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Author Topic: Advice appreciated on roof insulation  (Read 20690 times)
don0301
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« on: November 21, 2013, 03:01:36 PM »

I bought a Bryant home approx. 7 years ago, it's a 5 bed semi detached townhouse with the top 2 rooms half into the roof with a toblerone type loft at the top.  The first few years the house was rented so although I was made aware that the top 2 rooms were cold I only recently discovered why.

I recently had someone fitting extra loft (floor) insulation and whilst up there he discovered there was little or ill fitting 'kingspan' insulation over approx. 90% of the roof, from the loft floor down to the bottom of the roof. Hope I'm making sense.

Amazingly this is not covered by my NHBC 10 year warranty!! But after conning NHBC to come inspect (along with a Taylor Wimpey rep), the rep said 'if something is wrong' we will fix it. Bryant became Taylor Woodrow, became Taylor Wimpey.

The rep said someone would come today to fit 'kingspan' but he turned up with someone who looked in loft again, and said no way you could do that because of lack of space.

They said they will now speak with a 'specialist' to try to find an alternative.

They spoke about a foam spray, but I spoke to a specialist company who said they would not do it, due to potential damage to the tiles, or plasterboard from expansion.

It appears to me, the only way to do it properly would be to remove the roof tiles etc, and re-lay it properly?

So, any advice? I'm wary of being too 'pushy' as basically (even though it was done wrong in the first place) this is a 'goodwill' gesture.

TIA for any advice.

Don

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sunandwindy
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« Reply #1 on: November 21, 2013, 03:31:43 PM »

There's more than one foam filler type insulation. The most basic being Vermiculite that can be poured/blown into a gap/cavity. There's also a fluffy cotton (looking like) substance that is blown in to cavities. By using a blown method, you'd only need to drill 3/4" holes in your plasterboard to fill the cavity, thus saving on a lot of making good.

I'm not saying all major insulation companies are cowboys, but the two kids who did mine skimped on the number of holes they drilled in the wall so there are big gaps without cavity insulation. How do I know, well I've altered/changed some of windows, thus enabling me to look in to the cavity to see the huge voids!
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stannn
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« Reply #2 on: November 21, 2013, 04:23:15 PM »

What is the rafter depth, Don?
Stan
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don0301
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« Reply #3 on: November 21, 2013, 05:12:20 PM »

Hi Stan

Just over 70mm?

Don






« Last Edit: November 21, 2013, 05:15:37 PM by don0301 » Logged
solar_cambridge
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« Reply #4 on: November 21, 2013, 05:24:15 PM »

From your description, you seem to be saying the insulation is behind the plasterboard walls/ceiling. Is that correct? If so, and you probably don't want to hear this, the only viable solution is to remove all the plasterboard. Then cut the 70mm insulation to fit and foam fill the gaps. Overboard with 25mm insulation then plasterboard.

I've seen many jobs done by builders who haven't bothered to foam fill the gaps. They don't comprehend the fact that air can circulate to the warm side.. facepalm

Can you DIY? They aren't going to do this as a goodwill gesture as its a serious amount of work to do properly. Also a lot of mess in the house. Avoid any type of loose fill insulation or injected foam.
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don0301
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« Reply #5 on: November 21, 2013, 05:36:22 PM »

Hi S_C

The top rooms have about 18 inches of vertical wall, then runs up at 49 degrees to ceiling height/loft floor height.

The insulation (actually the lack of!) I'm talking about is behind that, ie should be between the roof and the plasterboard, up to the celing height, ie the loft is 'cold space'.

Hope I've explained it correctly.




Taylor Wimpey rep has said (verbally) if it's wrong, they will put right.

But as you've said I think to do properly is either all plasterboard off or roof off....

Like you, I fear they won't go that far.

Don
« Last Edit: November 21, 2013, 05:38:05 PM by don0301 » Logged
offthegridandy
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« Reply #6 on: November 21, 2013, 05:55:55 PM »

Points to consider would be the type of roofing membrane, ie is it a breathable type? Taking the roof of would be a non starter I suspect and only relevant if it was supposed to be a "warm roof" with insulation over the joists.

