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How to Spec Mullion, Dam, and Thermal-Break Parts: What to Send H-O for a Quote
Mullion and thermal parts are the easiest items on a curtain wall to underspecify because no single drawing owns them: a plug here, a dam there, a break strip at an anchor. What H-O quotes is not a foam block but a part tied to an extrusion section, a detail condition, and often an assembly fire file. This is the checklist the applications team works from, drawn from the parent page own quote-information list, with what engineering does with each item and what comes back.
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What turns a hidden-parts RFQ into a quotable set?
The Mullion and Thermal Break page is built around the discipline of finding these parts at the BOM walk before the mockup finds them. The checklist below collects the information that makes each hidden part repeatable and quotable, so the quote prices the right geometry and grade rather than a stock foam block. Send as much as you have; partial specs are welcome and engineering fills the gaps during quote review.
| Send this | What it decides |
|---|---|
| 1. Extrusion section or cut-off | The plug geometry: designed interference against the actual cavity, so the plug is repeatable instead of a stuffed block. |
| 2. Gutter and weep detail | The end-dam geometry: the dam stands water off and routes it to the weeps, die-cut to the gutter section. |
| 3. The recurring metal-to-metal details | The break-strip and isolator-pad set: conduction lines take strips, clamped details take dense pads. |
| 4. Design interior humidity and exterior condition | The condensation case: the dew-point threshold the isolated surface must stay above, confirmed in the section model. |
| 5. Assembly fire-qualification path | The controlled-item posture: whether the spandrel insulation is inside an NFPA 285 file, where grade and thickness are fixed. |
| 6. Spandrel cavity dimensions and constraint | Aerogel for thin cavities at a fixed thermal target, polyimide where weight and fire-smoke behavior lead and the cavity is protected. |
| 7. Standing-water positions | The chemistry: closed-cell crosslinked PE and EPDM where water stands; open-cell polyimide stays above the water line. |
| 8. Geometry: DXF, STEP, or PDF, or a sample | The die program: plug outlines, dam sections, break-strip lengths, baffle splice geometry, and insulation panels. |
| 9. Kitting and attachment preference | Plain, PSA-backed, kiss-cut on liner, or kitted per elevation or unit labeled to the detail numbers. |
| 10. Prototype and production volumes | Converting method and price structure. Every part is made to order; prototype quantities through full production runs are equally accepted, and MOQ varies by material and part. |
What engineering does with the list
Item 1 sizes the SCE neoprene plug with designed interference; item 2 the EPDM or crosslinked PE end dam. Items 3 and 4 set the break-strip and isolator set, XLPE strips on conduction lines and dense EPDM under clamp loads, against the condensation model. Items 5 through 7 pick the spandrel insulation, ArmaGel aerogel for thin cavities and SOLIMIDE polyimide for light, protected ones, with the assembly file governing.
Items 8 through 10 become the converting and kitting plan and the pricing. The reply cites each recommended grade TDS values with the test method named.
What happens after you send it
- Drawing review. Engineering reviews the extrusion sections, the details, the condensation conditions, and the assembly fire path against the vendor TDS and the C518/NFRC/NFPA framework.
- Material direction and quote. A family and grade direction with the TDS attached, the converted format (plugs, dams, strips, pads, insulation panels), kitting per elevation, and pricing at your quantities.
- Samples. Typically 3 to 5 business days for common die-cut configurations on materials we keep on hand.
- Production. Standard runs ship about two weeks after drawing approval, including kitted and kiss-cut-on-liner configurations; expedited service is available when a mockup or glazing date is closing. Ongoing parts run with material traceability and lot-code TDS records.
Documentation available on request: material technical data sheet, certificate of conformance, lot traceability, and first-article inspection, under our ISO 9001:2015 certified quality management system. H-O die-cuts and converts the layer around the extrusion; the structural thermal barrier inside a thermally broken extrusion comes from the extruder, and assembly U-factor and NFPA 285 fire performance belong to the assembly, not the converted part.
The mistakes this checklist prevents
| Spec mistake | What it causes | Checklist item that catches it |
|---|---|---|
| Plug called a foam block | It walks loose and the bypass opens after a year | Item 1, extrusion section |
| End dam left off the BOM | The gutter becomes a duct and the corner leaks | Item 2, gutter detail |
| Anchor detail left bare | It condenses every January and reads as a leak | Items 3 and 4 |
| Insulation swapped in a 285 wall | The qualified construction no longer matches the file | Item 5, controlled item |
| Open-cell foam where water stands | It soaks and the detail stays wet | Item 7, standing-water chemistry |
| Baffle drawn continuous, butt-spliced in reality | Every splice is a slot the air test finds | Item 8, splice geometry |
Frequently asked questions
What information does H-O need to quote mullion and thermal parts?
