Tiling a conservatory roof

Discussion in 'Builders' Talk' started by polybear, Mar 31, 2013.

  1. polybear

    polybear Member

    Hi,
    I have a hardwood lean-to style conservatory with solid blockwork parapet end walls, measuring approximately 4.4m by 2.7m and with the roof constructed using Wickes conservatory components.  The roof is now 18 years old and starting to leak; maintenance of the roof (especially the flashing) has always been a fairly regular exercise and I'm getting p***ed of with it.  It's too hot in the summer, too cold in the winter too....
    So I'd quite like to have the roof replaced with a tiled roof, with appropriate felt, battens, board, timber structure as required.  It may be that the existing roof timbers may be suitable already, possibly with the addition of joist hangars where the purlins meet the wall plate.  The existing pitch is currently only 10 degrees though.  I've seen some tiles called "Envirotile" which seems to be a good system.  I'd appreciate any thoughts, experiences of similar projects etc. you may have please.  I'm aware of conservatory roof systems by Guardian etc. which achieve a similar aim; however at the moment I'm more of the view that a traditional construction etc. is likely to last longer, be easier to maintain if required and probably cheaper too.  Any experiences of such systems would also be of interest though.

    Many thanks.
    polybear
  2. You might have problems tiling the roof with a 10% pitch, it would be far easier and cheaper to board over the timbers, if they are strong enough, use osb3 t&g roof boards, then fit an epdm roof.
  3. Hi Polybear.

    Cotswold is the pro on here, no question. He gives now't but sound advice, and ain't pedantic either - he doesn't try and score or prove a point; he's just professional. Basically, he'll says things the way he'd do things, and you just know it'll be the right way and his customers will get a good job.

    Me, I'm not like that ;). I'm a chancer. I'm happy to push the regulations chust a weeee bit. Mind you, I'm doing these jobs for myself - not for others.

    Ok, I'm not that bad, really :).

    I've had a look at the roofing tiles you've mentioned, and they are reckoned to be fine to a very low 12.5% pitch. So, I'm thinking - how much lower is 10% to that? (Don't take the p - I can do the math...) It's, er, not much lower. And it'll almost certainly be absolutely fine unless you have some seriously weird weather conditions, with rain being blown horizontally up yer lean-to with a humongous force. In which case your roofing felt will take care of that unlikely scenario - a wee bitsy rain being blown up betwixt t'tiles.

    What I'm saying is, Cotswold wouldn't fit a roof like that. Of course, not - he's a pro. If it went pear-shaped, he'd be liable. And rightly so.

    But... It just ain't - in the real world - going to be a problem, is it? Nah. Would I do what you are suggesting? Yep. No question. And it'll almost certainly be absolutely fine.

    And it'll look a sight better than a smooth EDPM roof (which, of course, is completely reliable...)

    Whether your exisitng roof timbers are strong enough is another matter. You need to look at the weight per m2 of these tiles, and check that your timbers are up to it. Obviously, they are ok in terms of forces caused by changing air pressure, so my guess is that they'll be fine for these lightweight tiles too. However, you'd almost certainly want to add further rafters in between the existing so's your felt ain't draping too much.

    What kind of roof insulation are you thinking of? Just batten, felt and tile, leaving a void below and then fit a flat insulated ceiling? Or else insulate the actual pitched roof? In which case you have two further alternatives - 'warm' or 'cold'.

    It's your choice. But the tile you referred to will almost certainly be fine for the job.

    Imo. Which needs to be taken with the requisite pinch of salt. And stuff.
  4. surfermick

    surfermick New Member

    or, splice is some fillets to increase the drop ;) i wouldnt risk tiling a 10% roof myself, if it leaks you have a useless roof full of expensive tiles that are of no use to you.
  5. surfermick

    surfermick New Member

    ive seen this done, customer pulled me in to check a leaking lean to roof, it was shallow pitch with slate tiles,i said its to shallow for those tiles, they said thats what the builder said but they insisted on having natural slate, i guess the last builder thought, ok, i'll do it then, you pay me, im off thanks, dont call when it leaks so they called me i just said its all a waste, they cried, i left.
  6. Fair point. But have you seen the OP's chosen tile? They are plastic and pretty much interlocking. They are designed to suit down to 12.5%, so I'd lay odds that a couple of per-cent more will be within its design margin.

