--- title: Is it OK to install a second roof deck on top of the original roof deck? Could a vented nail base be used? description: Here is some information about creating a 2nd roof deck and using vented nail base. --- [Skip to content](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/is-it-ok-to-install-a-second-roof-deck-on-top-of-the-original-roof-deck#main-content) English Show submenu for translations ![GBAD Full Color.png\]](https://help.gibraltarbuildingproducts.com/hs-fs/hubfs/GBAD%20Full%20Color.png?height=40&name=GBAD%20Full%20Color.png) - [Default HubSpot Blog](https://semetals-1971711.hs-sites.com/blog) Open main navigation Close main navigation - [Default HubSpot Blog](https://semetals-1971711.hs-sites.com/blog) - English Show submenu for translations - Go to www.gibraltarbuildingproducts.com Go to www.gibraltarbuildingproducts.com Hello. How can we help you? - There are no suggestions because the search field is empty. 1. [Help Center](https://help.gibraltarbuildingproducts.com/migration/en/knowledge?hsLang=en) 2. [Ventilation](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en) 3. [Ventilation](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#ventilation) - [Metal Roofing](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/metal-roofing?hsLang=en#main-content) - [Metal Roofing](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/metal-roofing?hsLang=en#metal-roofing) - [Oil Canning](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/metal-roofing?hsLang=en#oil-canning) - [SMRIB Profile](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/metal-roofing?hsLang=en#smrib-profile) - [5V Crimp Profile](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/metal-roofing?hsLang=en#5v-crimp-profile) - [Job Packs](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/metal-roofing?hsLang=en#job-packs) - [Roofing Accessories](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/metal-roofing?hsLang=en#roofing-accessories) - [Rainware & Gutter](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/rainware-gutter?hsLang=en#main-content) - [Gutters](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/rainware-gutter?hsLang=en#gutters) - [Soffit](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/soffit?hsLang=en) - [Trims & Flashing](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/trims-flashing?hsLang=en#main-content) - [Other](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/trims-flashing?hsLang=en#other) - [Ventilation](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#main-content) - [Ventilation](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#ventilation) - [Intake](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#intake) - [Edge Vent](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#edge-vent) - [Whole House Fan](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#whole-house-fan) - [Ridge Vent](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#ridge-vent) - [Power Fans](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#power-fans) - [Ice Dams](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#ice-dams) - [Internal Weather Filter](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#internal-weather-filter) - [External Wind Baffle](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#external-wind-baffle) - [Exhaust Vent](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#exhaust-vent) - [Solar Power Fans](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#solar-power-fans) - [Roof Louvers](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#roof-louvers) - [Undereave Vents](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#undereave-vents) - [Mini Louvers](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#mini-louvers) - [Bath/Dryer Vent](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#bath-dryer-vent) - [Continuous Soffit Vents](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#continuous-soffit-vents) - [Wind Turbines](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#wind-turbines) - [Foundation Vents](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#foundation-vents) - [Skylight Tubes](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#skylight-tubes) - [Shingles](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#shingles) - [Underlayment](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#underlayment) - [Vented Drip Edge](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#vented-drip-edge) - [Wall Louvers](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#wall-louvers) - [Kwikmesh](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#kwikmesh) - [Flue Guard](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#flue-guard) - [Off Ridge Vent](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/ventilation?hsLang=en#off-ridge-vent) - [Material](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/material?hsLang=en#main-content) - [Gutter Protection](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/material?hsLang=en#gutter-protection) - [Customer Service](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/material?hsLang=en#customer-service) - [Warnings](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/material?hsLang=en#warnings) - [Material Type](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/material?hsLang=en#material-type) - [Fasteners](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/fasteners?hsLang=en) - [Uncategorized](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/uncategorized?hsLang=en) - [Trims and Flashings](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/trims-and-flashings?hsLang=en#main-content) - [Trims and Flashings](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/trims-and-flashings?hsLang=en#trims-and-flashings) - [Customer Service](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/trims-and-flashings?hsLang=en#customer-service) - [Other](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/other?hsLang=en#main-content) - [Other](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/other?hsLang=en#other) - [Miscellaneous](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/other?hsLang=en#miscellaneous) - [Flashing](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/flashing?hsLang=en#main-content) - [Flashing](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/flashing?hsLang=en#flashing) - [Siding](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/siding?hsLang=en#main-content) - [Siding](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/siding?hsLang=en#siding) - [Soffit & Fascia](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/soffit-fascia?hsLang=en#main-content) - [Soffit & Fascia](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/soffit-fascia?hsLang=en#soffit-fascia) - [Pipe Flashing](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/pipe-flashing?hsLang=en#main-content) - [Pipe Flashing](https://help.gibraltarbuildingproducts.com/migration/en/knowledge/pipe-flashing?hsLang=en#pipe-flashing) # Is it OK to install a second roof deck on top of the original roof deck? Could a vented nail base be used? ## Here is some information about creating a 2nd roof deck and using vented nail base. Some situations require the addition of a second roof deck on top of the original. These cases require some special steps to ensure that the system will perform properly. A vented nail base could be used in these cases, however make sure the air space is sufficient. The best way to apply a second deck is to lay 2 x 4s down on edge similar to a rafter and apply the new deck over 2 x 4s. This will yield an airspace of roughly 3 inches in height which should be more than adequate. Be sure that the intake vent detail accounts for a path for the air to go from intake vent opening to the new vent space. Another important aspect to consider is condensation control. Moisture must be a given an easy path to pass through the airspace. Thus, provide holes in the original roof deck so any moisture that does get into the insulation under the original roof deck can work its way into the new airspace and be vented out. If the holes are not cut, the original roof deck will be at outside temperatures because of the new air space directly above it and the trapped moisture underneath it will be able to condense on the underside of the original deck. - [Default HubSpot Blog](https://semetals-1971711.hs-sites.com/blog) [![Gibraltar Building Accessories Logo](https://help.gibraltarbuildingproducts.com/hs-fs/hubfs/GBAD.jpg?width=2500&height=777&name=GBAD.jpg "Gibraltar Building Accessories Logo")](https://www.gibraltarbuildingproducts.com/) www.gibraltarbuildingproducts.com Help Center Copyright © 2026, Gibraltar Building Accessories Division