Tag Archives: air/moisture barrier

EIFS/Stucco On ICF

Posted by Admin on October 27, 2010 None comments

With rising concerns over global warming and energy efficiency, construction materials like EIFS (“stucco”) and ICF (Insulated Concrete Forms) have become increasingly popular. Both incorporate varying thicknesses of insulation to decrease the amount of heat lost (during the winter) or gained (during the summer), thereby lowering the amount of heat that needs to be generated/removed. This not only means less fossil fuels are used, but that what you pay to heat and cool your home is decreased. While EIFS is seen in both new construction and renovations, ICF is primarily new construction, but the two products are not mutually exclusively. Actually, one of the larger EPS manufacturers in Toronto supplies the insulation for both products.

EIFS being applied on ICF

EIFS has been around for decades in various forms, while ICF has really only begun to take off in the last 10 years or so. EIFS newest form incorporates a weather barrier with drainage which has been shown to be the most effective at managing moisture, compared with any other cladding. ICF lacks the weather barrier and drainage channels to properly accommodate moisture that will at some point get into the wall.

So what is the correct method of applying EIFS to ICF? All joints in the ICF should be taped with EIFS mesh, and a full cementitious weather barrier applied. This surface should serve as the base of which to apply a full EIFS system including the insulation and vertical channels of adhesive. This provides a drainage layer to ensure the insulation will last as long as possible. ICF being styrofoam itself, one could even groove out vertical channels into the ICF forms through which moisture could drain out when placing your EPS board layer on top.

Adding another layer of insulation will increase the R-value, though typically not to an appreciable degree. ICF walls themselves provide more-than-adequate resistance to thermal transmission through walls. Ensuring that areas such as the roof is properly insulated, and windows are properly sealed would be an intelligent idea, as they would likely be the weak points on a home.

More often than not, what is typically done is to simply apply the mesh, basecoat and finish coat directly over top of the outer layer of insulation in the ICF. While the styrofoam used in the ICF is suitable to apply EIFS over, contractors should make sure it is free from dust, dirt and grease (it’s not uncommon to have dirty ICF forms). Doing this turns the EIFS into a barrier system as opposed to a Dual-Barrier, it will entirely lack a drainage layer which is the key to ensuring walls last as long as possible.

From a design standpoint, it would be simple to add stucco reveals right into the ICF itself as a unique architectural feature.

NRCC Report On Vapour Barrier Use In Wood Frame Stucco Construction

Posted by Admin on October 11, 2009 None comments

The National Research Council of Canada released a report last month covering a study of various tests done using wood frame stucco construction and vapour barriers.

ABSTRACT: This paper investigates the role of the vapor barrier in exterior wood-frame stucco walls with the help of a two dimensional hygrothermal simulation tool, hygIRC-2D. For this purpose, the wall is subjected to the exterior weather conditions of six different North American geographic locations and three different interior climatic conditions. Seven different vapor diffusion strategies, generated by varying the water vapor permeance of the vapor barrier, installed outboard of the interior finish, have been studied to generate critical understanding on the role of vapor barrier in the wood-frame stucco walls.
The outputs from the simulations have been analyzed with the help of a novel moisture response indicator called RHT index. Simulation results indicate that the vapor transmission characteristics of the vapor barrier, in terms of water vapor permeance, play a very important role in the overall moisture response of the wood-frame stucco wall. A very high or low vapor permeance of the vapor barrier does not produce the optimum moisture management strategy for the wood-frame stucco wall. Moreover, simulation results indicate that the removal of vapor barrier from the wall system can result in a heightened moisture response and a considerable accumulation of moisture in the interior gypsum board that may lead to severe consequences in particular, the premature deterioration of the interior facing gypsum board.
It has also been observed from the simulation outputs that the optimum vapor diffusion strategy, that of limiting the vapor permeance of the vapor barrier, is not a function of interior climatic conditions considered in this study.
It is hoped that the results reported in this paper will shed some light on a number of concerns raised in recent years on the role of vapor barrier in wood-frame stucco wall construction.

