Hi folks,
I know there are a few posts out there about external wall insulation but none quite address the query I have - I hope you might be able to help.
I've got three quotes for external wall insulation on my 3-bed end of terrance. They are all very close in price (all around €13,000). One supplier provides EPS (expanded polystyrene), another phenolic and the third rockwool.
Which is best? I'm inclined, from what I've read here to date, to chose rockwool. However, I'm concerned about its water absorbency - I don't want it absorbing like a sponge in the event of rain during installation or degradation of the integrity of the render system. Also the rockwool contractors are recommending a slightly thicker depth of insulation than the EPS or phenolic contractors.
I'm also curious, given that rockwool and phenolic are considerably more expensive than EPS, why the EPS quote is nearly equal to the phenolic and rockwool quotes... but that's something I should raise with the EPS contractor.
Hope you can help...
Phenolic foam is the best, in that it has the lowest U value, usually around 0.02w/m2K. EPS is around 0.035 - 0.038, the lower being graphite injected. Rockwool is in the similar range as the EPS. The main differences are to achieve the required overall U valve or R value, you will have to use thicker levels of the higher U valued products. So in cases, where restrictive thickness are required, then you will require phenolic foam to achieve the required R value. (R Value being the overall required value of the total fabric)
EPS is by far the cheapest. Rockwool is a nice material but it will lose some of it's U value over time as it depends on air within it to achieve it's U value. Similar to how fibre quilt behaves in an attic space. New, it's nice, thick and fluffy, 5 years time, half the thickness and a bit limp, 10 years: throw it away. Phenolic foam on the otherhand should last a lifetime. It is also closed cell, in that when it comes in contact with water or moisture, it will not affect the integrity of the material, whereas, open cell materials, such sprayed insulation loses it's thermal properties on contact with moisture.
If cost is an issue, phenolic foam being the most expensive, then you could opt for an in between called polyiso. This has very similar properties to phenolic foam and has a U value of 0.023W/m2K. It is also closed cell. You will have seen it before, such as insulated plasterboard slabs for walls, rigid roof insulation particulary in dormer bungalows, floor insulation, etc.
Either way, you should have a detailed calculation carried out giving the required building regulation U value, each contractor giving you what their product will achieve, what guarantees they will give you and how long it will perform for at this overall R value. Get references and CHECK THEM OUT.
Also most manufacturers of insulation offer free consultation, free calculations, performances, etc. and are extremely helpful.
Check out: Kingspan Insulation, Xtratherm Insulation & Quinn Insulation. All will offer the above service free of charge.
Hope this helps....
phenolic has been reinstated about 3 months ago on weber certs
thanks, found it [broken link removed]
wonder what did they to counteract the issue of the phenolic breaking down when wet???
i see a minimum of 5 mechanical fixings per board is required, thus increasing the thermal bridging.
personally id prefer to increase EPS depth to counteract any perceived loss of performance, when comparing EPS with PHS. I see that IAB cert for both EPS and PHS has a max thickness of 200mm. I wonder why as EPS can easily do 300mm.
also the thermal conductivity value of 0.02 for PHS is not assessed as part of the cert and is only down as the manufacturers declared value, not that im challenging that.
It's never easy...
Less than two weeks before our external insulation work is due to start... Quotes got and accepted, scope of works agreed... Have registered and been approved for SEAI grant... ESB and UPC have been informed and have done their necessaries... Other works that had to be done before the start of the external insulation works are finishing up today... we're all set and ready to rock and roll... toasty house, here we come...
... and now the bloody insulation contractor has pulled out of the job altogther!!
GRRRR!!!!
Am now chasing up the next contractor in line and deciding whether to get them to requote for EPS (their original quote was based on rockwool but I have concerns about it's moisture resistance)
Really, I just needed to vent but am also keen to get recommendations for (good, reliable!!) external insulation contractors who work in the Dublin area.
Less than two weeks before our external insulation work is due to start... Quotes got and accepted, scope of works agreed... Have registered and been approved for SEAI grant... ESB and UPC have been informed and have done their necessaries... Other works that had to be done before the start of the external insulation works are finishing up today... we're all set and ready to rock and roll... toasty house, here we come...
... and now the bloody insulation contractor has pulled out of the job altogther!!
GRRRR!!!!
Am now chasing up the next contractor in line and deciding whether to get them to requote for EPS (their original quote was based on rockwool but I have concerns about it's moisture resistance)
Really, I just needed to vent but am also keen to get recommendations for (good, reliable!!) external insulation contractors who work in the Dublin area.
Had this work done earlier this year-dont know what area u are in-we used Insulateyourhome.ie....Kevin is the main man....around €85 per m2 I think...did a good job...but more importantly...found Kevin good to deal with...if u want any other info let me know-but not too technical!
The Overlooked Choice of Exterior Wall Insulation Materials
In many construction projects, Exterior Wall Insulation Board materials tend to be limited in variety. This is often due to insufficient consideration by contractors, who typically select Insulation Materials based on short-term cost control rather than long-term performance and economic benefits.
