junglejim

My understanding is that for vented svp I can go down to 75mm pipe. Is this internal or external diameter? I’m struggling to find this. Can anyone point me in the right direction? Many thanks

I’m building a timber frame home. we have a large opening at the back for bifold doors which is framed with an RSJ. The window installers have said they can’t fit until this is sheathed in wood so looking for advice on the best way to do this. Externally I was going to add wool insulation, noggins then osb but haven’t really thought about bringing this into the reveal. Any advice etc greatly appreciated. Thank you

Thank you for all of the advice so far. i don’t know if this complicates it at all but also worth noting that our sewage and grey water will go to a small pumping chamber sink in the drive which in turn pumps to the main sewer. @Iceverge @ProDave @tuftythesquirrel @Conor

Thanks Conor, that’s interesting. I mentioned that to a plumber who said bc would need external vented svp… do you know where I can find more info about this?

Hi, I’m looking for the best route/method to install the svp. My understanding is that it needs to be 3m from a window opening so will need to go between rafters and exit the roof near the ridge. The roof construction is osb, rafters with rigid insulation between rafters then osb beneath rafters And another layer of insulation. Cutting through this to install an svp feels counter intuitive and could introduce cold bridging… does anyone have any advice in the best way to install, products etc to maintain thermal efficiency. Thanks

Sorry no pics …. Can take some at the weekend. The main roof is on and timber for hip and overhangs is being fitted soon so trying to work out the best way of tiling this section.

I’m doing my own roof and ok so far with all the straight edges but the detail on this end is a bit more technical so I’m looking for advice on how to do this. The roof will be osb solid deck with membrane, counter battens and battens. I’m wondering how best to create the hip and match it in to the roof and also any tips on joining the front porch overhang to timber frame? Thank you in advance for any advice.

Hoping someone can give me some suggestions on this? Thanks

I’m doing my own roof and ok so far with all the straight edges but the detail on this end is a bit more technical so I’m looking for advice on how to do this. The roof will be osb solid deck with membrane, counter battens and battens. I’m wondering how best to create the hip and match it in to the roof and also any tips on joining the front porch overhang to timber frame? Thank you in advance for any advice.

@nod thanks for help. Also any tips on putting the vcl flashing up underneath my breather membrane above the window which is beneath the counter battens? Presumably need to cut back the counter battens to accommodate? Thanks. Appreciate all the tips before I get stuck in.

I’m in the process of roofing our cassette roof (osb sandwich) on new timber frame build…. Felted, counter battens and tile battens are in. I haven’t started tiling yet but will be soon (sandtoft rivius). I’m hoping to start fitting velux tomorrow but have a question… The window openings have been pre made in the factory. Windows are in several different positions so setting out tiles to windows is unlikely to work for all and I’ve already set out horizontal battens based on optimum gauge for my roof (310mm) As the window position is fixed I’m wondering if there’s anything I can take into account to ensure sufficient overlap between flashing and tiles at the bottom and top of the window and ensuring sufficient width of tiles either side. Or… as I suspect will be the case… when I tile, what should I take into consideration? All advice and learning gratefully received.

Thank you for all the tips 👍

Thanks @Dave Jonesand @joe90 That was my initial thought but worried about splitting the batten end by needing to nail it so close to the end. Joining in a counter batten only gives the ends 25mm to nail into. my maximum spacing between counter battens is 400mm and a number of gaps are more like 300 (and a few even less) so wondering if it’s better to have ends between the counter battens so that the ends are overhanging. I wonder if a 150mm overhang is better than nailing close to the end. I figure there must be regulations on maximum allowable unsupported overhang but I can’t find anything.

Curious what the best way to join roof batten ends? They are laid over 50mm wide counter battens. Note sure whether to share a counter batten each overlapping 25mm or whether I need to double up the counter batten?

Soups = Should 😜

I’ve lapped breather membrane over the ridge and will be fitting dry fix vented ridge tiles. I’m hearing mixed opinions about whether I soups cut the felt at the ridge or not. The roof is osb Cassette with 50mm vent gap between insulation and osb… any suggestions? Layers above osb are: membrane, counter batten, tile battens, tiles Advice greatly appreciated 👍

Thanks. Because the roof is a cassette system sheathed in OSB I need to ensure airflow between rafters (soffit vent) and also above the osb and membrane (between counter battens) hence the over fascia vent being above the drip tray. Or at least that’s my understanding.

This is what I’m thinking at the moment so wanted to check for advice… The vent strip seems a bit unnecessary but think it might be something that BC want to see. Any thoughts/feedback welcome

Thanks Mike. Yes approved and have 50mm void beneath sheathing however I don’t think I need ventilation between sheath and membrane and I’m following timber frame guidelines on membrane on osb but it feels like a vent above the membrane and up between counter battens would be useful.

Thank you for the detailed reply. That all makes sense but the membrane is beneath the counter batten so surely the vent needs to go above the eaves tray to enable clear airflow?

Thank you. That’s a really helpful picture... couple more questions if that’s ok? 1. does that mean screwing through the membrane and tray? Is that a possible problem for water ingress? 2. That vent looks much better… yes mine is a corner one … will have to see if the store have anything else. 3. I notice you’ve cut the counter battens short… I’ve realised that I’ve come too far down and just started cutting back to enable membrane to lift. Presumably you continued cutting them back all the way along. 4. Sub Fascia: nice chunky piece of wood… tempted to do similar as have lots of rafters left over… architect specified ply but can’t see why not use timber. however I’m reluctant to sit tiles on incase I ever need to take off. I was going to create a short fillet and run an extra batten along the bottom edge to do this instead although thinking about it if the vent is also attached I won’t be able to remove anyway. (Hmm) also my tiles have ridges in which I assume is to enable ventilation as there are clear channels when it is sat on the batten. I feel like BC might insist on a vent strip though? Thank you… any more pics/advice greatly appreciated as having a bit of a struggle with this.

Thank you. However my batten space is above the membrane as roof is osb. So when I run membrane/tray over the vent they would be in the way.

Still struggling with how to finish my osb cassette roof at the eaves…. Problems: 1. Drip tray: if it goes above the vent then the vent is basically useless. If it goes below then it will compromise the integrity of the drip tray. 2. Lower tiles support. I can see the advantage of supporting using the fascia but this doesn’t feel particularly good in terms of future proofing. If I need to replace the fascia then that would dislodge the bottom row of tiles. My solution is to add a lower batten at the bottom edge of the roof, supported by a fillet. This would also mean I can begin laying my tiles before installing fascia/soffit which I’m undecided on. I’d like to get started on this to cover my roof but panicking in case I’ve missed something important or doing the wrong thing. I can see how the vent etc works in a roof with open rafters but struggling to see it for a solid roof. Thank you for everyone’s help. ps. The images are me playing around with options.

On closer inspection I’m not sure an eaves vent is even necessary given that the tiles have ridges in the bottom which essentially do the same but should probably include as per BC spec any way. Any more thoughts??