Introduction<\/p>\n\n\n\n
Building a campervan subfloor in a van involves dealing with the factory metal floor, which has raised ridges (corrugations) with valleys in between. A common question among van builders is whether to\u00a0fill those low valleys before adding insulation and subfloor<\/strong>. The decision can impact thermal performance, noise, and floor height. In fact, there are \u201ctwo schools of thought\u201d on this issue and\u00a0endless debates online<\/strong>\u00a0(Bedrug VanTred Cargo Liner: Drop-In Floor Insulation for Vans?<\/a>). This guide will break down the pros and cons of\u00a0filling vs. not filling<\/strong>\u00a0the floor corrugations, and recommend best practices given your priorities:<\/p>\n\n\n\n By drawing on van conversion experts and community experiences, we\u2019ll help you decide the optimal approach for your Transit subfloor.<\/p>\n\n\n\n The van\u2019s cargo floor is thin metal stamped with\u00a0corrugated ridges<\/strong>\u00a0for strength. The ridges (~0.3\u20130.4\u2033 high) create an uneven surface with hollow channels in between. When insulating and building a subfloor, you have to choose how to handle these channels (\u201cvalleys\u201d). Key considerations include:<\/p>\n\n\n\n Understanding these factors, let\u2019s examine the two main approaches for the ridged floor: filling the valleys<\/strong> versus leaving them open<\/strong> under your XPS insulation.<\/p>\n\n\n\n What It Involves:<\/strong> Cutting pieces of insulation (or other material) to fit snugly in the low channels so they are flush with the tops of the metal ridges. Commonly, builders use strips of rigid foam (XPS or polyiso) or a closed-cell foam like minicell, glued in place. Some older methods use wood furring strips, but as we\u2019ll see, that has drawbacks.<\/p>\n\n\n\n Pros of Filling the Valleys:<\/strong><\/p>\n\n\n\n Cons of Filling the Valleys:<\/strong><\/p>\n\n\n\n How to Fill Properly (If You Choose To):<\/strong> If you decide the benefits are worth the work, here are a few tips from the community:<\/p>\n\n\n\n (DIY Van Floor – Insulation, Subfloor & Covering Install Guide – FarOutRide<\/a>) A drop-in BedRug VanTred cargo liner being installed in a Ford Transit. The foam-backed mat fills the floor\u2019s corrugation valleys, providing a flat insulated surface. This is an alternative to cutting individual foam strips by hand.<\/em><\/p>\n\n\n\n What It Involves:<\/strong> In this approach, you do not<\/strong> put anything in the low grooves. You lay your insulation board (XPS, polyiso, etc.) on top of the ridges, effectively \u201cbridging\u201d over the valleys. Then you add your plywood subfloor on top. The foam and plywood span the gaps created by the ridges, and the space in the channels remains an air gap. In essence, the subfloor is supported only by the metal ridges and wherever the foam touches those high points.<\/p>\n\n\n\n Pros of Not Filling:<\/strong><\/p>\n\n\n\n Cons of Not Filling:<\/strong><\/p>\n\n\n\n How to Succeed with an Unfilled Floor:<\/strong> If you choose not to fill the valleys, follow these best practices to ensure a quiet, sturdy, and well-insulated result:<\/p>\n\n\n\n Both methods \u2013 fully filling the ribs or leaving them empty \u2013 can and do work<\/strong>. In fact, FarOutRide has used each approach on different builds (filled on their first van, unfilled on their second) and observed success in both (DIY Van Floor – Insulation, Subfloor & Covering Install Guide – FarOutRide<\/a>). Here\u2019s a quick recap of the trade-offs, as highlighted by experienced van builders:<\/p>\n\n\n\n To quote a balanced perspective from FarOutRide\u2019s review of this topic: \u201cBoth methods are commonly found in van conversions, but we still haven\u2019t seen any real-world, long term evidence proving for sure that one method is definitely wrong.\u201d<\/em> (Bedrug VanTred Cargo Liner: Drop-In Floor Insulation for Vans?<\/a>) In other words, neither choice will make or break your build<\/strong> as long as it\u2019s done thoughtfully. Many vans have hit the road with unfilled floors and many with filled floors \u2013 both can last for years without issue.<\/p>\n\n\n\n Given your priorities (thermal first, then sound, then minimizing height), here is a recommended path forward:<\/p>\n\n\n\n\n
Understanding the Transit Floor and Your Priorities<\/h2>\n\n\n\n
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Option 1: Filling the Floor Valleys (Insulation Strips)<\/h2>\n\n\n\n
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$300<\/code> extra to get minicell for filling, and was looking to skip it (Do I need to fill the ribs in my floor before laying XPS? : r\/VanLife<\/a>). If cost or availability is an issue, you could use strips of the same XPS you already have (many have done this successfully (How to Build an Insulated Subfloor in Your Van Conversion | by Jeremiah Luke Barnett | Medium<\/a>)). Just be aware to secure them well (spray adhesive works) so they don\u2019t rattle loose.<\/li>\n<\/ul>\n\n\n\n\n
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Option 2: Leaving the Valleys Unfilled (Floating Floor)<\/h2>\n\n\n\n
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Comparison of Approaches (Summary)<\/h2>\n\n\n\n
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Recommendations for Your Build<\/h2>\n\n\n\n
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