Grosey Posted December 2, 2016 Share Posted December 2, 2016 Just wondered if I could have peoples thoughts on a flat roof solution for my Balcony. Felt Mastic Asphalt Fibreglass Other? Finished floor will eventually be slabs or decking on top of the flat roof solution. Glass and stainless steel balustrading also to be added at a later date - another question is how I fix this to the deck without compromising/piercing the roofing system, but that may be best for another thread? Link to comment Share on other sites More sharing options...
Temp Posted December 2, 2016 Share Posted December 2, 2016 I suggest you plan now/ahead for the balustrading as some solutions need to be partly installed before whatever waterproofing layer you choose is added. One option that doesn't are systems that fix to the wall and have cranked balustrades to go around any overhang/gutter. Link to comment Share on other sites More sharing options...
MrP Posted December 3, 2016 Share Posted December 3, 2016 I would definately recommend mastic asphalt, virtually bombproof, will last forevever and allows seamless detailing around corners, outlets etc. Couple of points though - from what i can see there is no cavity tray in the external walls built adjacent the doorway, you will undo all the hardwork and £k's spent on waterproofing if water gets in to the cavity and gets behind. Secondly whats the plan at the doorway - i.e. are you introducing an upstand - IIRC NHBC standards which most warranty providers work to require min 75mm upstand at doorways. Thirdly how are you getting rid of water - i.e. falls in roof and outlet positions? Also temp is absolutely right about the balustrading. This needs a lot of thought before anything is done but i think you are right that is for another thread... Link to comment Share on other sites More sharing options...
Grosey Posted December 3, 2016 Author Share Posted December 3, 2016 Hi Mr P, thanks for your comments Cavity closers will be added next week, and the cavity around the front of the balcony will also be closed. 100mm kerb (block laid flat) will be installed in the doorway and sliding doors installed on this. Not there yet as it would be a serious trip hazard! Looking at creating a fall towards the front of the balcony and then a gutter. Either with concrete screed over the whole balcony then Asphalt. Or some fibreglass companies are on about installing firrings then t&g chipboard to create the fall. Link to comment Share on other sites More sharing options...
Mr Punter Posted December 3, 2016 Share Posted December 3, 2016 How will you stop the cold bridge with the beam and block running through to the outside? Also, is there habitable space below? Link to comment Share on other sites More sharing options...
Grosey Posted December 3, 2016 Author Share Posted December 3, 2016 The balcony side I plan to insulate from underneath, internally there will be 75mm celotex then 75mm screed. If I wanted to insulate the balcony and have a warm roof I think I could only fit 25mm celotex due to the type of doors I'm having. Underneath is garage/workshop officially but at some point I plan to convert this to habitable rooms. Link to comment Share on other sites More sharing options...
Bitpipe Posted December 3, 2016 Share Posted December 3, 2016 We under-thought our balcony & balustrade and have had to compromise a little so well done for getting ahead of it now! Our bedroom balconies are about 3m x 1.5m and are over the living area - they were built with joists and OSB decking, each has a fall to their narrow edge. We decided on GRP for the roofing as this was being used for other flat roof areas and is pretty bomb proof. We then realised that we could not put balustrade pillars on this as it would get compromised, so investigated doing wall mounted pillars. However we'd not build sufficient support into the walls for this (twin wall timber frame) so ended up with a neat (but more expensive) solution from Elite Balustrades. Essentially its an aluminium deck overlaid with composite boards and the balustrade panels hang off the side. It will only need a few fixing points to the wall where there is sufficient support. http://www.elitebalustrade.com/gallery/qwickbuild-decking-frame.html Looking at yours, as you have block work walls, you can probably fix your balcony to the wall. Link to comment Share on other sites More sharing options...
Grosey Posted August 14, 2017 Author Share Posted August 14, 2017 (edited) Resurrecting my own thread. I'm now at the moment where I need to sort the balustrade. The balcony above was completed with a fibreglass flat roof covering. However I now need to sort fixing balustrade posts down in to it, I understand that a popular method is to fit a secondary timber pad on top of the existing covering, then fibreglass this as well, then fix the posts in to this pad. However I cannot find any info on this method whatsoever, videos or forum guidance - not sure of what Google terms to use but everything I've tried hasn't worked. Im mainly trying to find out if after doing this does the screws for the post only attach to the new timber pad, or does it still penetrate both layers of fibreglass and attach in to the subfloor (block and beam overboarded with ply) Thanks and all comments / guidance welcome. Edited August 14, 2017 by Grosey Link to comment Share on other sites More sharing options...
