Building control document and plaster requirement pls help

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omoeko

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Hi All,

First time poster.

I am trying to understand my building control document and the kind of extension that i am having, I gave my architects far too much control and I am at a position now where they have been paid and not really returning my calls.


Please see the picture below in terms of the specification of the external walls, its a side extension, and its such that it overhangs, as in not sitting on the existing downstairs blockwork.

I need to understand from a lay mans term the composition of the walls, when looking from outside to inside.

What I usually see is one skin of block work, void for insulation and then another skin of block work.

In one of my notes with the architect, he said Stud work + EML + Sand/Cement render
Capture.PNG
 
Last edited:
this is a timber frame construction. not blockwork.

but i wouldnt sand cement a timber frame .
i would investigate a aquapanel exterior renderboard and thincoat system.
internal looks fine.
 
Dansouthcoast84 said:
this is a timber frame construction. not blockwork.

but i wouldnt sand cement a timber frame .
i would investigate a aquapanel exterior renderboard and thincoat system.
internal looks fine.
Click to expand...

Architects love the "20 mm two coat S&C". It's probably the first thing they come to on their list of finishes with calculated u-values.
 
imago said:
Architects love the "20 mm two coat S&C". It's probably the first thing they come to on their list of finishes with calculated u-values.
Click to expand...
they still state 7mm skim sometimes or 9mm board. bloody copy and paste for amount they get paid.

atleast this one has remembered the air flow...
 
Dansouthcoast84 said:
they still state 7mm skim sometimes or 9mm board. bloody copy and paste for amount they get paid.

atleast this one has remembered the air flow...
Click to expand...

All I ever see is "20 mm two coat S&C" or "facing brick to match existing". As you say ctrl-C, ctrl-V.
 
Dansouthcoast84 said:
this is a timber frame construction. not blockwork.

but i wouldnt sand cement a timber frame .
i would investigate a aquapanel exterior renderboard and thincoat system.
internal looks fine.
Click to expand...

What is the reason for not sand cement a timber frame ? I was told this is some EML stuff
If the architect has already done the plans, and the building regs are all done as well. Can I still change it and tell him to use blocks ?
Does it also affect the structural calculations ? As this is currently underway.
 
omoeko said:
Hi All,

First time poster.

I am trying to understand my building control document and the kind of extension that i am having, I gave my architects far too much control and I am at a position now where they have been paid and not really returning my calls.


Please see the picture below in terms of the specification of the external walls, its a side extension, and its such that it overhangs, as in not sitting on the existing downstairs blockwork.

I need to understand from a lay mans term the composition of the walls, when looking from outside to inside.

What I usually see is one skin of block work, void for insulation and then another skin of block work.

In one of my notes with the architect, he said Stud work + EML + Sand/Cement render
View attachment 18724
Click to expand...

@Runswithscissors :D
 
omoeko said:
Thanks for all the responses.

Just another question, is the below what the architect has specified ?
View attachment 18726
Click to expand...


yes this is pretty much what he has spec.

timber moves. sand and cement doesnt and is very heavy in short.

if you change render to carrierboard and thincoat render this im pretty sure would be lighter than sand cement option so yoi shouldnt have any worries there.
 
omoeko said:
What is the reason for not sand cement a timber frame ? I was told this is some EML stuff
If the architect has already done the plans, and the building regs are all done as well. Can I still change it and tell him to use blocks ?
Does it also affect the structural calculations ? As this is currently underway.
Click to expand...

To change to block you'd need a new set of plans and they'd need to be resubmitted to building control. Yes, it would affect the structural calcs as they'd be based on a completely different structure.
 
Dansouthcoast84 said:
yes this is pretty much what he has spec.

timber moves. sand and cement doesnt and is very heavy in short.

if you change render to carrierboard and thincoat render this im pretty sure would be lighter than sand cement option so yoi shouldnt have any worries there.
Click to expand...

I thought the timber is the frame, and the sand cement is the final finish. So are you saying that in this design, the timber is the flaw here ?

If the render is changed to carrier board & thin coat, what will change in terms of the specification and what advantage does that give me ?

Is it also considerably more expensive, the objective of the project is a refurb + flip on so not a personal house.
 
your eml ,sand and cement render is behind the times. you need a Knauf aqua panel, cement board. it is labour saving and a good quality finish if fitted correctly.
 
malc said:
your eml ,sand and cement render is behind the times. you need a Knauf aqua panel, cement board. it is labour saving and a good quality finish if fitted correctly.
Click to expand...
We are getting somewhere now:bananahappy:
So what does the composition look like

outside visible to the eye = aqua panel + rendering
after that insulation board
then from the inside plasterboard or what ?

