Realistic U-values of brick & block?

[bgmill]

We're about to receive planning permission and move to detailed design stage so the all-important build method needs to be decided imminently.

 

Now, having lived in TF houses previously we had decided early on that we didn't want to build one. We have 3 noisy kids and sound travels far too easily in timber houses for our sensitive ears, slamming doors rattle windows in adjoining rooms etc. For this reason we were originally planning on going with ICF. Unfortunately, we can't find any contractors locally that have enough experience in ICF and we also don't want to be the guinea pig build where they make all their mistakes.

 

So we're now looking back to traditional brick/block with a large cavity (blown bead fill) and wet render on the inside. We'll couple this with a SIPs roof as we have vaulted ceilings upstairs.

 

My question is: what's a real-world u-value we could expect to achieve going this route? and, what could/should we specify to improve things?

 

We're not on mains gas and don't want an oil burner (which we have in our existing bungalow) so have specified ASHP with MVHR in the planning application. Would this still be viable given the lower u-values of a B&B build?

[nod]

We’ve built in Block and Block x render 

and intend to do the same again 

Partly cost and as you say TF are quite noisy 

Im not sure what our u values are as we upgraded the insulation and fixed insulated plasterboard to all exterior wall

But I can say it’s the warmest house I’ve ever lived in and cheaper to heat than our previous mass produced home That was just over half the size 

[joe90]

24 minutes ago, bgmill said:

given the lower u-values of a B&B build?

well that depends on your cavity size, windows and doors etc, not just that’s it’s B@B. I don’t know what my U value is but I built ours this way with 200mm cavity with rockwall batts . We have a small 5kW ASHP and the heating is rarely on. The only thing I would have done differently due to noise is ceiling sound insulation, I don’t have noisy kids but I am disappointed with noise transmission between floors, I wish I had used doubled boards and sound bars.

[SteamyTea]

1 hour ago, bgmill said:

My question is: what's a real-world u-value we could expect to achieve going this route? and, what could/should we specify to improve things

Look up the R-Values and calculate.

 

You can always build a timber frame place inside it, that will stop the noise getting out.

(Your noise issues are build quality/design, not an inherent problem with timber frame.  Most of your floors are going to be timber, unless you are going for poured concrete.

Edited July 18, 2021 by SteamyTea

[CalvinHobbes]

44 minutes ago, joe90 said:

well that depends on your cavity size, windows and doors etc, not just that’s it’s B@B. I don’t know what my U value is but I built ours this way with 200mm cavity with rockwall batts . We have a small 5kW ASHP and the heating is rarely on. The only thing I would have done differently due to noise is ceiling sound insulation, I don’t have noisy kids but I am disappointed with noise transmission between floors, I wish I had used doubled boards and sound bars.

We were hoping to build with blocks and use concrete slabs for the floors upstairs with a concrete staircase, all to cut down noise. Saw another thread re 10mm door space under door tosuit Mvhr confounding sound proofing.

[tonyshouse]

300mm cavity for me but I start with a target U-value of 0.1 

[SteamyTea]

3 minutes ago, tonyshouse said:

300mm cavity for me but I start with a target U-value of 0.1 

Much easier knowing where you want to end up than trying to find materials that get you there.

[Mr Punter]

5 hours ago, bgmill said:

My question is: what's a real-world u-value we could expect to achieve going this route? and, what could/should we specify to improve things?

 

You will need to do some maths here to find the sweet spot between internal area, cost of footings, cost of wall ties and cost of insulation.

 

A 150mm cavity gets a passable u value with platinum blown beads.

 

Use thermally broken cills and lintels.

 

Use Marmox or Foamglas course at the base of the internal blockwork.

[joe90]

1 minute ago, Mr Punter said:

Use Marmox or Foamglas course at the base of the internal blockwork.

Or do the founds like I did…..

[Mr Punter]

1 minute ago, joe90 said:

Or do the founds like I did…..

 

Were those basalt wall ties expensive?

[tonyshouse]

Yes, but in the great scheme of things it pales into insignificance 

[Declan52]

It's not just about ticking a box with 150/200mm insulation in the cavity and you will have a toasty house. Lol You have to adopt a whole house policy. High quality Windows and doors, triple glazed of the budget allows, good depth of insulation in the floor and roof, very good airtightness throughout etc. 

I've a block house and my kids still move around like hippos and slam doors. After years of in depth research the final conclusion I have reached to stopping them slamming doors is to remove the door. 

[Oz07]

It's ok making your house airtight but how many times do you shut a door and it slams because the Windows open. Happening to me regularly atm. You get used to the room having a certain amount of vaccum then SLAM

[joe90]

1 hour ago, Mr Punter said:

Were those basalt wall ties expensive?

I didn’t use them, losses through ordinary ties are minimal.