Construction and SAPS

[80BSY]

59 minutes ago, Ian said:

@80BSY

With the new build ones I imagine that your issue with SAP and all electric panel heaters is that it can be very difficult (impossible?) to get a pass score unless you also have some solar panels or other renewables. 

I'm fine with that, just want brick and block walls, and no gas central heating. 

[Mr Punter]

I can't see any issue with brick and block.

 

Does the PV need to be 3 separate systems?

 

How much did they quote to put gas in?

 

If you ever want to sell these individually, I think the PV will complicate it.

[Ian]

11 minutes ago, 80BSY said:

I'm fine with that, just want brick and block walls, and no gas central heating. 

If you can find out what 'U' value you need to achieve for the current timber frame walls then I can easily work out what thickness insulation you'd need with a masonry wall solution.

[80BSY]

1 hour ago, Ian said:

If you can find out what 'U' value you need to achieve for the current timber frame walls then I can easily work out what thickness insulation you'd need with a masonry wall 

The wall value says 0.17w/metre2 per k, if that means anything? 

[Ian]

24 minutes ago, 80BSY said:

The wall value says 0.17w/metre2 per k, if that means anything? 

Assuming the following wall build-up from inside to outside:

15mm wet plaster

100mm medium density blockwork

cavity with full-fill insulation

100mm facing brick

 

You'll need a 200mm cavity fully filled with mineral wool or EPS beads in order to achieve a 'U' value of 0.17.

That gives a total wall thickness of 415mm

 

[80BSY]

39 minutes ago, Ian said:

Assuming the following wall build-up from inside to outside:

15mm wet plaster

100mm medium density blockwork

cavity with full-fill insulation

100mm facing brick

 

You'll need a 200mm cavity fully filled with mineral wool or EPS beads in order to achieve a 'U' value of 0.17.

That gives a total wall thickness of 415mm

 

The architect reckons he's achieved that value with 102mm face brickwork, 50mm cavity filled with 50mm Celetex GA4000, a breather membrain, studs to be filled with 90mm Celatex GA4000, then vcl clad internally with 12.5mm gyproc wall board. Is that likely to be right? 

[ProDave]

19 minutes ago, 80BSY said:

The architect reckons he's achieved that value with 102mm face brickwork, 50mm cavity filled with 50mm Celetex GA4000, a breather membrain, studs to be filled with 90mm Celatex GA4000, then vcl clad internally with 12.5mm gyproc wall board. Is that likely to be right? 

Is that describing a timber frame?  If so you normally have an air cavity between the brick and the timber frame but that says 50mm cel;otex.  That is not a wall make up I recognise.

[Ian]

23 minutes ago, 80BSY said:

The architect reckons he's achieved that value with 102mm face brickwork, 50mm cavity filled with 50mm Celetex GA4000, a breather membrain, studs to be filled with 90mm Celatex GA4000, then vcl clad internally with 12.5mm gyproc wall board. Is that likely to be right? 

Sounds like it would probably be okay although GA4000 is not the correct product for a full-fill cavity. Celotex do a different product for that type of installation (CF5000). Also, I wouldn't normally recommend a 50mm full-fill cavity however Essex is one of few exposure zone 1 low risk areas of the UK where it is acceptable in the Approved Documents of the Building Regs.

The problem with using a solid insulation board like Celotex in a cavity is that the boards are unyielding and won't adapt to the varying shapes of the cavity. As a result, there is a greater risk that the insulation won't perform as well as it should. Although mineral wool is not as efficient thermally it's easier to get a tight fit with it in the cavity.

Edited February 11, 2019 by Ian

[80BSY]

1 minute ago, ProDave said:

Is that describing a timber frame?  If so you normally have an air cavity between the brick and the timber frame but that says 50mm cel;otex.  That is not a wall make up I recognise.

The 50mm cavity between the frame and the brick skin is filled with 50mm of Celotex. 

[ProDave]

1 minute ago, 80BSY said:

The 50mm cavity between the frame and the brick skin is filled with 50mm of Celotex. 

Not a construction method I have seen. It would not be allowed here but as the post above shows it may be okay where you are.

[80BSY]

3 minutes ago, Ian said:

Sounds like it would probably be okay although GA4000 is not the correct product for a full-fill cavity. Celotex do a different product for that type of installation (CF5000). Also, I wouldn't normally recommend a 50mm full-fill cavity however Essex is one of few exposure zone 1 low risk areas of the UK where it is acceptable in the Approved Documents of the Building Regs.

The problem with using a solid insulating insulation board like Celotex in a cavity is that the boards are unyielding and won't adapt to the varying shapes of the cavity. As a result, there is a greater risk that the insulation won't perform as well as it should. Although mineral wool is not as efficient thermally it's easier to get a tight fit with it in the cavity.

I can't see how what he's made that wall up with could possibly have the same values as you have. You're using 50mm more insulation, and a 100mm block in place of a sheet of plasterboard. 

[ProDave]

2 minutes ago, 80BSY said:

I can't see how what he's made that wall up with could possibly have the same values as you have. You're using 50mm more insulation, and a 100mm block in place of a sheet of plasterboard. 

Blown beads is a less good insulator so needs to be thicker, BUT it stands a LOT more chance of being done right and actually working,

 

The big problem with solid boards is detail. It is very easy to cut them a bit under size and have air leakage past the insulation making it very much less effective. Do you really trust the builder to spend the time and care to get it right when your "target" is as cheap as possible?

[80BSY]

24 minutes ago, ProDave said:

Blown beads is a less good insulator so needs to be thicker, BUT it stands a LOT more chance of being done right and actually working,

 

The big problem with solid boards is detail. It is very easy to cut them a bit under size and have air leakage past the insulation making it very much less effective. Do you really trust the builder to spend the time and care to get it right when your "target" is as cheap as possible?