    Unless the cove's lean-to is facing a hugely exposed prevailing weather front, I doubt very, very much whether he'd have any probs at all. And any tiny let-by would be handled by the felt.

    C'mon, peeps - live dangerously...
  7. polybear

    polybear Member

    Hi all,

    Many thanks for the replies so far - hopefully there'll be more pearls of wisdom to come.  The Envirotiles are here:
    http://www.greenrooftilecompany.co.uk/#/benefits/4571549747http://

    - Apparently they have achieved the best ever performance for slates/tiles ever tested at the BRE  (I've read the BRE report also, which backs up this claim).  As for weight, they come in at 8.4Kg per sq. metre.

    However, I see where Cotswold & Surfermick are coming from on this (thanks guys :).

    I was thinking along the lines of someform of lightweight boarding across(hopefully) the existing roof beams, then some form of felt/membrane/EPDM? covering, followed by Envirotile secured to battens.  And proper leadwork, and not the tiniest piece of that flashband sh**e anywhere :)

    There are currently 7 hardwood roof beams, the end two of which are screwed to the blockwork end walls (as well as being secured to the wall plate and also the front face of the conny.  Beams are at approximately 29" centres; the beams are 5.5" deep by 1.75" wide.  However, there is a smaller cross-beam (2.75" x 1.75")  running the entire width of the roof (i.e. between end walls, not front to rear) meaning the main roof beams are notched at their mid-way point such that they are reduced to a depth of 3.75" at this point. (The notches have been cut well though, with close fitting joists).  My main worry though is where the beams join the wall plate.  The plate is 3" deep, and the end of each beam has been notched such that the beam is resting on top of the wall plate as well as butting up against it, with hardwood infill pieces on top of the wall plate between each beam (hopefully that makes sense).  The roof has supported my weight on numerous occasions (using a ladder section supported by spreader bars across two roof beams) with no problems; however adding the weight of a boarded & tiled roof might be different .
    I was thinking of adding some form of steel joist hangars at the beam/wall plate interface (can you get them at 10 degree angle, or adjustable angle ones?).  I'd prefer hangars that support beneath the beam, and not simply L-shaped brackets screwed into the sides of the beams.  Obviously any such brackets could only be fitted to the existing structure, so will differ from those fitted at new-build.  Any ideas, suppliers please?  If need be I could get a blacksmith etc. to knock up suitable items.
    Hopefully that all makes sense, and you haven't fallen asleep reading it all :'(

    polybear

    p.s. The job will be done by a builder/roofer - my back ain't what it used to be :(

    p.s.s Since the internal finish will possibly be a plasterboard/plaster skim finish (open to suggestions here guys...) I may well construct sub-ceiling support beams & wall plate etc. beneath the existing roof construction such that (a) the existing roof isn't loaded up with yet more additional weight (e.g. plasterboard/plaster) (b) to make plasterboard/plastering easier - otherwise there'll be some crazy angles to deal with, and not just a flat ceiling, and (c) make additional room for Kingspan? type insulation.
  8. polybear

    polybear Member

    Devil's Advocate mentioned "warm" or "cold" pitched roof insulation.  Can you enlighten me here please, with pro's and con's   Thanks!

    polybear
  9. Warm roof construction is insulation above the roof joists with ply already glued to them.

    If you go the tiling route Id suggest, put a layer of torch on felt preferably green mineral, over the boards then counter batten, breathable felt, batten and tiles.
    This way if the pitch is to low, any water drawn up by caphillery action will at least be diverted by the torch on felt.
  10. A 'cold roof' is what you'd get if you added insulating to the underside of the rafters. The roof itself is on the 'cold' side of the insulation, hence - I understand - the name.

    You'd have to leave a min 50mm gap betwixt the insulation and the roof sheeting above, so's it's kept ventilated and no condenstaion can form on the underside of the roof which could cause rot. Vents would have to be provided at the top and bottom of your roof for this - a real pain. If you simply stuffed between the rafters with insulation not leaving a gap, warm moist air would still get through and condense on the underside of the cold roof sheeting - damp + rot would ensue.