  Some years ago I used to work on site  including Bryants and I Never Ever saw the joins in the Celotex board being sealed with foil tape as per spec.

There used to be a product on the market that consisted of 12mm PB bonded to about 25mm PU foam.  To minimise disruption would it be possible to fit this to the sloping wall section of the rooms.  Detailing around window reveals might need some thinking out but you would not have to do any destruction so could be a cleaner option than pulling of existing PB.

Andy
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don0301
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« Reply #7 on: November 21, 2013, 06:08:36 PM »

Hi Andy

I presume the membrane would be breathable.

The top 2 rooms are 'in the roof' mostly.

The issue is most of the roof has no/little/ill fitting insulation.

As Taylor Wimpey have said they will fix, I'm all for roof off to be done properly!

Waiting now to see what they come up with after speaking with a 'specialist' but for me, it seems foam spray isn't a good solution.
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solar_cambridge
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« Reply #8 on: November 21, 2013, 07:01:22 PM »

There used to be a product on the market that consisted of 12mm PB bonded to about 25mm PU foam.  To minimise disruption would it be possible to fit this to the sloping wall section of the rooms.  
Yes. I've used it, but there is some caution with that stuff as it doesn't include a vapour barrier. I removed some after a few years installed and some parts had gone mouldy. I would now always use regular foil backed 25mm insulation and bond PB to it myself.  

They won't take the roof off, that is for sure. You may have to get your own independent report to say that the plasterboard has to come off etc. As Andy says, you want to ensure the spec says all joins have foil tape. And make sure the installer uses it and doesn't just fob you off  fight  When the PB is off, look at all the little gaps etc that heat can escape from.
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daserra
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« Reply #9 on: November 21, 2013, 07:33:27 PM »

What about wait and see what they offer and then ask them how much extra to do it properly, that way you get what you want for less expense and they don't have to stomach a total loss and get to feel like they did the job properly.
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don0301
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« Reply #10 on: November 21, 2013, 07:47:42 PM »

Yes, of course I will wait and see what they come up with.

I'm hoping their specialist will say no to foam type, which should naturally lead to a better solution.

I will post as I hear anything! Fingers crossed!
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A.L.
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« Reply #11 on: November 21, 2013, 08:02:10 PM »

hello,

Yes, of course I will wait and see what they come up with.

-if built in 2006 in Eng/Wales the 2002 Part L probably applies as planning permission would probably have been given before the 2005 regs came into force.

- go round to your local planning and get the plans to see what was supposed to have been installed and accept no less

- there were three pathways available to builders at the time to achieve the standard, try to find out which one was used, but anything less than 100mm of Kingspan would be unlikely to be sufficient
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billt
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« Reply #12 on: November 21, 2013, 08:45:00 PM »

Point of information - Planning and Building control are entirely unrelated. Drawings used for a planning application don't need to show any detail about construction methods and almost certainly won't.

It's possible that Building Control would have constructional drawings if the LA were used rather than an approved inspector, but they will almost certainly charge for a record search and may well not let you have a copy of the plans as the copyright will be owned by a third party.
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dhaslam
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« Reply #13 on: November 21, 2013, 10:43:11 PM »

As well as  heat loss there  is also the problem  of transmitted noise through the roof.   Plasterboard with foam backing is available in  52mm and 62mm overall thickness with a thinner  version for window reveals.  Even though the original insulation is thin and patchy  adding an extra  layers should help a lot for both sound and heat loss.   
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« Reply #14 on: November 21, 2013, 11:00:54 PM »

To do a 100% job the plaster board will have to come off and the bats installed tightly, or PU foamed in.  You could then over board to minimise the cold bridiging from the rafters.

The bonded board is very expensive, I would use standard PIR with taped joints and duplex plaster board over that with screws through to the timber, cost  will be around half of the bonded board.

 


I think the cut of the this says it all really.

Cheers

Jon
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My advice is based on me spending my money doing this and my job spending others money doing this.
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