From Newsgroup: uk.d-i-y

Could someone kindly point me to a chart giving worked examples of using exterior foam insulation materials?

I have skimmed through John's house cladding job in the Wiki.

The tenancy of my old pig fattening shed (now Robot Centre!) has changed
to the Son on a new agreement. I suspect this will alert the local
authority and trigger interest in current E values:-(

Solid floor, single story, rendered blockwork walls, double skin steel
roof including 100mm foam insulation. Too many wall mounted fittings to consider internal work.

Gutter overhang not huge but I might get 100mm on, finished with feather
edge boarding to match neighbouring structures.

An upside is that the introduced internal moisture is limited to
breathing and their kettle:-)

Tim
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

Timatmarford <tim@marford.uk.com> wrote:

Could someone kindly point me to a chart giving worked examples of using exterior foam insulation materials?

I don't have a chart, but
https://www.ubakus.de/en/r-value-calculator/

allows you to experiment with different material stackups and tells you the
U values as well as condensation, drying time, heat capacity and heat
transfer delay.

Use it in demo mode unless you want to save the results, or want access to branded materials. The standard materials are a bit lacking in places - eg
use PUR instead of PIR board.

Solid floor, single story, rendered blockwork walls, double skin steel
roof including 100mm foam insulation. Too many wall mounted fittings to consider internal work.

Gutter overhang not huge but I might get 100mm on, finished with feather edge boarding to match neighbouring structures.

An upside is that the introduced internal moisture is limited to
breathing and their kettle:-)

The key to getting something good is in the detailing. It's easy to forget about how eg walls and roof interface, which can lead to poor performance
like draughts or cold bridges. Also you need to ensure that there is sufficient drying potential, otherwise you may have moisture retention and eventually rot.

Theo
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 15/09/2026 22:41, Theo wrote:

Timatmarford <tim@marford.uk.com> wrote:

Could someone kindly point me to a chart giving worked examples of using
exterior foam insulation materials?

I don't have a chart, but
https://www.ubakus.de/en/r-value-calculator/

allows you to experiment with different material stackups and tells you the
U values as well as condensation, drying time, heat capacity and heat transfer delay.

Use it in demo mode unless you want to save the results, or want access to branded materials. The standard materials are a bit lacking in places - eg use PUR instead of PIR board.

Solid floor, single story, rendered blockwork walls, double skin steel
roof including 100mm foam insulation. Too many wall mounted fittings to
consider internal work.

Gutter overhang not huge but I might get 100mm on, finished with feather
edge boarding to match neighbouring structures.

An upside is that the introduced internal moisture is limited to
breathing and their kettle:-)

The key to getting something good is in the detailing. It's easy to forget about how eg walls and roof interface, which can lead to poor performance like draughts or cold bridges. Also you need to ensure that there is sufficient drying potential, otherwise you may have moisture retention and eventually rot.

OK Theo. I'll have a look. The building occupation is sporadic in that
the bulk space is rarely occupied: with fan heaters used for the office
areas and the remainder storage. Sadly I doubt District Council E value consultants will accept that.

Tim

--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 15/09/2026 18:12, Timatmarford wrote:

Could someone kindly point me to a chart giving worked examples of using exterior foam insulation materials?

I have skimmed through John's house cladding job in the Wiki.

The tenancy of my old pig fattening shed (now Robot Centre!) has changed
to the Son on a new agreement. I suspect this will alert the local
authority and trigger interest in current E values:-(

Worth noting that the introduction of tightened EPC rules on rented accommodation have been delayed to Oct 2030 now.

Solid floor, single story, rendered blockwork walls, double skin steel
roof including 100mm foam insulation. Too many wall mounted fittings to consider internal work.

Gutter overhang not huge but I might get 100mm on, finished with feather edge boarding to match neighbouring structures.

An upside is that the introduced internal moisture is limited to
breathing and their kettle:-)

There are some figures and typical u/k values here:

https://wiki.diyfaq.org.uk/index.php?title=Heat_loss

For retrofit internal or external wall insulation, you are looking for
0.30 W/m^2K or better. (there is an exception that allows that to rise
to 0.7 W/m^2K in worst case situations where you can't feasibly hit the preferred target). [1]

Not sure what type of block you have (a heavy concrete one has *very*
poor insulating properties - and a thermal block not bad), but if you
can get at least 80 mm of PIR foam on top, then it does not matter much
since the insulation alone will meet the target.


[1] See table 4.3 https://assets.publishing.service.gov.uk/media/662a2e3e55e1582b6ca7e592/Approved_Document_L__Conservation_of_fuel_and_power__Volume_1_Dwellings__2021_edition_incorporating_2023_amendments.pdf

(I probably aught to add that to the wiki page)
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk | \=================================================================/
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 16/09/2026 13:00, John Rumm wrote:

On 15/09/2026 18:12, Timatmarford wrote:

Could someone kindly point me to a chart giving worked examples of
using exterior foam insulation materials?