The extrusion section or cut-off, the gutter and weep detail, the recurring metal-to-metal details, the design interior humidity and exterior condition, the assembly fire-qualification path, the spandrel cavity dimensions, the standing-water positions, the geometry (DXF, STEP, or PDF) or a sample, the kitting and attachment preference, and the volumes. Partial specs are welcome; engineering fills the gaps during quote review. Every part is made to order, and lead times are confirmed with your quote.
Can these parts come kitted per elevation or per unit?
Yes. Kitting is a converting service: the plugs, dams, baffles, break pads, and insulation panels for one unit or one elevation arrive bagged together and labeled to the detail numbers on your shop drawings, so the line and the field crew stop sorting loose foam. Kiss-cut-on-liner formats suit factory unitized lines and compression-fit parts with no adhesive suit field stick installation.
Kitting also closes the omission gap this page warns about, an empty pocket in the kit is visible where a missing BOM line is not. Ask for kitting on the RFQ with the detail list.
Can you cross-reference the foam parts in our system manual?
Usually, yes. Send the system manual accessory pages, the incumbent TDS, or physical parts, and engineering cross-references to families H-O converts, matching chemistry, closed-versus-open cell, ASTM D1056/D3575 class, water-absorption behavior, the relevant data lines (C518 thermal, E84/E662/UL 94 where called), and the die-cut geometry.
The result is an engineering cross-reference verified against the vendor TDS before quoting; where a part sits inside an assembly-level qualification such as an NFPA 285 path or a tested mockup, the re-qualification consequence is called out honestly rather than papered over.
Do you supply the thermal barrier inside the extrusion or the parts around it?
The parts around it. The structural thermal barrier inside a thermally broken extrusion, the poured-and-debridged polyurethane or the rolled-in polyamide strut, is part of the extrusion and comes through the extruder. H-O converts the die-cut layer at the assembly details: plugs, dams, baffles, break strips, isolator pads, and spandrel insulation. If a detail needs both, the extrusion barrier comes from the extrusion supplier and the converted parts come from H-O, coordinated on the shop drawing, with H-O parts lot-coded to their TDS.
Send the checklist, get a mullion and thermal parts quote
Attach the extrusion sections and the detail list with as many of the ten items as you have. A sample part works when no drawing exists, and partial specs are welcome.
Samples typically ship in 3 to 5 business days for common die-cut configurations on materials we keep on hand; standard production runs about two weeks after drawing approval; expedited service is available. MOQ varies by material and part.
Family-owned in Winsted, Connecticut since 1971 · ISO 9001:2015 certified · OEMs worldwide send us a drawing — and get back their part.
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Request a quote for your curtain-wall mullion thermal break part
Send H-O your drawing or describe the part—engineering reviews every RFQ and converts samples on your geometry.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
References
- ASTM D1056 (cellular compression-deflection grades); ASTM D3575 (crosslinked polyethylene foam); ASTM D3574 (flexible polyurethane foam); ASTM D2240 (durometer).
- ASTM C518 & C177 (thermal conductivity); ASTM C1363 (hot-box thermal performance); NFRC 100 (U-factor framework); ASTM E283 (air leakage); AAMA 501 series (mockup verification).
- NFPA 285 (exterior wall assembly fire propagation); ASTM E84 (surface burning); ASTM E662 (smoke density); ASTM C423 (acoustic absorption); UL 94 (flammability classes, per grade).
- Manufacturer technical data sheets for the SCE neoprene, EPDM foam, crosslinked PE, silicone sponge, dense EPDM, ArmaGel aerogel, and SOLIMIDE polyimide families named on the parent application page.
This checklist supports a quotation workflow; it is not thermal, condensation, or fire design guidance for any specific wall. Frame U-factor belongs to the assembly under the NFRC 100 framework and ASTM C1363, and fire performance belongs to the assembly under the NFPA 285 path. Grade-level values are confirmed on the manufacturer's current technical data sheet at quote time.
All parts are custom manufactured to order; minimum production run quantities vary by material and part. H-O is a die-cut converter and does not extrude the structural thermal barrier inside aluminum extrusions.