fisherman 72 Posted January 5 Share Posted January 5 Just arrived here, can I pick your brains straight off, for which I apologise. I did this low pitched tile roof over a porch, (pic below, hopefully) fibre cement 200x400 tiles, 16degs. 35 years on have leaks and rotten battens. I am going to strip it. Remove battens and tight membrane. Install slack membrane. Battens on rafters, cross battens. The question is about using one of the low pitch roof products by Permavent. There is the rubber gasket under the tile edge, https://www.permavent.co.uk/products/easy-slate/ expensive, or the plastic metre long x 220mm along the battens, https://www.permavent.co.uk/products/plain-easy/ not so deep. Or is it possible to simply cut a 400mm strip of membrane and fit it under each row of tiles? Thanks for looking, any help appreciated. Link to comment Share on other sites More sharing options...
SteamyTea Posted January 5 Share Posted January 5 Right. Have you thought of using GRP, I am assuming it is the lean to bit of roof. Link to comment Share on other sites More sharing options...
fisherman 72 Posted January 5 Author Share Posted January 5 Yes, well versed in GRP from boatbuilding, in fact I have most of the materials to hand, but you'll appreciate I want to retain the tiles. The white stone wall is full of water. Tight membrane, water has probably blown or crept up under the tiles, and sat against the battens and come through nail holes. Possibly pooled on the membrane at the bottom as well, see when I strip it. The 400x200 tiles, now unobtainable but I can cut four from a 600 x 600 thrutone which is a good match assuming I don't break too many. Otherwise I'll use 400x250 over the whole lower section, or even a spanish slate. Link to comment Share on other sites More sharing options...
SteamyTea Posted January 5 Share Posted January 5 8 minutes ago, fisherman 72 said: but you'll appreciate I want to retain the tiles. I was thinking you could still do that. Basically set up the tiles upside down, then lay up the GRP on the back. Will have to work out a way to overlap the 'sheets of tiles' and include an angled tab to slide under the main roof tiles. Or just have a word with Shape near Redruth and see what they charge. What are you thinking of doing about roof insulation? Link to comment Share on other sites More sharing options...
joe90 Posted January 5 Share Posted January 5 24 minutes ago, fisherman 72 said: 35 years on have leaks and rotten battens. 35 years is not bad IMO for the felt that would have been available at the time, I have had to strip several similar low pitch roofs over the years where the old felt has come to the end of its life. Modern felt/membrane is far more robust especially if you use felt support trays. Draped felt is better to allow damp to run down the roof and not soak into the battens. I do find that some people don’t allow fir the felt to drain right to the guttering so water pools under the last tile/slate so make sure this happens, overlap the felt more and I think it will outlast the previous 35 years without getting too technical 🤷♂️ Link to comment Share on other sites More sharing options...
saveasteading Posted January 5 Share Posted January 5 34 minutes ago, fisherman 72 said: is it possible to simply cut a 400mm strip of membrane and fit it under each row of tiles How refreshing to have this simple explanation that you want to improve your own work. 35 years isn't too bad. It isn't a big roof so you'd be as well to strip it and redo, i think. You could probably rebuild it in modern materials and reslate over to preserve the appearance. Link to comment Share on other sites More sharing options...
fisherman 72 Posted January 5 Author Share Posted January 5 Thanks. The original membrane is the plastic with the mesh in it, the ad was a pic of Geoff Capes standing on it between rafters, holding two rolls. Just not knowing anything at the time, stretched it tight, and may not have detailed it well at the eaves. Felt tray this time. With cross battens there will be more clearance over the wall, I may have to replace the 3in thick wall plate with thinner. The insulation is all up to scratch 250mm. Since then I got quals as a site chippy and found out how much I did that was wrong. 1 Link to comment Share on other sites More sharing options...
joe90 Posted January 5 Share Posted January 5 1 minute ago, fisherman 72 said: Since then I got quals as a site chippy and found out how much I did that was wrong. Every day is a school day (even at my age 🤯) Link to comment Share on other sites More sharing options...
fisherman 72 Posted January 5 Author Share Posted January 5 These are for sale in Truro, expensive, and still have to work round the front roof and stink pipe. https://www.ebay.co.uk/itm/295355347548 Link to comment Share on other sites More sharing options...
joe90 Posted January 5 Share Posted January 5 13 minutes ago, fisherman 72 said: The original membrane is the plastic with the mesh in it Horrible stuff 12 minutes ago, fisherman 72 said: These are for sale in Truro, I would just strip and re felt/membrane, new battens and better detailing with original Slates. 1 Link to comment Share on other sites More sharing options...
saveasteading Posted January 5 Share Posted January 5 Slates do more than look traditional. They will catch 99% of the rain and the wind. Ghen your underlay jusg takes some dribbles. Plus the weight holds ig alll down in thd worsf of gales. Can you make them fit back over the available depth? Link to comment Share on other sites More sharing options...
