Finished size is not cut size
A banner is quoted at its finished dimensions and cut at something larger. Every hemmed edge folds material back, so a two inch hem on all four sides adds four inches to both the width and the height of the cut piece. A pole pocket adds considerably more: the material has to wrap the pole and return far enough to be welded, which in practice means roughly twice the pocket depth plus an inch of turn. A three inch pocket top and bottom therefore adds about fourteen inches to the cut height, and a banner that looked like it fit the roll no longer does.
This matters commercially as well as practically. If you quote material at the finished square footage on a small banner with deep pockets, you have undercounted by a fifth. The calculator shows both figures for that reason.
Grommet spacing
The conventional practice is a grommet roughly every two to three feet along any hemmed edge that carries fixings, with one at each corner without exception. The corners are not a rounding detail. A banner tied at its mid points and not at its corners flaps its corners until they tear, and the tear then runs along the hem. Spacing wider than three feet leaves a span that can billow enough to load the two grommets either side of it hard.
The count in this calculator comes from dividing the edge by the spacing, rounding up, and adding one for the closing corner. That is why the actual spacing it reports is always a little tighter than the figure you asked for — ten feet at two and a half foot spacing gives five grommets at exactly two and a half feet, but eleven feet gives six grommets at two point two. Tighter is the correct direction to round.
Wind
A solid banner is a sail. Its whole face catches moving air and everything it catches goes into the grommets, the ties and whatever frame or fence they are attached to. This is the failure mode for banners, not the printing and not the fabric. Two things exist to reduce it. Half moon wind slits cut into the face let some air through, at the cost of appearance and with a real reduction in the strength of the material around the cuts. Mesh media is perforated so that a substantial fraction of the face is open, which is why large building wraps and fence banners are usually mesh rather than solid vinyl.
What this page will not do is give you a wind rating, and you should be suspicious of anyone who does casually. Banners are not rated for wind speed, and what a given installation will survive depends on the media, the hem, the reinforcement, the fixings, the ties, the structure behind it and how exposed the site is. If the banner is going somewhere that failing would hurt someone or damage property — over a road, on a building face, on scaffolding — that is a question for the person responsible for the structure, and in many cases it needs a permit as well.
What the local authority thinks about your banner
Temporary signage is regulated. Many municipalities limit how large a banner may be, how long it can stay up, how many a business may display, where it may be mounted, and whether it needs a permit at all, and those rules differ between neighbouring towns. Banners across a public right of way are usually a separate approval. None of that is on this page and none of it can be inferred from a size calculation. Ask the local authority or a sign shop that works in that jurisdiction before you print, because the printing is the cheap part and taking it down is not.
Hanging it is separate again. Anything installed above head height needs proper access equipment, and anyone working off a ladder over a sidewalk with a large sail in their hands is having a worse day than they planned. If there is any electrical work involved in lighting the banner, that is licensed work.
Related
Check that the copy is big enough for where the banner hangs with the sign letter height calculator, and that the artwork holds up at size with print resolution and enlargement. For cut lettering rather than print, see vinyl and decal material. Other large surface jobs: wall panels, window film and wallpaper.
Questions people ask
How far apart should grommets be?
Conventional shop practice is every two to three feet along the hemmed edges, always with one at each corner. The calculator defaults to two and a half feet and rounds the count up, so the real spacing lands slightly tighter than you asked for. Go closer than that on anything exposed, on tall narrow banners, and on any edge that will be tied to a fence rather than pulled tight between two points. Going wider saves a few grommets and costs you the banner.
How much extra material does a pole pocket need?
About twice the pocket depth plus an inch, per pocketed edge. The material wraps the pole and has to return far enough past the weld to hold, so a three inch pocket consumes roughly seven inches of height. Measure the actual pole or rod including any end fittings before you settle on the depth — a pocket that will not slide over the hardware is a banner you have to unpick. If the pocket is for a spring rod or a tensioning system, the supplier of that system will state the pocket size it needs and you should use their figure over any default.
Will wind slits stop my banner tearing?
They reduce how much air the face catches, which reduces the load, but they also cut the material and the area around each slit is weaker than it was. They are a compromise that shops use on exposed sites where a solid banner is not lasting. Mesh media, which is perforated across the whole face, does the same job without a hundred stress risers in the print, and it is what large exposed installations generally use. Neither one is a wind rating. If failure would be dangerous, the mounting and the structure need someone competent to look at them, not a heavier banner.
Do I need a permit for a banner?
Often, and it depends entirely on where you are. Temporary sign rules are set locally and commonly cover maximum area, how many days the banner may be displayed, how many banners a business may have at once, mounting location, and whether it may face a public street at all. Some places require a permit for every banner, some for banners over a size, some not at all. Enforcement is real and usually arrives as an order to take it down. Call the local planning or code office, or ask a sign shop that already works in that town.
Should the banner be printed one piece or seamed?
One piece if the cut size fits your roll width in either orientation, which is why this calculator asks for the roll width and flags it. Rotating the artwork so the height runs across the roll solves a lot of these cases at no cost. Beyond that, seaming is normal on large work and a welded seam is stronger than the material, but it is visible under raking light and it should be placed where the design tolerates it rather than wherever the roll happens to run out. Plan the seam in the artwork, not at the finishing table.