Dry Ridge System & Loft ventilation

30 Aug 2021
Reaction score
United Kingdom
I've got a standard trussed roof with sarking felt and wish to have the mortared ridge tiles replaced with the dry ridge system mainly because the mortar under the ridge tiles keeps falling away. Looking at the various dry ridge system manufacturers websites, they claim the dry ridge system improves loft ventilation (which would be an added bonus).

However, looking at some YouTube clips and speaking to a local roofer, the piece of sarking felt that overlaps the apex of the roof is not cut, removed or replaced during the installation of the new dry ridge system so I don't understand how loft space ventilation improves after fitting it.

Can anyone enlighten me?!
Sponsored Links
The Instructions for the kits tell you to trim back the felt to an appropriate distance.
The instructions are usually pretty good and available online.
See attached, 5 - 8mm gap left each side in this case.


  • MBP-0746-00-I---GDRR-Roll-Out-Dry-Ridge-Fitting-Instructions.pdf
    2.1 MB · Views: 165
Last edited:
Thanks. 2 question then...

1. I've read the instructions for the Manthorpe system and they recommend 'when refelting the roof, leave a 5-8mm gap at the apex'. As my sarking felt overlaps the apex, presumably, there's nothing preventing me cutting this gap into the existing felt before installing the brackets?
2. I see the vent roll that is stuck on to the tiles has a vented mesh along its length - assuming I cut the 5-8mm gap in the felt, what prevents horizontal rain under high winds being blown up under the top tile, over the vent roll and to then seep into the loft space?
1). That's correct!
Also, in the case of retro-fitting, the brackets may be attached to the ridge board rather than the rafters. If this is possible, it may save removing the top row of tiles and battens.
2). I don't think anything will stop it in this circumstance. But the rate of leaks must be sufficiently rare for this not to be an issue. I may be wrong though!
Sponsored Links
I think you're right. There's a British Standard BS 8612 for dry ridge systems and it suggests the system, if fitted correctly and accredited to that standard, is weather tight...

Many thanks.
Thanks but does either system preclude me from cutting the overlapping felt?
Also, what's the fundamental difference in each of those systems please?

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links