |
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Roger R
Basic Member
Posts:131
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| 22 Jul 2013 09:12 PM |
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Posted By Midsouth ICF on 22 Jul 2013 05:39 PM
Fur the wall out and spray foam it.
Why frame and spray? I'm not sure I understand the advantages. Can you please explain? Thanks |
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Chris Johnson
Advanced Member
Posts:878
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| 22 Jul 2013 10:26 PM |
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Nudura makes a Retrofit panel, 2.5" and 3.5" thick, 4x8 sheets with built in 1x material. Place it against the CMU wall, tapcon through the 1x to the CMU, drywall attaches to the face and fastens to the 1x material.
I think most major ICF manufacturers have a loose panel that can be used for this purpose, question is...who has the better mouse trap |
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| Chris Johnson - Pro ICF<br>North of 49 |
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Roger R
Basic Member
Posts:131
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| 22 Jul 2013 11:27 PM |
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Posted By Chris Johnson on 22 Jul 2013 10:26 PM
Nudura makes a Retrofit panel, 2.5" and 3.5" thick, 4x8 sheets with built in 1x material. Place it against the CMU wall, tapcon through the 1x to the CMU, drywall attaches to the face and fastens to the 1x material.
Chris,
The Quad-Lock system keeps the foam about 1/8" off the CMU, which seems like a good idea for moisture control.
On Nudura's web page they mention their panels can be used on exterior walls also. Do the Nudura panels have any lifters molded into them, to keep the panels off the CMU a little bit? |
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Chris Johnson
Advanced Member
Posts:878
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| 23 Jul 2013 07:44 AM |
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Airspace = Condensation Area (Moisture), not sure why you would want to allow that. The tighter the sandwich, the less chance of unwanted foreign items (moisture). No Nudura panels do not have a standoff
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| Chris Johnson - Pro ICF<br>North of 49 |
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d'techguy
New Member
Posts:35
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| 24 Jul 2013 06:35 PM |
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The R-ETRO system has been issued an engineering report that confirms that the 6mm air gap is an effective drainage mechanism, and does not promote condensation. Any assumption to the contrary is not based in good building science.
DJB |
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Roger R
Basic Member
Posts:131
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| 29 Jul 2013 10:52 PM |
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Posted By d'techguy on 24 Jul 2013 06:35 PM
The R-ETRO system has been issued an engineering report that confirms that the 6mm air gap is an effective drainage mechanism, and does not promote condensation. Any assumption to the contrary is not based in good building science.
DJB
Does this mean that the 6mm space (between the CMU and the backside of a foam product) is "better" than foam glued/screwed directly to the CMU, or is a flat - tight (glue/screw) fit equally good? |
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Dana1
Senior Member
Posts:6991
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| 30 Jul 2013 03:09 PM |
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An air gap is a capillary break to limit wicking of moisture which has nothing to do with condensation. EPS is not hygroscopic, and will not wick moisture, so inserting the air-gap capillary break serves no real purpose, and an air gap CAN become a thermal bypass if air can get in there.
In an air-conditioned building with the EPS on the exterior outdoor air leaking into the air gap adds moisture to the CMU, increasing the latent air conditioning load, which is what I'm guessing Chris Johnson was getting at. It would only condense on (or adsorb into, really) the CMU if the temp of the CMU were below the outdoor air temp, but even without condensation the RH at the susceptible paper facers of the wallboard could potentially run at a higher humidity, with a correspondingly higher risk of mold.
Air tight is always right, once you're inside the insulating layer. Outside the insulating layer a ventilated air gap as a capillary break from the siding is often useful. Inserting the gap as a drainage gap would only be useful if the layup did not have a real weather resistant barrier/drain-plane on the exterior side of the foam, or if the window & door flashing were set up to drain at the exterior of the CMU layer which would be pretty crummy design for new construction, but may be the case in retrofits. If that's what's happening here, a liquid-applied weather resistant barrier could be applied to the CMU layer, with a micro-gap (6mm would be extreme overkill) between the CMU & foam. |
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Roger R
Basic Member
Posts:131
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| 09 Aug 2013 01:39 AM |
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I have read an article on Building Science and I am still wrestling with the best method of attaching EPS foam to my CMU building. Since it is foam to CMU and then furring strips and cedar shingles to the foam, the whole moisture - mold process is important to get correct.
