Yours truly is very annoyed.

[MikeSharp01]

After 4-5 weeks of cajoling our BC provider has final got back to us, for the second time with many of the same issues from the first time, despite me pointing out that they had all the answers, bar one on day 1. One is wondering if they read the stuff you send them. Here is what our BC wrote.

"I have check through this package of drawings, and we still seem to be missing the following details.

 

1.    Please provide details of the fire resistance to external walls within 1.0m of the boundary. This should be in terms of its minutes of fire resistance from inside and outside.

2.    Please provide design specification for the proposed MVHR ventilation system. We have a layout but need the design details.

3.    Please confirm the provision of network access to the new dwellings.

4.    Please provide design details for the proposed staircase, and guarding to low level glazing.

5.    As an extra item I picked up, please can you confirm that Bedroom 3 will have an escape window as it is an inner room."

 Here are the portions of our documentation that applies, and I admit that I assumed that when you gave BC a fire rated class EG AA they could work out that it is 1 hour, and that is just the outer cladding.

 

1. The architects drawings, see above, refer to details under these headings as do the structural drawings and calculations in terms of charring.

External walls within 1000mm of a boundary. The external walls are clad with fire cement tiles in line with the architects specification the tile specification will be as Marley Thrutone and these are rated CLASS 0 as is required within 1000mm of a boundary. Details can be found in the properties and performance page of THIS (hyper link) document from Marley.

 

2. To comply with BR Part F1 Section 5 A whole house MVHR system will be installed to provide ventilation in excess of the minimum required. Flow rates will be verified during commissioning of the MVHR system. Details of pipe runs and locations of Plenums are shown on the architect’s drawings but may alter slightly as the build progresses alongside the development of MVHR technology in the wider sphere. All the Extracts from WC, Bath rooms and Kitchen area will be sized to exceed the requirements of Part F Section 5 – Table 5.1a and whole dwelling ventilation Part F Section 5 – Table 5.1b against the 3 bedroom dwelling criteria.  The Kitchen Cooker hood will be a carbon filtered recalculating unit. In addition to the MVHR system and to support summer cooling a passive stack circulation system has been designed into the build using the electrically controlled high level opening roof lights. - AND IN THE SAP CALCULATIONS SECTION - (Full MVHR System – unit TBA, but probably the Airflow Adroit DV145  but Efficiency of at least 90%)

 

3. The building is connected to the main telephone and ADSL network via the utilities building, adjacent to the telegraph / power pole in the front garden, and is then ducted into the main house from the utilities building.

 

4. A final design for the stair case is not yet complete but it will be so designed as to meet the requirements of BR Part K. (I admit I did not specify guarding of low level glazing but the architects specification refers to toughened glass everywhere.)

 

5. Means of Escape: All habitable stairs connect directly to the main entrance area and external doorway. Both first floor bedrooms will have clear openings that meet the acceptable dimensions in BR Part B section 2.8. The ground floor bedroom (Bedroom 3) will also have a clear opening that meets the acceptable dimensions in BR Part B section 2.8.

 

What have I got wrong?

 

I could tighten up 1 and work out the delay times both ways and that I will do. Do they want air flows, volumes etc for all the rooms and spaces in 2. Not sure I can be clearer in 3 (The drawings do show the duct). 4. Seems acceptable to me but maybe I have to complete the design before they will sign off the plans. 5. I don't think I could be clearer.

 

Calm me down someone or tell me I am wrong, in which case I will open my second beer and do it all again.

 

 

 

[Ferdinand]

Oooer. 

 

I think I am keeping clear until after your 4th beer.

 

(But it looks OK to me. Friday problem at Building Control?)

 

It happens I just submitted representations against a planning appeal - deadline is midnight today.

 

If you want a good night's sleep I can send you my document to read.

 

F

[ToughButterCup]

Most people do not read. Especially on a computer screen

 

They skim,         pause,         read,          skim on. STOP at KEY words.      Then      think and     possibly    respond.

 

Look at the dense text you present above. You know it inside out and backwards The reader doesn't, and probably doesn't care either.

