revelation

Maybe a silly question, but are their different grades of fibre? What should I be looking out for or questions to ask to a installer?

Thats really interesting, someone else had advised that closed cell spray foam may work on the bottom as it will expand and fill in any gaps therefore there isn't anywhere for condensation to form. I have mentioned it as an option but so far no one else that has replied has said its a good idea or will definitely work.

The step is approximately 250mm, I don't know the exact height of the upstand and the glazing, but where the glazing finishes is level with where the step comes (so approximately 250mm). The glazing has attached frame which comes over the upstand so as the insulation increases so does the starting point of the upstand. I have attached some images if the roof light on a previous post.

Unfortunately all the joists have been set in place and bricked in, we also have set of large sliding doors in the kitchen below which are effectively floor to ceiling (approx 2500mm) so even if we wanted to lower inside we couldn't really do that.

We will be getting a glass rail put in at a later date, we didn't initially apply for planning to use it as accessible roof. So will look to have that done once that's approved.

Hi Peter, Yes we can raise the deck but then it comes higher than the doorways, there is some brick/block-work to go on-top of the steels. I would ideal love to have everything flush as soon as I walk out of the door. So the current planned make up was giving us a perfectly flush finish. All the suggested solutions of putting insulation below, including spray foam haven't had any reassuring feedback. So it looks like we have no choice but to increase the insulation above. Then have a small step as you come out of the door, ideally its not something we wanted to do though.

So essentially, if I raise the insulation I have to raise the curb, which leaves the glass roof light higher. Considering the expense we have gone to to buy the glass so it fits flush, thats what we would ideally like.

What would be the main advantage of fibre glass over felt? I keep hearing different things, the guys that deal with felt rubbish GRP, the GRP guys rubbish felt.

The roof window does just sit on the curb it, it sits around the side so has some overhand that has to sit above the final felt or fibreglass layer. I have attached an image of the type of roof light. I hope that clarifies

I would love to just add some more insulation. The door we have had that made already, The problem is that the final finish would either finish higher than the doors or if we lower the decking then the glass roof lights will sit up higher than the decking so will create a trip hazard and aesthetically not look great.

With the current door the sill would sit about level with the decking there maybe about 20mm of play but thats it. If we get put in more insulation we could keep the deck at around the same level using short legs but the glass roof light would have to come up so we wouldn't get a flush finish and it would create a trip hazard (especially having two young kids).

I don't follow, the size of the roof is approx 8m x 5.5m

Well noticed, after doing them I realised that I missed them off. There are firing to create a fall to direct the water to the gullies and the gullies down to the drain.

Thank you, but do you think if its something thats done in the next few weeks will be done well considering the temperature and constant rain?

The problem is with our doorways, any raising of the deck will mean the deck coming higher than the door going out onto the balcony. We have a minimum amount of play.

Hi Peter The decking will come above our doorways. If we are doing it according to our original plan the decking comes close to flush with the door sills. Right now its only the first layer of OSB and the Alutrix membrane that has been put down. After reading al the advice I put a stop to any further work on the roof until we were sure of what we were doing. I would bite the bullet and pay for spray foam to be done if it meant that we will get the balcony exactly how we want it. Why do you think spray foam won't work?

Hi All We were planning to put a raised roof deck on our flat roof to run level with our walk on roof windows. We hadn't really paid that much attention to the flat roof finish, whether it was felt, GRP or rubber. We now need to decide, what would you recommend as the best surface for a raised deck (like in the images attached)? It will need to support the legs that the decking boards will sit on and allow the water that drains below to easily run off.

Thank you everyone, without doubt it seems like our current set up is going to be a huge problem. So I am going to be making some changes. My current builders are good, the previous guys made a mess of the levels which has caused us the issues with the levels. I have attached some images showing what was going to be the set up and what I think my options are with this. The image shows one of the doorways going out onto the roof, there is still a block to go on that steel, but we don't have a lot of room for the build up. ORIGINAL PLAN definitely been scrapped. PLAN A This would be the least disruptive (if you guys think it will work as it changes nothing on the roof above) I have been advised that if I have insulation below the OSB that there will be air gaps and voids where you can get condensation. If I were to get spray foam insulation (closed cell) which will effectively fill in any air gaps leaving nowhere for condensation to form? PLAN B. As a couple of people suggested, I shouldn't have more insulation below than I have above. Therefore if I add on some insulation above and then an equal or slightly lesser amount below would this work. The only issue I have is the walk on roof glass not sitting flush with the decking, which would be a possible trip hazard and aesthetically wouldn't look very good. Considering the cost of the glass its going to be a shame if we can't finish flush as we wanted.

Most pf the top is 50mm, we have had to form gullies down the side that are 25cm wide, they are the parts where there is 25mm insulation. I think it will be a challenge creating a void in the joists as we have posi joists. So open webs throughout. I need a solution that makes the best of a bad situation, that will leave us well insulated but minimise the risk of issues. Or at least if those issues occur it will kick that a lot of years down the line... Just thinking a little outside the box, would it be totally crazy to leave one MVHR extract duct pipe in the poi joists? Desperate time

Unfortunately part of the roof has been already done and lots of other things have been set up according to the roof make up now.

Thats helpful, I will try my best with it. In terms of the insulation I put in below, will it make a difference wether its closed cell foam, rigid insulation, or rockwool?

We have a parapet wall, so not too sure as to how to turn this into a cold roof and part of it has already been done.

I think we will have to insulate below as otherwise we just won't have enough insulation. The warm flat roof will be on pozi joists I don't know if that will make the slightest difference. We could put a vapour barrier but won't that be pierced when we screw the plaster board to the ceiling, also we have to bring three vents through the ceiling for our heat recovery system.

That really doesn't sound good. We started off with a set of builders who really messed things up, they didn't consider the build up of the initial warm roof. We were planning to have 120mm-150mm of insulation in the warm roof. But as we had doors that were supposed to open out to the balcony they would have been blocked off due to the room build up going higher than the bottom of the doors. So we thought if we reduce the insulation on the outside and have extra insulation on the inside (below), that should balance things out. Would it potentially work if it was say a closed cell spray foam insulation below? We do have a heat recovery system so I am hoping that will help keep moisture levels in the house down.

In your experience is there a significant enough cost saving to go down the taping route. Ours is a decent sized 4 bed semi, and if skimming gives a better finish and is more durable water resistant etc... And the cost difference is only 10% or so, then its a no brainer for me.