I need to order some footing blocks, what types?

[epsilonGreedy]

9 minutes ago, Declan52 said:

What depth of insulation and concrete is going on top of the beams.

 

 

Probably 120mm + 75mm with UFH pipes embedded.

[Declan52]

28 minutes ago, epsilonGreedy said:

 

Probably 120mm + 75mm with UFH pipes embedded.

You should be looking at 150mm min pir type insulation.

Been a long time since I used Jeremys heat loss calculator but you should put in 120mm and 150mm in the floor section and see what the difference is and take it from there.

[epsilonGreedy]

On 20/07/2018 at 00:13, Declan52 said:

You should be looking at 150mm min pir type insulation.

Been a long time since I used Jeremys heat loss calculator but you should put in 120mm and 150mm in the floor section and see what the difference is and take it from there.

 

 

Yes I feel the same, think 120mm just scrapes past building regs.

 

I have been delaying doing serious number crunching on SAP calcs.

[Declan52]

You kind of need to know your finished floor height before you start your founds as all your measurements will be based around this. 

Time to get the calculator warmed up.

[epsilonGreedy]

5 hours ago, Declan52 said:

You kind of need to know your finished floor height before you start your founds as all your measurements will be based around this. 

Time to get the calculator warmed up.

 

 

Ok. As a matter of interest why would it not be possible to up the PIR by 30mm to 150mm just before scheduling the screed contractor? Something to do with door thresholds perhaps?

[PeterW]

Door thresholds, ceiling heights, outside doors, the list goes on... 

[epsilonGreedy]

15 minutes ago, PeterW said:

Door thresholds, ceiling heights, outside doors, the list goes on... 

 

 

Right I need to up SAP calcs into next week's todo list. I had assumed that my plan to use aerated blocks for the inner wall coupled with 25mm PIR lined internal walls would give my SAP score such a boost only 120mm under the floor would be just enough.

[epsilonGreedy]

The order for 1300 block was confirmed Friday. Acting on the advice of my part time adviser I suggested a "direct delivery" with the BM when placing the order hence my blocks will arrive direct from the manufacturer at a keen price of £0.79 per block. No bad for my first interaction with a builder's merchant.

[PeterW]

Is that lights or heavys..?

[epsilonGreedy]

23 minutes ago, PeterW said:

Is that lights or heavys..?

 

 

Heavies. 19kg each

[PeterW]

10.4N rather than 7N then ..?

[dpmiller]

5 hours ago, PeterW said:

10.4N rather than 7N then ..?

dunno about that, our 7N are around that weight.

[Declan52]

10 hours ago, epsilonGreedy said:

 

Right I need to up SAP calcs into next week's todo list. I had assumed that my plan to use aerated blocks for the inner wall coupled with 25mm PIR lined internal walls would give my SAP score such a boost only 120mm under the floor would be just enough.

It's not just a matter of putting enough insulation in to make sure your house passes. As you are going for ufh you want as much of that heat coming up into the room. Not much point in going to all this trouble and the worms under your floor think they are living in Florida with the nice toasty b&b floor above them. The longer you have to run the ufh  to get the slab up to temp the more it will cost you in either oil,gas or electric.

You need to figure out this detail so you can tell the brickies that my beams will sit at this height X and my finished floor will be y above this. They can then work out how to get to these heights from the concrete in your founds.

[epsilonGreedy]

9 hours ago, PeterW said:

10.4N rather than 7N then ..?

 

 

They are standard 7.3N.

 

In comparison Stowell 7N blocks are 21Kg.

 

18Kg is typical and I found one example online at 14.5Kg. I guess the weight varies depending on how much recycled material is included. I purchased 6 blocks from Jewson in the week to model the course layup and those included a lot of glass granules.

[epsilonGreedy]

17 minutes ago, Declan52 said:

Not much point in going to all this trouble and the worms under your floor think they are living in Florida with the nice toasty b&b floor above them.

 

 

My longterm concern with UFH has always been that it will be good for worms and bad for my bank balance, so you are talking my language here.

 

However a little reading up on this subject leads me to conclude that passiv house aspirations of many here means that received forum wisdom deviates from industry norms. A builder told me last month that he puts 100mm of PIR his upmarket UFH builds. I will aim for 150mm though 120mm seems ok.

 

This page says that 50mm of reinforced screed is ok and a high performance insulation sheet allows for 75mm. I have a total of 195mm to play with by default so I am not too concerned about all of this. Shaving 30mm off ceiling height is not a concern, internal doors will not be compromised providing my final floor layup is sorted before lintels go on and with m-spec ramps to figure out I am sure 30mm can be accommodated.

[dpmiller]

Poured screeds can go down to around 40mm, 25mm pipe cover.

[Declan52]

Are you restricted on your overall ridge  height??

As it's not even built yet I would bump that 195mm up to 225mm and that will be plenty gd. Come the time you can go with 150mm pir and a 75mm sand cement screed or if the wallet is still flush 175mm pir and a 50mm Flo type screed.

Have you priced up the high performance type boards yet like the kooltherm from Kingspan. They aren't cheap.

[epsilonGreedy]

3 minutes ago, Declan52 said:

Are you restricted on your overall ridge  height??