I have skimmed through John's house cladding job in the Wiki.

The tenancy of my old pig fattening shed (now Robot Centre!) has
changed to the Son on a new agreement. I suspect this will alert the
local authority and trigger interest in current E values:-(

Worth noting that the introduction of tightened EPC rules on rented accommodation have been delayed to Oct 2030 now.

Would that apply to a commercial workshop?>

Solid floor, single story, rendered blockwork walls, double skin steel
roof including 100mm foam insulation. Too many wall mounted fittings
to consider internal work.

Gutter overhang not huge but I might get 100mm on, finished with
feather edge boarding to match neighbouring structures.

An upside is that the introduced internal moisture is limited to
breathing and their kettle:-)

There are some figures and typical u/k values here:

https://wiki.diyfaq.org.uk/index.php?title=Heat_loss

For retrofit internal or external wall insulation, you are looking for
0.30 W/m^2K or better. (there is an exception that allows that to rise
to 0.7 W/m^2K in worst case situations where you can't feasibly hit the preferred target). [1]

Not sure what type of block you have (a heavy concrete one has *very*
poor insulating properties - and a thermal block not bad), but if you
can get at least 80 mm of PIR foam on top, then it does not matter much since the insulation alone will meet the target.

Hmm. Cheapest possible blocks available in 1960! Certainly concrete and unlikely to have thermal voids.>

[1] See table 4.3 https://assets.publishing.service.gov.uk/media/662a2e3e55e1582b6ca7e592/ Approved_Document_L__Conservation_of_fuel_and_power__Volume_1_Dwellings__2021_edition_incorporating_2023_amendments.pdf

My brain hurts. They seem pretty adamant about using professional
designers.>

(I probably aught to add that to the wiki page)

Thanks John. I should have looked more closely before bleating for help!>

--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 16/09/2026 20:50, Timatmarford wrote:

On 16/09/2026 13:00, John Rumm wrote:

On 15/09/2026 18:12, Timatmarford wrote:

Could someone kindly point me to a chart giving worked examples of
using exterior foam insulation materials?

I have skimmed through John's house cladding job in the Wiki.

The tenancy of my old pig fattening shed (now Robot Centre!) has
changed to the Son on a new agreement. I suspect this will alert the
local authority and trigger interest in current E values:-(

Worth noting that the introduction of tightened EPC rules on rented
accommodation have been delayed to Oct 2030 now.

Would that apply to a commercial workshop?>

From a quick search, the rules for letting commercial space are
different (and also depend on the size of the property). I believe you
need a EPC grade E or better at the mo. There is an exemption that can
be applied for that allows F & G rated building to be let if you can demonstrate the payback on the cost of insulation is longer than 7 years.

Solid floor, single story, rendered blockwork walls, double skin
steel roof including 100mm foam insulation. Too many wall mounted
fittings to consider internal work.

Gutter overhang not huge but I might get 100mm on, finished with
feather edge boarding to match neighbouring structures.

An upside is that the introduced internal moisture is limited to
breathing and their kettle:-)

There are some figures and typical u/k values here:

https://wiki.diyfaq.org.uk/index.php?title=Heat_loss

For retrofit internal or external wall insulation, you are looking for
0.30 W/m^2K or better. (there is an exception that allows that to rise
to 0.7 W/m^2K in worst case situations where you can't feasibly hit
the preferred target). [1]

Not sure what type of block you have (a heavy concrete one has *very*
poor insulating properties - and a thermal block not bad), but if you
can get at least 80 mm of PIR foam on top, then it does not matter
much since the insulation alone will meet the target.

Hmm. Cheapest possible blocks available in 1960! Certainly concrete and unlikely to have thermal voids.>

Cinder block was common then... probably comparable to a modern medium strength block (thermals a bit better than protected brick)

[1] See table 4.3
https://assets.publishing.service.gov.uk/
media/662a2e3e55e1582b6ca7e592/
Approved_Document_L__Conservation_of_fuel_and_power__Volume_1_Dwellings__2021_edition_incorporating_2023_amendments.pdf

My brain hurts. They seem pretty adamant about using professional designers.>

Yeah, I skip over those bits :-)

(I probably aught to add that to the wiki page)

(I did add another section about "how much" insulation to use)

Thanks John. I should have looked more closely before bleating for help!>

Its good to talk as they say :-)
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk | \=================================================================/
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 15/09/2026 18:12, Timatmarford wrote:

Could someone kindly point me to a chart giving worked examples of using exterior foam insulation materials?

FYI I have also added a section to the heat loss article to include
notes on calcs using Surface Thermal Resistance figures...

https://wiki.diyfaq.org.uk/index.php?title=Heat_loss#Accounting_for_surface_thermal_resistance

(seemed like it might help clarify why Hugo's example calculation
includes them)
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk | \=================================================================/
--- Synchronet 3.22a-Linux NewsLink 1.2