http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc51406.pdf

EIFS Insulates and Controls Moisture Better Than Hardiboard, Brick, Stucco

Posted by Admin on March 22, 2009 1 comments

The results of a Phase II U.S Depart of Energy study on EIFS (synthetic stucco) have been provided, and confirm what building professionals have known for years: EIFS insulates walls and manages moisture better than alternative building products including hardiboard, brick and (traditional) stucco. The study was done over the course of 3 years in the worst climate possibly — a mixed, coastal, Zone 3 (hot and humid) climate.

This puts EIFS as the front-runner for U.S President Obama’s stimulus package, which includes provisions to re-clad buildings with a more energy efficient siding. Add to these results the fact that EIFS is typically less expensive than alternative cladding products and has the widest range of design options (you can match ANY colour, there are multiple varieties of textures, and an unlimited possible designs via architectural mouldings), you have a clear winner among the siding options available for buildings today.

View EIMA’s executive summary of the study at: http://www.eima.com/pdfs/EIMA%20ORNL%20ExecSum%20Final.pdf

Stucco Vs EIFS

Posted by Admin on November 3, 2008 4 comments

EIFS (pronounced “eefs”) stands for Exterior Insulation Finish System. The cladding is also referred to as “Synthetic Stucco”, “Acrylic Stucco” or just “Stucco” (the latter being ambiguous with plaster stucco). Although initially developed around the ’40s to retrofit war-torn WW2 buildings, it is among the newest and most attractive styles of cladding available to homeowners today. EIFS differs from traditional Stucco (cement) in that it is applied using different materials — in multiple layers, providing greater flexibility and benefits.

At Toronto Stucco Contractor, we only recommend and install EIFS. We believe that it is a superior system to cement stucco because it incorporates drainage to prevent mould, has insulation (in toronto insulation is important) and provides a more attractive finish.

So what are the differences between EIFS and traditional stucco (plaster)?

  • EIFS is softer and sounds hollow when tapped
  • EIFS has a finely textured finish coat
  • EIFS provides insulation and water management
  • Cement stucco is solid and cement-like
  • Cement stucco is typically rough and contains large swirls
  • Cement stucco may trap water behind the wall

Not a DIY (do-it-yourself) Project
Contrary to conventional wisdom, EIFS actually contains 4 layers:
- An Air/Moisture or Vapour barrier depending on the requirements of the building
- Insulation, fastened either chemically (using cement) or mechanically (using screws)
- A polymer-modified base coat with an embedded fiber glass mesh
- A beautiful, durable acrylic finish coat
While a skilled drywall plasterer may not find the various trowel-applied layers difficult, it takes a certain knowledge of the finer details to ensure the system is installed 100% correct.

The Long and Winding Road
In the past decade EIFS has come under fire for “moisture problems”. While the issues were real, the biggest problem was arguably the quality of the installations in a fledgling industry without any real guidelines or enforcement. EIFS Manufacturers were quick to update their “recommendations” and have gracefully pulled their industry out of a downward spiral. Among the changes are:

  • A continuous, trowel-applied moisture barrier which goes over the substrate to keep water/moisture away from the substrate
  • Removal of recommendations to use mechanical adhesive methods (screws) as it punctures the moisture barrier, thereby allowing moisture penetration
  • The use of flashing above windows and other openings and caulking around wall penetrations
  • The most dramatic improvement — the specification of a “drainage channel”. The styrofoam is adhered to the air/moisture barrier in vertical channels of cement; allowing water to drain out of the system.

The Verdict
There’s an old saying that whatever doesn’t kill you makes you stronger – and nowhere does this hold more true than in the EIFS industry. EIFS has undergone more scrutiny than any other cladding product and as a result has a mountain of research and technology backing it and supporting it. It still has a stigma to lose, but is currently a safe and attractive alternative to classical brick and mortar siding.