SteamyTea Posted January 5 Share Posted January 5 16 minutes ago, fisherman 72 said: are for sale in Truro, Someone over orded then. Can I see your house from Marina Terrace? Well before it rains again. Link to comment Share on other sites More sharing options...
fisherman 72 Posted January 5 Author Share Posted January 5 I'm down on the Lizard Link to comment Share on other sites More sharing options...
fisherman 72 Posted January 5 Author Share Posted January 5 (edited) 57 minutes ago, saveasteading said: Slates do more than look traditional. Can you make them fit back over the available depth? If I don't break too many. The cross battens will make the tiles 19mm higher than now, unless I use 50x25 rather than 38x19. I have to get under the flashing to the cottage end wall, or form a box gutter. Edited January 5 by fisherman 72 Link to comment Share on other sites More sharing options...
SteamyTea Posted January 5 Share Posted January 5 27 minutes ago, fisherman 72 said: I'm down on the Lizard Right, enough said. Helston is still closed on a Sunday. Link to comment Share on other sites More sharing options...
fisherman 72 Posted January 6 Author Share Posted January 6 So is there any significant problem with the idea to put DPC strips under each row of tiles, end to end, 400mm same as the tiles? As well as rectifying the membrane, battens and eaves detailing. 16 deg is well under the recommended pitch. Link to comment Share on other sites More sharing options...
joe90 Posted January 6 Share Posted January 6 8 minutes ago, fisherman 72 said: So is there any significant problem with the idea to put DPC strips under each row of tiles, I guess not, belt and braces I suppose. Link to comment Share on other sites More sharing options...
Russell griffiths Posted January 6 Share Posted January 6 What is the head-lap of those slates. Do you realise that as the pitch decreases you need a bigger head-lap you might even find that 16 degrees is not recommended for that product. Link to comment Share on other sites More sharing options...
Russell griffiths Posted January 6 Share Posted January 6 I think the cause of your problems might become more obvious as you strip the roof back. How about some thin ply with a grp covering, then batten and re tile. Link to comment Share on other sites More sharing options...
SteamyTea Posted January 6 Share Posted January 6 9 minutes ago, Russell griffiths said: How about some thin ply with a grp covering, then batten and re tile. As I was sitting on the side of the A30 this morning (my car eventually packed up) this occurred to me. Basically make a jig at the correct angle, two bits of ply and a couple layers of 450 g.m-2 CSM and a decent topcoat glaze. 1 Link to comment Share on other sites More sharing options...
fisherman 72 Posted January 7 Author Share Posted January 7 On 06/01/2024 at 14:26, Russell griffiths said: I think the cause of your problems might become more obvious as you strip the roof back. How about some thin ply with a grp covering, then batten and re tile. Having just fitted a GRP deck in a boat I am aware of the cost, the roof is 16 sq m. Ply £100, GRP poss about £250. Battens would have to be screwed through the GRP, lots of holes to seal. At least with membrane I can use nail sealing tape, plus the cross battening will make a difference. I am more interested in finding any experience of the permavent products I linked. Link to comment Share on other sites More sharing options...
joe90 Posted January 7 Share Posted January 7 On 06/01/2024 at 14:38, SteamyTea said: my car eventually packed up) Sorry to hear that but not bad for the mileage it has done eh? Link to comment Share on other sites More sharing options...
SteamyTea Posted January 7 Share Posted January 7 18 minutes ago, joe90 said: Sorry to hear that but not bad for the mileage it has done eh think it is an electrical problem, so may be a cheap fix if it can be traced. Link to comment Share on other sites More sharing options...
joe90 Posted January 7 Share Posted January 7 30 minutes ago, SteamyTea said: think it is an electrical problem, so may be a cheap fix if it can be traced. Recently a mechanic I know said cars are failing electrically before mechanically nowadays. Link to comment Share on other sites More sharing options...
MPH243 Posted January 8 Share Posted January 8 I used the Easyslates on a garage, they were quite easy to fit and and stops any water going sideways off the join with the thin plastic upstands. The only way it could go is to the top of the slate. Link to comment Share on other sites More sharing options...
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