Had a Roofer visit today as we have noticed a discolouration in an area of a bedroom ceiling. They could find no issues internally with the roof but an external inspection revealed alot of ridge line tiles have lifted from their mortar bed and need resetting which could explain the moisture. They have suggested either re-mortaring the existing ridge line or replacing the mortar bed with a dry ridge system which involves seating the tiles on baton attached trays and a sealing membrane underneath. Anyone had similar work undertaken or experiences with the options and care to offer their thoughts?
In 2015 when given that option, i asked three friends for advice, one was a builder, one a civil engineer, and other an electrician, however they all knew exactly what a dry edge system is and what it entailed. They all said go with the dry ridge… so i did.
However i have since regretted it, not that the roofers did a bad job, i think it is more to do with the product they used, the top ridges are fine but the gable ends are quite horrid IMO. It does make sense to use a dry edge but only if it’s done using a good product.
The gable ends on my house use a one piece straight length edge that works okay but just doesn’t look good, plus maybe i’m a bit of a traditionalist and i’d have preferred the gable edge to look at intended. A good mortar edge should last 50+ years all going well, but i can’t see the plastic edge on my gables lasting half that span of time.
Also the black plastic edge is gradually greying due to sun exposure, it just doesn’t look right, doesn’t look good, and it’s plastic
I have seen an option where the end tiles are mortared to give the traditional appearance and then the dry ridge system starts under the first tile rather than the end but in our case all the walls have pitched roofs atop so hopefully no ends would be visible straight on.
I had a new roof this year and they fitted a dry ridge system with mortar filling the edges of the ridge. Apparently a much better system from a maintenance, performance and longevity perspective. Very happy with it.
The primary job description of my roof was fixing a leak (it was where a few years earlier an aerial fitter had accidentally stuck one of his size 10s though the sarking board, and then put the tile back over the damage and deliberately kept quiet about it).
Plus; investigating why black mould was appearing on the bedroom sloping ceiling next to dormer windows.
Plus; clean out all the valleys - and improve the drainage from valley to gutter (as this is what was causing the damp and black mould) This was well diagnosed by the roofers and they did a really excellent job fixing it. They also replaced 1980s under-felt beside the dormers due to it showing signs of biodegrading.
Plus; fit a chimney pot on the stack, a beautiful octagonal square base from the reclamation centre.
Plus; fit new guttering & down pipe back and front.
Also, the original idea was to re-mortar the ridge tiles and gable ends - but this plan got changed into the fitting of the plastic fantastic
TBH, when agreeing to go with the dry edge system i thought it only involved the horizontal ridges, and not the gables, live and learn eh?
While the scaffolding was up, there was plenty of time to decorate the woodwork and render.
There is much talk on the internet about a younger generation of roofers who have lost the skill of mixing and applying mortar for tiles, apparently there is a lot to be said about doing it properly.
However the builders who built my house in 1989 were hopeless, they didn’t crop the tile batons in enough to give the mortar the required depth of room, hence premature cracking up of the mortar and then damp affecting the sticky-out roof batons - see picture below and weep:
Given the increasing extremes of weather being seen driving enhanced movement in rooves and, personally, not having great faith in mortar (whether well-mixed, using good quality ‘strong’ sand) to survive without cracking et al, I’d veer towards the dry ridge system so long as it looks robust to my eyes. Some I’ve seen appear to bolt together.
I had ridges & hips done many years ago by lifting and re-bedding. The amount of mortar used was material and wasn’t comforting in how it was used in the joins, noting mortar is only water resistant.
@Debs – I think they tend to run the battens out that far to protect against wind-lift of the boards. I’ve got an over-hang > the fascia of ~40mm. You’re right, it doesn’t look great but the battens are above the membrane – and allowing a bit more room for the render to bite would be sensible.
The battens hold the cement board on so as the mortar mix can can be used. If they only used 100mm cement board which is probably the norm this is why the battens are near the end. They usually sit back about an inch from the end. I prefer the cement verge but I would go with the dry ridge system as they are very good & very low to no maintenance.
That is what the roofers went with for my re-roof. The felt on the old roof had degraded somewhat and a couple of bodged repairs hadn’t helped either, so some timbers in ladders (I think they are called) needed replacing. Time will tell if it is the right choice but I am sure it will likely outlast me as the original roof just about lasted 50 or so years.
it would appear near universal recommendation for the dry ridge approach aside for any cosmetic considerations. thankyou all for your replies as building works are a bit of a knowledge gap for me… time to sort some quotes
Noting the ceiling stain, and as you are sorting things, I would suggest you also check whether your roof tiles have been installed properly, and whether the under-felting has been done to spec (if at all). My experience in a late 1960s build:
1- Whilst roof was watertight, the tile headlaps were only ~50/60mm, whereas the manu’s (Marley) reco was min 75mm, rising to 100mm (IIRC) for lower pitch rooves (which mine is!).
- also take care to check any tile gutters (on side overlaps) if you have these. I’ve found that while tiles can look OK from the ground, breaks in the gutters can be well hidden.
3 - In my case, it appears they were running short of underfelt and didn’t overlap it towards the top of the roof elevation – and you can guess what happened!
Thanks for the tips👍
An interesting debate, here. Thanks to all.
My simple question would be this. Surely the ‘life’ of a conventional ridge is ‘long enough’…? If a ridge has lasted say 20 years or more, why not just repair/replace with the same again…?
According to my roofers, the dry ridge system is better at coping with the normal movements of a roof which should mean that it needs maintenance/repair less often. Time will tell.
For us, its less expensive to go with the dry ridge system than re mortar so my concern was more if it was better or worse than the conventional approach
You’re right to question IMHO, as some of these ‘new systems’/new products, do set the grey matter going e.g. the rubber roofing systems with trims are far from perfect, and some of the dry roof verge trims being advocated are UPVC/GRP. Cheaper doesn’t always mean better IME.
A healthy level of scepticism is required!
Thank you. I cam across a similar thing with flat roofs. There are a number of ‘better’ (and more expensive) products than the normal, standard (old school) material. But the normal one will last 10 years or more - and is less money…? Hmm…
OK, go with the Long Life if you are positive that you will be staying in the house that long. Otherwise… just replace, as is. IMO… YMMV, as always.
At the risk of diverging from @Deeg 's thread (I hope OK ), one issue with flat roofs is that insurance cover for hot-laying felt has become very expensive. Rubber products (think like bicycle tyre tubing) are attributed a longevity and hardiness it’s difficult to credit IMHO (plus some of the trim methods are highly suspect IMV), and expensive GRP (which isn’t that expensive) can be problematic, as it’s brittle when say abutting to an existing roofline, where thermal movement may arise.
I have rubber, felt and tile roofs for my sins…and some of the quotes I’ve received were an attempt to extract the you-know-what.
And then you get to the supposed HSE diktat of needing a scaff!
Five or so years ago we had a flat roof over our kitchen replaced with a pitched roof which is vaulted with big Velux windows in it. The building control people insisted that we used the dry system for the ridge and it hasn’t given us any problems so far. I’m happy with it.