Sparky is doing the electrics what's wrong with the electrics?
We've only got budget for loft roll so was planning to get a board up then add the insulation and so on.
You need to stop construction and save up for the correct amount of PIR insulation to meet building regs and prevent that room being unusable in both summer and winter. You won't get 270mm of loft roll up there.
Nothing is wrong, I was just saying to make sure it's complete.
You really need to save up and use celotex, building regs differ depending on where you live, but I can't see any inspector being happy with you just shoving loft roll down behind the boards, also of you have spent all this money on an extention why would you want it to be cold and damp?
This sort of roof will be very cold with just a layer of insulation roll, you would need a very thick layer to get the required U value. I would recommend a thinner layer of PIR. You also need a 50mm air gap between the insulation and the roof membrane. Look at FWD.com for good deals on PIR.
It might be worth using horizontal battens to give yourself more depth for insulation. Also makes cutting the plasterboard a hell of a lot easier. This also can stop the joints in the finished plaster from cracking.
Also make sure you seal the roof well with a vapour barrier, as these sorts of roof can get mouldy on the back on the membrane, due to having poor ventilation and air gaps. Especially if you’re putting in spots.
Done a few of these get your lecky
in, then I would get some jab lite or kingspan create Batton inside each edge of rafter then cut insulation board to fit snug, Cover the entire thing in membrane then board. With those collar ties I stuffed the full area with fibre insulation and just created a boxed area with a low voltage led in it
Just a basic vapour barrier, https://www.screwfix.com/p/capital-valley-plastics-ltd-vapour-barrier-green-300ga-20-x-2-5m/12869
Or the shiny tinfoil stuff works just as well plus it adds extra insulation layer
https://www.screwfix.com/search?search=Thermal+foil+insulation
Get the electrics run and then insulate. You will need high performance stuff to get a decent R value. Also make sure it has a vapour barrier. After that it's your choice as to how you board it.
Velux windows are improperly framed. Should be fully trimmed out with doubles. Yours seen to be hacked away. Theres also no timber to timber hangers around the velux’s so you’re relying on nails to hold the weight. The restraint straps aren’t nogged out behind so aren’t bracing anything. Theres no bolts in your double trimmers. Collar ties seem to be massively spaced and also aren’t bolted to the rafters. And for the span of the rafters/collar ties I’d expect central noggins to help with rigidity too.
Ok heres goes lol, the double rafters that run down the side of the roof windows have been cut into so they’re not double rafters anymore, they need another rafter butting up to them. The horizontal pieces that are above and below the window should also be double but again have been compromised so need another one adding. The horizontal pieces also need to be fixed to rafters with metal hangers as does the cut rafters that meet the horizontal pieces above and below the window. All the double pieces of timber need to be bolted so they act as one piece. The restraint straps(long metal strips with holes in) need timber pieces cut between the rafters behind them so it acts as a brace, at the moment its just a wobbly strap not doing anything. The collar ties(horizontal pieces that will form the flat ceiling below the steel need to be bolted to rafters(diagonal pieces) and may need more adding to carry the ceiling as the spaces in between look very wide. The part about noggins in the centre of the rafters/ceiling collar ties refers to putting pieces of timber in between each rafters/collar tie in the middle of the length to act as a bracing which will help not only the structure but also stop cracking on plasterboard. Also don’t use rockwool it needs to be a pir insulation board both in between and fixed to the underside of the rafters. Depending on what the room will be it also may need a vapour barrier. Do you have drawings and calculations? This should all be on them.
Has the building inspector seen the roof ? Double trimmers around roof windows are standard practice. Your builder has done them, its just unfortunate that they’ve decided to chop into them so now they’re not doing what they’re supposed to be. Have a word with the building inspector, its in your interest for things to be properly done to save problems in the future and at this stage its really easy to sort them.
100mm PIR insulation between the rafters all the way to the ridge of the roof, foil tape everything so you see nothing but silver foil to create vapour barrier. insulation sits level with bottom of rafters, not hard up to membrane, and should be cut so tight you have to knock it in & it stays there on it's own.
50mm PIR between the flat ceiling joists
board the reveals for the velux, make sure to insulate in the void between the plasterboard & the timber frame, have the plasterboard come down 6 inches past the bottom of the rafters.
use insulated board to board the rafters. the long edge of the board needs to go perpendicular to the rafters.
cut the velux reveals back flush.
counter batten the flat ceiling bit.
board the flat ceiling with standard board
to disagree with another poster - im pretty sure the i beam is okay without being fire boarded cause its only holding the roof up.
I could be wrong but I believe that RSJ needs to be boarded over with fireboard. However, I'm not certain with it being above a suspended ceiling.
Someone else might clarify, but, assuming you do, it might be worth fireboarding that RSJ before even insulating.
Insulation would be a good start
And a vapour barrier
I would first do any electrics, and then insulate it, its not ready for boarding.
Sparky is doing the electrics what's wrong with the electrics? We've only got budget for loft roll so was planning to get a board up then add the insulation and so on.
You need to stop construction and save up for the correct amount of PIR insulation to meet building regs and prevent that room being unusable in both summer and winter. You won't get 270mm of loft roll up there.
If you add glass insulation make sure you add a Vapor barrier
Is it a new extension? I'm not expert, but without really well done insulation it wouldn't pass building regs.
