How to Prevent IronPDF Headers and Footers from Covering Content

IronPDF headers and footers cover body text when the page does not reserve enough vertical space for the rendered affix. Set a realistic Height or MaxHeight on each HtmlHeaderFooter, then set RenderingOptions.MarginTop and MarginBottom to values at least as large as the rendered header and footer, including padding, borders, images, and wrapped lines.

Iron Software’s example starts with a 20 mm header, a 15 mm footer, and 25 mm top and bottom margins. Treat these as starting values: increase the margins when content wraps, uses larger fonts, or contains images. See the official HTML header and footer example.

1. Reserve space when rendering new HTML

Configure the header and footer before calling RenderHtmlAsPdf. The body is laid out inside the page margins; the header and footer occupy the reserved bands.

using IronPdf;

var html = """
    <html>
      <head>
        <style>
          body { font-family: Arial, sans-serif; font-size: 12pt; }
          h1 { margin-top: 0; }
        </style>
      </head>
      <body>
        <h1>Quarterly report</h1>
        <p>The report body starts below the reserved header band.</p>
        <p>Add enough content to exercise page breaks and the footer area.</p>
      </body>
    </html>
    """;

var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
{
    HtmlFragment = "<div style='font-size:14pt;font-weight:bold'>Quarterly report</div>",
    MaxHeight = 20
};
renderer.RenderingOptions.HtmlFooter = new HtmlHeaderFooter
{
    HtmlFragment = "<div style='font-size:10pt'>Page {page} of {total-pages}</div>",
    MaxHeight = 15
};
renderer.RenderingOptions.MarginTop = 25;
renderer.RenderingOptions.MarginBottom = 25;

var pdf = renderer.RenderHtmlAsPdf(html);
pdf.SaveAs("report.pdf");

The values in this example are millimetres. A 20 mm MaxHeight does not make a 25 mm margin safe if the fragment’s padding, border, image, or wrapped text needs more room. Measure the rendered result and leave a buffer.

Header and footer sizing rules

Use Height or MaxHeight when you need a predictable band.
Keep the HTML fragment simple while diagnosing overlap.
Include all internal spacing in your estimate: CSS padding, borders, line height, images, and multiple lines.
Set MarginTop greater than or equal to the actual header height, and MarginBottom greater than or equal to the actual footer height.
Set left and right margins consistently so the affix and body share the same horizontal frame.

HtmlHeaderFooter supports HTML, CSS, images, relative resources through BaseUrl, and merge fields such as {page}, {total-pages}, {url}, {date}, {time}, {html-title}, and {pdf-title}. See the HtmlHeaderFooter API reference.

2. Prevent wrapping and late layout changes

Headers often grow after they are first measured. Long titles wrap, images load, and fonts change line height. Give the fragment a fixed or conservative maximum height, reduce unnecessary padding, and reserve extra margin for the largest expected variant.

Reserve a vertical band for each affix before the body is laid out.

renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
{
    BaseUrl = "https://example.com/assets/",
    HtmlFragment = """
      <div style='height:18mm;padding:2mm 0;box-sizing:border-box;border-bottom:0.2mm solid #999'>
        <img src='logo.png' style='height:10mm' />
        <span style='font-size:11pt'>Long report title that may wrap</span>
      </div>
      """,
    MaxHeight = 22
};
renderer.RenderingOptions.MarginTop = 28;

BaseUrl lets relative images, stylesheets, and links resolve. If a resource can be unavailable, replace it with a fixed-size placeholder or reserve space for the failure case as well.

3. Add headers or footers to an existing PDF

When the PDF already exists, use PdfDocument.AddHtmlHeaders or AddHtmlFooters. Use an overload with explicit margins when exact placement matters.

OverlapBehavior can warn or throw before stamping, but it does not reflow existing content.

using IronPdf;

var pdf = PdfDocument.FromFile("input.pdf");
var footer = new HtmlHeaderFooter
{
    HtmlFragment = "<div style='font-size:10pt'>Confidential</div>",
    MaxHeight = 25
};

pdf.AddHtmlFooters(footer, ContentOverlapBehavior.Throw);
pdf.SaveAs("output.pdf");

ContentOverlapBehavior.Warn reports affected pages. ContentOverlapBehavior.Throw raises an exception before stamping when overlap is detected. The check is a diagnostic gate: it does not move, resize, or reflow existing body content.

var header = new HtmlHeaderFooter
{
    HtmlFragment = "<div>Report title</div>",
    MaxHeight = 20
};

pdf.AddHtmlHeaders(
    header,
    marginTop: 25,
    marginLeft: 20,
    marginRight: 20,
    overlapBehavior: ContentOverlapBehavior.Throw
);

Use the corresponding footer overload for MarginBottom. Check the installed IronPDF version’s API signature because overload parameter order can differ between releases.