I also saw a house in the area, the render is now displaying like boxes with lines on it, so i am guessing this is something like aqua panel gone wrong, If done well, after rendering one should not even notice the join lines etc, this house looks like seeing a ceiling and where the plaster boards join up showing up, as in the lines etc. I will try and get a pic.
 
your build up will be the same.

insulated plasterboard internal
screwed direct to structual stud
insulation between stud.
plywood glued and screwed externally.

external will be.
breather membane.
vertical studs nailed to ply into structual studs.
creating a cavity for air flow
insect mesh wrapped around top and bottom openings to prevent vermin.
then instead of eml and sand cement.
screw 12mm aqua panel direct to your vertical studs.
leave 4mm gap between each board and fill with acrylic mastic.( this will help with the building movement).
finally a 6mm render basecoat with a silicone decorative topcoat.
ill post a pic of one we recently done
 
omoeko said:
We are getting somewhere now:bananahappy:
So what does the composition look like

outside visible to the eye = aqua panel + rendering
after that insulation board
then from the inside plasterboard or what ?

I also saw a house in the area, the render is now displaying like boxes with lines on it, so i am guessing this is something like aqua panel gone wrong, If done well, after rendering one should not even notice the join lines etc, this house looks like seeing a ceiling and where the plaster boards join up showing up, as in the lines etc. I will try and get a pic.
Click to expand...
Normally it's only plasterers that notice things like that
 
Hello Mate

The guys have been very honest about the perils of applying S&C to a timber frame

Please see within my signature links to the Knauf Aquapanel Exterior Brochure, that will show you best practice for applying a boarded render system to a timber frame. you have options as to applying various modern thin coat render basecoats, with then options for finish types and looks.....

Knauf Aquapanel Exterior is BBA Approved and therefore fully compliant with building regs, local building control and new build insurance

If you want more assistance, feel free to contact me directly for more information

Good Luck

Richard Lord
Knauf
Aquapanel Technical Manager
rlord@Knauf.co.uk
07918 766577
 
Tbh your architect is a clown as clearly not up to date on best practices & materials!

That's like a drawing from 1970s! & IMO you shouldn't be having to pay to get correct drawings using a thin coat render system he should correct it for free!
 
imago said:
"Contractor to check all dimensions on site." o_O
Click to expand...
Yeah....."I've drawn it like this, but if it can't be built like that ...............it's not my fault"..........."foundations 1m deep unless ground conditions dictate otherwise"............it's often "otherwise"
Saw one spec for "block and beam over a 150mm of hardcore with 100mm of concrete over that". - basically, block and beam over an Oversite........pfffttt
 
I called him yesterday and spoke about what you guys have said, he said we can use whatever as long as the surface is rendered.

He justified the timber frame with S/C by saying that was the cheapest/most cost effective way to achieve it. Sometimes it could just be lazy approach that causes them to copy & paste stuff, other times the cost difference between aquapanel & EML/Sand & Cement render is so negligible. In this case, I was not given the options cost/benefit etc. It was just a copy & paste from another job.

zombie said:
Tbh your architect is a clown as clearly not up to date on best practices & materials!

That's like a drawing from 1970s! & IMO you shouldn't be having to pay to get correct drawings using a thin coat render system he should correct it for free!
Click to expand...
 
This looks fantastic.
I really liked your explanation below.

insulated plasterboard internal
screwed direct to structual stud
insulation between stud.
plywood glued and screwed externally.

external will be.
breather membane.
vertical studs nailed to ply into structual studs.
creating a cavity for air flow
insect mesh wrapped around top and bottom openings to prevent vermin.
then instead of eml and sand cement.
screw 12mm aqua panel direct to your vertical studs.
leave 4mm gap between each board and fill with acrylic mastic.( this will help with the building movement).
finally a 6mm render basecoat with a silicone decorative topcoat.


I do have questions about the bolded areas.

Insect mesh, what is that called and can i see what it looks like ?
12mm aqua panel, is that similar to hardie backer board ?
Finally, I understand 6mm basecoat, I tried to google silicone decorative topcoat, I was confused. Is that a top coat whereby no need to paint ? It comes coloured already ?

If so, I want something that I can paint as I want to explore colours and have more freedom. Also, the decorative topcoat, is it similar to K-rend, I heard that any cracks in the house becomes an eyesore at it has a bould/gouge etc, does decorative silicone topcoat exhibit same behavior ?



Dansouthcoast84 said:
View attachment 18736
Click to expand...
 
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