jamiehamy Posted August 14, 2017 Share Posted August 14, 2017 hiya, as per @Bitpipes post, is the wall fixing method an option? This would avoid completely the need to interfere with the decking and it's waterproofing and would in all likelihood eliminate entirely any future possible issues with moisture ingress that *could* occur. That would be my preferred option. In our case we have a steel beam spanning across the whole deck onto which the balustrade channel is bolted, however that doesn't seem to be an option here. Might not be an option now if the wall is rendered tho in which case unpicking some of the decking membrane may be your only option. The other thing to look out for will be how the forces on the ballustrade are transmitted into the floor - and not putting pressure on the GRP which could cause it to fail over time. In that respect, rather than putting a timber pad ON TOP of the GRP, it might be better cutting out a section and bolting the timber pad directly, then fixing your stanchions/posts and then doing the GRP membrane over everything and lapped down over the existing GRP covering. That's probably how I would do it - you'll need to factor in how the water runs off. Is the floor flat or have a fall? Link to comment Share on other sites More sharing options...
Grosey Posted August 14, 2017 Author Share Posted August 14, 2017 It has a fall towards the front, with a drip bead that will go in to a gutter, the gutter is the piece that is causing my issues with face mounted posts - surely this is a common problem though? Link to comment Share on other sites More sharing options...
jamiehamy Posted August 14, 2017 Share Posted August 14, 2017 I would say so - yes. What type of ballustrade are you going for - frameless glass or something else? Looking at it now (and probably agreeing that wall mounted would be clumsy here with the gutter), I would stick with my above - take out a section of the grp and secure your timber pad into the BnB - which not only created something to bolt the upstand/base into but provides an upstand to minimise standing water at a complex join. You could leave 50/100mm beween that and the edge where the drip bead is, and create holes for the water to pass through. Does that make sense? That's just my thinking on the matter, others hopefully will have different ideas. Link to comment Share on other sites More sharing options...
Grosey Posted August 14, 2017 Author Share Posted August 14, 2017 I'd love a frameless system, however I cannot see how this will work with a base channel all along the front, as it would essentially prevent the water from running off. Could I mount a base channel up off the GRP on several raised pads at suitable intervals - thinking this could look a bit naff though? Link to comment Share on other sites More sharing options...
Onoff Posted August 14, 2017 Share Posted August 14, 2017 Is there any way you could affix to the "wood" clad wall at 1st floor level? Then you could have the standard feet on rubber pads. Years back I made a galv frame up for a small roof with no handrail and "weighted it" down with council slabs. Got the sketch somewhere still. All rule of thumb mind! Link to comment Share on other sites More sharing options...
Grosey Posted August 14, 2017 Author Share Posted August 14, 2017 1 minute ago, Onoff said: Is there any way you could affix to the "wood" clad wall at 1st floor level? Then you could have the standard feet on rubber pads. Years back I made a galv frame up for a small roof with no handrail and "weighted it" down with council slabs. Got the sketch somewhere still. All rule of thumb mind! Yes, I could drill through the Cedral cladding, to the block work behind, then pack out a long thunderbolt with some sort of tube washer to ensure I was only fixing against the block and not the cladding itself. Would fixing to the wall at 2 ends of a U shape be sufficient? Can the feet just sit on the GRP then? What about people leaning on the handrail? Link to comment Share on other sites More sharing options...
Barney12 Posted August 14, 2017 Share Posted August 14, 2017 You'll need to have a limited amount of deflection. Google these scintillating subjects: Two British standards apply; BS6180:2011 "Barriers in and about buildings - Code of practice" which relates to the code of practice for balustrades in buildings and BS6399-1:1996 "Loadings for buildings - Part1: Code of practice for dead and imposed loads" which specifies the information on loadings. For domestic dwellings this translates to: Handrails: For external balconies 0.74 kN/m. This can be compared to having one averagely weighing person 75kg applying the full force of their body on every metre of the balcony. Infill Panels/Rails: 0.5kN/m. Link to comment Share on other sites More sharing options...
Onoff Posted August 14, 2017 Share Posted August 14, 2017 Did something similar years back but it was down into a roof slab. Consisted of a resin anchored stud into the slab, 50mm OD st/st washer as below: Then a short length of thick wall st/st tubing and another washer as above. This was to avoid compressing the roof fixings. Got the full detail somewhere. Link to comment Share on other sites More sharing options...