    A 'warm' roof design is where you'd add the insulation on to the outside of the roofing sheets before overcovering it with whatever - EDPM or felt & tiles. You are efectively bringing the roof structure to the inside of the house, hence the term 'warm roof'.

    If you wanted to leave your internal ceiling space 'vaulted' for max headroom and perhaps a more spacious feel, then you'd need to consider which way to go - warm or cold. I think 'warm' is reckoned to be better (but I don't know for sure), but is usually a lot more costly since you'd have to remove the existing external roof covering first. Not a problem for you, of course, since you'd be doing that anyway.

    However, if you are thinking of fitting a new flat ceiling, then I suspect you can forget about needing to add insulation to the upper roof, and just add a layer to your new ceiling. And this would be a simple as screwing up tight-fitting sheets of insulation board (Celotex/Kingspan/or similar) to your new ceiling joists, taping the seams, and then over-boarding (well, underboarding) with p'board or similar. You'd still have to ensure the upper void is ventilated, but this could probably be done with just a series of small vent grills along the soffit - at the bottom of the sloping roof. You'd need to ask your pro roofer to advise, but hopefully you wouldn't also need vents at the top.

    If you are getting pros to do the job, then I doubt they'd fit even your wonderful Envorotiles since the pitch is too slight - these guys (like Cots & Mick above) need to work to the specs.

    EDPM and tiles - wow, you really want a permanent fix :).

    Poly, I thought you were going to DIY this, hence my suggestions. Since you intend to get pros to do it, you really need to call them out and discuss it with them.
  11. polybear

    polybear Member

    Many thanks for the reply.

    Would ply board or OSB3 T&G be best please, and at what sort of thickness?  Also, do the "two layers" of battens both run in the same direction, or is the first at 90 degrees to the second?  Lastly, any thoughts on whether or not the existing roof beams (and centres) are sufficient please, assuming the addition of some form of joist hangar at the wall plate (and possibly ply strengthening side plates either side of the beams in the region of the notch which accomodates the cross-beam)?

    I'm coming around to the idea of adding firring pieces to the tops of the beams also, in order to increase the pitch some more (I'm a little bit limited by the roof height at the house wall interface, but I haven't worked it out exactly yet).  Are such firring pieces available ready-cut by any chance?

    Whilst I'm looking to get this job done by a roofer/builder, any such advice you guys are able to impart is very gratefully received, as it (a) helps me explain to the pro what I'm after, and (b) helps me spot if the pro (or not!) is feeding me B.S. ;)

    Many thanks.

    polybear
  12. polybear

    polybear Member

    Hi again...

    As subsequently mentioned, I'm hoping the addition of firring pieces will sort the pitch issue; I've sent an email to Envirotile asking them if they can go down to 10 degrees though.  I've also found the following roofing system which can go down to 10 degrees:
    http://www.ecodeckingsystems.com/ESwhat.html

    - but I think I like Envirotile best ;)

    As for a permanent fix ......Oh Yes

    polybear
  13. You may well find that, when a roofer comes out, they'll be happy to go down to 10o if that makes the job easier and cheaper for you, tho' it certainly won't be a big issue to raise the slope a bit. They may well wish to add further rafters anyways.

    Anyways, I do like these new tiling systems you've found
  14. polybear

    polybear Member

    Thanks for the replies.  I've now found this system:
    http://www.guardianconservatoryroofs.co.uk/

    - Basically strip off the complete old roof and replace with an aluminium roof beam framework covered in roofing ply, breathable membrane then lightweight interlocking tiles (Metrotile "Slate"). About 150mm of insulation, covered internally with plasterboard and skimmed.  However, it doesn't come in cheap.  The roof has LABC certification and a U value of 0.18, which helps keep the BCO sweet I hope.  Also it's ok for 10 degree pitch.

    I've also asked for a quote from a roofer - retain the existing roof beams and add a few extras to narrow the pitch between beams, insulate, board over with 12mm ply, Metrotile & breathable membrane, vents top and bottom, plasterboard & skim, all lead flashing.  Basically the same thing though a little heavier (the difference between ally and wood beams) with a little less insulation (120mm +).  Hopefully somewhat cheaper than the Guardian system....I'll let you know...

    polybear
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    Message was edited by: Screwfix Peter due to unsuitable content

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