Overlap detection covers text and images. Vector or path content, including table borders and ruled lines, is outside the documented detection scope. Review representative pages visually when those elements are close to an affix. Read the headers and footers tutorial and PdfDocument API reference.

4. Choosing margins, Height, and MaxHeight

Setting	Use it for	Overlap risk
`MarginTop`/`MarginBottom`	Reserving body space	Too small leaves body content under the affix
`Height`	A fixed affix band	Content can clip or wrap if the value is too small
`MaxHeight`	Bounding a variable affix	Actual rendered content may still need a larger margin
`UseMarginsOnHeaderAndFooter`	Applying shared margins	One layout’s settings can misfit another

Iron Software documents dynamic header and footer sizing by default and recommends defining margins in the header or footer HTML when precise spacing is required. A practical process is:

Render the largest realistic header and footer.
Inspect pages with wrapped titles, images, and the longest footer text.
Increase the corresponding margin until no body text enters the band.
Keep a small buffer for font and rendering differences.

Avoid using shared margin mode for unrelated layouts. IronPDF warns that UseMarginsOnHeaderAndFooter applies the same margins to the header/footer and body, which can create overlap. Explicit margins provide more control.

5. Troubleshooting common overlap errors

Header covers the first paragraph

Cause: MarginTop is smaller than the rendered header, often because a title wrapped or padding was omitted from the estimate.

Fix: Increase MarginTop, set a realistic MaxHeight, and simplify or constrain the header HTML.

Cause: MarginBottom does not contain the footer’s actual height, or a page break placed the final row too close to the bottom edge.

Fix: Increase MarginBottom, reserve space for borders and padding, and inspect the page containing the final row.

Overlap appears only when an image loads

Cause: The image changes the fragment’s height after sizing.

Fix: Give the image explicit dimensions, provide a valid BaseUrl, set a larger MaxHeight, and reserve extra margin.

Header and body are horizontally misaligned

Cause: Inconsistent left/right margins, zero margins, or shared-margin configuration.

Fix: Set left, right, top, and bottom values together and avoid mixing unrelated margin modes. Iron Software documents Chrome-based alignment problems involving zero margins and UseMarginsOnHeaderAndFooter; see its support article.

`Throw` raises an overlap exception

Cause: The diagnostic check found text or image content in the stamping area.

Fix: Increase the explicit margin, reduce the affix height, or move the body content. The exception does not repair the PDF automatically.

No exception, but a rule still touches content

Cause: Borders and other vector paths are outside the documented detection scope.

Fix: Add visual review or image comparison for representative pages, and leave a larger safety gap around rules and table borders.

6. Reliability, performance, and production checks

Render representative variants: test the longest title, largest logo, wrapped footer, missing image, and a page with a table ending near the footer.
Fail fast for stamping: use ContentOverlapBehavior.Throw when an overlap should block delivery; use Warn when you want a report and a manual review path.
Keep fragments deterministic: fixed dimensions and local, reliable assets reduce layout drift.
Account for page size: a margin that works on A4 may be too restrictive on smaller paper or landscape pages.
Review vector artwork: automated overlap checks do not prove that lines, paths, or borders are visually clear.
Do not assume dynamic sizing is safe: dynamic adjustment can change with content, fonts, and resources; explicit limits plus conservative margins are easier to operate.

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8. FAQ

Should MarginTop equal MaxHeight exactly?

Use at least the actual rendered height and leave a buffer. Padding, borders, images, and wrapping can make the rendered height larger than the nominal value.

Does overlap detection reflow the body?

No. It warns or throws when affected text or images are detected; it does not move, resize, or reflow existing content.

Can it detect table borders?

Documented detection covers text and images. Vector and path content such as borders and ruled lines is outside that scope.

When should I use Warn instead of Throw?

Use Throw when overlap must stop a pipeline. Use Warn when you want affected-page diagnostics and a separate review step.

Why does a layout change between machines?

Font availability, image loading, wrapping, and margin configuration can change the rendered height. Use deterministic assets, explicit dimensions, and conservative margins.