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As a result, the selection of insulation materials often fails to align with the ongoing advancements in energy-efficient construction technologies. Additionally, some manufacturers remain hesitant or skeptical about emerging insulation materials, resisting change and failing to keep pace with the evolving industry landscape
Advantages of Exterior Wall Insulation Technology
Wide Application & Comprehensive
- technology is widely applicable, providing effective thermal insulation not only for specific parts of a building but for the entire structure. It helps maintain stable indoor temperatures, making it suitable for both cold and warm climates.
Enhanced Protection Against Environmental Factors
- By adding a protective insulation layer to the external walls, buildings gain improved resistance to UV exposure, wind, frost, rain, and snow, reducing direct damage to the structure. This also helps prevent water infiltration between building layers, minimizing long-term maintenance costs.
Thermal Bridge Elimination
- Proper insulation placement can effectively eliminate thermal bridges, preventing heat loss at weak points such as building joints and balconies, ensuring better energy efficiency.
Energy Efficiency & Indoor Comfort
- Exterior wall insulation systems not only help regulate indoor and outdoor air temperatures but also significantly reduce heat transfer from external walls. This leads to lower energy consumption, creating a more comfortable indoor environment and enhancing overall occupant satisfaction.
Selecting and Applying High-Performance Insulation Materials
Exterior wall insulation materials can be categorized into several types:
Expanded Polystyrene (EPS) Boards
- Widely used due to affordability, EPS has a thermal conductivity of approximately 0.041 W/(m·K). However, it offers limited fire resistance and mechanical strength, and installation can be labor-intensive.
Extruded Polystyrene (XPS) Boards
- Featuring lower thermal conductivity and good compressive strength, XPS is less permeable but may have adhesion issues with certain substrates.
Glass Wool
- Comprising fibrous materials with thermal conductivity ranging from 0.030 to 0.045 W/(m·K), glass wool provides sound absorption and fire resistance.
Phenolic Foam Boards
- With a thermal conductivity of about 0.020 W/(m·K), phenolic foam offers excellent insulation and fire resistance.
Polyurethane Foam Board (PU)
- Known for superior performance, PU foam has a thermal conductivity of approximately 0.020 W/(m·K) and excellent moisture resistance, making it ideal for roofing and below-grade applications.
Each material has distinct advantages and limitations, making it crucial to select the right insulation based on specific project requirements.
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For example, while EPS is affordable and widely used, its fire resistance is poor; XPS has excellent thermal performance but lacks breathability; Glass wool offers good fire resistance but requires careful moisture control; Phenolic Foam Board provides strong insulation, but quality varies by manufacturer; and PU foam Insulation Board delivers top-tier performance but comes at a premium cost.
Insulation Materials in Engineering Applications: A Real Case Study
In an earlier GFI client project, a client switched from traditional glass wool to Polyurethane Insulation. As a result, the wall’s thermal conductivity improved from 0.040 W/(m·K) to 0.024 W/(m·K), significantly enhancing the building envelope’s thermal efficiency and reducing heat loss.
According to the client’s final feedback:
- Indoor temperature stability improved, with fluctuations reduced from ±1.5°C to ±0.5°C.
- System failure rates dropped by 40%, lowering annual maintenance costs by 18%.
- These changes substantially reduced operational expenses, highlighting the superior performance of advanced insulation materials and equipment in HVAC applications.
While insulation materials played a critical role in these achievements, proper construction methods and quality control were equally important.
Best Practices for Exterior Wall Insulation Construction
1. Preparation Before Construction
- Clean wall surfaces thoroughly to remove dust and debris, ensuring optimal insulation adhesion.
- Apply a leveling plaster to create a smooth and even surface.
- Develop a construction plan based on local climate and building type to ensure conditions are suitable for installation.
2. Optimizing Construction Design
- Consider building structure, climate, and environmental factors to determine the appropriate insulation material, installation method, and thickness.
- Use eco-friendly materials to support sustainable development.
3. Quality Control During Construction
- Regularly inspect wall flatness to ensure insulation materials adhere properly.
- Pay special attention to critical areas such as corners, windows, and doors to prevent gaps, cracks, or detachment.
- Seal all joints to eliminate air leakage and moisture infiltration.
4. Enhancing Energy Efficiency
- Choose low thermal conductivity materials to prevent heat loss.
- Utilize insulated materials that reduce cooling and heating loads for improved energy efficiency.
- Integrate smart temperature control systems to optimize building performance.
5. Attention to Detail
- Monitor material composition and coating thickness to maintain quality standards.
- Ensure proper sealing at wall corners and connection points to avoid defects.
- Follow environmental regulations by selecting sustainable and non-toxic materials.
Conclusion
With advancements in energy-efficient technologies, the adoption of high-performance insulation materials is essential for improving building thermal efficiency and reducing long-term operational costs. As the global construction industry continues to emphasize energy conservation, buildings utilizing polyurethane and other advanced insulation materials will achieve superior energy efficiency, occupant comfort, and reduced maintenance costs.
By implementing precise insulation design and strict quality control, Exterior Wall Insulation projects can maximize performance and sustainability, contributing to the advancement of green building initiatives.
GFI Duct’s polyurethane and phenolic insulation boards offer exceptional thermal efficiency, low thermal conductivity, superior moisture resistance, and long-term durability, providing high-performance energy-saving solutions for global markets that demand eco-friendly and efficient building materials.
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