Your message is a high-stakes one.   Sent to someone who  doesn't  give a toss. She has 55 others to read before having a nasty commute home. 

 

If it's a high-stakes message, make it visually easy for people to access your message.

 

Thus

 

1. The architects drawings (above),

 refer to details under these headings as do the structural drawings and calculations in terms of charring.

• External walls within 1000mm of a boundary.  and are
• clad with fire cement tiles  and are
• in line with the architects specification
• the tile specification will be as Marley Thrutone and  are
• rated CLASS 0 as is required within 1000mm of a boundary.  
• Details  here.

There are loads of other visual tricks to apply. Here's an online resources which, with a few tweaks, will help

 

Make it easily legible to  a tired, pissed off,     distracted        idiot. Make it easy for a local Donald Trump to read. 

[Ferdinand]

Agree with RA approach.

 

But I might do a short and blunt summary first.

Edited March 17, 2018 by Ferdinand

[ToughButterCup]

12 minutes ago, Ferdinand said:

Agree with RA approach.

 

But I might do a short and blunt summary first.

 

Excellent idea.!

[MikeSharp01]

Thanks all. I am in the process of highlighting the answers and will.send him just the answers but referrng to where in the main portfolio it came from. 

[Temp]

I know it's a pain but I don't think you have answered their questions with the detail they expect...

 

1) Your response to refers them to other drawings and hyperlinks which probably has the info but heck I would just tell them how many "minutes of fire resistance" the design provides as well a providing the references.

 

2) You are effectively  saying "it will meet or exceed Building Regs". Where as they appear to want projected flow rates so they can check it will meet building Regs.

 

3) They want you to show how you will meet Part R. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/517789/BR__PDF_AD__R__2016.pdf 

I think you need to tell them that the duct and cable between the "service providers access point" and the "occupiers network termination point" will be Cat ?? Cable supporting upto ?? Mb/s which is "well in excess of the 30 Mbps required of Approved Document R requirement R1".  Part R also says developers should refers to PAS 2016 which has info on duct dimensions

 

more in a moment.

 

 

 

 

 

[Temp]

4) Tell them you will send the stair details when you have them. Sorry if you know this but guarding is not  just about toughened glass it's about stopping you falling if the glass breaks.

 

5)

13 hours ago, MikeSharp01 said:

5.    As an extra item I picked up, please can you confirm that Bedroom 3 will have an escape window as it is an inner room."

 

Have they just made a mistake or does it have a window? If possible echo their words... "I can confirm bedroom 3 will have an escape windows with a clear opening width of ?? which is in excess of that required by Part B"

[MikeSharp01]

Thanks @Temp I will take your advice and increase the detail. Most of which I have anyway in the PHPP for the flowrates etc.

 

The fire resistance is a bit tougher as I cannot find any mathematical models for our wall construction. The outer surface is class 0 so gives 1 hour I believe then there is an air gap then 40mm of PUR then 15mm of OSB then 300mm of glass wool insulation in between I joist uprights then the air tight membrane then a service void then 12.5mm of plasterboard. So going out to in is at least 1 hour unless radiated heat from the inside of the cladding ignites the PUR. Going in to out think the PB only gives 15 minutes but to get to the outside you have a long way to go before you hit the backs of the class 0 cladding which is a further hour but by then the structure is all gone. I need to do a lot more reading or just put two layers of firestop PB on the inside which gives me 45 minutes, before you get into the structure, I think but is so much more expensive.

[PeterW]

From memory you only need 1hr from the outside and skimmed PB is 30min anyway. 

 

You don’t need to make it all 1hr or you couldn’t have timber in it ...

[Mr Punter]

Just confirm to them that the wall is 30 mins fire resisting from both sides.

 

Regarding MVHR tell them the min flow rates for the rooms and the dwelling from the regs.  It is not always good just to say "exceeds the regs" best to say "kitchen min 13 l/s" etc.  You don't need to tie yourself to a manufacturer as long as what you fit meets what you specified.

