Re roofing, when do they put the insulation?

[Nasa89]

So we are getting a reroof at present as it was some of an urgent matter. The roofers seem to be the only ones working and able to get supplies at present so we chose them for that reason (and a few good reviews online but can you trust them nowadays?
The just finished one side, the other one has 30% of tiles on. I just looked behind our loft walls in the slope towards the ceiling and there is no kingspan There! This was supposed to be done according to building regulations. My husband said the roofers said they would slide the kingspan up the rafters when they finish.

Is that legit? How can you ensure if you are sliding the insulation up that is going to sit tight against the wall and keep the 50mm away from the membrane? How can you ensure there is no air gaps? I have looked a couple of roofing son YouTube and they seem to put the insulation BEOFRE the membrane and then the Battons and tiles.

Have we been ripped off?

Sorry for the typos... my phone’s autocorrect is playing up (or I have fat fingers 😂😂😂)

There put some kingspan sheets in the bottom bit on the wall on the eaves. This is 200mm wide.

Would that be thick enough for building control approval?

20mm wide sorry, which I don’t think is enough for building control

Is this a loft?

Or a habitable room in a loft conversion?

The external construction of the roof is done first to make the roof watertight. So the membrane, battens and tiles. Then on the inside they would usually have air gap then eg 100mm insulation between the rafters and say 50mm on the front plus battens and plasterboard, or 62.5mm insulation-backed plasterboard.

So no they haven't done anything wrong. Yet.

The air gap: if the roofing felt is the old black type, which is not permeable, they need min. 50mm gap and ridge and eaves vents. It's far more likely they've used breathable membrane, so they'll need a 25mm air gap only.

200mm is very thick for the insulation. Are you sure it's that? It would need the rafters to be min. 225 deep, which is unusual. Normally rafters would be 150/175/maybe 200. Old rafters are often less and they add a timber to the front of them to make them deeper, so there's enough depth for the insulation. Or they put new deeper rafters next to them.

I wonder if they could only get 200mm because of the crisis? Although now it's actually fine to get the right stuff as so many merchants are online or doing order and collect. I think. Unless there's a factory shortage.

I hope they aren't thinking to cut it down to be less, then put the rest on the face of the rafters. That sounds a bit messy and I don't know if it's ok to do that. Kingspan has a foil face and the insulation underneath. If you cut eg 100 off the back to make it 100mm thick maybe that's fine, but you couldn't use the bit you've cut off as it will have no foil on it.

If it's Kingspan, it should be K7 or TP10. These are their pitches roof insulation boards. Kingspan are a top quality brand with a wide range of specific products. Some other brands have less range and more universal products (ones that will do for eg both pitched and flat roofs). Kingspan products are more specialised.

I'm wondering if they've got a different Kingspan product - floor insulation goes thicker, so could be 200mm I think. The TP10 and K7 boards don't come that thick, I think.

So check:
Type of membrane
Plan for air gap, how much insulation between and how much to face of rafters
Type of insulation board

However you as client shouldn't need to check anything as Building Control should, if you're replacing more than 25% of your roof or having this done as part of a bigger project.

At the moment they're accepting a description and photos instead of coming out to look in most areas I think.

Disclaimer: don't take my word for all that!! Ask your roofers and or ask an architect or call Building Control to check.

If you don't trust them, why have you got them doing it? Just ask them nicely to confirm the plan, I'd say.

And yes all that only if a habitable room. Otherwise a loft space just needs mineral wool insulation on the floor and nothing between rafters etc.

It a an habitable room “loft conversion that was done 20 tears ago. Therefore they have no way to add the insulation from inside unless they remove current walls. I made a mistake measuring, The kingspan is 20mm only!!
I textes him briefly Last night and he said that there will be no kingspan on the ceiling and inclined walls to the ceiling, only in the small walls to the eaves!!! He said it will be warm enough like this. I beg to differ with him. So he removed the 20 year old quilt that was there to leave a plasterboard of 15mm thickness between the bedroom and the cold outside??
The worst thing is, building control won’t come to the house, they will accept pictures in a few weeks time.
I am really afraid we had contracted an incompetent roofer 😤

So my problem is: 1. Kingspan at the eaves vertical wall is 20mm and it qctually touches the membrane.

1. There is nothing between thin plasterboard and membrane in the ceiling and pitched walls of the loft conversion. 20 cm gap quite drafty
2. He is telling me that this is going to be warm, despite a freezing winter there with the old insulation wool.

Stop any more work until you resolve it. Otherwise you won't be able to get building regs sign off once they start working aside from having a freezing room.

What idiots

We will the sad thing is the roof is nearly done, they were meant to finish today. He had us for 2 days wondering when he was going to put the kingspan and giving us excuses until yesterday he said he never agreed to insulate “all around”. Luckily I have our conversation via text messages where I emphasise in building regulations and the loft insulated in walls and ceilings and he assured me the quote included insulation “all around” the loft conversion

I see examples like yours so often in here whereby builders start work with no contract or specification within the contract. At least you have the texts and given the work isn't building regs compliant that will help you. Don't pay a penny and start putting everything in emails to him

Ok thanks for the advice. I’ll try to come to an agreement for them to put it right. But quite honestly I don’t trust them anymore and I’m sure they will be annoyed that they are losing money with this job so they will try to cut corners. I’d love to tell them to leave and get another roofer

'Insulation all round' is the key item in your texts.

It means yes he has to remove existing plasterboard and supply and fit insulation between and to the face of rafters, extending them as I described if necessary, and then ideally finish with new plasterboard and then plaster.

You didn't have this all detailed in the agreement but it's what should have been agreed.

I don't know how big the loft room is but this is quite an extensive internal job. It's not something he will 'tack on' if he didn't have it in.

I don't know how much you've paid but him saying 'yes insulation all round' is very vague. He himself should have itemised as I have above and charged accordingly. Obviously 20mm is not anything of use really.

There are lots of builders operating. I don't know where you are. IMO you should ask him (written down in text or email) what he had included. And building control are answering emails so you should check with them what's needed.

Ether you need a full plan (eg from BC) about what's needed and to agree with the builder that this hadn't been properly detailed and agree a cost for the additional work less what he'd included, or to settle up with him for the external roof work and get another builder for the inside.

And yes BC do need to have photos of all stages. While scaffold is up get the builder to take photos of external roof construction.

Actually just reread your comments and he is an asshole to say that 'it'll be warm enough' ! It's not up to him! That's why we have Building Control!

I'd settle up for outside and smile and say thanks lovely job no probs about inside and get shot of him.

You could relay all this info with your own measurements and images to building control to see what they have to say about it

they may try to blackmail you, threatening to walk off and leave your roof half-open to the elements. Try to find another roofer by personal recommendation (not an advertising website) who will do a proper job.

Preferably not one of the existing roofer's buddies, but someone who considers themselves better than him.

If you drive around you may see roofers at work on other local houses. Try to speak to the houseowners. It's worth photographing the signboards and vans of builders locally, outside the houses they are working on, before you need to find one for yourself.

BC are not being very helpful just giving me prefab responses. I will send videos and pictures and see what else they need.
Roofer offered to shove 50mm of kingspan from the eaves up to the top. The rafters are 110mm so no more space to put more insulation (they check with a few building merchants and they only have 50mm or 100mm. I wonder if BC will be ok with that since the roof and walls are pre existing and you would have to throw them out to put the required amount of insulation