Target isn't as cheap as possible, and yes, the builder I'm now using will make a superb job, especially as I've got a 3 bed high standard bungalow to do afterwards. Would it be safe to assume solid board is twice as insulating as blown beads? Block, 100mm solid board, then brick plinth, and block with render on the outside would be perfect outcome. 

[80BSY]

49 minutes ago, Ian said:

Sounds like it would probably be okay although GA4000 is not the correct product for a full-fill cavity. Celotex do a different product for that type of installation (CF5000). Also, I wouldn't normally recommend a 50mm full-fill cavity however Essex is one of few exposure zone 1 low risk areas of the UK where it is acceptable in the Approved Documents of the Building Regs.

The problem with using a solid insulation board like Celotex in a cavity is that the boards are unyielding and won't adapt to the varying shapes of the cavity. As a result, there is a greater risk that the insulation won't perform as well as it should. Although mineral wool is not as efficient thermally it's easier to get a tight fit with it in the cavity.

Celotex website says GA4000 is correct for timber frame buildings. 

[Declan52]

Cavity boards have a better u value but and it's a big but how they perform in a real world setting will be down to the guy sticking them in the cavity.  If he pushes a bit of motar out into the cavity  laying a block the board can't be tight to the blocks which means it ain't worth Jack.  Same goes at the corners and door and window revels where you're relying on how straight he cuts the boards will have a massive impact on how they perform. 

If you go for beads they drill holes in the wall and blast the beads into the cavity leaving not a single gap any where.  So this means one less thing to worry about. 

[PeterW]

52 minutes ago, 80BSY said:

Celotex website says GA4000 is correct for timber frame buildings. 

 

Correct. However you’re no longer using in a timber frame building at that point, you’re using it as a full fill cavity board which is not it’s purpose 

 

Are these 3 storey or 2..? I would move the 50mm insulation inward, just give yourself a 50mm cavity as @Ian has suggested and then use insulated PB or even clad the inside with 25mm celotex and create a service void. 

 

Also you have to get through the sound tests - there is no “soft” insulation or air gaps in any of this - have you read the Robust Details for this sort of build ..??

[80BSY]

36 minutes ago, PeterW said:

 

Correct. However you’re no longer using in a timber frame building at that point, you’re using it as a full fill cavity board which is not it’s purpose 

 

Are these 3 storey or 2..? I would move the 50mm insulation inward, just give yourself a 50mm cavity as @Ian has suggested and then use insulated PB or even clad the inside with 25mm celotex and create a service void. 

 

Also you have to get through the sound tests - there is no “soft” insulation or air gaps in any of this - have you read the Robust Details for this sort of build ..??

The bit about GA4000 was regarding Ian saying it wasn't the right stuff for the timber frame but Celloxtex saying it was. I've no real idea on any of this, just knew I wanted brick and block, and have now fully established my architect isn't clued up enough to sort things. What you've just said would be ideal, if it'll do the value. 

[PeterW]

25 minutes ago, 80BSY said:

The bit about GA4000 was regarding Ian saying it wasn't the right stuff for the timber frame but Celloxtex saying it was. I've no real idea on any of this, just knew I wanted brick and block, and have now fully established my architect isn't clued up enough to sort things. What you've just said would be ideal, if it'll do the value. 

 

So a real fag packet :

 

12.5mm PB with skim

25mm Celotex

100mm light block

150mm blown EPS

100mm brick

 

0.17 W/m2K

 

12.5mm PB with skim

50mm Celotex

100mm light block

100mm blown EPS

100mm brick

 

0.18 W/m2K

 

Both could be done with either insulation backed PB or battens. 

[80BSY]

11 minutes ago, PeterW said:

 

So a real fag packet :

 

12.5mm PB with skim

25mm Celotex

100mm light block

150mm blown EPS

100mm brick

 

0.17 W/m2K

 

12.5mm PB with skim

50mm Celotex

100mm light block

100mm blown EPS

100mm brick

 

0.18 W/m2K

 

Both could be done with either insulation backed PB or battens. 

Could I go 12.5 PB, 100mm block, 100mm Celotex, or 50mm Celotex, plus 50mm air gap, then the outside blocks? 

[PeterW]

You can go 100mm full fill celotex but you need to bear in mind that you need a specialist version as it isn’t easy to build in. 

 

50mm won’t meet building regs. 

[80BSY]

On 11/02/2019 at 20:41, PeterW said:

You can go 100mm full fill celotex but you need to bear in mind that you need a specialist version as it isn’t easy to build in. 

 

50mm won’t meet building regs. 

 

[80BSY]

Finally it's sorted, brick and block, like I wanted in the first place, that's guys, all conforms. 

I still need the. 75 solar panels as expected, any ideas on what I should be paying, and the best sort of people to use?  

[PeterW]

What is the final build up of the walls then..??

 

And 75 panels ..??!! Is that a typo..??

 

Start with someone like Wagner Renwables or ask @Nickfromwales for his contact. 

[80BSY]

9 minutes ago, PeterW said:

What is the final build up of the walls then..??

 

And 75 panels ..??!! Is that a typo..??

 

Start with someone like Wagner Renwables or ask @Nickfromwales for his contact. 

Brick, full fill celotex, block, just as you said. Yes, should have been 0.75kw.

[PeterW]

Is that per unit ..?? That’s only 3 panels in honest, would be nice if you went the GSE in roof route too as they actually work out nearly as cheap as tiles and look a lot nicer.

 

TBH I would use micro inverters on all of them - one per panel - and then run to each unit and forget about it. Quick, simple and only one isolator in each build.