[ADLIan]

Surface spread of flame (Class 0 etc) is a different part of BS 476 than the fire resistance tests. A Class 0 facing material does not automatically give 30min or 60min resistance (PUR insulation can be Class 0 and look at Grenfell). For external walls normally 60min resistance is required from BOTH sides. It appears that I-joists are being used and this may be the issue as they are only as strong as the relatively thin web in the BS 476 fire resistance test and this may be ringing alarm bells with your BCO. Perhaps have a chat with the I-joist manufacturer as there is no mathematical modelling here, reliance is made on actual test results.

[MikeSharp01]

31 minutes ago, ADLIan said:

Surface spread of flame (Class 0 etc) is a different part of BS 476 than the fire resistance tests. A Class 0 facing material does not automatically give 30min or 60min resistance (PUR insulation can be Class 0 and look at Grenfell). For external walls normally 60min resistance is required from BOTH sides. It appears that I-joists are being used and this may be the issue as they are only as strong as the relatively thin web in the BS 476 fire resistance test and this may be ringing alarm bells with your BCO. Perhaps have a chat with the I-joist manufacturer as there is no mathematical modelling here, reliance is made on actual test results.

Thanks, that is is an interesting perspective and maybe what they are driving at. I will see what finnjoist have to say!

 

@PeterW we are not skimming the PB, dry lined so I guess it will all be down to thicknesses of Fireproof PB.

 

[MikeSharp01]

OK people and thanks all ( @ADLIan@Mr Punter@PeterW@Temp@Ferdinand )  I may have found the answer to the fire resistance in the Finn joist literature. It says for 60 minutes, Horizontal plane (As in an internal floor) you need (bottom up) 2 x 12.5mm of fireline board then the joists (insulation is optional so takes no part in the first resistance) then 18mm OSB on the outside, we have a vertical wall,  15mm OSB covered in 40mm of PUR then the gap then the cladding. So we have lost just 3mm of OSB but gained a whole lot more on the way in and out including what should be increased fire insulation both ways because of the PUR. So I am hopeful that this will convince them. (I do not want to go to 18mm OSB as it is so heavy.) Looking at the british Gypsum White book it says 2x12.5mm Fireline as well. So I guess I just need to adjust the drawings to show fireline 12.5 x 2.

[MikeSharp01]

Here is my first response on the MVHR - part F stuff, I have tidied up the spreadsheet I used for my initial spec design to include all I can see as relevant from part F. Any comments greatly appreciated - I hope I have not tied myself down too much?

 

SSP090 - Systems calculations.pdf

[ADLIan]

Hi Mike. Don’t want to rain on your parade but I’m not sure the fire resistance value for the floor can simply be extended to cover the wall too. Also from memory the white book gives solutions for one hour fire resistance based on solid timber studs plus plasterboard - note different stud sizes for 30min & 60min.

[MikeSharp01]

Yes I saw that but decided that a horozontal fire boundary was having to work harder than a vertical one given the thermodynamics of fire.  The l- joist wall is a pretty standard thing so there must be info out there I just need to find it. Or create a test panel and get it tested (not). If there are no mathematical models one wonders how we got this far without them. 

[MikeSharp01]

Hey I found this which sets out the euro codes (must still apply one guesses) and this uses the additive method, page 108 ish,  Maybe the maths is out there. https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://eurocodes.jrc.ec.europa.eu/d oc/2012_11_WS_fire/presentations/08-FRANGI-EC-FireDesign-WS.pdf&ved=2ahUKEwipkMqb5vPZAhXMCsAKHcZZDZIQFjABegQICRAB&usg=AOvVaw0bpNVlmIHXRbz0b4H8haOV 

[Mr Punter]

I think you only need 30 mins fire resistance, so a layer of p/board is fine.  No calcs or maths needed.

[MikeSharp01]

On 17/03/2018 at 16:58, Mr Punter said:

I think you only need 30 mins fire resistance, so a layer of p/board is fine.  No calcs or maths needed.

