Anyone have the MBC open panel 140mm wall system?

[Dreadnaught]

I wonder, has anyone here used the MBC open panel 140mm wall system (as compared with the 300mm twin stud)?

 

I know quite a few on here have used the MBC 300mm passive-house twin-stud wall system but for a range of reasons* I am thinking of specifying the open panel 140mm wall from MBC instead with external-wall upgrade to U-Value 0.11W/m2K.

 

I have some questions about the airtightness with the open panel system using the Protect VC Foil Ultra airtightness layer.

 

(* If anyone is interested in the reasons I would be happy to explain.)

Edited January 5, 2019 by Dreadnaught

[vivienz]

* Oh, go on, don't keep us hanging!

[Dreadnaught]

@vivienz haha. OK:

 

The reasons for choosing 140mm wall system over 300mm twin stud:

1. My site has restricted access and the craning of panels is likely to be severely limited and may be impossible, at least with a big crane like the huge one on your site. The panels will likely need to manhandled into position. The 140mm system is far lighter and less bulky
2. A frame using the 140mm system is about 30% cheaper (excluding foundations) and my build is being planned with one eye on saleability

 

[Thedreamer]

What type of insulation will you fill the 140mm gap with?

[Dreadnaught]

2 minutes ago, Thedreamer said:

What type of insulation will you fill the 140mm gap with?

 

Here you go (from MBC) …

Edited January 5, 2019 by Dreadnaught
Swapped the image for the right one.

[Russell griffiths]

Is your build @Dreadnaught not single storey ?

if so I would think no crane needed, just a telescopic forklift with a mast extension. 

 

Or a tracked mini crane, lots about nowadays, typically used for installing heavy windows, I can’t think that any of your panels will be that heavy. 

What sort of weight are you talking about 

[Dreadnaught]

19 minutes ago, Russell griffiths said:

Is your build @Dreadnaught not single storey ?

if so I would think no crane needed, just a telescopic forklift with a mast extension. 

  

Or a tracked mini crane, lots about nowadays, typically used for installing heavy windows, I can’t think that any of your panels will be that heavy. 

What sort of weight are you talking about

 

Quite right, @Russell griffiths, single storey. But I lack the glorious expanse of your truly lovely site (nor to mention your vast and wonderful wildlife pond)!

 

On mine, the first limitation is that there is nowhere to site a crane as it is surrounded by buildings, trees and crotchety neighbours. The second is that the entrance gate is obstructed by the low branches of an overhanging mature chestnut tree. The third is that there is little manoeuvre room inside the gate nor, crucially, on the outside in the access road. Having seen a telescopic forklift being (skilfully) driven around @vivienz site, I doubt even it would fit in the cramped confines of my site. I can easily see the lorry carrying my frame stopping at to the end of the service road, some 40m away, and then each panel being carried or wheeled on dollies (possibly forklift) down the road and squeezed through the gate on to site, with the height restriction being the limiter.

 

I had one frame company come to site and another looked carefully at it on Google street view, supported by some of my photos . Both were concerned about the access. One upped their quote by a few thousand because of it, saying they could find a way by making panels smaller, etc. The other did not quote. Anything I can do to make the panels smaller (by choosing 140mm over 300mm, for example) helps I think.

 

 

 

 

 

[vivienz]

That's a good point, @Russell griffiths

My windows were all unloaded and then the upper ones put onto the top lift of scaffolding using a telehandler.  The big windows are far heavier than any of the twin wall cassettes were.

 

I guess the only possible issue is whether they need a crane to offload any steel beams.

[Dreadnaught]

29 minutes ago, vivienz said:

I guess the only possible issue is whether they need a crane to offload any steel beams.

 

Good point about steels. Have not got to the detailed frame design quite yet. I guess that will be in about March. 

[PeterW]

@Dreadnaught get the overhanging branches trimmed ASAP ..! If it’s your drive then you can cut them back. 

 

Telehandlers come in all shapes and sizes - a baby Merlo or JCB will still lift a panel to over 4m which is plenty high enough. 

[Dreadnaught]

4 minutes ago, PeterW said:

@Dreadnaught get the overhanging branches trimmed ASAP ..! If it’s your drive then you can cut them back. 

