A buyer copies a waterproof figure off a competitor's spec sheet, drops it into the brief, and figures the seam question is closed. It is not. The figure describes the fabric. A seam is a separate line of needle holes with its own fix, and a custom camping tent design brief has to name that fix on every seam line: method, material, which seam. Without those lines, two suppliers read the same page and build two different tents, and nothing on the sheet tells you which one you approved.
Why a Waterproof Number Won't Spec Your Seams
Most sourcing teams assume a waterproof figure on the fabric covers the seams. In fact it does not. That number is a fabric-level result; the seam is a different question, and manufacturers keep it as a separate decision with three options on the table.
The cost shows up in the first round of quotes. Both suppliers see the waterproof figure and each closes the seams the way their own line usually does — one tapes, the other seals. Prices come back built on different work, and the samples you approve are two different builds. You cannot compare unit price when the unit is not the same tent.
Three Ways to Stop Water at a Seam
Three options, not one. To prevent infiltration, tent manufacturers can tape the seam, seal it, or make the seam construction itself strong enough to do the job, and those are alternatives rather than three words for the same process.
That is what a seam spec line has to carry: one written instruction per seam line, naming which of the three is used there, with what material. The fly gets its own line, the floor gets its own, and any sewn pole sleeve or vent frame gets one too. Two lines on the same tent can legitimately carry different methods, so one statement covering the whole tent is too coarse to build from.
Half-specified is the usual failure. It rarely looks like one: a brief that names a method for the fly and leaves the floor line empty reads finished, and it is only half a tent.
Tape Under the Seam vs Sealant Across It
Taping is a layer of tape — technically a polyurethane film — placed under the seams to block any water that enters the needle holes from making its way into the tent. Sealing works from a different position: it is like applying a layer of glue, or sealant, across the seams.
That is a different step in the build, and it changes what you are buying. Whether the sealant goes on at the factory before packing or is left for the user to apply is a real question on its own, and the answer moves labor and instructions to a different party.
The Third Option Is the Seam Itself
Suppose a supplier comes back with 'strong seams' and nothing else. You have no material named, no description of how the seam is built, and no way to sit it beside the other quote. That third option really is a strong seam construction, and the description stops there: stitch type, thread, and construction detail are not spelled out, so none of it can be lifted into your brief.
Turn the gap into questions instead. Ask what the seam construction is on the model being quoted, where it is used instead of tape or sealant, and how the supplier writes it on their own spec sheet. A photo of the seam cross-section helps if one exists. A supplier who answers those three things has handed you a defined option. One who answers with a slogan has told you the option is still undefined.
What Actually Goes on Each Seam Line
Most buyers assume seam treatment is a factory default they can leave off the page and still receive. It is not a default. The brief is where the choice between tape, sealant, and seam construction gets recorded, and whatever the page leaves blank, the factory fills in for you.
Each seam line can record the method, the material, where the material sits relative to the seam, and who applies it. Those fields follow from the physical difference between taping and sealing, not from house style. Treat this as a drafting convention for your RFQ, not a standard and not a supplier commitment.
Suppose the brief names tape on every seam and no material. Imagine handing that page to two factories. Both can follow it and still build different seams, because 'tape' names a method and not the film placed under the needle holes.
RFQ Lines That Replace a Waterproof Claim
None of that replaces asking the supplier what they can do. Custom capability, minimum order quantity, price, lead time, available tooling or molds, and certifications are open questions on a first RFQ, and every one of them stays a question until the answer arrives in writing.
Ask which seam-related test reports the supplier holds and which model each was run on, rather than accepting a waterproof figure printed in a catalogue. A report tied to a model tells you something about that model. A number with no model attached tells you where the copy came from.
Set the boundary in the same email. Nothing in a seam spec supports a flammability, flame-retardant, hydrostatic, CO, wind-rating, or all-weather claim, so keep it out of the brief. Tolerances and acceptance thresholds come from the model's own documents and from what both sides agree in writing, not from a template someone downloaded.
The One Check Before You Approve a Sample
One check stands above the rest. Before you pay a deposit or sign off a sample, make the supplier write the seam method and the seam material onto every seam line of the approved spec, then confirm the physical sample in your hands matches those lines.
Approving a sample is a comparison between a document and an object. If the spec line does not say tape or sealant, and with what material, there is nothing to check the sample against, and the sign-off certifies a look rather than a build.