Building Science said to attach the insulation to the 'outside' of the CMU whenever possible. It seems that the best method of attaching would be to "glue" the foam directly (flat - no air gap) to the CMU - which is easier said than done, as the furring strips need something to screw into and I feel that long tapcon's through the foam and into the CMU will sag over time.
The Quad-Lock Re-Etro System is already engineered, easy to obtain, and has built in plastic clips to hold the furring strips. The plastic clips also hold the foam off the CMU approx 6mm - which forms a 6mm air gap.
This is not perfect, but do you think it is ok? There will be an air gap behind the cedar shingles as well, but the one between the CMU & the backside of the EPS concerns me. Is this a big deal with the cabin being in a marine climate, or am I over thinking the process? |
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ColoICF
New Member
Posts:34
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| 09 Aug 2013 09:36 AM |
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The afore mentioned NUDURA panels are available in several thicknesses from 2-5/8" to 3-7/8"; some with plastic furring strips molded-in, some with wood.
I prefer GRK concrete screws to Tapcons; less breakage in my experience.
FM |
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jonr
Senior Member
Posts:5341
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| 09 Aug 2013 10:51 AM |
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I feel that long tapcon's through the foam and into the CMU will sag over time. Metal doesn't tend to sag over time. But I'd put glue between the wall and the foam and between the furring strip and the foam. And use some stainless steel screws through the furring strip and foam and into the CMU to hold it all tight while the glue dries. |
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Dana1
Senior Member
Posts:6991
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| 09 Aug 2013 12:09 PM |
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Posted By Roger R on 09 Aug 2013 01:39 AM
I have read an article on Building Science and I am still wrestling with the best method of attaching EPS foam to my CMU building. Since it is foam to CMU and then furring strips and cedar shingles to the foam, the whole moisture - mold process is important to get correct.
Building Science said to attach the insulation to the 'outside' of the CMU whenever possible. It seems that the best method of attaching would be to "glue" the foam directly (flat - no air gap) to the CMU - which is easier said than done, as the furring strips need something to screw into and I feel that long tapcon's through the foam and into the CMU will sag over time.
The Quad-Lock Re-Etro System is already engineered, easy to obtain, and has built in plastic clips to hold the furring strips. The plastic clips also hold the foam off the CMU approx 6mm - which forms a 6mm air gap.
This is not perfect, but do you think it is ok? There will be an air gap behind the cedar shingles as well, but the one between the CMU & the backside of the EPS concerns me. Is this a big deal with the cabin being in a marine climate, or am I over thinking the process?
A 6mm air gap between the insulation and CMU is a potential thermal bypass, which means you have to take greater pains for air sealing either the interior or exterior of the foam (or both) which can be awkward to execute in some situations. The notion that masonry screws will sag is not well founded. TapCons & GRKs aren't crummy mild-steel imitation screw thingys, they're purpose made for structural applications (and priced accordingly.) They wouldn't support 4" bricks on a 4-5" moment arm screwed into CMU 24" o.c. but they'd support just about any other siding type. If you were hanging inch-thick stone siding you'd may have to tighten that up to 16" o.c., and you'll want at least an inch of bite into the CMU. An OSB nailer + cedar shingles just isn't that much weight. |
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Roger R
Basic Member
Posts:131
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| 09 Aug 2013 01:48 PM |
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Posted By Dana1 on 09 Aug 2013 12:09 PM
A 6mm air gap between the insulation and CMU is a potential thermal bypass, which means you have to take greater pains for air sealing either the interior or exterior of the foam (or both) which can be awkward to execute in some situations.
The notion that masonry screws will sag is not well founded. TapCons & GRKs aren't crummy mild-steel imitation screw thingys, they're purpose made for structural applications (and priced accordingly.)