 

 

Oh, if only! It is an admired tree in a conservation zone, and nigh-on worshipped by the neighbours. It has already been trimmed: a crown lift by a proper tree surgeon and guided by an arboricultural method statement.

 

Yes, one of those baby telehandlers might just fit or one of these off-road fork lifts:

 

 

 

[Declan52]

A 13t digger with an extension in the boom will lift whatever you need esp if it's only  a single storey.  You can get diggers with no tail swing that will be not much more than 2m wide. 

[Gone West]

3 hours ago, Dreadnaught said:

 

Here you go (from MBC) …

 

I may be completely wrong but isn't that U factor of 0.11W/m2K better than the standard 300mm twin stud wall with cellulose insulation which I thought was 0.12Wm2K. So why not use it?

[lizzie]

4 hours ago, Dreadnaught said:

I wonder, has anyone here used the MBC open panel 140mm wall system (as compared with the 300mm twin stud)?

 

I know quite a few on here have used the MBC 300mm passive-house twin-stud wall system but for a range of reasons* I am thinking of specifying the open panel 140mm wall from MBC instead with external-wall upgrade to U-Value 0.11W/m2K.

 

I have some questions about the airtightness with the open panel system using the Protect VC Foil Ultra airtightness layer.

 

(* If anyone is interested in the reasons I would be happy to explain.)

Tom I believe it is what I have.... we had access issues and this suited us better, Will look out my spec

[lizzie]

5 minutes ago, lizzie said:

Tom I believe it is what I have.... we had access issues and this suited us better, Will look out my spec

Found it......I recall we ended up with slightly different insulation on site as supply issues for MBC but overall u value the same

 

mbc wall spec.pdf

[Jeremy Harris]

Just to throw my usual observation into the debate, worth looking at the decrement delay for the various options.  U value is, on its own, not a good indication of the comfort level that may be achieved.  A low decrement delay build up, like the thinner foam panel lined walls, will have a much shorter decrement delay.  This may not have a massive impact in winter, but it will almost certainly be noticeable in hot, sunny weather, where heat will be transmitted into the house more quickly than would be the case for walls with the same U value but a longer decrement delay.

 

Not an issue if you have a relatively fast response heating/cooling system, though, as that should be able to adjust for the lower decrement delay OK, but may be an issue if, like us, you have a relatively slow to respond heating/cooling system.

[Dreadnaught]

3 hours ago, PeterStarck said:

I may be completely wrong but isn't that U factor of 0.11W/m2K better than the standard 300mm twin stud wall with cellulose insulation which I thought was 0.12Wm2K. So why not use it?

 

Yes, @PeterStarck, you are exactly right.

 

I suppose the advantages of the 300mm double-stud over the 140mm open are:

1. Improved decrement delay, as @JSHarris rightly says above. More on that in the next post
2. Improved sound proofing
3. In some nebulous way that I cannot put my finger on, less cold bridging. (I am aware that a U-value (as compared with, for example, a λ value) should take into account but I have feeling I am missing something here)
4. Less carbon embodiment

Have I missed anything?

 

 

 

 

[Gone West]

@Dreadnaught

 

1. You would have to decide how important decrement delay would be at your site.

2. Not sure about that, we have foam insulation and good sound proofing.

3. I doubt that as the studs are covered with insulating board.

4. I think the recycled newspaper goes through several processes before becoming insulation so I don't know about carbon embodiment.

 

I can't think of anything else but I'm sure someone will.

[Nickfromwales]

10 minutes ago, Dreadnaught said:

Improved sound proofing

Should read MASSIVELY improved sound proofing. 

It really makes a huge difference in my direct experience. PIR is pretty ‘transparent’ as a wrap for a home. 

@Dreadnaught  I’d stick to your guns and see if the 300mm sections can simply be fabricated in smaller sections as a couple of days of extra man handling is nothing for the MBC team imo. 

 

The best thing to do is tell the MBC guys that they CANNOT do it, and watch them  then prove you wrong ?. ???

