Rendering details in TF

[darrenu]

Hi all, I am in the very early planning stages, trying to get land sorted for a build. 
 

however doing as much of a detailed costing as I can in my mind. I’m looking at getting an @off the shelf” 5* kit from Scotframe. on a passive slab. Going to build to passive standards - not sure about going for the certification though. 
 

my question is, if I go single skin with rendered outside, the render has to finish above DPC, how do I finish below that? 
 

also, render carrying board is more expensive than 50mm foam and mesh. Is there any reason I shouldn’t do it that way? 
 

would the insulation need to be on batons or direct to kit paper? 
 

thanks 

[recoveringbuilder]

So are you not intending to brick or block up the kit which is normal in Scotland?

[nod]

If you are intending to use the insulation as an outer layer Rather than brick or cement board 

BC would allow it 

First reason would be the insulation and fibre mesh are not strong enough without something behind them 
 

You can use a bellcast bead on top of the dpc render below or plant bricks slips 

[the_r_sole]

Just be careful with the scotframe kit details, I'd say you'll fall well short of passivhaus standard with their kit...

[ProDave]

Can you give more detail of what external insulation and cladding you are considering?

 

When I was looking, I had a discussion with Scotframe, and let slip that i was considering a standard timber kit and adding extra insulation and they ended the conversation, they were not happy with you altering the design.

[SuperJohnG]

My advice (slightly off topic) would be to look away from scotframe.  Its a circa 25% markup using them compared with others. Fleming homes (located in the borders) seemed to offer a very competitive price when compared to scotframe.  

 

As a background to the above... I'm located in Scotland and at the final stages just about to select a supplier for my kit currently between SIPS ECO (sips kit obviously) and fleming homes for their factory insulated TF kit. Either kit will be finished with render board and render mounted in batons to provide my external cover. I did weigh up block and render as that seemed more 'sturdy' but...it added cost to the insulated foundation for an extra ring beam..and I can't be doing with relying on brickies turning up and at ridiculous rates and having a messy wet trade. 

 

I'm aiming towards high levels of airtightness and insulation but not to passivhaus levels (budget driven). 

 

I'm also going for an insulated raft foundation semi DIY. Save yourself time and just look at Kores foundation system. Half the cost of others out there for me  such as isoquick and izodom.  

 

From under your render board down to cover your insulated foundation edge you would use cem-rock I believe. That's what kore says and shows on their wall buildup. See attached. Hope this helps

Kore IFS Standard Details Rev 4-TF_46.pdf

[darrenu]

10 hours ago, Christine Walker said:

So are you not intending to brick or block up the kit which is normal in Scotland?

 

I wasn't planning to, only because i had read on here that it wasn't required. I hadn't taken in to account geographical differences and whether it would be accepted or not. I will speak to my father in law who is a retired architectural technician and get his views. We haven't discussed it much with him yet as we are trying to source land first. And unfortunately despite what we have been told by the agent, the owner may not want to split up his land! 

 

 

9 hours ago, ProDave said:

Can you give more detail of what external insulation and cladding you are considering?

 

When I was looking, I had a discussion with Scotframe, and let slip that i was considering a standard timber kit and adding extra insulation and they ended the conversation, they were not happy with you altering the design.

 

 

Through my work i occasionally have dealings with a large cladding contract in council houses. They use a grey polystyrene product, they usually use 100mm then render on top but i am not sure i would need that with what is in the Kit already. Is there such a thing as too much insulation though? I have only had a couple of emails from scotframe, really about it, i liked what they offered in theory. I will learn more about the details and check things with them before proceeding. I also liked that they have a house design "off the shelf" which we liked and on paper could afford... However they don't erect so Vat payable (claimed back at the end) The kit we liked was Scotframe forth

 

I would want the kit erected and then do everything else myself, we have just completed a large extension at home and did the same thing, so i know what i would be letting myself in for except on a much larger scale. 

 

There are another couple of things that people have commented on and i will comment myself later, but splitting childcare while we both work from home, so i am about to go and play with a Thomas the tank train set...

