Dry ridge systems

[kreyszig]

Howdy.. long time no see! Also not much progress since I last posted here a thousand years ago.
I'm finally looking at replacing our late Victorian slate roof, which has decorative cloverleaf pattern ridge tiles, as per the image below.
Also hip tiles which are overlapping ("crested", might be the terminology?), again see images below.
We're not listed but I'd still like to retain these.
One of the roofers that actually bothered to get back to me is telling me I need to use a dry ridge system, and isn't sure if there's a system that will work with the existing tiles.
By any chance does anyone here have any experience with this?
A quick google seems to suggest that I might be able to find something that will work with the clover leaf ridges, but I'm still not sure if that's the case, and as for the overlapping ones, I haven't found anything yet.
Would really appreciate some pointers!
(p.s. pasting images directly into the post, how times have changed!)

 

[a twig]

There is wiggle room in "the regs" that repairs to existing roofs don't need to have a dry ridge - when ours was done, we had an understanding roofer who did the roof as "5 repairs of less than 25% of the roof" as we then didn't need to faff around with all the other stuff that "a new roof" would entail. Re-using the existing tiles / slates would support the "it's a repair not a new roof" argument.
I suspect you might struggle to find a roofer willing to take a relaxed approach though, as dry ridges are cheaper and faster to install. I've not come across any products that would help solve your problem I'm afraid - a company like Weinerberger (brochure) do provide mechanically fixed ridge and hip tiles that might be worth a look, but obviously they would be new rather than keeping your existing.

 

[kreyszig]

ha, nice one. interesting. I am reusing the original slates, something tells me building control round here won't be too impressed with trying to call it a repair!

 

[malcolm]

Why do they want a dry ridge system? Dry ridge will look awful. When my roof was done 10 years ago (with building regs) we went for a breathable membrane and some eaves ventilation but building regs didn't require any ridge ventilation. There seems to be plenty of ventilation up there.

Building regs said modern houses have only the breathable membrane and no other ventilation, but because the ceiling would likely be sealed less well in an older house a bit of eaves ventilation was required too.

 

[kreyszig]

building regs now apparently want the ventilation of a dry ridge, as well as mechanical fixings.
This is the link the local building control sent me:
Changes to BS 5534: what specifiers need to know | Marley
Looks like BS5534 is about mechanical fixing of all tiles, then an amendment to it refers to BS8612, which is about ventilation and dry ridges (so I understand).
The above seems to imply there might be some scope for heritage buildings doing things differently - would be nice if I could read the actual standards instead of Marley's distillation - don't suppose anyone has a way of getting a copy of these?

 

[a twig]

Why do they want a dry ridge system? Dry ridge will look awful. When my roof was done 10 years ago (with building regs) we went for a breathable membrane and some eaves ventilation but building regs didn't require any ridge ventilation. There seems to be plenty of ventilation up there…

The latest version of BS 5534 which came out in 2018 now basically says that if you are doing a new roof that you have to have a dry ridge, the only way you avoid that is if it is a repair to the roof of an old house which doesn’t already have one, or if it is a listed property.

That said BS 5534 is a code of practice (aka guidance) not a legal requirement so you can ignore it when replacing an entire roof (provided you can get your local building control to agree), or avoid building control’s involvement entirely by merely doing “repairs”

 

[malcolm]

A Victorian roof with a ridge like that is certainly historic. Removing the ridge would detract from it's character and probably the local area.

Sounds like some leg work is needed - a chat with the council building regs about how the roof can be sensitively repaired. If they turn out to be muppets you could phone a private building regs guy explaining you want to find a way to keep the historical feature. Likely you'll end up employing building regs directly and asking the roofers to quote for an approved spec.

It's an annoying nonsense. I should imagine more people will complain over the next few years and the system will become replace like for like on a traditional roof that has lasted three times the lifespan claimed by the dry ridge manufacturers.

 

[paulc]

The latest version of BS 5534 which came out in 2018 now basically says that if you are doing a new roof that you have to have a dry ridge, the only way you avoid that is if it is a repair to the roof of an old house which doesn’t already have one, or if it is a listed property.

That said BS 5534 is a code of practice (aka guidance) not a legal requirement so you can ignore it when replacing an entire roof (provided you can get your local building control to agree), or avoid building control’s involvement entirely by merely doing “repairs”

have been watching a neighbour building an extension over the last year which included stripping the entire roof off the property, When it went back on, no dry ridge fixing were used, just traditional mortar. As the whole project is subject to planning, building control will be involved, and I assume they are quite happy with cement being used.

 

[kreyszig]

thanks all, trying to have a reasonable conversation with building control now, taking the above into account

 

[a twig]

have been watching a neighbour building an extension over the last year which included stripping the entire roof off the property, When it went back on, no dry ridge fixing were used, just traditional mortar. As the whole project is subject to planning, building control will be involved, and I assume they are quite happy with cement being used.

Yep - as it’s a code of practice so long as you can convince Building Control that your traditional approach is fine, then happy days. There’s no reason you shouldn’t be able to justify it but as we all know not all BC departments are entirely reasonable hence my preference to not unduly trouble them where possible

Based on bitter experience I just try and

 

[kreyszig]

Just by way of update - had building control out to have a look, they seemed pretty reasonable and happy we will be able to sort something out when the time comes

 

[kreyszig]

further update.. they've changed their minds and are now saying I need a dry ridge..grrr
Have noted the advice above to look into private building regs

 

[kreyszig]

Hmmm I'm now looking into using "Glidevale Fulmetal Rediroll", which doesn't appear to be too visually intrusive, and it will work with crested ridges.
A supplier of reproduction ridge tiles put me on to it. Apparently with crested ridges you can alternate the side you fix on the diagonal of the crest. Think I saw an S clip somewhere as well.