Tag Archives: drainage

What Are Geometrically Defined Insulation Boards?

Posted by Admin on February 12, 2011 None comments

A relatively new modification to modern Exterior Insulation Finish Systems (EIFS, or “Synthetic Stucco”) are what is called (geek alert) Geometrically Defined Insulation Boards. What exactly does that mean?

It’s a complex way of saying insulation with grooves cut into the back. The purpose of the grooves is to provide a way for water to drain out that gets behind the system. This helps to ensure that no moisture becomes trapped, causing mould or rot.

Why is this necessary? Well, it’s not if EIFS is installed by a skilled applicator, but was implemented to further assuage the fears of Architects. The problem is that even when the Architect properly specifies a system, General Contractors (and home owners) don’t always pay for true skilled applicators – and the applicators who charge less typically do so because they’re inexperienced. Less experience means higher chances of screwing up some part of an EIFS installation.

A popular argument against EIFS with drainage channels formed from cementitious adhesive (the grey streaks in the picture above) is that  the ribbons are flattened out once  the exterior insulation is pressed in place on the wall. The argument goes that if the ribbons are flattened, there is no longer any way for water to drain out if it gets behind the system. Unfortunately, there is an element of truth to the statement – I have seen insulation torn off walls as part of an inspection and observed a complete lack of drainage space because the insulation was pushed against the wall too hard.

If this was to happen, the weather-barrier that is required by EIFS manufacturers would help to protect against mould and rot problems. The majority of the time however, the vertical ribbons of adhesive stay in tact when the insulation is pressed in place (by a skilled applicator).

The Cause Of The Problem

As with all potential problems with skilled trades, it comes down to hiring the right contractor. Selecting the cheapest bid will not get you actual skilled applicators who know how install EIFS properly. This is the case with all skilled trades though, and not a problem exclusive to the EIFS industry. The problem is that every idiot GC or home owner brags when they get EIFS installed for $6 per square foot, when what they’re really doing is shooting themselves in the foot. The $6/sf “contractor” is typically an applicator who was in the industry for a couple of years and is willing to charge less because they won’t take the time to install the system properly. Whether that’s because they’re not aware of how to properly install EIFS or they just aren’t ethical people is another topic entirely. Other people hear about this then think that paying $6 per square foot for EIFS is the norm, and are shocked when something inevitably goes wrong. The few hundred or thousand dollars they save ends up costing many thousand in the long-run and in their ignorance they blame EIFS.

The purpose of the geometrically defined insulation boards is to help “idiot-proof” an EIFS installation. By creating a second layer of drainage that is difficult to clog up (in addition to the cementitious ribbons), the EIFS industry is essentially helping general contractors and home owners who are otherwise too ignorant to hire the right contractor. While the industry is aware I’m sure that someone out there is working hard to create a better idiot – it’s still a step in the right direction and will undoubtedly help a few projects.

Additional Thoughts

Notice that in the image above, the edges of the insulation board are also cut back so that there is additional means of drainage around the perimeter of the insulation boards as well as within it. Also note that this only works if the insulation boards are installed horizontally (how it’s being held in the picture) so that water can drain vertically down the cavities.

Some people have commented that cutting into the insulation reduces it’s R-value. Studies by the EIFS manufacturers have found the reduction in R-value to be negligible as less than 5% of the insulation is removed to create the channels.

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.

EIFS Sales in Positive Trend (Chart)

Posted by Admin on March 22, 2009 1 comments

Ever since EIFS’ introduction into the US and Canadian market, it has been on an upward trend. Even with it’s problems through the 90′s it has countinued to climb in popularity due to it’s insulating value and vast range of design options. With the moisture issues formerly plaguing it now solved (and new research indicating it’s actually superior to alternative products), it’s reasonable to expect the trend will countinue and even intensify.

As an additional consideration, U.S President Obama’s plan to re-clad buildings to be more energy efficient as a part of the economic stimulus package will produce a spike in sales over the next decade.

A bar graph showing the positive trend in EIFS Sales over the years

A bar graph showing the positive trend in EIFS Sales over the years

Drainage EIFS Wall Section: Durabond EW17

Posted by Admin on November 8, 2008 2 comments

Here’s a diagram of a “dual barrier” EIFS wall cross section. Notice there are 4 substrates shown: Concrete, Masonry, Glass Mat Gypsum Board and Cement Board. A Water Penetration Barrier is designed to keep incidental water off the substrate, similar to a building wrap. Unlike a building wrap however, insulation can be adhered using insulation adhesive in drainage channels, to allow incidental water to run down the wall. Because the insulation is not mechanically attached (using screws) — you don’t have anything penetrating through the water barrier. The remaining components are similar to all other synthetic stucco cladding.

