Short answer: The phrase 400 x 400 usually describes a nominal roof-vent size, not permission to cut a 400 mm square into every vehicle. This Accessoryout product is the complete 400 x 400 mm caravan roof vent fan. Before ordering or cutting, compare the installation drawing and actual cut-out requirement, roof thickness, internal clearance, sealant system and power arrangement. Measure twice and confirm the exact SKU; a similar-looking 360 x 360 variant is a different fit. 400 x 400 mm caravan roof vent fan is the documented product used for this comparison.
Nominal size and cut-out are different checks
The phrase 400 x 400 usually describes a nominal roof-vent size, not permission to cut a 400 mm square into every vehicle. This Accessoryout product is the complete 400 x 400 mm caravan roof vent fan. Before ordering or cutting, compare the installation drawing and actual cut-out requirement, roof thickness, internal clearance, sealant system and power arrangement. Measure twice and confirm the exact SKU; a similar-looking 360 x 360 variant is a different fit. The phrase 400 x 400 usually describes a nominal roof-vent size, not permission to cut a 400 mm square into every vehicle. This Accessoryout product is the complete 400 x 400 mm caravan roof vent fan. Before ordering or cutting, compare the installation drawing and actual cut-out requirement, roof thickness, internal clearance, sealant system and power arrangement. Measure twice and confirm the exact SKU; a similar-looking 360 x 360 variant is a different fit.
Confirm the exact 400 x 400 SKU
| Dimension | Meaning | Check |
|---|---|---|
| 400 x 400 mm | Product size label | Confirm what the manufacturer measures |
| Cut-out | Opening required in the roof | Use the installation drawing |
| Roof | Vehicle panel and structure | Check thickness, ribs and clearance |
| Seal | Weatherproof installation | Use a compatible method |
Roof thickness and clearance affect installation
- Measure the roof location and internal clearance.
- Read the supplied installation dimensions.
- Mark and recheck the opening before cutting.
- Seal, wire and test only within the installation instructions.
Do not cut before the drawing is confirmed
The public product facts do not specify the cut-out size, roof thickness range, airflow, noise, power draw or every sealant requirement. Do not use a placeholder rating as a product fact.
Treat 400 x 400 as the start of the measurement
Buy the complete 400 x 400 SKU only after the actual cut-out and vehicle roof checks are confirmed. For related context, see Campervan Roof Fan 400 x 400: UK Installation Planning. For related context, see Caravan Roof Vent 400 mm Cut-Out: How to Check Before Cutting. The documented next step is the 400 x 400 mm caravan roof vent fan.
Use the product page as the final check for the documented model, included items and stated limits before ordering.
Use the product page as the final check for the documented model, included items and stated limits before ordering.