A support system for roof formworks comprising: - at least one purlin defined by a profile comprising a flat lower surface supportable on the upper surface of one or more purlin holders longitudinally slotted on said upper surface and; - at least one slotted purlin holder defined by a profile comprising a flat upper surface; wherein at least one end of the profile of the purlin comprises a terminal having a descending extension configured as a bearing point in the slot of said slotted purlin holders; wherein the slotted purlin holder comprises at least one slot in the longitudinal direction in the upper surface, suitable for receiving the descending extension of the terminal of the purlin, so that said terminal of the purlin is resting in said slot of the slotted purlin holder, wherein one end of said slotted purlin holder is configured to rest in a supporting seat of a the support element for purlin holders, such that when in use said seat provides continuity as a bearing point of the terminals of the purlins for the surface of one of the slots of the slotted purlin holder; wherein the external edge of the extension of the purlin forms an angle less than 90°, being defined as the bearing point in the slot, while the extension has a sufficient length to be able to remove the purlin from the slotted purlin holder by pivoting it downwards with respect to said external edge without the purlin raising the supported formwork; characterised in that the length of the extension of the terminal of the purlin is such that, in the resting condition in said slot, the lower surface of the profile is at the same level as the upper surface of the purlin holder, while the terminal has a base defined by an inner corner adjacent to the profile and an outer corner longitudinally opposite from the previous one, the descending extension being in the outer corner, the base comprising at the same time a groove in the lower face thereof, transverse to the longitudinal direction of the profile and located between the inner corner and the outer corner, the depth and width dimensions of which enable there to be the necessary space in order to remove the purlin from the purlin holder by pivoting it downwards with respect to said outer edge without the purlin raising the supported formwork. - at least one purlin defined by a profile comprising a flat lower surface supportable on the upper surface of one or more purlin holders longitudinally slotted on said upper surface and; - at least one slotted purlin holder defined by a profile comprising a flat upper surface; wherein at least one end of the profile of the purlin comprises a terminal having a descending extension configured as a bearing point in the slot of said slotted purlin holders; wherein the slotted purlin holder comprises at least one slot in the longitudinal direction in the upper surface, suitable for receiving the descending extension of the terminal of the purlin, so that said terminal of the purlin is resting in said slot of the slotted purlin holder, wherein one end of said slotted purlin holder is configured to rest in a supporting seat of a the support element for purlin holders, such that when in use said seat provides continuity as a bearing point of the terminals of the purlins for the surface of one of the slots of the slotted purlin holder; wherein the external edge of the extension of the purlin forms an angle less than 90°, being defined as the bearing point in the slot, while the extension has a sufficient length to be able to remove the purlin from the slotted purlin holder by pivoting it downwards with respect to said external edge without the purlin raising the supported formwork; characterised in that the length of the extension of the terminal of the purlin is such that, in the resting condition in said slot, the lower surface of the profile is at the same level as the upper surface of the purlin holder, while the terminal has a base defined by an inner corner adjacent to the profile and an outer corner longitudinally opposite from the previous one, the descending extension being in the outer corner, the base comprising at the same time a groove in the lower face thereof, transverse to the longitudinal direction of the profile and located between the inner corner and the outer corner, the depth and width dimensions of which enable there to be the necessary space in order to remove the purlin from the purlin holder by pivoting it downwards with respect to said outer edge without the purlin raising the supported formwork.