You are broadly correct but I chose to do the MATHS anyway so I could be happy with my outcomes. Essentially the component additive model in EUROCODE 5 is not that difficult but it does lack a load of tested materials, fortunately type F and A PB, OSB, I-Joists and Rock Wool insulation all have values to plug into the various equations.  Going outside in the outer tiles, Fibre Cement and the PIR insulation don't have values although they are both class 0. So when the fire does get through the tiles it will have to fight the PIR for the next 40mm. Again fortunately I eventually found what the AA stands for in AA (National Class) or Broof(t4) (European Class) which the tiles have in addition to class 0 as referenced in table A5 of part B means - you can read it here essentially AA means. First A = Those specimens which have not been penetrated within 1 hour. (so 60 glorious minutes), while the second A = Those specimens on which there is no spread of flame.

 

Going from inside out is a bit tougher but as we have a service void behind the PB there is no mechanical transmission into the wall fabric, other than at the battens. As part of the Fire safety in timber buildings Technical guideline for Europe 2010 the structures like ours, with I-joist have been traceably tested and an equation is available for just the outer layer and that, type F PB at 12.5mm meets the requirement on its own. Working through the other layers, for which I have all the component values as far as the outer OSB sheath I get about 50 minutes but by this time the structure will be gone so no point in trying to work out the PIR, v-battens & tile battens and the tiles as they won't be standing up by then! So I have put all this into my document but as headlines just said that both ways the walls within 1000mm of the boundary meets the 30 minute requirement. Will will see if it is enough.

 

Thanks everybody for your help.

 

 

[TerryE]

Mike, what I find crazy about this is that you get this 20/20 drill down into all sorts of fine detail about your build -- where I am absolutely sure that in reality you are conforming to the spirit of the BReg and far more on the letter than any typical major constructors dwelling build (you are after all putting your lives at stake in getting this right) -- yet we can refurbish tower block like Grenfell and have copper gas mains without any fire protect in safety corridors where the live of 100s of occupants depended  on their integrity, where their claddings were death waiting to happen. Yet all unchecked.   Where is the sense of proportionality?

 

 

[Triassic]

I’ve also had the same problem,,sent BC a huge wodge of document, yet he asks questions covered by the documents.

 

maybe you should reply to each question with a separate short email. Maybe then he’ll read it , tick the appropriate box and move on.

[MikeSharp01]

8 hours ago, TerryE said:

Where is the sense of proportionality?

I suspect it comes down to a perceived trust between the BCO of the Grenfell works and the contractor, the BCO thinks they know what they are doing so we can largely leave them alone. Meanwhile in my build, which happens to follow the Grenfell tower disaster, the BCO does not know me form Adam and the construction has some elements of Grenfell - eg air gap behind the gladding and the PIR (no aluminium sandwich). This means they want all the Ts crossed and I's dotted. The annoyance for me was the lack of reading the original document which had most of the answers. Only the Fire resistance, and to some extent the MVHR, was not covered in that document. We will wait and see today.

[TerryE]

15 hours ago, MikeSharp01 said:

the BCO thinks they know what they are doing so we can largely leave them alone

 

Mike, I think that you are excusing corporate or systemic incompetence.  Issues of trust and risk need to be tempered by an assessment of the consequences.  You are getting hosed about 30 min fire risk in a single dwelling, one in which the self builder is proposing to live in and as nod says 12mm plasterboard + a skin will give more than that in most circumstances.  Grenfell Tower had 120 flats.  The 71 confirmed deaths and the total number TBD had a single exit route which had unprotected gas pipes running along it.

 

I am not blaming the individual LA BCOs because I do think that they have a thankless job, but I am challenging the systemic environment and management policies which -- in my view at least -- mean that they can't put their focus where society needs them to and instead have to vent their frustrations on individual self-builders. 

[MikeSharp01]

7 hours ago, TerryE said:

I think that you are excusing corporate or systemic incompetence

Sorry Terry, slopy language on my part, my "the BCO thinks they know what they are doing so we can largely leave them alone " is a symptom of the problem and I agree leads to the systemic incompetence. you describe. It is indeed wholly unacceptable and has so many consequences across all aspects of our housing stock.