Drainage EIFS Wall Section: Durabond EW17

To have the EW17 system installed on your home in toronto, visit: stucco toronto and request that Durabond be used as the supplier.

Renovating House Siding With Stucco: Substrate Considerations

Posted by JamesCarnegie on November 5, 2008 None comments

On renovations and other non-new construction, the potential for hidden problems (read: costs) is always there. This holds particularly true in renovating your siding, where you never know what condition your substrate is in. Does this mean you should avoid the issue altogether? No. As they say: Kill the monster while it’s small, before it has the chance to become a full grown problem.

Replacing old Siding
You may be looking at EIFS for a multitude of reasons; saving money on your heating bill, damaged siding, or you may just be looking for a more modern look. A good portion of homes built in the 70s, 80s and even 90s used unattractive and incorrectly installed vinyl or board and batten siding. These days, not only is the siding considered retro and shows signs of aging, but in most cases it wasn’t properly sealed and may be covering serious rot and mold. The fact is you don’t know if the subdivision builder slapped the walls together as quickly and cheaply as possible, at a time comparable to medieval age in terms of knowledge about weather resistance.

Stucco Substrate Condition
In replacing your siding with stucco, you will be forced to take a good look at your substrate and it’s suitability for synthetic stucco siding. Any instance of mold or rot will need to be replaced before the trowel-applied weather barrier can be applied. The substrate is required to be free of surface contamination, including (not not limited to); dirt, form release agents, efflorescence, oil, chalkiness, and cracks greater than 1mm. Even in situations where the substrate is fine, it may not be approved to have EIFS applied over it. EIMA defines a suitable substrate as: “gypsum sheathing in compliance with ASTM C 1396 (formerly C 79), glass-mat gypsum sheating in compliance with ASTM C 1177 (Dens-Glass Gold® or BPB GlassRoc), and gypsum fiber panels in compliance with ASTM C1278 (Fiberock® Brand, Aqua Tough™)” and certain manufacturers such as Durabond have products for exterior grade plywood (which also acts as lateral bracing). Felt paper or building wrap is no longer recommended because it requires mechanical attachment, which penetrates the weather barrier, allowing moisture in. Certain substrates such as exterior-grade drywall (gypsum sheating) may also require lateral bracing between studs. Lateral bracing is used to prevent excessive horizontal movement and assist in absorbing wind loads transferred to it from the stucco wall. When in doubt, you may want to have an engineer look at your walls so as to avoid having your siding crack down the road. A final note is that most EIFS manufacturers require less than 1/4″ deflection per 60″ span (L/240) — a feat that a good portion of construction projects wouldn’t meet if measured.

Retrofiting Stucco with Brick and CMU
With brick and CMU (concrete masonry units), your sheating and cladding may not need to be touched at all. Brick contains an air gap between itself and the substrate — usually covered in a building wrap. This means that while you may need to level the brick face with basecoat to properly adhere the styrofoam, you need not worry about replacing the substrate, adding a drainage layer or the stucco causing moisture problems. Along the same lines, CMU construction can not rot or support mold growth and usually acts as a partial weather barrier (note: they usually have poly installed between the masonry and interior drywall.) In this case, the styrofoam may be applied directly to the CMU. Even on brick and masonry, it is a good idea to to have the drainage channel to prevent water from becoming trapped behind the EIFS cladding; and they still need to comply with sheating requirements (free of dirt, form release agents, efflorescence, oil, chalkiness, and cracks greater than 1mm.)

Overview
It’s important to realize that whatever is currently on your house will have an impact on how any siding replacement proceeds, and stucco is no exception. It is a good idea to have some extra money budgeted and an agreement with you stucco contractor as to what will happen in the event you run into unsuitable substrate. Stucco Contractors rarely do sheating replacement and you will likely need to find a general renovation contractor to do this before they can proceed. You will also need to have a large bin on site to dispose of your old sheating and substrate, or specify this as part of your general contractor’s job. In the case of applying stucco directly over brick or masonry, you may even be able to save some money because there’s one less layer to be applied.