[Dreadnaught]

1 hour ago, JSHarris said:

Just to throw my usual observation into the debate, worth looking at the decrement delay for the various options.  U value is, on its own, not a good indication of the comfort level that may be achieved.  A low decrement delay build up, like the thinner foam panel lined walls, will have a much shorter decrement delay.  This may not have a massive impact in winter, but it will almost certainly be noticeable in hot, sunny weather, where heat will be transmitted into the house more quickly than would be the case for walls with the same U value but a longer decrement delay.

 

 

Your usual observation is very welcome. Through your repeated emphasis on the such matters I have learnt so much.

 

Here's the conundrum. In my design, most of the walls of my bungalow will be shaded by an overhanging simple pitched slate roof. Thus, sun's energy that could risk overheating in the summer predominately falls on the roof. Now here's the key part. The section I showed above is only for the walls, the roof is different. The roof system that MBC specifies to go along with the 140mm open stud wall system has 400mm of blown-cellulose insulation (see below). Thus, I am putting the cellulose in the place it is most needed for enhancing decrement delay, the roof. 

 

Thus I am getting the best of both worlds, while also reducing panel bulk, and saving the 30% price premium. Am I right?

 

From MBC again …

 

Edited January 5, 2019 by Dreadnaught

[Thedreamer]

Just going back to the opening post regarding Protect VC Foil Ultra.

 

I've noticed that a few of the PIR manufacturers have suggested that if you tape the boards together you are effectively creating a VCL/airtight layer, prehaps useful on large areas like gable walls, but is this an inferior option compared to using a membrane like Protect VC Foil Ultra.

 

 

[Dreadnaught]

22 minutes ago, Nickfromwales said:

Should read MASSIVELY improved sound proofing. 

It really makes a huge difference in my direct experience. PIR is pretty ‘transparent’ as a wrap for a home. 

 

Fair challenge @Nickfromwales. Personally, sound proofing is important to me. I like peace and quiet and the location of plot is prone to occasional raucous May-Week and bonfire-night parties, etc. And when I heard some time ago @JSHarris saying, presumably half in jest, that he would struggle to hear a Chinook throbbing overhead through his 300mm of WarmCel, I liked that the sound of blown cellulose very much.

 

And I do concede that the timber studs that bridge directly through the Earth wool to the PIR will be channels for sound conductance. 

 

However, as well as the PIR in the section above there is 140mm of Earthwool in the walls too. Isn't that like Rockwool, which is used for sound insulation in internal walls? 

 

Moreover, is not the main source of sound ingress into a home that which comes from the windows rather than through the walls? Wouldn't upgrading from double to triple glazing have a bigger impact on sound proofing £-for-£ than spending 30% more on Warmcel in the walls? And wouldn't attention to good airtightness (which I understand has a big impact on quietness too) also make a big difference?

 

I am happy to be contradicted.

Edited January 5, 2019 by Dreadnaught

[Dreadnaught]

13 minutes ago, Thedreamer said:

I've noticed that a few of the PIR manufacturers have suggested that if you tape the boards together you are effectively creating a VCL/airtight layer, prehaps useful on large areas like gable walls, but is this an inferior option compared to using a membrane like Protect VC Foil Ultra.

 

 

Thanks @Thedreamer. Yes having read a little about it, Protect VC Foil Ultra does sound like a good product, assuming of course that it is well installed and not punctured. It has embedded tapes at its edges but the manufacturer recommends it also be taped at the edges and joints (double taping) to ensure even higher levels of airtightness. I have asked MBC if they routinely do this.

Edited January 5, 2019 by Dreadnaught

[Jeremy Harris]

Sounds like a reasonable compromise.

 

I can wholeheartedly echo @Nickfromwales comment about soundproofing.  We are still amazed at how quiet our house is.  It's spooky, in that we cannot hear anyone driving up the drive, even noisy diesel delivery vans, and have to rely on the CCTV motion sensor alarm to let us know someone has driven up.  Nice during the night, though, as the house is completely silent - we don't even hear the noisy ducks/swans/pheasants outside in the morning.

[lizzie]

My house is very quiet and well soundproofed, we hear no external noise.....I do have very good triple glazed windows.