Onoff Posted August 14, 2017 Share Posted August 14, 2017 Got any pictures of the balcony / parapet detail and how wide is the frontage? Looks 7-8m wide? Link to comment Share on other sites More sharing options...
jamiehamy Posted August 14, 2017 Share Posted August 14, 2017 5 hours ago, Grosey said: I'd love a frameless system, however I cannot see how this will work with a base channel all along the front, as it would essentially prevent the water from running off. Could I mount a base channel up off the GRP on several raised pads at suitable intervals - thinking this could look a bit naff though? I don't think it would work anyway - you don't want to be clamping down a base channel on top of the GRP - and sealing the full length of a baserail to GRP - destined to fail. I'm assuming (like us) your architect and engineer failed to come up with a decent design for this? J Link to comment Share on other sites More sharing options...
Grosey Posted August 14, 2017 Author Share Posted August 14, 2017 6 minutes ago, jamiehamy said: I don't think it would work anyway - you don't want to be clamping down a base channel on top of the GRP - and sealing the full length of a baserail to GRP - destined to fail. I'm assuming (like us) your architect and engineer failed to come up with a decent design for this? J Yep, the is the only mention of a balustrade in a the plans - very detailed Ive looked in to it a little more and apparently they are never installed flush to the ground anyway, you have a "drain plate" underneath each bolt which raises the whole base rail between 2-5mm to allow water to flow underneath. So this could work and allow the water to flow out to the gutter? Link to comment Share on other sites More sharing options...
Onoff Posted August 14, 2017 Share Posted August 14, 2017 I've always struggled with structural calcs tbh but is it something on the lines like this? Do you add on the loads for the infill panels? Gut feel that a top and bottom member would make everything stiffer, so 4 fixing points back thru the cladding. Link to comment Share on other sites More sharing options...
Grosey Posted August 14, 2017 Author Share Posted August 14, 2017 26 minutes ago, Onoff said: Got any pictures of the balcony / parapet detail and how wide is the frontage? Looks 7-8m wide? I don't have any photos since the GRP was done, but essentially it has small risers along the short edges and this screed created the fall to front. Dimensions are approx 2m x 7m x 2m Link to comment Share on other sites More sharing options...
Onoff Posted August 14, 2017 Share Posted August 14, 2017 (edited) So is there a structural slab under there? Those wall blocks don't look too thick for an expanding anchor. How thick are they? Through stud with a big plate washer on the back? Cold bridging? Don't get me wrong I'd "come up with something" if it were mine but SE job I reckon. Edited August 14, 2017 by Onoff Link to comment Share on other sites More sharing options...
Onoff Posted August 14, 2017 Share Posted August 14, 2017 CT1? Link to comment Share on other sites More sharing options...
Grosey Posted August 14, 2017 Author Share Posted August 14, 2017 12 minutes ago, Onoff said: CT1? spoke to a friend earlier to has a similar situation, 30m of balustrade over GRP. He just fixed the post bases directly to his timber sub floor and used a soudal sealant on every possible location that water could ingress and then some more! 3 years on he hasn't had any issues... Link to comment Share on other sites More sharing options...
Barney12 Posted August 15, 2017 Share Posted August 15, 2017 8 hours ago, Grosey said: spoke to a friend earlier to has a similar situation, 30m of balustrade over GRP. He just fixed the post bases directly to his timber sub floor and used a soudal sealant on every possible location that water could ingress and then some more! 3 years on he hasn't had any issues... As long as the design is such that it can't put any stress on the fibreglass roof deck (I.e. Absolutely no flex) then that would be fine IMHO. I would be drilling the holes through the fibreglass oversize by at least 3mm to allow for expansion and contraction of the deck. If this was a handrail on a fibreglass boat then you you would use this stuff at the fixings and any joints: http://solutions.3m.co.uk/wps/portal/3M/en_GB/MarineSolutions/MarineSupplies/ApplicationProcesses/MarineSealersAndAdhesives/ Be warned though, its sticky, hard to work and slow drying. But, once cured its stronger than anything I've ever seen. Makes CT1 look like play dough Careful detailing is key, each one of those holes is a water ingress point which is "less good" on a flat roof. Link to comment Share on other sites More sharing options...
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