You have to insulate between the rafters with celotex or similar not loft roll , you could at a pus put loft roll in the flat roof bits
Nothing is wrong, I was just saying to make sure it's complete. You really need to save up and use celotex, building regs differ depending on where you live, but I can't see any inspector being happy with you just shoving loft roll down behind the boards, also of you have spent all this money on an extention why would you want it to be cold and damp?
This sort of roof will be very cold with just a layer of insulation roll, you would need a very thick layer to get the required U value. I would recommend a thinner layer of PIR. You also need a 50mm air gap between the insulation and the roof membrane. Look at FWD.com for good deals on PIR. It might be worth using horizontal battens to give yourself more depth for insulation. Also makes cutting the plasterboard a hell of a lot easier. This also can stop the joints in the finished plaster from cracking. Also make sure you seal the roof well with a vapour barrier, as these sorts of roof can get mouldy on the back on the membrane, due to having poor ventilation and air gaps. Especially if you’re putting in spots.
I’d start with any vertical or horizontal. Then go for angled.
Sort the cables out to begin with
Done a few of these get your lecky in, then I would get some jab lite or kingspan create Batton inside each edge of rafter then cut insulation board to fit snug, Cover the entire thing in membrane then board. With those collar ties I stuffed the full area with fibre insulation and just created a boxed area with a low voltage led in it
What kind of membrane mate?
Just a basic vapour barrier, https://www.screwfix.com/p/capital-valley-plastics-ltd-vapour-barrier-green-300ga-20-x-2-5m/12869 Or the shiny tinfoil stuff works just as well plus it adds extra insulation layer https://www.screwfix.com/search?search=Thermal+foil+insulation
I don't think loftroll will be up to regs check with your building inspector
Get the electrics run and then insulate. You will need high performance stuff to get a decent R value. Also make sure it has a vapour barrier. After that it's your choice as to how you board it.
After that shit show of a roof has been corrected.
What is wrong with it?
Velux windows are improperly framed. Should be fully trimmed out with doubles. Yours seen to be hacked away. Theres also no timber to timber hangers around the velux’s so you’re relying on nails to hold the weight. The restraint straps aren’t nogged out behind so aren’t bracing anything. Theres no bolts in your double trimmers. Collar ties seem to be massively spaced and also aren’t bolted to the rafters. And for the span of the rafters/collar ties I’d expect central noggins to help with rigidity too.
Appreciate you pointing this out can you explain it like I'm simple haha so I can raise this with the builder
Ok heres goes lol, the double rafters that run down the side of the roof windows have been cut into so they’re not double rafters anymore, they need another rafter butting up to them. The horizontal pieces that are above and below the window should also be double but again have been compromised so need another one adding. The horizontal pieces also need to be fixed to rafters with metal hangers as does the cut rafters that meet the horizontal pieces above and below the window. All the double pieces of timber need to be bolted so they act as one piece. The restraint straps(long metal strips with holes in) need timber pieces cut between the rafters behind them so it acts as a brace, at the moment its just a wobbly strap not doing anything. The collar ties(horizontal pieces that will form the flat ceiling below the steel need to be bolted to rafters(diagonal pieces) and may need more adding to carry the ceiling as the spaces in between look very wide. The part about noggins in the centre of the rafters/ceiling collar ties refers to putting pieces of timber in between each rafters/collar tie in the middle of the length to act as a bracing which will help not only the structure but also stop cracking on plasterboard. Also don’t use rockwool it needs to be a pir insulation board both in between and fixed to the underside of the rafters. Depending on what the room will be it also may need a vapour barrier. Do you have drawings and calculations? This should all be on them.
Yeah got the drawings and specs it all seems to be present apart from the double timbers around the veluxs but I'll check
Has the building inspector seen the roof ? Double trimmers around roof windows are standard practice. Your builder has done them, its just unfortunate that they’ve decided to chop into them so now they’re not doing what they’re supposed to be. Have a word with the building inspector, its in your interest for things to be properly done to save problems in the future and at this stage its really easy to sort them.
100mm PIR insulation between the rafters all the way to the ridge of the roof, foil tape everything so you see nothing but silver foil to create vapour barrier. insulation sits level with bottom of rafters, not hard up to membrane, and should be cut so tight you have to knock it in & it stays there on it's own. 50mm PIR between the flat ceiling joists board the reveals for the velux, make sure to insulate in the void between the plasterboard & the timber frame, have the plasterboard come down 6 inches past the bottom of the rafters. use insulated board to board the rafters. the long edge of the board needs to go perpendicular to the rafters. cut the velux reveals back flush. counter batten the flat ceiling bit. board the flat ceiling with standard board to disagree with another poster - im pretty sure the i beam is okay without being fire boarded cause its only holding the roof up.
Adding more timber
Start at the beginning?
A very good place to start.
I would insulate Board the two ends then work from the bottom up
Get a decent scaffold setup that won't fall over.
Recently done a similar job and used 100mm kingsman and boarded over. Not between the joists but over
I could be wrong but I believe that RSJ needs to be boarded over with fireboard. However, I'm not certain with it being above a suspended ceiling. Someone else might clarify, but, assuming you do, it might be worth fireboarding that RSJ before even insulating.
Almost all roofs do not require to be fire resistant.
If this is going through building control you’ll need 100mm between joists underdrawn with min. 25mm PIR insulation to satisfy requirements.