Please can you check Newbies wall construction?

[Warrentdo]

Hello, Part 2, now the walls.

 

102.5 Brick

150 cavity

100 insulation Eco cavity partial fill (Cavity) 0.022 W/mK

100mm Block 0.11 W/mK or 0.15 W/mK

 

0.11 W/mK  block should give me 0.15 W/mK

0.15 W/mK block should give me 0.16 W/mK

 

Does anyone have any recommendation on the block and if its worth it i.e. losing the ability to fix things to it.

I'm also getting different thermal efficiencies with every online calculator I use.

 

Regards

 

Warren

[Iceverge]

5 hours ago, Warrentdo said:

100 insulation Eco cavity partial fill (Cavity) 0.022 W/mK

 

Please don't. EPS beads or mineral wool batts everytime. 

 

Use normal medium density blocks and widen the cavity for better U values. If you can play with the numbers yourself you can see how useless lightweights

 blocks are as insulation. 

 

The difference between 0.15-0.16w/m2k is almost imperceptible and anyway it's unrealistic. Above 0.18 was the best I could make from your above materials. 

 

[Warrentdo]

DPC is already in so im afraid im stuck with a 150 cavity!

I have found Kingspan 108 (0.019 W/mK) if that helps?

 

102.5 Brick

150 cavity

100 Kingspan 108 (0.019 W/mK)

100mm Block 0.15 W/mK

 

I've also seen that people have used a 10mm residual cavity. i.e. 100 cavity, 90mm insulation leaving a 10mm gap?

I have already got a 150 cavity so could I stuff more than the noted 100mm in it?

What could I do with what I've got?

 

Regards,

 

Warren.

[crispy_wafer]

34 minutes ago, Warrentdo said:

What could I do with what I've got?

full fill with beads or full fill with mineral wool, may even cost less than PIR as well

 

Also, get onto U-value calculator | ubakus.com and have a play

Edited October 26, 2022 by crispy_wafer
adding Ubakus

[Moonshine]

This was my build up which gave a u-value of 0.18

 

 

if you have a brick outer leaf you would get 0.19, but you have to be very careful using brick will a fully filled cavity due to wind driven rain penetration (you will need to have advice on this)

 

 

there are products that allow / certified for a 10mm residual cavity (e.g. Kooltherm K106) but the max thickness of this product is 115mm.

 

This is calculated to give a indicated U value of 0.14

 

[Moonshine]

3 minutes ago, crispy_wafer said:

full fill with mineral wool

yes but but caution to use with brick faced walls due to wind driven rain.

[crispy_wafer]

2 minutes ago, Moonshine said:

yes but but caution to use with brick faced walls due to wind driven rain.

Yes, true, speak to BC.

[Warrentdo]

Thank you for that link! superb.

So it looks like I can get 0.174W/mK.  ive had to use Ytong (0.16 W/mK) instead of celcon standard 0.15 W/mK 7kg

 

Also the K108 i want (0.019 W/mK)  is better than the K8 listed (0.021 W/mK)

Any more for anymore? I'm I ok to order?

Regards

Warren.

 

[Iceverge]

Insulation boards in a cavity wall are bad news. 

 

The theoretical perform is almost impossible to achieve. Mortar droppings will get on the joints of the boards. Wall ties will not line up properly the boards will not sit flat against the inner leaf due to the nature of blockwork. All these gaps mean that on a windy day the wind will blow freely through the gaps. Your insulation is then doing little more than it would if it was thrown in the garden. Thermal bypass/thermal looping are some names for it.

 

The only realistic procedure I can see for board in a wall is to build the inner leaf first. Use properly aged boards that won't shrink. Foam and fix boards individually to the inner leaf as per an EWI job. Ensuring all the gaps around wall ties and between boards are filled with a good age proof expanding foam trim back the excess and tape with foil backed tape to cover every gap. You'll need to tape the edges of the board's too if you're using foil faced boards like PIR or pheonlic (kingspan) to prevent gas migration or the performance of the board will decrease with time. 

 

Your bricklayer will hit you on the head with a breeze block of you ask him to do all this. 

 

Insulation manufacturers are shysters and snake oil salesmen. Before you buy the kooltherm consider that it is 3 times the price (pre install) of EPS beads for the same U value installed and will perform worse in real life. 

 

The last few 0.01 W/m2K of a wall U value makes almost no difference anyway compared to airtightness and ventilation losses. 

 

EPS beads/mineral wool batts, real world U value of 0.21 and forget the boards is my advice.  Medium density blocks internally, wet plaster and you'll have a very cheap and high performing wall. 

 

 

 

 

 

 

 

 

[joe90]

7 hours ago, Moonshine said:

yes but but caution to use with brick faced walls due to wind driven rain.

Well I have full fill with rockwall batts and a brick face, the insulation has a BBA certificate fir full fill. The west face gets very wet and the bricks were saturated but when core  drilling for the ASHP although the inner face of the outside bricks were wet it had not gone into the insulation. As a precaution I coated that wall with sealer and now the water runs of it like glass. 

[joe90]

20 minutes ago, Iceverge said:

mineral wool batts, real world U value of 0.21 and forget the boards is my advice.  Medium density blocks internally, wet plaster and you'll have a very cheap and high performing wall. 

 

+1 (it’s what I did)