How material selection for subgirts plays into the bigger picture
When looking to select subgirt material, it is important to consider all factors. Construction is notorious for being just good enough. Materials are specified for a reason. When VE happens, what was designed as a thermally efficient envelope with the highest efficiencies goes away — usually going for something that is just good enough but not best practice for the desired results. Why isn’t everyone striving to be insanely great? When you make things insanely great, it is a win for everybody involved. As we look to improve thermal efficiency, let’s do that — let’s try and make things insanely great, using best practice techniques. Let’s try to improve the categories that we’re in. That’s where Advanced Architectural Products is taking the commercial building and continuous insulation industries.
Composite sub framing and thermally efficient subgirts for continuous insulation systems
There is now a building code requirement for continuous insulation in all buildings. Buildings are one of the single largest wasters of energy, due to inefficient use. The government understands that if a layer of insulation wraps the outside framing of a building, it will have higher energy efficiency, less waste, and less greenhouse gases. It’s now being required by building code authorities both in the United States and around the world.
What are the solutions?
In approaching that, various companies have tried several things trying to create a solution. Some companies simply put insulation on the outside of a building and run a bunch of screws through, others have done clips and brackets with just a thermal spacer on the back side. These are still in metal, and obviously hundreds of thousands of holes through your building isn’t really a good idea unnecessarily. You’re improving one thing and making it worse overall. People are cutting insulation around clips and brackets and all the cold is still getting behind the insulation at that level. The third approach is composite sub-framing, which replaces metal sub framing.
SMARTci has been creating composite sub-framing for about 10 years now, using best practice philosophy to implement a continuous insulation subgirt framing system.
We’re going to come out and use best practices. That’s the only way we’re going to discuss things right now — it’s the only way to do things in construction. Anything else really is accepted practices, accepted best approaches and making the product better or equal to, or better all the categories that it interfaces with.
Subgirt Material Selection
The first thing we’re going to talk about is composite subgirts. For a composite subgirt, there’s three types of material that we’re going to look at. Our baseline is metal, then there’s composite. For this, we’re going to be talking about a thermoset pultrusion. It’s the only practical use, and it’s the best use of plastic materials for this application. It has fiberglass reinforcing a resin with fire retardant. A hybrid of metal and thermoset pultrusion plastic uses the best of both of those worlds.
With material selection we’ll explore what each material can bring to the table — its strengths and weaknesses. We have metal only, composite only, and then the hybrid of the two materials.
With metal, the negatives are a high thermal conductivity and it has a uniform flat surface, so there’s no features. You can’t put any weather-tight features in there; it’s smooth and flat.
With a pultruded composite, some of the weaknesses include that it doesn’t hold faster torque. If you put a screw in it, it’s going to be loose the next moment; it doesn’t hold it’s torque. It’s a tendency in the industry for 50 years that it has always recommended that you use bolted connections. They’re not friendly to tech fasteners. Additionally, composite has low fire resistance, it’s relatively low strength and is 10 times less stiff than metal. With this, you have to really watch your engineering. And then because of that high flexibility you get force singularities. There can be a point load on it and it’s already maximum stressed out, so you have to be careful of these things.
Composite Metal Hybrid Material
Now, however, you can combine both metal and composite in a product for the subgirt material selection. With a composite metal hybrid, you’re going to end up with a high fire resistance, retention and enough torque, and low thermal conductivity. You can put in three dimensional features like an extrusion for seals and gaskets. You get a really good strength to weight ratio, and you can actually optimize the strength where it needs to be on the girt. Additionally, there is interlock ability. When we talk about fasteners, we’re gonna talk about interlock ability because if you go just pure composite, you’re going to have a cantilever problem. With the composite metal hybrid, there is also durability. With composite metal hybrid material, you’re using the best of both worlds. This is the sweet spot of material selection.
The SMARTci continuous insulation systems use an sFRP GreenGirt subgirt, leveraging composite metal hybrid material technologies. Through this subgirt material selection and design, buildings are able to achieve up to 98% thermal efficiencies when using GreenGirt in their continuous insulation system. Learn more about SMARTci and contact ustoday for a quote.