As it's not even built yet I would bump that 195mm up to 225mm and that will be plenty gd. Come the time you can go with 150mm pir and a 75mm sand cement screed or if the wallet is still flush 175mm pir and a 50mm Flo type screed.

Have you priced up the high performance type boards yet like the kooltherm from Kingspan. They aren't cheap.

 

Yes ridge height is limited. So far in my design we have got away with regular roof trusses coupled with 2.4m and 2.38 ceiling heights. My neighbour has gone for raised joists in his roof trusses.

 

My budget for floor insulation was based on some threads here about where to source this stuff at a keen price, so probably not hi-performance stuff.

 

Re. flow screed... everyone in the local area assumes this is what I will be doing even though on all other matters conservative traditional building techniques rule.

[Declan52]

With regards to flow type screed make sure you do your research here as some need a lot of work afterwards to get tiles etc to stick to them. They do heat up quicker than sand cement but they will also cool down quicker as they aren't as thick.

My sand cement screed is 75mm thick and takes around 90 mins before you can feel heat on your feet but it will stay warm for maybe 2 hrs after the stats have stopped calling for heat. Plus being sand cement there aren't any issues getting tile or wooden flooring to stick to it.

 

[PeterW]

2 hours ago, epsilonGreedy said:

A builder told me last month that he puts 100mm of PIR his upmarket UFH builds.

 

That doesn’t meet Building Regulations so if he is, he’s a cowboy. To meet the 0.11 elemental value you then you need 140mm of PIR. 

 

I suggest a bedtime reading of the Building Regulations may enlighten on a few points. 

 

 

[epsilonGreedy]

19 hours ago, PeterW said:

 

That doesn’t meet Building Regulations so if he is, he’s a cowboy. To meet the 0.11 elemental value you then you need 140mm of PIR. 

 

I suggest a bedtime reading of the Building Regulations may enlighten on a few points. 

 

 

Where does your 0.11 U for a floor come from, a Kingspan advert perhaps? 

 

Part-L building regs quote max allowable u-values (limiting fabric parameters) for building elements and another set of more demanding figures for ideal "notional" model u-values.

 

A house may have a floor u-value of 0.30 if it otherwise meets a total energy performance target. The notional target u-value for a floor is 0.13.

 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/540326/BR_PDF_AD__L1A__2013_with_2016_amendments.pdf

[PeterW]

 

Does your local builder add 55mm of additional internal PIR wall insulation to his “top end” builds too to make sure his 100mm floor insulation is sufficient to meet the overall DER/TER..?

 

Happy to have the debate. I’d suggest a light read of SAP 2012 (Appendix R may be useful) and then run your build through with 0.30 as the floor numbers and see where the DER comes out. 

 

What you will quickly realise is the floor and roof losses in SAP will dwarf any of your other losses so unless you get to below 0.13 and preferably 0.11 for floor, your chances of hitting the DER will be nil without 480mm of conventional insulation in the attic, or 200mm rigid with 40mm overlay at roof level. (The next largest loss in a building fabic exc windows.)

 

Given the massive cost and complexity of this, adding an additional 40mm below the floor seems a no brainier to me...?? 

 

 

[ADLIan]

A ground floor U-value of 0.3 W/m²K would give an automatic fail under the English Regs - must be 0.25 W/m²K or less, area weighted average.

 

100mm PUR probably gives better than U=0.2 in a typical floor, perhaps closer to U=0.16. This can easily be offset elsewhere in the construction.

 

Note the DER/TER requirement can still be easily met depending upon fuel, heating system - air source heat pump, addition of solar PV etc helping reduce CO₂ emissions. High individual U-values will impact on the DFEE/TFEE however and will be more difficult to resolve.

[epsilonGreedy]

10 minutes ago, ADLIan said:

A ground floor U-value of 0.3 W/m²K would give an automatic fail under the English Regs - must be 0.25 W/m²K or less, area weighted average.

 

 

Why would the government's own official building regs standard quote a limit if this would lead to an automatic fail? The standards docs says a significant better figure is likely required to achieve overall conformance.

 

We have been discussing 100mm as a minimum which delivers about 0.16, hence the builder in question cannot be damned as a cowboy.

 

My default 120mm delivers 0.14 and 140mm bumps this up to 0.13.

 

If my walls are comprised of full cavity beads, aerated blocks and 25mm of PIR lining the inner block wall my guess is that I will meet thermal requirements. Anyhow it is time to prove this mathematically with the @JSHarris spreadsheet.

 

[PeterW]

Where is your DER/DFEE that was submitted as part of your building regs submission ..?? That is your starting point. 

 

And I stick by what I said - high end UFH and 100mm PIR do not equal quality build. On Saturday I did a pre-plaster inspection for a house that is circa £825k when complete - it has UFH too - and I’ve done a list of about 40 items to be rectified before it’s closed up. I will need to go back and check them before it’s finished however I’ve got a good relationship with the site manager now who understands I’m picking up on detail that their client expects on a major project such as this. 

 

The house has been inspected by a major warranty provider and BRegs supplier and has been passed however none of what I have picked up would be classed as not meeting the Approved Documents. Getting a decent air test result with 2 blocks missing in a wall into an integral garage could be fun though ... devil is in the detail ..!