Emergency Insulation question

DLBuild

Sinnerboy, Is the structural screen between the slabs and the insulation a must? What purpose does this serve?

sinnerboy

the structural screed ties the precast floor slabs together - so you end up with a floor-plate , not a collection of independent slabs .

Mellor

It also allows you to use thinner slabs, of course the fact that you use a screed returns this. I wouldn't say its essential, we have used precast wideslab units that where larger and more solid than hollowcore slabs, in there a structural screed was not needed

DLBuild

I've got 200mm pre stressed hollow core slabs on order. I believe these are quite strong i.e. no need for acros etc. Would i be correct to assume that I don't need a screed for structural reasons on these?

ircoha

DLBuild wrote: »

I've got 200mm pre stressed hollow core slabs on order. I believe these are quite strong i.e. no need for acros etc. Would i be correct to assume that I don't need a screed for structural reasons on these?

This is an IMPORTANT issue for ur designer as it is a function of the span, what loads are applied from above etc.
DONT assume in this case please:(

DLBuild

Okay yeah, I should have added that the company providing the slabs have specified the depth of slab etc based on my plans. I will ask a few questions but would be relatively confident things are done correctly.

ircoha

DLBuild wrote: »

Okay yeah, I should have added that the company providing the slabs have specified the depth of slab etc based on my plans. I will ask a few questions but would be relatively confident things are done correctly.

Thanks, u need to be certain, also re acrows
In relation to the use of acrows, u need to consider the possibility of a load of concrete blocks being places on the floor by a transporter etc during construction.

I have many many years experince in the pcast business and you cant be too careful

sinnerboy

DLBuild wrote: »

Okay yeah, I should have added that the company providing the slabs have specified the depth of slab etc based on my plans. I will ask a few questions but would be relatively confident things are done correctly.

based on what ? are you going to live under these things ? or just some poor unfortunate tenants ?

Here's a novel idea - hire professional advice . Posting queries here on this ( or any thing else ) is a very very poor substitute

marielle

sydthebeat wrote: »

have you no professional engaged to inspect or supervise this build?

Firstly, he should not have incorporated 60mm polystyrene into the walls. That hasnt been acceptable for 5 years now. Its a good job you demanded 50mm insulated plasterboard, this may bring you up to minimum regulations. A quick calculation of 60 EPS and 47.5mm insulated plasterboard in a trad cavity wall gives a u value of 0.26.. .thats just below the min of 0.27....
not exactly optimal when you are installing air to water HP and UFH.

The HRV system is a must.

I completely agree with sinnerboy re multifoils, they are unprovable as an insulator... and they are an expensive vapour check membrane.

I wouldnt bother insulating the ceiling downstairs since there is no insulation below the screen on the first floor.

You need to give more info as to the exact make up of the ground floor construction.


But most important to guarantee the best performance at this stage is to hire a competent professional to inspect this 'old school' guys work......

ok, I went and tried to calculate a U value figure for my walls and here is what I came up with. Can anyone tell me if I'm missing something here?
I am adding the thermal resistance of all the elements that make up my wall. From the outside :
Thermal resistance or R for the outside wall : 0.06
R for 100mm concrete block wall = 0.09
R for the cavity = 0.18
R for 65mm Pearl expanded polystyrene cavity insulation = 2.096
R for 100mm concrete block wall= 0.09
R for 38mm PU insulation = 1.52
R for 12.5mm plasterboard = 0.078
R for inside surface = 0.12
This gives me a total Resistance for the wall of 4.234 and therefore a u-value of 0.236.
Am i correct? And if so, isn't that well below the 0.27? Is this considered good or not?

ardara1

Hi Marielle -
Your internal resistance should be 0.13
external - 0.04

I make it 0.24 - if the PU is directly to the wall - if on dabs or battens, you've another (bridged) cavity to include.

sinnerboy

Marrielle u value is ok - meets min regs for walls . ( you need to adjust your calcs a little to take account of wall ties and board fixings , but this is not the point )

this ain't enough

Air to water heat pump ( ATW HP ) will struggle with our varying air temps and relative humidity . you shouldn't go cold but I would not care for your ESB bills . The better you insulate the better you offset this reality .

the quick response UFH method for your conc first floor - I wouldn't use because you will make the ATW HP runtime into daytime - you won't run on night rate ESB .

I say again - you are better to install low temp rads upstairs . Or use thick screed .

Get a BER assement NOW . You have to assess

U values
Ventilation
air tightness ( hope you got in touch with company I pm'd )
Heating method

In combination to calculate energy demand / c02 emmisions
You will see actual indications , not general , like forum posts have to be .

And the day will come when you literally legally will HAVE TO get a BER assesment that is - when you sell ( or possibly even when re mortgage ) or let the place So get the most out of a process you will have to undertake anyhow .

bauderline

What should we be aiming for wall wise 0.15 - 0.19 ?

b.

sydthebeat

bauderline wrote: »

What should we be aiming for wall wise 0.15 - 0.19 ?

b.

you should aim for what is practically possible, budget allowing.
theres a huge difference between 0.15 and 0.19.

ircoha

bauderline wrote: »

What should we be aiming for wall wise 0.15 - 0.19 ?

b.

