Insulation and u value

[charly]

hello just stumbled across this forum whilst looking for some information about u value and what insulation and fixings for stone walls .Is there anyone that can help me understand what i actually need to put on the walls please ? noone seems to be able to advise me and i am going round in circles Thanks in advance

 

[hotrod]

Hi Charly the required U-values and insulation methods/fixings will be dependant on a number of factors. So,

1. Is this a new build or refurb?
2. Are you going through Building Control for Building Regulations compliance?
3. Are you wanting to install the insulation in the cavity or to the internal walls of the dwelling?
4. Can you confirm the existing wall construction (e.g. 12" solid stone - no cavity)?

 

[charly]

Hi Charly the required U-values and insulation methods/fixings will be dependant on a number of factors. So,

1. Is this a new build or refurb?
2. Are you going through Building Control for Building Regulations compliance?
3. Are you wanting to install the insulation in the cavity or to the internal walls of the dwelling?
4. Can you confirm the existing wall construction (e.g. 12" solid stone - no cavity)?

Hi thanks for reply
it is a refurb, going thru building regs, insulation is for internal walls on external walls if you know what i mean and is about 16 inch solid stone .
was hoping to battern out walls as have 3x2 wood already but not sure if this possible ??

 

[stuart45]

Google Energy Saving Trust Primer.

 

[hotrod]

it is a refurb, going thru building regs, insulation is for internal walls on external walls if you know what i mean and is about 16 inch solid stone .

Required U-value for your walls to satisfy BRegs is 0.3W/m²K. To achieve this with 16"stone walls you're best using a PUR type board (Celotex / Kingspan). You will need to install a minimum thickness of 50mm insulation so your plan to stud out with 3"x2" should provide the required depth - just (watch you don't get undersized scant ).

You will need confirmation this is acceptable from LABC so run it past Building Control first.

hth

 

[charly]

Thanks very much i shall enquire at builders yard tomorrow about PUR type board and get some prices

 

[mikric]

http://www.celotex.co.uk/Other-Resources/U-value-Calculator
Good tool for calcs

 

[charly]

Thanks for that link i just had a look but i will have to do tomorrow , trouble is i trying to do this work on my own and it all a bit over my head sometimes

 

[AndrewSchofield]

undersized scant

At last, another soul calls it scant!! When the joiner fitted our stairs last year he turned to me and asked if i had a bit of 'scant' he could use. I looked at him like he was talking a foreign language until he explained what he meant. I've asked around and no-one else had heard of 'scant' either, until now!!

Just going back to the celotex u-value calculator, if that still leaves you a bit puzzled charly, then give celotex a call or e-mail them with the details of your wall and the u-value you're trying to acheive - the technical helpline is fantastic and should be able to tell you exactly what you need and i've always had a response to e-mail enquiries within 24hrs. They'll also provide you with a u-value calc you can submit to BC to support your application.

 

[mointainwalker]

@ hotrod

I don't understand your sugestion of 50 mm PUR to meet a U of 0.3 as this on its own will give you U 0.5.

Are you guessing at the the U (or R ) of the stone wall and including it and if so, what is this based on ?

 

[legs-akimbo]

Default U value for stone walls as yours is 2.1.
If you use this as your starting point for whatever method you employ to insulate.
Any questions e mail me at xxxxxxxxxxxxxxxxxx

 

[hotrod]

@ hotrod

I don't understand your sugestion of 50 mm PUR to meet a U of 0.3 as this on its own will give you U 0.5.

Are you guessing at the the U (or R ) of the stone wall and including it and if so, what is this based on ?

Hi mointainwalker, when I made that statement I said the minimum the O/P would have to use would be 50mm PUR to achieve 0.3W/m²K. He hasn't listed his external finish so it would be impossible to confirm either way. That said, a quick check on Celotex's U-value calculator confirms that
400mm stone
50mm GA3000
Plasterboard Int finish (No Ext finish)
=0.31W/m²K

But as said above by myself and others the O/P needs to run his plans past LABC and Celotex (or whichever manufacturer) and make sure they are happy with the given U-values and application.

 

[jeds]

Charly, for renovated retained walls you need to achieve a U-value of 0.35W/m²K. My standard spec for stone walls is 50mm Lafarge 'Thermalcheck K' laminate board. This takes up the minimum space and is pre-finished with plasterboard. It's also very easy to fix and reasonably priced. The U-value is 0.33 on a 300mm wall so you will get about the same on your walls.

Note; the spec must be for 'K' board. Lafarge also do a standard and XP boards but these are lower performance so would not meet the U-value.

 

[charly]

Thanks everyone for taking the time to reply it is all a bit clearer now am hoping that my batterns will not have to be too big to cover wonky walls and do not take up too much of my room space I will let you know how i get on

 

[charly]

Right well i hope i have got this right have today ordered 37 8x4 sheets of Kingspan/celotex insulation TP10 60 mm . builder has had to batten out with 3x2 wood to get around wonky walls and then be covered with plaster board .