 

Thanks

[ProDave]

What frame make up are they proposing? What sort of wall and roof U values?

[darrenu]

15 minutes ago, ProDave said:

What frame make up are they proposing? What sort of wall and roof U values?

 

Thermal kit specs  i was going to go for 5 star kit. 
 

[ProDave]

4 minutes ago, darrenu said:

 

Thermal kit specs  i was going to go for 5 star kit. 
 

That looks pretty good, my point of enquring was to show you don't need extra insulation on the outside, just suitable render board and render.

 

the one thing I would do yourself is line the inside with an air tightness membrane. I see no mention in Scotrames blurb about any air tightness expectations.

[the_r_sole]

34 minutes ago, ProDave said:

That looks pretty good, my point of enquring was to show you don't need extra insulation on the outside, just suitable render board and render.

 

the one thing I would do yourself is line the inside with an air tightness membrane. I see no mention in Scotrames blurb about any air tightness expectations.

 

they only give you the air tightness info after you've paid their deposit - I had to sign a NDA to get it to pass on to a sap assessor!!

 

The window reveal details are awful with Scotframe, they are very resistant to put insulation around the inner reveal (even though it's usually required by building control!)

[ProDave]

It's easy and not expensive to fit an air tightness layer before the service void battens go on.

 

With the house design you have chosen does it actually have a loft space? or is it a warm roof with the room ceilings following the roof slope?

 

A warm roof is imho a far better detail is so many respects.

[the_r_sole]

13 hours ago, SuperJohnG said:

Either kit will be finished with render board and render mounted in batons to provide my external cover. I did weigh up block and render as that seemed more 'sturdy' but...it added cost to the insulated foundation for an extra ring beam..and I can't be doing with relying on brickies turning up and at ridiculous rates and having a messy wet trade. 

 

 

 

you just have to be very careful with this approach, really millions of fixings and movement joints etc otherwise you'll get cracking in the render as the timber frame settles 

[MarkW1979]

On 26/06/2020 at 00:53, SuperJohnG said:

Either kit will be finished with render board and render mounted in batons to provide my external cover. I did weigh up block and render as that seemed more 'sturdy' but...it added cost to the insulated foundation for an extra ring beam..and I can't be doing with relying on brickies turning up and at ridiculous rates and having a messy wet trade.

 

Hi SuperJohnG,

 

Who/what did you use for your render board system? For our build I had originally decided on blocks and render but for some of the reasons you describe I am now considering a render board system. I have heard that some lenders are funny about "non-traditional" systems, did you have any issues? My build is in Scotland also (West Lothian) and I am currently looking for good local tradesmen.

 

Thanks in advance,

 

Mark

[SuperJohnG]

11 hours ago, MarkW1979 said:

 

Hi SuperJohnG,

 

Who/what did you use for your render board system? For our build I had originally decided on blocks and render but for some of the reasons you describe I am now considering a render board system. I have heard that some lenders are funny about "non-traditional" systems, did you have any issues? My build is in Scotland also (West Lothian) and I am currently looking for good local tradesmen.

 

Thanks in advance,

 

Mark

Hi Mark, I used K rend system which is TC15 a thin coat silicone render system finished in limestone white. 

 

I put it on knauff aquapanel boards and used the proper screws and everything, my joiners done a brilliant job mounting the boards to mm perfect which helped and I used a k rend  recommended applicator. Albeit there are 15 in Scotland they would only recommend  2 in scotland. 

 

Simon from SJT plastering in Glasgow and Barrie Morrison from over your way, both do a great job and if you go k rend I'd stump the extra cash and use Barrie as your in West Lothian. You won't regret using a really good applicator. 

[MarkW1979]

Thanks John, that is really very helpful. Do you know what it came in at per m2?

 

 

[SuperJohnG]

33 minutes ago, MarkW1979 said:

Thanks John, that is really very helpful. Do you know what it came in at per m2?

 

 

50m2 labour only. 25m2 for the materials. So 75m2 all in. 

 

I did get quotes for supply and fit for 50m2 whose work was good but weren't fully approved and I wanted the warranty