Short answer: A roof-vent cut-out must come from the installation drawing for the exact product, not from rounding the name 400 mm. The Accessoryout offer is a complete 400 x 400 mm roof vent fan. Before making an opening, mark the location, check roof structure and inside clearance, confirm the cut-out and plan weatherproofing and wiring. The product facts do not provide a cut-out measurement, so the correct next step is to obtain that detail rather than assume it. 400 x 400 mm caravan roof vent fan is the documented product used for this comparison.
400 mm in a title is not a cutting instruction
A roof-vent cut-out must come from the installation drawing for the exact product, not from rounding the name 400 mm. The Accessoryout offer is a complete 400 x 400 mm roof vent fan. Before making an opening, mark the location, check roof structure and inside clearance, confirm the cut-out and plan weatherproofing and wiring. The product facts do not provide a cut-out measurement, so the correct next step is to obtain that detail rather than assume it. A roof-vent cut-out must come from the installation drawing for the exact product, not from rounding the name 400 mm. The Accessoryout offer is a complete 400 x 400 mm roof vent fan. Before making an opening, mark the location, check roof structure and inside clearance, confirm the cut-out and plan weatherproofing and wiring. The product facts do not provide a cut-out measurement, so the correct next step is to obtain that detail rather than assume it.
Use the exact SKU's installation dimensions
| Measurement | Use |
|---|---|
| Product size | Identify the exact 400 x 400 offer |
| Cut-out size | Obtain from the drawing |
| Roof clearance | Check ribs, trim and equipment |
| Sealing | Select a compatible installation method |
Check structural and interior constraints
- Locate the roof area and inspect both sides.
- Get the exact cut-out figure.
- Mark and remeasure before cutting.
- Complete sealing and electrical work safely.
Seal and wire within the vehicle's requirements
Cut-out, roof thickness, airflow, current draw and sealant compatibility are not specified in the product page facts. A 400 mm label cannot fill those gaps.
Measure the opening from evidence
Do not cut for this 400 x 400 vent until the actual cut-out and vehicle constraints are documented. For related context, see Caravan Roof Vent 400 mm Opening: UK Fit Guide. For related context, see 400 x 400 Roof Vent Fan UK: Size, Cut-Out and Fit Checks. 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.