Dana, When you mentioned "air sealing" the foam, are you talking taping all joints with DOW tape or some similar foam tape?
I wasn't clear about the Tapcon's "sagging"as I agree that they are a great product. I meant that I could imagine that the foam would sag (drop with gravity) and that some Tapcon's would inevitably be screwed into the CMU a little off a perfect 90˚ angle, and that the CMU isn't a perfect product and might have a flakey attachment here & there. etc. |
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Dana1
Senior Member
Posts:6991
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| 09 Aug 2013 02:14 PM |
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I don't know of any tapes that would cut it for sealing unfaced EPS. In addition to the seams, the edges, particularly at the top & bottom would need to be sealed. Sheet products like housewrap detailed as air barriers would probably be easier & more reliable.
The weight of 1.5lb per cubic foot foam is quite small compared to that of the nailer + shingles, and distributed along the moment-arm, not near the end. With 15psi foam you're not really going to have a compression issue causing sag using 1x4 furring, it's quite dimensionally stable over time. |
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Roger R
Basic Member
Posts:131
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| 09 Aug 2013 02:24 PM |
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Posted By Dana1 on 09 Aug 2013 02:14 PM
I don't know of any tapes that would cut it for sealing unfaced EPS. In addition to the seams, the edges, particularly at the top & bottom would need to be sealed. Sheet products like housewrap detailed as air barriers would probably be easier & more reliable.
Are you talking about sealing for moisture intrusion - from the outside, leaking into the inner air space and then into the CMU? |
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Dana1
Senior Member
Posts:6991
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| 09 Aug 2013 03:05 PM |
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Posted By Roger R on 09 Aug 2013 02:24 PM
Posted By Dana1 on 09 Aug 2013 02:14 PM
I don't know of any tapes that would cut it for sealing unfaced EPS. In addition to the seams, the edges, particularly at the top & bottom would need to be sealed. Sheet products like housewrap detailed as air barriers would probably be easier & more reliable.
Are you talking about sealing for moisture intrusion - from the outside, leaking into the inner air space and then into the CMU?
No, I'm talking about thermal bypassing, which is air-intrusion from the exterior getting past the foam (ergo "...housewrap detailed as air barriers..." ) and convecting heat in or out of the space, undercutting the performance of the insulation. Whenever there is a temperature difference there will be stack effect forces driving convection into that channel- unless meticulously air sealed air can move into & out of the gap, it'll be taking heat (& moisture) with it. |
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jonr
Senior Member
Posts:5341
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| 09 Aug 2013 03:32 PM |
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I don't think that you want to vent the middle of a wall (ie, insulation on both sides). While in some cases you could avoid condensation, you would still create conditions for high humidity. |
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Roger R
Basic Member
Posts:131
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| 09 Aug 2013 03:43 PM |
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So I would lose a little "R-Value" correct?
Is it "a little" R-Value only, if we seal the seams and other areas of concern as well as possible? Would this leakage promote mold on the inside walls (between the CMU and sheetrock that is "glued" directly to the CMU)?
I could lose a little R-Value, as right now the unfilled CMU is under R-2, so 4" of EPS will be w-a-y better than we've ever had. But I do not want to promote mold growth. |
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BrucePolycrete
Advanced Member
Posts:524
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| 09 Aug 2013 03:56 PM |
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Warehouse Bay's Anchor III plate for EIFS is specifically designed for the mechanical attachment of EPS insulation board to various substrates including wood, metal and masonry. The 2" diameter plate holds the insulation board firmly in place. The openness of the plate allows the base coat materials to penetrate through, over and around the washer to lock the base coat to the insulation board and onto the washer. The 3/8" fingered screw chamber creates a thermal break in the washer. Packaged alone or assembled with the proper sized exterior coated screw for the insulation thickness and substrate materials being used. Comes in packages of 1000, 500 or 250 pieces per box. Contact your local EIFS Distributor for additional information and availability. |
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