Just checking, u sure u mean 0.15 for a wall: a savage requirement if I may say so.

See page 69/70 of http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,16557,en.pdf

for current part L in Ireland.

sinnerboy

a better start point is

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,15662,en.pdf

9 different residential unit types .

1st 2 pages show what may be done to meet , Part L regs 2005

2nd 2 pages show what may be done to meet Part L regs 2007

find unit which is closest match to your building - note u values .... they often exceed min u values in TGD L

to repeat - compliance is mix of

u values
ventilation
heat source
air tightness
build quality

difficult ( I say impossible actually ) to achieve by self builder without professional help .

you will pay up front once ..... or indefinately later ( oil just past 100 dollar / barrell and rising .......)

sinnerboy

bauderline wrote: »

What should we be aiming for wall wise 0.15 - 0.19 ?

b.

I would guess 0.2 would be optimum .... but over long term better u value is better € value

blackiebest

what about windows?? I hope to build to .15 U for walls using regular 4" on the flat with 200mm outsulation (cellulose) but the big question is always the windows, especially as they often are 30% wall space, they will always be the weakest element, no matter how much you spend. Very good is 1.4 U overall unit however 1U is possible. Less than that is really marketing blurb when safety glass etc is taken into consideration. But people bang on about U's in walls floors roofs etc... the weakest by far are the windows, I know as I am in the window business:) By sure to buy well. Be happy with 1.4 unless you have a good wallet and even then you would probably be better off buying 1.4's and spending the difference in good curtains, now where in part L do they talk about curtains... or the SEI??? Really anyone ever seen thermal imaging will know what I am talking about. Good luck OP and hope you are getting the info here to have a good crack at the builder when you need to

ardara1

blackiebest wrote: »

what about windows?? I hope to build to .15 U for walls using regular

4" on the flat with 200mm

Block on flat or or usual 0 there's no difference thermally - if you push your cavity to 200mm - what wall ties do need to pentrate theinsulation layer to hold the house together - have these been calculated? When you do get the walls to such good levels - how do you plan to reduce the thermal bridging at juction - the accredited details don't cover such U-values in walls & floors? You''ll end up with condensation at joints - and you'll not get an A rating without proper detailing.

outsulation (cellulose)

How do you blow blow cellulose on the out skin to create 'outsulation?

but the big question is always the windows, especially as they often are 30% wall space, they will always be the weakest element, no matter how much you spend. Very good is 1.4 U overall unit however 1U is possible. Less than that is really marketing blurb when safety glass etc is taken into consideration. But people bang on about U's in walls floors roofs etc... the weakest by far are the windows, I know as I am in the window business:) By sure to buy well. Be happy with 1.4 unless you have a good wallet and even then you would probably be better off buying 1.4's and spending the difference in good curtains,

now where in part L do they talk about curtains...

Yes the do - the DEAP assumes curtains and knoock abour 0.02 off the U-value

or the SEI??? Really anyone ever seen thermal imaging will know what I am talking about. Good luck OP and hope you are getting the info here to have a good crack at the builder when you need to

Before you go pushing wall thickness's out - think about detailing

ircoha

This job just started nearby: house to be valued at 2 mill

sunnystreet

bauderline wrote: »

Folks,

I have hired a BER Assessor to provide FULL insulation specifications for me backed up with the calculations that I can provide in black and white to my builder. Cost was 100 euro, I would say the best 100 euro I will ever spend !

He is also going to work with me during the course of construction to advise on the various options for heating, water, ventilation, air tightness with a view to attaining the best possible rating for the house on completion. That will cost around another 400 euro but will include the final cert.

If you are going to build your own house get a professional in to draw up a formal spec for insulation and your energy efficiency rating as this stuff is now way too important to leave to guesswork.....

Sorry for hijack... but worth saying....

baud.

Hi there, new to this but could you please pm me the details too. thanks a mil.

sunnystreet

bauderline wrote: »

Folks,

I have hired a BER Assessor to provide FULL insulation specifications for me backed up with the calculations that I can provide in black and white to my builder. Cost was 100 euro, I would say the best 100 euro I will ever spend !

He is also going to work with me during the course of construction to advise on the various options for heating, water, ventilation, air tightness with a view to attaining the best possible rating for the house on completion. That will cost around another 400 euro but will include the final cert.

If you are going to build your own house get a professional in to draw up a formal spec for insulation and your energy efficiency rating as this stuff is now way too important to leave to guesswork.....

Sorry for hijack... but worth saying....



baud.

NOt sure if I sent this already but could you please pm the details of the Assessor too. Thanks

cwboy

bauderline wrote: »

Folks,

I have hired a BER Assessor to provide FULL insulation specifications for me backed up with the calculations that I can provide in black and white to my builder. Cost was 100 euro, I would say the best 100 euro I will ever spend !

He is also going to work with me during the course of construction to advise on the various options for heating, water, ventilation, air tightness with a view to attaining the best possible rating for the house on completion. That will cost around another 400 euro but will include the final cert.

If you are going to build your own house get a professional in to draw up a formal spec for insulation and your energy efficiency rating as this stuff is now way too important to leave to guesswork.....

Sorry for hijack... but worth saying....

baud.

could you pm me too if you dont mind