Roof insulation issue - Building Control

[jaydubya]

Hi All,

 

We’ve just had building control out to do the final inspection for sign off, and I cannot believe the pedantry from the inspector. There was no pragmatism whatsoever - I’m so annoyed about it, my blood is literally boiling.

 

Long story short, I can sort most problems out, such as a handrail modification, a grommet in a plug and other silly things but the one issue I can’t see a solution to is the broken insulation in our roof. 
 

See attached photo. Our hot water cylinder is slightly too tall which meant the Celotex insulation had to be cut around it. We still have insulation between rafters, but it has forced us to cut the insulation beneath. 
 

The inspector won’t offer a solution and has just said that the U-Value has to be maintained across the entire roof.

 

Is this correct and any bright ideas?!

 

Many thanks in advance!!

 

[Redbeard]

Hmmm.... Well, you could (if indeed this is the case, prove that the *area-weighted* U value does meet the B Regs target. I don't rely on area-weighting much since, however you can make the numbers work, you still have an area of lesser insulation where a moisture issue might occur.

 

Is this refurb or new-build? Have you worked out the U values? If you post the thicknesses and relevant areas I am sure someone could work it out for you. Is that under-layer 75 or 100 - cannot quite gauge it from here. How much is between the rafters?

[Russell griffiths]

Why was it not put in the tallest part of the loft. 
sorry but that’s fairly crap and needs moving over. Don’t just think about the insulation, what about the broken airtight layer, your asking for trouble with that void above the tank. 
 

im afraid I’m on building controls side. 
 

move the tank, re plumb it and fix the insulation. 

[Redbeard]

@Russell griffiths, it looks like the a/t layer is somewhat lacking anyway. Some blue foam but no  tape that I can see. OP, can we have a pic taken towards that block wall showing why the cyl could not go leftwards?

[dpmiller]

aren't batteries in the loft frowned upon too?

[JohnMo]

26 minutes ago, Russell griffiths said:

im afraid I’m on building controls side. 
 

move the tank, re plumb it and fix the insulation

+1 also. It all looks a bodge.  GMove cylinder get insulation sorted. Trim blue foam flush, tape all joints. You also need tape on the insulation and block work.

 

Finish insulation of pipe by cylinder.

[jaydubya]

We’re still detailing the airtightness of the loft. I was planning to add airtight control layer above, taped. We’ve detailed all of the house other than final part of loft taping all windows/doors etc.

 

Insulation is frametherm32 140mm between and 100mm Celotex below. 

[JohnMo]

14 minutes ago, dpmiller said:

aren't batteries in the loft frowned upon too?

Not really mine are in just the same space as the OP.

 

They are most likely Lifepo04. So chances of a fire or adding to are minimal.

 

https://www.evlithium.com/Blog/advanced-safety-features-of-lifepo4-batteries.html#:~:text=Non-flammable electrolyte%3A LiFePO4 batteries,battery is punctured or damaged.

[Alan Ambrose]

>>> aren't batteries in the loft frowned upon too?

 

Yeah, I think actually part p electricians are not supposed to install them there now.

[JohnMo]

1 minute ago, Alan Ambrose said:

aren't batteries in the loft frowned upon too?

Is it a loft or plant room? It's inside the thermal envelope so not susceptable to freezing etc.

[DevilDamo]

A bit of a c*ck up by the plumber I’m afraid. You can’t just go cutting into or destroying the thermal envelope of a building so things can “fit”.

[jaydubya]

Fair play - sounds like I need to get cylinder moved! Probably my dropped ball as I had the plumber do the work before it was fully insulated. You live and learn 👍 cheers all. 

[Redbeard]

1 minute ago, jaydubya said:

Fair play - sounds like I need to get cylinder moved! Probably my dropped ball as I had the plumber do the work before it was fully insulated. You live and learn 👍 cheers all. 

I think you are right in that. Also are those DC isolators in the low spot? How well are the cables taken through the insulation?

 

I think you could maybe prove that the area-weighted U value may work (though I am more au fait with refurb 'backstop' than new-build) but so many other shortcomings identified (is the insulation to the pipework just unfinished?) that I think it is worth grasping the nettle. BTW please use high-quality (and strength) air-and vapour-tight tape. Foil tape is not necessarily strong enough in tension (for example where you turn round from PIR to blockwork).

[ETC]

1 hour ago, jaydubya said:

Hi All,

 

We’ve just had building control out to do the final inspection for sign off, and I cannot believe the pedantry from the inspector. There was no pragmatism whatsoever - I’m so annoyed about it, my blood is literally boiling.

 

Long story short, I can sort most problems out, such as a handrail modification, a grommet in a plug and other silly things but the one issue I can’t see a solution to is the broken insulation in our roof. 
 

See attached photo. Our hot water cylinder is slightly too tall which meant the Celotex insulation had to be cut around it. We still have insulation between rafters, but it has forced us to cut the insulation beneath. 
 

The inspector won’t offer a solution and has just said that the U-Value has to be maintained across the entire roof.

 

Is this correct and any bright ideas?!

 

Many thanks in advance!!

 

Ask your BCO if you can submit a calculated trade off calculation.

[billt]

2 hours ago, JohnMo said:

Not really mine are in just the same space as the OP.

 

They are most likely Lifepo04. So chances of a fire or adding to are minimal.

 

https://www.evlithium.com/Blog/advanced-safety-features-of-lifepo4-batteries.html#:~:text=Non-flammable electrolyte%3A LiFePO4 batteries,battery is punctured or damaged.

 

https://diysolarforum.com/threads/house-burned-down.83098/

 

The chemistry might be relatively safe but they still store a lot of energy and there are other potential ignition sources. I would never install batteries in a loft.

[Conor]

Could stuff the void above the tank with a bit of mineral wool insualtion.

[JohnMo]

2 hours ago, billt said:

 

https://diysolarforum.com/threads/house-burned-down.83098/

 

The chemistry might be relatively safe but they still store a lot of energy and there are other potential ignition sources. I would never install batteries in a loft.

Your not really comparing apples with apples - 100kWh and looks like a DIY build (without reading 54 pages) with small fuses and enough battery power to jump the gap of a failed fuse. Not nice for the guy and family!